Turbo Test Engine - Test Completed

[Grumpyoldmen]

But the crankshaft is not considered as a weak link in the chain of "survival".??
The standard conrod bolt looks very tiny. What is the size of special made bolt?

The upgrade in size is redrilling the rod and cap to take a 3/8 bolt rather than 5/16 with the option of upgrading the quality of the bolt.

Scott

Yes it looks like there are some conrod "meat" that can give place for a 3/8 (or M10 as we use on the continent )

[ImpManiac]

I understand this very well as I am a mechanical engineer.

Me too!

The ARP bolts looks super! As if I have design them myself!! Give me 8 of them!!

Give Burton Power a call. Give them about £85 (VAT, delivery, etc.). They will give you some.

IM

[Grumpyoldmen]

The ARP bolts looks super! As if I have design them myself!! Give me 8 of them!!

Give Burton Power a call. Give them about £85 (VAT, delivery, etc.). They will give you some.

IM

But do they actually have the Imp bolts?

[ImpManiac]

But do they actually have the Imp bolts?

I doubt that ARP have ever heard of a Hillman Imp. The bolts that I used were the Lotus Twin Cam, Ford Cosworth YB / BDA, etc. type. Reg Patten needed to shorten mine a bit to allow them to fit the drilled and tapped connecting rods. Burton Power did not have the correct length in stock when I got mine, so I ordered longer bolts and Reg cut them down for me.

IM

[Grumpyoldmen]

But do they actually have the Imp bolts?

I doubt that ARP have ever heard of a Hillman Imp. The bolts that I used were the Lotus Twin Cam, Ford Cosworth YB / BDA, etc. type. Reg Patten needed to shorten mine a bit to allow them to fit the drilled and tapped connecting rods. Burton Power did not have the correct length in stock when I got mine, so I ordered longer bolts and Reg cut them down for me.

IM

I have a hacksaw, if necessary, a grinder, if that's not enough, I know a workshop man with a lathe! Now Burtons! Be prepared! ..........and doesn't these Rootes 1725 racing engine conrod bolts I have on the workbench also look very fragile............(well not "racing" to be honest, more like touring)

[cov_climax]

i've ARP bolts in mine, part number stamped in the head is ARP 2000 01, that could be a unique number for the bolt size/length or a stamping from which thay make various lengths. i don't know where they came from but i asked ARP for torque settings once and got the following:

We do not list a rod bolt for the Imp. However in the past I did help one chap and I believe with our: 200-6210 (5/16 UHL1.500"), did the job.

The general torque figure is: 26ft/Ibs with our moly lube and the stretch figure is: .0056 with our moly lube.

Regarding the re-use. Did you use stretch or torque? Did you measure the free length before the last installation?
Is you did and they have returned the that original measurement? What life has the engine done?

I would recommend to replace them for peace of mind if you are unsure of any of the above points. I have attached a list of our distributors
that will stock the part.


so a conscientious answer, i re-used them as engine hadn't done any work at that point

[benwick3]

Brian,

I think that person may be me as I had a chat to ARP and they supplied the bolts as described along with the torque figure which I use. I also have reused them may times with no problems. I believe I still have the invoices from them giving the part number. No need to go to 3/8 bolts in my opinion as that requires removal of material from the rod along with potential weakening in my opinion. Spadge Hopkins used to supply 5/15 ARP bolts when he was trading at a very competitive price, due I believe to buying in bulk on trips to the States, and also supplied a sheet with details for fitting in respect of tightening/loosening sequence and gave a torque figure of 25ft/lbs.

Ian Carter used to fit 3/8 cap head big end bolts torqued to 39 - 42 ft/lbs. However using these and the torque setting given required the bore of the rod to be checked for ovality with the necessarily machined bore diameter to be 1.7705 inches.

Pete Richards

[timbeardsley]

Not that long ago the Merc F1 engines had big ends on a 45 deg split and i bet that wasn't to get the rod ends down the bores.
The most common point of failure is at the end of the exhaust stroke at revs, think about it
But hats off to Eric for the test 875 bottom end lasting so well with that power and revs, its the revs that kill engines. 875 now i think thats how to build my 1st turbo engine.

[Grumpyoldmen]

Still.......150 bhp as Mr "Pimp" claims is a lot for an Imp engine and gearbox. Is it estimated, guessed. or "pipe dream" bhp or figures from some kind of rolling road?

[bks974c]

Gearbox failures did occur but Eric modified that too - check out his other postings.

General multiplication factor for turbo engines is 1.4 so 100bhp engine = 140bhp about same as claimed turn up the boost and ?

Scott

[pimpdriver]

Grumpy
The rolling road figures are an estimate of a couple of rolling roads i've been on. The original rolling road the engine was set up on figures, were unreliable because i was playing around the lower end of the 1200 hp 4 wheel drive rolling road. The other rolling road i went to again seemed to be unreliable because the revs didn't match the revs the engine did. On the RR the engine hit the limiter at 8000 rpm ( according to the RR) but in reality the limiter is set at 9000 rpm, the megasquirt i trust much more than the RR. In fact i was very dubious of the rolling road because they didn't use an inductive pickup on a HT lead to measure the revs, instead relied on hitting a button when the rollers were at a certain speed (not sure how that works).
So I cannot state exact figures from a Rolling Road, the engine could have been anything from 140 to 160 bhp, but on comparisons from other peoples results from the second rolling road, and figures they had obtained elsewhere from other RR's, it is in that ball park.
With turbo's, if you boost to 15 psi (1 atmosphere), you are effectively doubling the amount of air the engine ingests. If a well tuned 875cc engine produces 80hp, then a turbo-ed one at 15 psi should produce about 160 hp, I was running about 13 psi so 150 hp sounds about reasonable.
The engine definitely had a lot more power than my old approx 100 hp N/A engine. At Curborough sprint course, with the N/A engine i couldn't get more than 80mph over the finish line. With the Turbo i managed 96 mph.
Saying all that, i would much rather have a 1400cc 150 hp N/A imp engine, (if only that was possible). The turbo engine is not as nice to drive. Once you are over 50 % throttle, you are flat out. You can't just lift a bit round a corner to steady the car, unless you lift past 50%, nothing happens. Also coming out of corners you have to hit the throttle much earlier than normal, to allow the turbo to spool up. I recon a 150 hp turbo engine is about the equivalent of a 125 hp N/A engine when corners come into it.
I wouldn't say turbo is the only was to go, but when the class i run in (or used to) was up to 1400cc, i think the only way to be competitive is to go 1 litre turbo, you just can't give away 200-300cc Normally aspirated.

As Scott says, i've broken a JK 4 speed box, and a borrowed lowered 3rd and 4th box both at the tail end of 2009. I rebuilt the JK box with a new crown wheel and pinion, with a steel strap round the vulnerable main pinion bearing support and plenty of alloy plates welded around the box to strengthen it. Since then the box has been okay. I've really helped the 'box, by replacing the sintered AP racing 7 1/4" clutch with a Super Clutch 7 1/4" organic clutch (normal asbestos type material). This gives a much softer take up of drive, being able to slip it off the line and reducing the shock to the drive line.

I would love to fit a Hewland box, but i can't without modifying the floorpan, which if i run to Modprod rules, is not allowed.

Eric

[bks974c]

Eric

Sounds like you need an Anti Lag System - I presume its something you have looked into -what are the issues ?

Scott

[onomatopoeia]

I would love to fit a Hewland box, but i can't without modifying the floorpan, which if i run to Modprod rules, is not allowed.

The Tills ran a Hewland in their Clan in modprod, I never looked at the floor though.

[skamanfrank]

Out of curiousity... does any body here measure bolt stretch when building engines, or just go with an accurate torque wrench?

[cov_climax]

frank, on an imp rod you could only measure one of the bolts, the other is in a blind hole so not possible. I'd say vertually all people will use a torque wrench

[Grumpyoldmen]

frank, on an imp rod you could only measure one of the bolts, the other is in a blind hole so not possible. I'd say vertually all people will use a torque wrench

How often do you adjust your torque wrench?

[skamanfrank]

frank, on an imp rod you could only measure one of the bolts, the other is in a blind hole so not possible. I'd say vertually all people will use a torque wrench

Ah didn't realise that! Shows I've not looked at a conrod for a while!

[ImpManiac]

I thought that bolt stretch could be determined indirectly. With some connecting rod bolts, you torque them up to the required figure. Then you give them, say, a quarter turn of additional tightening, which stretches the bolt by a fixed amount depending upon the pitch of the thread on the bolt and in the connecting rod. However, the torque applied before you then apply the additional amount of stretch would depend upon manufacturer's design specification. Ditto the amount of stretch applied.



EDIT - The torque applied would also depend upon the use of the correct thread lubricant. For example, ARP supplies thread lubricant with its fasteners.

IM

[Lotus-e-Clan]

And it's worth pointing out again for the sake of the inexperienced engine builder that it's pointless using high grade bolts with a raised torque setting IF the assembly (BE cap) then distorts and binds.....and I've found not all std (unmodified) BE assmblies can take much over the std 18 lbft setting without distortion and some binding.

So make sure there is absolutely no bind in your bottom end after a final torque-up.

I'd advise first torquing to the std 18 lbft, then check the bottom end is free...then torque to the final setting (eg 24 LBft for uprated bolts) and re-check. If there is any increase in binding between the two settings then you would be stupid to run the engine in that state...in fact you'd be better off running with 18 LBft even if the bolts are uprated.

[Meltdown]

And it's worth pointing out again for the sake of the inexperienced engine builder that it's pointless using high grade bolts with a raised torque setting IF the assembly (BE cap) then distorts and binds.....and I've found not all std (unmodified) BE assmblies can take much over the std 18 lbft setting without distortion and some binding.

So make sure there is absolutely no bind in your bottom end after a final torque-up.

I'd advise first torquing to the std 18 lbft, then check the bottom end is free...then torque to the final setting (eg 24 LBft for uprated bolts) and re-check. If there is any increase in binding between the two settings then you would be stupid to run the engine in that state...in fact you'd be better off running with 18 LBft even if the bolts are uprated.

Best have a curry and a few beers then

[TTK 25L]

The turbo engine is not as nice to drive. Once you are over 50 % throttle, you are flat out. You can't just lift a bit round a corner to steady the car, unless you lift past 50%, nothing happens. Also coming out of corners you have to hit the throttle much earlier than normal, to allow the turbo to spool up. I recon a 150 hp turbo engine is about the equivalent of a 125 hp N/A engine when corners come into it.

Eric, it doesn't have to be like that. My old turbocharged road/hillclimb Morris Minor (2 litre Fiat 16valve 400bhp+) was very driveable on part throttle (ran it at around 1.3 bar boost) and went up to 8000rpm, also, my turbocharged 1200cc Radical is very driveable on part throttle. The throttle on both cars is very linear in response, I run blow through throttle bodies on both and positioned the dump valve within the airbox to ensure the air circulates through the airbox off throttle so when the throttles open again the air is already moving in the right direction. What is your set up like?

Martin

[pimpdriver]

Martin
My set up is, turbo - intercooler - plenum - 4 individual throttle bodies - engine, the dump valve is off the plenum chamber. I probably exaggerate about 50% throttle, its more like 70 %. I'm not saying its bad to drive, just not as nice as a N/A engine. I also think the R20 cam on an 875 is probably just not shifting enough exhaust gas to spool up the turbo quick enough, if its at all off cam then its off boost. You have to put your foot down earlier to get it on cam and then on boost.
Hopefully with the 998 i'll have 12% more air at the same revs so it should spool up quicker. I'm planning on leaving the R20 in for the moment to see how it goes, if its not improved, i might try an R17, The thing is i don't want too much low down torque, well the gearbox, clutch and donuts don't.
Maybe as well, the throttle bodies might be a bit too big at 36mm, 70% of those throttle bodies on an 875, maybe as good as fully open i.e no real restriction, again hopefully the 998 might be better.

Eric

P.s. i recognized the reg

[TTK 25L]

Ok, sorry about still using the old reg

Turbos like short exhaust cam timing to get them spinning, they need the short sharp pulse rather than the same gas over a longer duration if you see what I mean (I'm sure you already know this), my Morris ran 276 degree inlet, 242 degree exhaust cam timing (medium race turbo cams).
Is the turbo a bit big for the engine? I take it you did all the usual calcs to size the turbo for the engine?

[pimpdriver]

Martin
Don't worry, i'm not going to be using the reg.

The Turbo, A Gt17 off a 2 litre SAAB, is too big for an 875, but it should be a lot better with a 998. The R20 cam is a 280 degree cam (inlet and exhaust), If things progress i'm not adverse to having a cam specially made, but unfortunately at the moment i can't swap the exhaust cam like you can on your fancy twin cam beasties. . I still need the engine to rev, because of my gear ratios, but maybe a cam change would help it spool up quicker. I'm at the start of development.

Eric

[TTK 25L]

It will definately be worth the work though, good luck with the development.

[pimpdriver]

Cheers Martin - Have fun

[pimpdriver]

New engine is now fitted and working.

Spec

998cc , my original imp engine which had water loss issues - traced to leaking liners, which were re-glued in position.
Hepolite/powermax pistons (2nd hand) with lightweight 5/8 pins and new rings
Lightened and balanced imp rods with 3/8 cap head bolts.
Block strengthening plate (homemade) with blocks and M12 Studding
Std sump with lots of baffling
Extra large capacity oil pump.

The head gasket is a bit special, its a laser cut alloy plate 1.4mm thick with the 4 bores being the outside diameter of wills rings. Paper gaskets 0.25 mm thick are fitted either side and the wills ring is fitted inside the alloy plate. There are no grooves in the head or block, effectively the alloy plate holds the rings in position and the 1.4+0.25+0.25 = 1.9 mm gives the correct squash on the wills rings. This gives me a bit lower compression to suit the 12% bigger engine.

The rest of the engine, head, turbo, cam , injection etc is the same as the old engine

Fitted last weekend but couldn't start it, the turbo oil scavenge pump didn't work. Found out the old escaping cap had hit it and slightly damaged the outer casing, damaging the magnets in the process. A quick strip down of the motor and clean up and all was working.

Fired it up and it just ran, tweeked the fueling a bit at idle but thats about all i could do.

Took it today to Bradleys for Rolling Road tuning, and got 144hp at the wheels at 13 psi and 8000 rpm, which is about 165 hp (they recon 170) at the flywheel.
with peak torque being 132 lbft at 6200 rpm. very happy.

The engine has potentially more to give (more boost), but at that boost the engine was leaning off to 13.8 AFR at 8000 rpm. We increased the pulse rate but it made no difference, so we came to the conclusion that the Honda CBR600 injectors have run out of flow. Bigger injectors required or fit the 4 extra ones as fitted to Honda CBR600RR. Lowered the boost to 11 psi which stopped it going too lean, for safety, turbo engines tend to run rich at high revs and boost to help cool the pistons.

Anyway - i'm a happy bunny, and will be bringing it along to Anglesey on thursday for a laff (it will only manage about 4 laps on a full tank)

Eric

[Lotus-e-Clan]

Brilliant..a twin cam 4 valve per cylinder moterbiker-headed n/a Imp engine just wouldn't touch that!

Have you sneaked a blast in it yet? Can you feel the extra torque?

See you at the track evening hopefully.

[Grumpyoldmen]

....got 144hp at the wheels.....

Is the world "strain"?
Just came to think about that gearbox input shaft. It appears to be very slim......probably an illusion only.

[Lotus-e-Clan]

Come-on...keep up Grumpy!

Eric has blown a transaxle apart (tore out the bearing housing) with his previous 875 turbo and then he RE-ENGINEERED the casing to counter the weakness. Like yourself he is an engineer....but he's more than that.......he doesn't sit back and reflect on "training" he has a pretty good "nose" for development.

The transaxle will survive....the weak spot at the moment is the angle of the driveshafts. The Clan is lowered so much that the rotoflexes and driveshaft u/j's suffer due to the acute angle of the driveshafts from transaxle up toward the wheel hubs.

BTW. Williams F1 has copied him this season ...but they have a bigger budget so their acute angle driveshafts don't cause them problems.

[basil imp]

Well done eric! That is some achievement!

[Grumpyoldmen]

"..he doesn't sit back and reflect on "training"..."

Sorry, don't understand. Does it mean I am an armchair idiot???? If so: How did you know my secret!!!

[GURNSIMPS]

144 bhp @the wheels? AWESOME!!

[pimpdriver]

Peter
I haven't driven it yet - well off the rollers and reversing up to the trailer doesn't really count, the big downside of a non road legal car, is you can't just take it out for a blast . I'll have to wait for Anglesey to drive it, and then on saturday i'm nipping over to Harewood to compete and then popping back to Bangor. The poor old Scimitar tow car is going to sup a bit of juice next weekend

[Lotus-e-Clan]

"..he doesn't sit back and reflect on "training"..."

Sorry, don't understand. Does it mean I am an armchair idiot???? If so: How did you know my secret!!!

I thought I was being too subtle and you'd miss it !

No offence intended, and hopefully not taken either. I actually enjoy your forum contributions Grumpy .....they keep people on their toes, so keep them coming. I've probably got too much respect for Erics' development antics so maybe I jump in too quick to justify his stuff on occasion.

[Grumpyoldmen]

I thought I was being too subtle and you'd miss it !

I always miss it!! (I am a furriner!)

[TTK 25L]

Sounds good Eric, but watch that AFR, 13.whatever is pretty naughty for a turbo engine at high revs, could end in tears (as you probably know)

[tomrogers7]

I just wanted to say nice work. Would be nice to see a video of the engine in action.

I was wondering if you would consider the option of super turboing/ twincharging? A friend of mine has a seat cupra 1.4 twincharged and it really shifts. I thought I'd mention the idea. I'm a bit out of my depth here

Tom

[pimpdriver]

Tom
There are a couple of videos on Youtube, search for 'Clan at Gurston' and 'Clan turbo loton' and you should find them. Those are both with the old , now deceased, 875cc turbo engine.
I have thought of Twin-charging, but its a bit complicated and i was a bit worried about the extra weight of both a supercharger and a turbocharger and all the associated gubbins, upset the balance of the car. I think twin-charging is brilliant for the road use where you need to pull from 2000 revs, but on a competition car with a proper sized turbo and correctly spaced gears, turbocharging on its own, works great. In the Video from Gurston which was last year, you see me coming out of a left hand corner, and if you listen you will hear the engine being 'off cam' as i exited the corner. You will then hear me blip the clutch to spin-up the engine and turbo, which then powered me out okay. This was the downside of the 875 turbo. the turbo was a bit big and the cam a bit much for the little 875 engine. With the 998 version this year, i knocked 1.5 secs off my personal best, with the engine pulling great out of the same corner, in fact on my last run, i had a hint of power-oversteer. The new engine certainly pulls better from lower down than the 875 engine. say from 4750 now against 5500 on the 875 one.

Eric

[tomrogers7]

Tom
There are a couple of videos on Youtube, search for 'Clan at Gurston' and 'Clan turbo loton' and you should find them. Those are both with the old , now deceased, 875cc turbo engine.
I have thought of Twin-charging, but its a bit complicated and i was a bit worried about the extra weight of both a supercharger and a turbocharger and all the associated gubbins, upset the balance of the car. I think twin-charging is brilliant for the road use where you need to pull from 2000 revs, but on a competition car with a proper sized turbo and correctly spaced gears, turbocharging on its own, works great. In the Video from Gurston which was last year, you see me coming out of a left hand corner, and if you listen you will hear the engine being 'off cam' as i exited the corner. You will then hear me blip the clutch to spin-up the engine and turbo, which then powered me out okay. This was the downside of the 875 turbo. the turbo was a bit big and the cam a bit much for the little 875 engine. With the 998 version this year, i knocked 1.5 secs off my personal best, with the engine pulling great out of the same corner, in fact on my last run, i had a hint of power-oversteer. The new engine certainly pulls better from lower down than the 875 engine. say from 4750 now against 5500 on the 875 one.

Eric

holy moses wish my 875 ran like that! looking forward to seeing the 998. any events coming up?