Dyno print out from New Zealand

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Dyno print out from New Zealand

Postby pre65racer » Mon Sep 29, 2008 1:35 am

:D Hello

I've just joined up and thought I'd log some engine details from my latest dyno. Unfortunately the site will not except XSL files but I've uploaded a PDF. In short I've got 86.16 ft lbs at 6000 and 6500 RPM and 120.8 BHP (Gross SAE corrected) at 8500 RPM

There are a few of us who are very active in racing in NZ and we are still very active in developing the engines.

This 1040cc engine with .410 cam with 2 degrees cam advance runs on 98 unleaded at 30 degrees spark advance produces significantly more and flatter foot lbs and horsepower between 5000 and 7000 rpm on the same dyno than the almost identical wedge head with .385 cam running on 100 Octane

Significantly the BMEP is up there at 205 psi. Difficult to compare different dynos etc but happy to share ideas particularly on how to improve the spread of BMEP across the rev range.

Happy racing
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410Vs385 Wedge Head.pdf
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p65_D156018_Perry.jpg
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Re: Dyno print out from New Zealand

Postby ImpManiac » Mon Sep 29, 2008 9:06 am

Hi and welcome to the forum! 8)

Is that your car in the photo? It's rather nice, whoever it belongs to!

Over 120 bhp from 1040cc, eh? Not too shabby at all! Have you got any video of the engine on the dyno? Bet it sounds good...

So which series do you compete in? Any web links?

EDIT - Mr. Bayliss? Is that you? :?:

IM 8)
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Re: Dyno print out from New Zealand

Postby pre65racer » Mon Sep 29, 2008 6:48 pm

Hi & thanks

I did get about three seconds of video of the engine - headers cherry red - before the electrics cooked the hard drive of my camera. I did get some pictures though which I will post. The engine note is quite rough, a bit like a BDA, it really sounds aggressive when its working hard.

In New Zealand there is the usual classic racing pretty much along FIA lines but I compete in Pre 65 which has a North and South Island series. We run pretty much full on race cars, no slicks and no LSD's, so long as it was pre65 its legal (or so long as you don't get caught). Check out these sites.

http://www.pre65.org.nz &
http://www.pre65racing.co.nz

I have to say mine is not the quickest Imp (yet) in new Zealand but we could hold our own against pretty much anything similar in the UK. I grew up in Coventry, used to teach in Stratford (hello to the Sozanski's) many years ago now and I'm not Brian Bayliss - mind you he does have some nice Imps.
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Re: Dyno print out from New Zealand

Postby ImpManiac » Mon Sep 29, 2008 7:10 pm

I don't doubt that your car could hold its own against UK Historic racers. There is a lot of engineering experience down under too! :P

Your car looks spot on to me. I am about to explore the websites you linked to.

My 930cc Sunbeam motor does not sound classically like an Imp, I'd say. It does in some ways but it sounds much bigger than 930cc to my ears. I love the sound my car makes! :wink:

IM 8)
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Re: Dyno print out from New Zealand

Postby rootes » Tue Sep 30, 2008 9:04 am

ImpManiac wrote:
My 930cc Sunbeam motor does not sound classically like an Imp, I'd say.
IM 8)



thats because it needs tuning! did you ever balance those carbs?
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Re: Dyno print out from New Zealand

Postby ImpManiac » Tue Sep 30, 2008 9:52 am

^^ No, not yet, Si. I still haven't touched the engine, apart from changing the ignition coil and setting the ignition timing. It's on "the list!" :D

The torque and power curves seem flatter and more 'driveable' to me using the .410 camshaft. Makes for quite a nice engine, it seems. What is the valve timing like? Any idea? :?:

IM 8)
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Re: Dyno print out from New Zealand

Postby ChrisBenoy » Tue Sep 30, 2008 10:16 am

Thats a pretty interesting comparison. I like looking at all these different setups and the types of power they produce.
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Re: Dyno print out from New Zealand

Postby limjamrace » Tue Sep 30, 2008 10:58 am

Hey Paul,
I thought that you had tuned your Webers or whatever before that trackday!
When you get home tonight. Just stick a rubber hose about 1 dia in one of the intake trumpets...Then the next...and so on...Usually the pairs should sound the same hiisuuing sound with a background deft clunk of the valve resonnating....If the other pair sound different then they need balancing by twiddling the connecting screw/clamp.
This will only result in the engine sounding the way it should with instant pickup.
Opening the throttle causes an increasing inbalance which gets worse(flat) as you progress.

It's not untill the carbs are in line and ignition thereabouts can you make an impression on camshafts!

Generally the Imp engine seems to increase its performance like no other regarding only a small amount of engine size ...Must be the design :P Hence theoretically speaking the bigger the engine the milder(?) the cam gets.
Thanks to our Kiwi friend we can see that the 385 lift cam is as good as a 410 lift..
I have always thought that the higher lift cams (more than 350/360)are superior to the usual- but not that much!
Of course dynos are not to be compaired with any other..Its just a measuring device to tune a particulate unit..Taking it out to another might show 110 bhp..But flippin heck 123bhp is mindblowing to me...
We are of course talking about competition here and anyone thinking of this sort of thing for road use will be disappointed in overall ability-as we all know..
Power to weight ratio will have a lot to do with cam flexibility too!
A steel bodied Imp will struggle more with a ( for your example) R21 than a lighter weight car(Clan Dav Gin).
Having said that HGH went better on it's previous engine(mine)with a DSL2 reprofiled camshaft instead of a R20.. This might be because of it was a reprofiled from a R23 and as such was new(!!) instead of a used (worn) R20..If you see what i mean!
For your use Paul with the 930 cc engine i would try a knackerd 360 lift cam reprofiled to a bp285 specification...
Bob Hoare is so impressed with an Imp sport camshaft reprofiled to bp285 on his(ur-hum ..originally built by me)1070cc with twin webers! This is equipted to a heavy historic rally car!

Sorry to hijack your thread somewhat Mr Kiwi newcomer ,but it seems Paul is having orgasms over talk of massive outputs and talk of 1040cc ,and forced injection!
Like has been said ...Best if you concentrate on fixing your roof first - winters coming on! :)
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Re: Dyno print out from New Zealand

Postby ImpManiac » Tue Sep 30, 2008 11:12 am

Cheers, Dave. :D To relate what you've been saying to the original thread, it is important how an engine delivers its power rather than simply how much power it delivers. Delivery is what makes a car fun to drive!

It may be that I need to experiment with different camshafts with my engine setup. I have high hopes that, once the carbs are dialled in really well and the EDIS is up and running, it will be nice and driveable, even on the road. It is not too bad right now, considering it is mainly a competition car. It pulls from low revs (say 2000rpm) right through to 9000rpm, with only one notable flat spot just before the engine comes on cam at about 3200rpm (fuel stand-off due to resonant effects in inlet tracts).

I shall give it a proper tune-up and service. I just don't seem to get the time these days! :roll:

:idea: Back to topic... :wink: What is the general setup of your engine, Mr. pre65racer? 1040cc, I notice. Weber DCOEs or Dell'orto DHLAs? :?: Jetting?

IM 8)
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Re: Dyno print out from New Zealand

Postby StuartC » Tue Sep 30, 2008 11:46 am

Just to clarify: pre65racer, are you saying the engine with 410 has 'normal' head and engine with 385 has wedge head, both being 1040cc? How similar are the carb setups?

Thanks for posting the graph by the way - most interesting.

As an aside the used 410 cam on ebay sold for just over £220 earlier today.....
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Re: Dyno print out from New Zealand

Postby Englander » Tue Sep 30, 2008 12:15 pm

Hi Pre65,

Nice sites and racing down there, also some very nice Imps.

Your curves are quite surprising and I guess thats why you posted them - it would have been nice to have a Air/Fuel curve in there to see if that is causing any of the un-expected behavior. I assume they are both running identical carbs and ignition systems and that the cam profiles are similar.....The 385 curve looks fine, its just when you put the 410 curve in you want more of that torque/BMEP peak everywhere. How did you get your figures for the optimum ignition ? Where they detonation limited, or did the power just go off ?

What have you tried up till now ? did you already experiment with the cam timing ?

As Stuart said - nice post - Thanks

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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Sep 30, 2008 7:07 pm

Thanks for the interest

Just to clarify the wedge head is an Andy Chessman 1.38 inlet 1.21 exhaust GE3 head and was also 1040cc it runs webers while the "normal" head done here in NZ has 1.40 inlets and standard sport exhaust valves and runs dellortos - same chokes on both and roughly the same jetting - the normal GE5 requiring a half size smaller at 1.25 with 1.60 air correctors.

Not really a back to back fair comparision because of the variables like fuel, value sizes, etc the wedge head having 1.38 inlets and larger exhaust but the extra foot lbs from 5000 RPM are what makes the GE5 worth while. Both cams are timined in with split timing right down the middle so we still have work to do advancing or retarding the cam, by the way Imperwerks in NZ have developed a nice alloy adjustable cam sprocket to make this job easy on the dyno without taking the sprocket off.

The cam doctor came back showing that the GE5 has lobe seperation angle of 106 and the GE3 of 107 degrees. The key thing about the GE5 is the shorter duration, you would normally expect this to be a milder cam but it provides the better spread. As far as the ignition goes the big difference was Nology leads and a petronix distributor. This set up was back to back on the dyno and gave 2ftlbs and 2 bhp right across the rev range. See is believing! We backed the ingnition off from 32 degrees as far as we could without loosing tourque or power, since I'm using 98 Octane raod fuel not 100 race fuel we felt this would do no harm.

This engine you could drive on the road if you where mad enough, its pretty much like an R20 low down. I've heard of people using GE5's as rally cams and I now understand why.
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Re: Dyno print out from New Zealand

Postby pre65racer » Thu Oct 16, 2008 6:58 pm

Just to add to this string. Took the car out with the new engine and while I managed to go as fast as I've ever gone I had fueling problems at 6000 rpm - major problems comming out of corners.

One thing that a dyno does not test is the dynamic set up of the engine in the car and fuel pressures etc. Turns out the needle valves where worn and I'm flooding. Older dynos are gravity fed so you don't see this issue.

Anyway next race is this weekend.
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Re: Dyno print out from New Zealand

Postby AlastairC » Thu Oct 16, 2008 11:29 pm

Hi great to see another Imper in New Zealand. Brian Bradshaw sent me some pictures of your car the other day - very nice!
I have a pretty much standard mk 1 which I am tidying up/upgradeing abit. How's your supply of parts ? I'm quietly keeping my ear to the ground for something more exciting engine wise than the standard 875 my Imp has got in it at the moment. a second hand 998 or 930 or a sport 875 would be great if you know of anyone like that floating around.
Good luck with the racing!
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Re: Dyno print out from New Zealand

Postby pre65racer » Thu Oct 16, 2008 11:43 pm

Brian has a ton of stuff standard and competition. Everyone else pretty much sits on what they have as it is getting harder to find.

I'm assuming you have a MKI engine with the curly block?.

An easy perfromance upgrade is to replace with a 930 block and sport head or one of Brian's spec MKII heads. Brian can do all this for you. Not cheap but good reliable power increase.

Otherwise you really have to keep your ears and eyes open. There was a complete 930 Talbot Sunbeam engine for sale on trade me not so long ago which could have provided the block. I think this went to Chris Hay in Auckland.

Stay in touch however as I may be geting rid of some sport stuff - I've got too many race engines, I've even put one in the road car!
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Re: Dyno print out from New Zealand

Postby AlastairC » Fri Oct 17, 2008 12:12 am

Hi
Yes my car has the original motor - my options are I think; hope that a 998 or 930 turns up from somewhere or else go for the mk2 head and all the sport bits for the motor I have. Ideally I would like 930 with webbers etc (wouldn't we all) but think that a Impwerks mk2 head etc is probably more realistic - bank balance being what it is.
Brian bradshaw certainly makes Imping in NZ a whole lot easier - have known him for many years and he does such great work and is so passionate about all thing Imp!\
cheers
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Re: Dyno print out from New Zealand

Postby pre65racer » Fri Oct 17, 2008 12:23 am

Agreed his enthusiasm is great.

As it happens I have just such an engine just sitting on the bench - 930cc, enlarged sump, sport cam, comp distributor, alloy pulleys, Brian's spec head (sport plus 10%), small bore Janspeed with twin webers. Not as ecconomical as a standard engine but great round town and good for 6500rpm in top gear.

Looks great in the engine bay.

Can't make up my mind whether to keep it for spares as 930 blocks are rare in NZ, as I say stay in touch.
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Re: Dyno print out from New Zealand

Postby SimonBenoy » Fri Oct 17, 2008 8:59 pm

I suspect that the reason that the 410 engine drops away at higher revs might be the standard exhaust valves - normally you would have 1.125 with 1.4 inlets, but the 1.38, 1.21 combination is well regarded by our race engine builders.

This comparison would be enhanced if you could repeat it with the cams swapped over!!

We expect about 105-110 bhp at 998/1040 and around 120 for an 1120 but these figures are only really estimates. What really counts are the lap times....
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Re: Dyno print out from New Zealand

Postby limjamrace » Sat Oct 18, 2008 7:55 am

Hello Kiwi Imp man(havn't caught your name yet!),
Noticed in the background of your lovely photo a brace of what look like Fiat 850 Abarth's.
I am told that to be competitive(or really my reckoning)they need a A112 engine which is 1070cc together with an imported head from USA(eight port).
This is said to produce an easy 100bhp...Still removed from what can be obtained with an Imp engine...I supposed really i should visit a HSCC round and chat to Fiat competitiors,but i would be interested in your New Zealand version of affairs!
I have a Fiat 850 sport coupe to which i would like to compete with as well as my Imp...Although the 903cc stock engine doesn't hold anything to an Imp unit.
yours David L.
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Re: Dyno print out from New Zealand

Postby benwick3 » Sat Oct 18, 2008 2:13 pm

David,

No need to go to America for Fiat parts as they are all available in Europe, particularly Germany. The series I race with in turn races with an Abarth series and their cars are fantastic. I hate to admit it but some of the 998's are tremendous and I struggle to keep with them. They have the advantage, in my opinion, that all performance parts are available new including crossflow heads. Put Abarth Coppa Milla in google and sit back and enjoy the results.

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Re: Dyno print out from New Zealand

Postby limjamrace » Sun Oct 19, 2008 10:09 am

Yep..Thanks for that Pete..Uncle Ted gave me a massive book one Christmas all about Abarths by a Luciano Greggio.Since then it has been a refreshing re-life from Imp involvement for decades..
Recently a Rory Cole who has masses of 850 sport experience lives down in Sussex sent information and exciting details so i am getting closer to an idea about a power plant and transmission. The standard transmission seems feeble ,again compaired to an Imp transaxle.
I was thinking of using the Imp Stuff i have ,but it doesn't seem right somehow!
When i first obtained the car a replica of 1600cc twin cam as Abarth 1600cc version was on the cards..I have an adaptor for a Fiat twin cam engine to VW transaxle already(not exactly how Carlo did it though).
Will have to do some(lots) more research before i take to the hills as i dont want to be plonked in the special/libre class!
Anyhow HGH is being revamped in earnest at present so the Fiat 850 sport can be ponderered over for a few weeks.
Hopefully my Son will get his employment scene sorted so he can join me in the HSA local rounds .
The days of forking out bundles of money on Karting are now finished!
As for myself i need to get focused on one car(or two)...as having an Imp,Triumph TR6,Fiat 850 Sport Coupe,and my late Fathers Mk 1 Cortina around is not good for ones state of mind!

Getting back to topic ...From what you are competing against in Germany seems to be rather exotic and probably out of my pocket . They must be something special to be as or faster than your Clan!..Still my research will reveal i'm sure..I am hoping Pre 65 racer has something to add to what is available over there..Or maybe Englander knows something more on the European scene!
David L.
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Re: Dyno print out from New Zealand

Postby Englander » Mon Oct 20, 2008 9:38 am

Just a quick answer for Dave (not wanting to take this off topic !)

Pete knows the guys in the Abarth series better as he is racing against them - they are very friendly - get accross to one of the meetings you will find out more there than a year on internet ! Best Meeting is Nurburgring in June as everyone wants to do that one, but there will always be some people to talk to. The 3 series that race together (Abarth, NSU and Minis) all have a few top cars which fight it out for overall honours, I hope Pete does not mind me saying that when everyone is there (or should that be when I am there !) he is racing with the second group for places from about 6th to 10th. The top 2 or 3 Abarths are very well prepared, seem to be very light and are well driven, these are the cars Pete is talking about, the rest he generally beats....plus all but the best 1300 Minis and NSUs !

Simons idea of the cam swap for comparison is of course the simplist answer, if you have enough piston - value cleance in the GE3 engine.... wouldn't it be nice to have a dynomometer in the garage, then we could have the answer to that one tomorrow, latest at the weekend !

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Re: Dyno print out from New Zealand

Postby benwick3 » Mon Oct 20, 2008 10:56 am

Kevin,

No offence but I'm getting there. Only 1 Abarth and 1 NSU in front of me at Hockenheim. Still those pesky 1300 Mini's but I even finished ahead of all but 4 of them as well. All achieved whilst needing to hold it in 3rd gear. Must have been luck generated by placing a posy of wild flowers on the Jim Clark Memorial.

Finally sorted a fully working transaxle for Nurburgring in a couple of weeks. That's the third one fitted in the past week. Unfortunately it has a lower top gear, 5.30 instead of 5.05, so it looks like I'll be on the rev limiter before the Veedol chicane on the back straight. Maybe I'll just up the limiter by 500rpm.

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Re: Dyno print out from New Zealand

Postby moose » Mon Oct 20, 2008 1:30 pm

Gearbox problems Pete? need any bits? mine is out of the car if you want to borrow anything.


regards mike
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Re: Dyno print out from New Zealand

Postby limjamrace » Mon Oct 20, 2008 7:00 pm

Many thanks for the information Kevin and Pete!
You have given me a good idea/excuse now to visit Nurbergennring. I went there once on a Page & Moy holiday either before or after a Monaco Grand Prix that year sometime in the mid 1970's.It was a ADAC Sports/GT race...supporting that was a VW GTi race and after we saw them off,we sat down again for a good 20 mins waiting for them to come round again...Although i would assume the long circuit has now been abolished due to safety reasons!
If i don't get what i am after from Rory Cole i think i have no alternative but to seek out further afield. I saw a Fiat HSCC back in the 1990's when Adrian Oliver started off,but that had merely a single D/dr Weber,so i do not know if things are more competitive now for Fiats as everyone wants to use an Imp in that class!
Interesting to have a mention about the NSU ...Presumably the TTS 1200cc...Don't know much about those or who does the tuning,but all the same jolly interesting to have such a variety of equal competitive cars apart from Minis (and Imps in this country),which are more commonplace!
Would also assume the class structure where .P.R. races is up to 1400cc to which is the problem in Hillclimbs and Sprints.
If this is the case then those Minis must have some 140bhp..if the NSU and Abarths are up there too then the power output must be nearby.. It's not all BHP though as we all know!
All in all it is exciting and interesting finding out about new avenues of the opposition cars just as it must be for newcomers learning about Imp engines..
David L.
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Re: Dyno print out from New Zealand

Postby benwick3 » Mon Oct 20, 2008 8:02 pm

Sorry but we appear to be hijacking this thread. Anyway David I raced a Fiat 1300 X1/9 some years ago when I was having problems with Imp engine parts. Ian Carter did the head as he had done the work on Steve Soper's Surprisingly the head is very similar to the Imp and the chamber shape he arrived at was vitually identical to what he used with the Imp. I ran with twin downdraft Webers along with a custom tubular manifold. The problem with the engine was the camshaft. All Piper or Kent offered as full race were in fact copies of Ford profiles and I can assure you that they just did notwork. The best power figures we obtained were in the range of 80 - 85 bhp which was nowhere enough to be competitive bearing in mind the weight of the car. I also looked at what the Americans were also doing with the same engine and with similar mods they were quoting 150 bhp, I think they must have been using small ponies.

I had sourced an Abarth camshaft from Italy in an attempt to up the power but then the car was virtually destroyed in a 13 car startline shunt at Cadwell Park and the result was the Clan was brought out of retirement and the remains of the Fiat sold off.

The series I race in in Europe are upto 1300cc with the Minis having in excess of 130bhp. The NSU's are all based on the TTS and have variable engine capacities in and around 1200cc with power figures for the best ones being I estimate just below that of the Minis. The fastest Abarth has I understand been subjected to 30 years continuous development and runs an alloy crossflow head with twin Weber 45's

As Kevin (Englander) has said the Oldtimer Festival at the Nurburgring is well worth a visit. It's usually in the middle of June with the racing being on the GP circuit. It's a 3 day meeting with a mixture of races for both cars and classic bikes and sidecars. We've noticed an increase in the number of British spectators over the last couple of years having met an talked to a considerable number of repeat visitors. The majority seem to be combining the event with laps of the nearby full circuit.

Pete Richards
Last edited by benwick3 on Mon Oct 20, 2008 10:20 pm, edited 3 times in total.
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Re: Dyno print out from New Zealand

Postby limjamrace » Mon Oct 20, 2008 8:34 pm

Well thats that then...i know what my birthday(June 12th) present will be now- a trip to the Nurburbring!
All i have to do is find someone to look after my G.S.dog + Tortoise and away i go!
Just imagine if the TR6 is still around ...all that way with the top down 8) ..Hmm burnt hooter :( !

Btw.
Don' t reckon we are hijacking this thread.....Merely enhancing a spin off from pre-65's interesting post!

Interesting story about the X19 ..I think it is more chalanging finding out and making your own development over competition cars -or even a road going car come to think of it..This is what gets on my wick hearing about this Imp sport engine lid sport head exhaust monte carlo springs and spax dampers lark all the time!
Thanks pre65 racer,Kevin,Pete..you have given me even more oommmpphh to spend many more hours around the barn thinking of a way to put the Stuart Cairney and Son in the shade in 2009!
HGH & Fiat for me and hopefully James...hmm what a wonderful life!
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Re: Dyno print out from New Zealand

Postby Clive Brown » Mon Dec 08, 2008 7:23 pm

I'm sorry , but anyone with a decent Historic 1 litre Imp who gets beaten by a legal period Abarth 1000TCR should be summarily court-martialled , have their epaulettes of rank ripped off , be booted out of the Imp Club , and be forced henceforth and in perpetuity to race a M*n* .

This sanction cannot , though , be applied in the US , because the constitution there prohibits cruel and unusual punishments ....
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Re: Dyno print out from New Zealand

Postby onomatopoeia » Tue Dec 09, 2008 12:06 pm

Clive Brown wrote:This sanction cannot , though , be applied in the US , because the constitution there prohibits cruel and unusual punishments ....


[trivia]
The constitution here prohibits cruel and unusual punishments, where do you think the colonials copied the words from for the 8th amendment! :lol:

That excessive Baile ought not to be required nor excessive Fines imposed nor cruell and unusuall Punishments inflicted.
(Bill of Rights, 1689)
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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Dec 09, 2008 7:03 pm

To bring this string back to Imp engine tunning I've a bit more to add.

http://www.pre65.org.nz/latest.php

My friend has just completed a 1040cc wedge head with GE5 (.410 lift) and ran it up on the rolling road. We have learnt a few things about rolling roads from this process. Not all operators know what they are doing and some just want to take your money.

To cut a long story short the engine was run with the cam 5 degrees retarded and 1.30 main jets and produced huge horsepower at the rear wheels - or so we thought. First race out the engine performed worse than before it was rebuilt and almost cooked itself because it was running lean.

Next step was to find someone who knew what they where doing. This time round the cam was dialled in at the centre line (135 thou lift at no1). The jets increased to 1.40. The results looked worse with only 78 bhp at the rear wheels. In fact on the track the car was a rocket ship going faster than Cortinas, Anglias, Minis and even some 6 cylinder machinery. The lap times where also faster than this engine had been before.

Result - don't always believe dyno readouts or operators who tell you they can make huge gains. Where it counts is on the track - lap times and places the rest is just bull.

Out of interest does anyone have any experience with the GE5? Looking at the profiles we believe we will improve top end by advancing a few degress (about 165 thou lift at No1). We have never come across an Imp race engine that likes to have a retarded cam particularly as on the track we never go below 5000 rpm.
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Re: Dyno print out from New Zealand

Postby benwick3 » Tue Dec 09, 2008 8:41 pm

I didn't comment on your dyno readings previously as to me they could not be true based on my experience of building and using Imp race engines over the last 20+ years.

It looks that you have now found this out.

The figure of 78bhp at the rear wheels would tend to agree with the figures I am familiar with for a good 998 engine.

I can't however see why you should be using the main jets you quote for even a 1040. I consider a 120 to be the maximum necessary and for the past 5 years have used nothing above a 115 to achieve more than respectable power figures and results. The jets would alos be dependent on the other carb settings, particularly the chokes.

The second thing I can't fathom is the lift you quote for the cam you are using. Unfortunately I don't have any experiuence of the GE5 cam but over the years I have used R22, R23 and currently a GE3. For a R22 I use a lift at tdc on No 1 of 162 thou, for a R23 the figure is 170 thou and the GE3 is set at 178 thou. These are all published and accepted figures and compared to these your figure seems extremely low.

I've never seen the need to use a 410 lift camshaft as the small additional power is negated by the loss in torque. Several years ago a friend who I raced against had a 998 fitted to his car whilst I was running a 1040 with a R22. We had the cars set up on the same rolling road with the reslt that he had 2bhp more than me. However, when it came to the torque curves his was extremely peaky and with a very low rev range whereas mine was higher and virtually constant over a greater rev range with a lower starting point. The trouble was he now knew my secret.

Getting back to your post I seriously think that you need to find more information on your cam lift figures as I believe this along with your carb settings is probably holding your enging back from delivering it's full potential.

Good to see that you've come round to my way of thinking about dynos and rolling roads. I tend to only look at the improvement figures obtained not the actiual quoted outputs.

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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Dec 09, 2008 9:17 pm

Thanks for the comment.

The reason for using the additional lift cam is to improve the spread of power and torque which with the right head/value set up we have proved it does (and so did Andy Chesman and Hartwell when I used to talk to them back in the late 70s). I doubt very much if we will get any significant increase in power over an R23. In fact my friend has done the same best lap times with R23, GE3 and now GE5 but its more about how the engine pulls when racing other cars than on a clear track.

The reason for the 135 degree lift is that is what we got when we dialled the cam in on the lobe centre from the cam doctor sheet - agreed this is just the starting point. The GE5 having singficnatly less lift than the equivalent GE3 at 50 degress. The differnece is the in the ramp angles. It has lesser duration which gives the better spread of power because of the reduced inlet/exhaust overlap and reduction in loss of inlet charge down the exhaust port. In fact the GE5 has the same exhuast lobe profile as the GE3 just with more lift. If you look at the Dyno print outs from my earlier posting you will see that I'm getting more torque than my friends GE3 engine so if its set up right a higher lift cam does not equate to a peaker engine in fact the reverse should be true.

The thinking behind the higher lift is that is gives the same overall effect of a long duration by throwing the value past the optimal opening ie the value stays longer at the optimal point because it goes up to and beyond this on the way up and down.

Not that I want to say your wrong either because its all about getting the right marriage of head/values and cam.

The 140 jets where also a surprise to me as I run between 125 to 130 on my similar .410 engine both have 32mm chokes. I think that just proves that you can't have hard and fast rules and each engine is different. I would say however that our engines do seem to need a bigger body of fuel than I would expect - this could be more to do with the type of fuel we run in NZ being 98 pump fuel.

By the way I would say these engines do deliver there is not a single 1340cc mini in our class that can stick with either of us and we give 1600cc Anglias and cortinas in the next class up a hard time - Not to mention 6 clyinder Holdens. we just like experiementing to get the maximum.
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Re: Dyno print out from New Zealand

Postby benwick3 » Tue Dec 09, 2008 9:42 pm

One thing I forgot to mention in my last post was the ignition timing you are using. At 30 degrees this is some 6 degrees lower than I have found to give the most power. The figure of 36 degrees I have found to work the Aldon Ignitor I previously used and this compares with the maximum of 37 degrees currently used with Weber Alpha ignition. I also use 98 octane pump fuel.

So to sum up it looks to me that using less ignition advance along with less cam timing and more fuel is resulting in you obtaining very similar figures to me.

Again I would point out that my engine is also extremely docile on normal roads and will pull cleanly at 30mph in top gear. In fact It was used for the road run on Saturday at Imp08 after being used on the track day on the Friday.

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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Dec 09, 2008 10:09 pm

Good point on the advance we do use 30 to 32 degrees but this is set on the bench dyno for each engine by coming down to a point that provides minimal change in power and torque. We like to be conservative here because of the variable fuel quality and extreme temps that we often race under.

I agree that the GE3 and in our experience the GE5 are very tractable down low but the last thing we want to do is drive our race cars home. Pre 65 in NZ is pretty much a gutted and stripped race car class. We have to lose every Kg to be competitive, neither of us drop below 5000 rpm in any race even in the heat of battle so we look for the best spread between 5000 and 8500.

Gary was clocked at one circuit on speed gun at 129mph on 185 tyres with, I think, rally 4th. It gives you an idea of the real world horespower we achieve.

We would both love to fly the cars over and compete head on in the UK with the likes of Adrian Oliver, others and yourself - that may have to wait until we win the lottery!

Good chatting......
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Re: Dyno print out from New Zealand

Postby driver » Tue Jun 21, 2011 8:52 pm

i had good results wit a molested g5 cam . its all about the long duration, lift will give you nothing ... reg pattern will remember this conversation ,, :D £1,100 later and a 'issed off cnc boy i had excellent flow characteristics of virtually a 16v head but imp engines are so flexible block liners move i threw it in the shed and gave it 4 yrs detention . got it out this weekend and will get it around a track near you next year ,lots of fun ,lots of headache lots of money,,,,, did someone mention bike engines :P
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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Jun 21, 2011 9:16 pm

I agree duration is very important. We have used a wide range of cams duration, lift and lobe phasing are all important. Its more about building the whole package correctly and understanding what the cam is doing and matching this to the design of the head. For example nothing wrong with the R23 it still does the job and very well. The GE3 is better but since I started this string we are getting better results from some Piper and other grinds with an advanced exhaust lobe rather than symetrical lobe phasing.

Although these comments are all relative to the design of the ports, values and angle of the "wedge" of the head. Unfortunately all the talk is only proved right or wrong on the track, pitty we can't come over and race against each other. Check out Pre 65 hillman Imps or Rush-in-Imp on You Tube.
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Re: Dyno print out from New Zealand

Postby pre65racer » Tue Jun 21, 2011 11:23 pm

Just picked up on another point in the string above. The Imp block and head does move and is very flexible even with the usual stiffening plates etc. The liners distort when the head is pulled down and go very slightly oval This can be minimised by doing the final honing with a plate bolted to the top of the block to reproduce the distortion the honing then brings the distortion back to true and gives a better ring seal.

The heads are also very soft especially if they have been over heated or welded. It is essential to get them re hardened and tested on the Rockwell scale. If they come out hard enough then you can do away with the wills rings and go back to a good quality gasket, much cheaper. If the head is soft it buckles and no amount of torque will provide a good seal, wills rings or not.
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Re: Dyno print out from New Zealand

Postby Lotus-e-Clan » Wed Jun 22, 2011 9:10 am

pre65racer wrote:I agree duration is very important. We have used a wide range of cams duration, lift and lobe phasing are all important. Its more about building the whole package correctly and understanding what the cam is doing and matching this to the design of the head. For example nothing wrong with the R23 it still does the job and very well. The GE3 is better but since I started this string we are getting better results from some Piper and other grinds with an advanced exhaust lobe rather than symetrical lobe phasing.

Although these comments are all relative to the design of the ports, values and angle of the "wedge" of the head. Unfortunately all the talk is only proved right or wrong on the track, pitty we can't come over and race against each other. Check out Pre 65 hillman Imps or Rush-in-Imp on You Tube.


I use a GB 72 cam which is a George Bevan cam made by Piper....this one is not asymetricl though. It has loads of torque on a 1.4 /1.125 head with std shaped (no inlet valve relief) combustion chambers on 1040 cc giving 11.8:1 static comp ratio. ...and isn't a big lifter.

GB 72 timing:
Timing: Inlet 49/71 Exhaust 71/49
    Lift: 0.352 Inlet & Exhaust
    Clearance: 0.010" Inlet & Exhaust
    Full lift in degrees after TDC for inlet: 101
    Full lift in degrees before TDC for exhaust: 101
    Lift at TDC (inlet): 0.157"
    Lift at TDC (exhaust): 0.157"
    Duration 300 degrees
    Overlap 98 degrees

And George Bevan had some success on circuit IIRC.

The Piper BP 320 is more or less the same cam and I think is still available from Piper new.
BP320 info on Frankas site
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Re: Dyno print out from New Zealand

Postby pre65racer » Wed Jun 22, 2011 10:59 pm

Thanks for that that is one cam I have not tried. I do like Piper cams they certainly know what they are doing and I have a piper version of a GE3 that Ben Boult did for me with advanced exhaust lobe and slightly less duration than a "typical" GE3. This worked very well when I used a lower compression ratio and (lower octane) pump fuel.

The thinking behind lift is that every valve size has a peak flow at a set amount of lift. So higher lift cams go beyond this peak flow point but as they come down again the peak flow point is reached for a second time giving a longer time when the valve is at, or around its peak flow point. That does not mean the cam is better thats just the way it works and the head shold be designed to maximise this effect similarly with asymetrical phasing its just a different approach to the try to produce a cam that has tourque and power rather than advancing the cam timing. Unfortunatley the imp does not have variable valve timing so we are stuck with a compromise whatever cam you use. Every design can work some are based on more "modern" thinking but not better or worse. Everything in the design of the engine has an impact from acceleration of mixture on opening of the valve, to the extraction effect of the length from trumpet to end of exhaust, etc, etc, etc it all has an effect. In fact some people would argue that the flow and suck of inlet and exhaust charge pulses have a greater effect on cylinder filling than the movement of the piston especially at high RPM but I digress. Its all about building the engine to match how you want it to peform or more accurately how you want to drive it.

Cam sheets, flow figures, dyno sessions only provide useful discussion points and comparisions that indicate how the car will perform in the real world. I've been excited about an engine based on its dyno readings only to be disapointed by lap times simply because the gear ratios and my driving style could not get the best out of the engine.
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Re: Dyno print out from New Zealand

Postby pre65racer » Fri Jun 24, 2011 3:46 am

Checking the timing numbers above your GB cam is so close to the Piper that I would say it is the same.

To be honsest I though the Bevan cars used R23's so good to have a bit of new information.
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