VPL Rolling Road Day

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Cartermotor
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VPL Rolling Road Day

Post by Cartermotor » Wed Nov 25, 2015 5:46 pm

Hello all,

Took my Stiletto, VPL 814 G to Peter Baldwin's Rolling Road last Monday, 16th November, to get it set up, he re-mapped the ignition timing and got some great power outputs showing 94 BHP at 5000, 117 at 6000 and 134 at 7000 and again 134 at 7400 all this from 1120 cc of Denis Allt rebuilt Ian Carter engine with R20 cam, twin 40s and large bore Janspeed set up. I'm sure these are not accurate figures Peter recons they should be taken as 5% less flywheel figures rather than at the wheels but they are of course comparable with a 1293 Cooper S set up on the same rollers which got a best of 84 BHP, since Peter Baldwin is a mini racer I'm sure this hurt a bit. He also balanced the carbs, set the slow running improved the jetting, lowering the main jet and compensating with the air corrector, this stopped the over rich condition at 5000 RPM and still made 134 BHP at 7000 and 7400 RPM, the car is now much smoother, ticks over at a steady 890 RPM and is still fabulously revvy and mighty quick. Not too shabby I'm sure you will agree!
Roger
Imp028
Regards

Roger
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Re: VPL Rolling Road Day

Post by bazzateer » Wed Nov 25, 2015 6:45 pm

Excellent results Roger, I may need to bend your ear about this guy for future tuning of LNK.......
If I told you I was a pathological liar, would you believe me?
Barry Blackmore - Chiltern ACO, apparently.......................
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Re: VPL Rolling Road Day

Post by benwick3 » Wed Nov 25, 2015 11:23 pm

From experience the setup will be the best you can get but just don't take the hp figures as gospel.

Pete Richards
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Re: VPL Rolling Road Day

Post by Cartermotor » Thu Nov 26, 2015 10:57 am

I agree the figures are optimistic but the set up is great and in real comparative terms with other vehicles on the same rollers it is really great.
Regards

Roger
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Re: VPL Rolling Road Day

Post by benwick3 » Thu Nov 26, 2015 4:36 pm

Do you have any before figures as the difference is in my opinion more relevent.

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Re: VPL Rolling Road Day

Post by Cartermotor » Thu Nov 26, 2015 6:40 pm

Peter,

The before figures were not too much lower the only increases were seen in the ignition timing, the jetting did not change the power outputs at all, just reduced the over fueling at lower revs at 5000 rpm it started at 88bhp and rose to 94, at 6000 it started at 111bhp and rose to 117bhp and at 7000 rpm it was 128 and rose to 134, at 7400 it didn't change much at all as the advance was pretty much spot on the first figure being 132.
The biggest benefits being the slow running/tick over is now fantastic, a small flat spot around 4500 has gone and the car is much smoother if slightly more cammy at low revs when off the cam it's also more economical; what more could I ask for?
Regards Roger
Regards

Roger
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Re: VPL Rolling Road Day

Post by cov_climax » Thu Nov 26, 2015 7:47 pm

Some years back Eric Morrey took his hill climb imp to a mini specialist for rolling road session, this was before he turbo'd it.

It might have been baldwins, but I' do recall the power figure being high for an imp engine of 998cc, Eric was sceptical on the numbers, but did take note it was better than larger capacity mini's that had been across the same rolling road, so the comparison was valid, just not absolute number

Brian
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Re: VPL Rolling Road Day

Post by Peter Hurst » Thu Nov 26, 2015 8:02 pm

benwick3 wrote:From experience the setup will be the best you can get but just don't take the hp figures as gospel.

Pete Richards
The figures do look high to me and agree better to look at gains
I dont know what the gain is with the extra capacity over a 998 but with a R20 cam the 5000rpm figure of 94 seems very high.
I may be completely wrong and someone may correct me but on a 998 with big valve head, Webers etc etc at 5000prm I would not expect much more BHP than a 998 with sports head and Strombergs and be in the 60 bhp range.
Its as the revs keep increasing that the sports cam and smaller valves cant breathe much more and the power tails off but with the R20 and big valve head you continue to get more fuel air mixture in and so the power keeps climbing as the revs rise
Generally when you see the power curves of "tuned" engines compared with a standard reasonably efficient engine eg like an imp, the power curve may well be lower than the standard at lower RPM, equally it at higher rpm and only nearer the limit of the standard engine will the power start to improve and continue to climb due to the improved breathing.
The usual trade off of the better top end is worse performance like for like in lower rev range. Extra capacity eg 875 to 998 or bigger helps offset losses at lower revs

When I first had my 998 Clan I took it to a rolling road with the instruction not to get any more power but to get the low rev running better and car more driveable.
I cant find all the graphs but sheet I can find quotes various figures
At 6370 rpm, P-norm of 69.5 and P-eng 66.5 P-wheel 38.0 and P-drag 28.5 and 83 Nm at 5230 The power curve was still climbing but wasn't too concerned in maximum power but optimise at bottom end. I beleive the maximum was about 80bhp. Compared with 134 BHP my 80 seems very poor but are we comparing like with like?
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Re: VPL Rolling Road Day

Post by pimpdriver » Sat Nov 28, 2015 8:17 am

Peter Baldwin is an excellent tuner, just don't believe what his rolling road tells you. As Brian says, I took my first Hillclimb Imp there for tuning and he set it up absolutely perfectly. At the time, and he probably still has the same one, his rolling road didn't produce printouts, just a gauge. Mine was quoted at 118 bhp and was was only about 25hp out. A 998 with slightly bigger valves and an R20 cam is more like 90 hp.
A tuner can get the best out of a set up, and Peter Baldwin certainly does that. What he can't do is perform miracles. There is no way an 1120cc 2 valve engine can produce 134 bhp at 7400 revs. That is 120 hp / litre. My rough figures are 90 Hp /litre at 7800 for an R20, 100 hp/ litre at 8400 for an R21/R22 and maybe 110 hp /Litre at 9000 for an R23/410 lift cam. This all assumes everything on the engine is modified to suit, and is set up perfectly.
People love to hear big HP numbers from rolling roads, and rolling road operators know this and are happy to oblige. The Imp engine is a cracker, but it is still a 2 valve engine. You can get good power out of it mainly because of its short stroke and big pistons allows good breathing and you can rev it to get the power. One beauty of the Imp engine is its power at the top of its power curve. The imp engine with the R20 - R22 cams is really flat near the top end, in a good way, the power is within a few hp of peak, about a 1000 revs either side of peak power. This means it is producing that power for a good amount of time, not just all or nothing, and you can rev past peak power to enable you to change up a gear more into the power band.

Out of interest, whilst I was at Peter Baldwins, after tuning the hillclimb car he was waiting for the next car to arrive, so I asked him to set up my Tow car, a 1972 Reliant Scimitar with the 3 litre 'Essex' engine. He completely changed the jets and set up on Idle, and transformed the engine from a rough idle to a beautifully smooth 600 rpm idle. He then set the engine up for best fuel economy at cruising revs and only then did he look at full power. That car and engine has done another 100,000 miles since then and i have never touched the carb since and it managed 34 mpg on a trip to Le Mans.

Roger, be happy that the engine in your Stiletto is running beautifully. To me, for a road engine, it sounds like the perfect Imp engine. Torquey and powerful with a lovely "just keeps on pulling" type power curve, it will be a joy to drive. Peter Baldwin does take the time, and has the knowledge, to set an engine thought out its whole rev range, not just max power. But 134 BHP , no way, I reckon it is around the 100-105 BHP mark.

Eric
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Re: VPL Rolling Road Day

Post by The Nun » Sat Nov 28, 2015 10:35 am

pimpdriver wrote:People love to hear big HP numbers from rolling roads, and rolling road operators know this
Eric
Years back we put a VW Beetle on a rolling road we loved to hear the result too, and all had a good laugh, it was chucking out 9 BHP or as the Germans might say Nein BHP lol:
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Re: VPL Rolling Road Day

Post by Cartermotor » Sat Nov 28, 2015 12:54 pm

Hello Peter I agree that the figures are really immaterial as its the improvement that is important, but it is still valid to compare them with others from the same rolling road. By the way its an 1120 not a 998 with an Ian Carter heart shaped port Sprint head so I suspect that the real figure is nearer to 120BHP. As you say he is a great tuner and has made the car nicer to drive as well as faster.

Regards
Regards

Roger
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Re: VPL Rolling Road Day

Post by benwick3 » Sat Nov 28, 2015 2:52 pm

Theres no point in arguing about bhp figures but based on my experience I think Eric is being generous in respect of your 1120 with R20 etc and I would think that you would be doing well to get 110bhp. Where you will be winning is in the torque figures Remember bhp sells engines but torque wins races.

Pete Richards
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