Speak Up!!!

[Purple AK]

Sorry you'll have to shout! Just returned from a Rolling Road session with N20 COB, 116 dbs at full chat!! He, I and the Nutter on the Rollers were well impressed with the output of his BAE Chevy! 267 bhp at the wheels (380ish at the flywheel)@5000 rpm, Started at 237 bhp, couple of tweaks, + 30 bhp!! Does what it says on the tin. Tester said what a lovely engine it was, and the cam worked really well with it! :tu £88 Not a lot of money for 30 bhp

[plod]

Blimey, nice set of underslungs..


Paul

[Philip]

Hi Chris,
Im curious as to where they come up with the figure of 113bhp loss from the crank to the wheels?
Phil

[Sime]

Sounds like a worthwhile rolling road session. Well done.

However, I agree with Phil. If it made 267 at the wheels then a true, more accurate flywheel figure is much closer to 325/330 bhp I'm afraid.

If it was 380 at the flywheel it would make around 312 at the wheels !

Rolling road people are notorious for "embellishing" bhp figures.

[skid]

Chris you buying/bought Paul's car, or just along for the ride???

I fully agree that a rolling road is well worth the smaall investment.

I posted about 6-8 months ago my experience. I've got a Huddart engine which started off about 240 at the wheels I think and with the carb jetted properly went off te scale at 270 bhp, though I concur that there's only about 70 hp loss through the transmission so hopefuly I'm looking at a minimum of 330.

From the point of cheap horse power gain I cannot stress how important that is. I found out that mine was running way too lean which ultimately could have caused damage.

Any bench test by the engine builder is irrelevant once you put an engine in a car and restrict the air flow to the carb.

For the record Goodwood measured my db at 4000 rpm at 113db. Just fitted straight through 3 inch NON perforated tubes just for the hell of it.

Mo Fo it's the end of the world! {-}

Whose road did you use?

[Purple AK]

The 380 ISH bhp was worked out on his thoughts on power loss at the top end. I did think it may be over the top, but he's been doing it for 20yrs so who were we to argue! :} The road is in Tonbridge, and he does all the work in the evenings if anyone is interested.
Cheers

[plod]

Obviously I have no idea how these things work and no real wish to. He said 267 at the wheels and though it wasn't measured, was confident of being over 350 by a decent margin at the busy end..

I assume the loss ia due to wastage somewhere. Seems a lot I know but he works on the fact the engine will lose 20-30% at the tope end. That being the case, at 20% loss would give 333 at the wheel, 25% would give 356 and 30% giving 381..

Whatever it does and I'm inclined to agree with some good ol fashioned old school who ran the test, it does go some and without doubt, surprised the chap who carried it out. He'd earlier thought around 210 at the wheels max, based on the set up.

Anyway, defence over..

Chap is called Simon, I have his number, does mostly freelance stuff and the garage I went to was in Tonbridge. Runs, races, tweaks and He's taking a 30 grand engined thing to the Le Mans Classic.. yum yum

Paul

[Philip]

Hi,
sorry, I wasn't saying the power loss was too high, but it seems that vertually all the rolling roads calculate power at the crank in different ways. Thats why I was interested, the only thing they can actually measure is torque at the wheels, my local dyno reckons on 25% on our setups and 33% loss on 4 wheel drive vehicles, not that any of it matters anyhow, as long as your pleased thats all that matters :tu
Phil

[plod]

Thanks Phil,

The chap did say there are ways of coverting this to that etc.. but he wasn't totally convinced and kind of echoed abut different people doing different things to get an idea of other figures..


Paul