The V8 Owners Forum -

Shame I set the limitter at 6000rpm, 50 rpm more and it would have hit 450BHP, very happy though!
Big thanks to Ray at V8Developments and Shaun from MS2Tuning.com

Engine is 5325cc RV8 (V8Developments) with 8psi of boost from a Rotrex C38-81 into a charge cooler. Fully Sequential injection / Ignition using one of my MS3 ECUs.

Hi Phil
I can't help thinking you could do with new valve springs, or a much heavier set if the ones you have are new. . . you seem to have quite a bit of valve bounce after 4500 revs. A very good figure though and probably quite a few more to come when you have the torque curve without the upsy downsy top end bit.
Best regards
Mike

Hi Mike,
hadn't concidered that to be honest. It went rich on their lambda and lost a little around 5500, but my lambdas didnt pick it up and the fueling looked roughly the same on the datalogs, so I have no idea what happened there. The only thing I can think of is the water injection cut in, I havent set that up yet, but it got very hot (38C intake) so water came on and I guess messed it up a little.

I will have to look into the springs, they are the double spring type, but I dont know if they are new! Will see if Kent do them, as they supplied the cam and followers.
thanks
Phil

A cracking result Phil

Very impressive

Cheers,
thats at 8psi of boost, could probably get away with going up to 12 and hit 500BHP but how reliable it would be is anyones guess. (8.9:1 cr)
To be honest its quicker than I can drive now!

Looking at the dyno run and the logs Shaun seems to think it could have been a miss fire, maybe oil, as my lambda picked up a lean spot at the same point theirs picked up a rich spot. Shaun seems to think if it was valve bounce it wouldnt have recovered like it did.
But I may get roller rockers sorted and new springs anyhow, something to do over winter.

Ive not seen it before whilst tuning it on the road, so Im not worried at the moment.

Phil

Should take more boost quite safely with that CR, but then again what's the point - 450 should be plenty scary enough on the road and why give the engine a hard time.

Yeah, its plenty quick enough for me, would be nice to achieve 500BHP, but Im happy with it as it is, I fancy getting roller rockers next. Anyone know of a source for them?
thanks
Phil

Nice one Phil,
was chatting to Shaun tonight while we were tweaking the cold start running on mine about yours,

Tony,
You need to get yours on the dyno, would be good to see what sort of power yours is giving, your running a lot more boost than I am too!
Phil

Shaun and I have a few more tweaks to do first,
then it should be ready mate.
mines topping out at 5830rpm this is where the boost levels off and no more is being made,
But im happy its giving me 14psi

That's some impressive power figures there Phil, good work!

Coops wrote:Shaun and I have a few more tweaks to do first,
then it should be ready mate.
mines topping out at 5830rpm this is where the boost levels off and no more is being made,
But im happy its giving me 14psi

Sounds like your heads are maxing out on flow there Tony. Your engine should be capable of 7k rpm

It's the old debate about flow through a venturi. As the venturi (port) approaches its max flow you will see an increase in pressure but flow remains constant (or constant as near as makes no difference). While boost is good you still need to have sufficient air flow to feed the engine and what I suspect you're seeing is the heads not being able to flow enough air despite the boost, in fact it could be because of the amount of boost that your flow has dropped off.

It would be interesting to see if by reducing the pressure you moved the max flow point up the rev range and therefore released more power.

Rossco wrote:
Sounds like your heads are maxing out on flow there Tony. Your engine should be capable of 7k rpm
.

That might not be an issue for long cause according to another post some Merlins might come up for sale soon...

Rossco wrote: It would be interesting to see if by reducing the pressure you moved the max flow point up the rev range and therefore released more power.

That's what I experienced on my 3.5 running 12 psi with the roots blower It just stopped after peak power as the blower was robbing to much horsepower for the engine.
Went back to 8 psi with slight more bhp and more rpm as a result.

Dont want to hijack this thread but JP makes a good point about horsepower being soaked up by the blower.

I understand that changing boost on yours means sending the charger away for a pulley change. I've got a spare Vortech V3, the pulley is a simple thing to change. You wanna try the V3

Nice figures Phil