Mark McClure

Recently I upgraded my 2.7 for a 3.0SC with an Injection Perfection injection system and a Microtech computer and RSR twin plug heads. The engine was used in the Porsche cup here in Australia. The guy said it was a 240hp engine. It has just been on the Dyno......135hp tops...at the rear wheel. Is this good/bad/terrible?

911SOUK

That seems low. If you assume a 15% loss of HP between the crank and rear wheels, you would see only about 158.8 HPs at the crank.

Mark McClure

<a href="http://boards.rennlist.com/upload/jpmotor1.jpg" target="_blank">http://boards.rennlist.com/upload/jpmotor1.jpg</a>

A picture of the motor in its previous car.....looks interesting! drives only slightly better then the 2.7 I had in. What sort of figures do other people have for HP at the rear wheel.

Cheers

Mark....

Adrian

Dear Mark,
Me thinks there is something terribly wrong here. A 240HP motor should deliver to the rear wheels circa 210HP. 135HP is a 44% (105HP) transmission loss.
Ciao,
Adrian
911C4

JBH

Yep - that is way off the mark for a 3.0 liter engine. A stock SC engine puts out 185hp. I would start looking at the fuel management system to ensure it is delivering what you expect.

Mark McClure

Thanks guys.....so a 3.0 should put out 185 at the crank or the rear wheel? Is a 15% loss or greater expected? What is considered to be unacceptable?

Cheers

Mark

JBH

15% loss is sort of a rule of thumb.

But I suspect you have an engine capable of putting out quite a bit more. You don't change out the fuel system and go to twin plugs unless there are other modifications to the engine intended to put out more hp. I would expect that you have a higher than stock compression ratio and a more aggressive camshaft.

What do you know about this engine? What kind of header/exhaust system is on it? A free flow system will give an additional 10hp. You need help in finding the source of your problem - I expect it will be well worth it.

CamB

To add to what has been said already, I'm getting a 3.0SC engine with 9.5:1 pistons, ported twin plug heads, early s cams, 40mm throttle bodies and (older model) MoTeC injection which I am promised should have about 250hp. Exhuast is SSIs plus 2 in 1 out.

Thus for you 240hp is not out of the question (if you do already have other stuff, like higher compression and a camshaft change), and should be 200-205 at the wheels (I have a dyno reading showing 12% loss for a 901 gearbox, so 15% is probably about right).

135hp at the wheels indicates something is very wrong - is it pulling smoothly? Does it feel powerful????

Ed Bighi

135? Something is definetely wrong. My sc 3.0, which is stock with the exception of my own muffler and cat bypass puts out 178hp to the rear wheels. And it has 210,000 miles in it. There has got to be something going on there. Go dyno it again somewhere else maybe.

PelicanParts.com

That is terrible. You didn't mention what injection system that you're running. Also, why the twin-plug? High compression pistons in there?

-Wayne

Chris Martin

It might be a case of the engine just not being tuned correctly. With the injection you mention you might need some dyno time to dial it in. Assuming the timing is close and the cam's are timed correctly, you could just be suffering from bad fuel maps and so on. You might also use this time to tune the exhaust, once you get away from factory fuel/ignition management you really need to tune it correctly.

Best of luck

Mark McClure

Thanks for everyones input....To add abit more detail the cams are specials and the compression has been raised. When the guy put the engine back together he said that he put the cam timing in the middle? mentioned that either side of this would give either better top end or better acceleration. The other thing is the injection/ignition system is set up for TPS (throttle position). It does not use the sensors. I think that the O2 is missing.

I am getting hold of the wiring diagram and talking to the guy who originally built it to see how it was setup.

After the dyno session.....it does have a bit more power....hesitates at pickoff and has a huge flatspot at 2K......Oh yes and I need a fuel tanker to follow me to keep it topped up!