Does anyone have an idea of what hp/torque potential exists on a 2.5 head?

 

how fast do you want to spend?

the factory only ever got 152hp from the 2.5 8 valve head. i'm sure its capable of more than that, but they significantly enlarged the ports/valves when going to the 2.7 engine which made a whopping 10 more HP. under boost its a whole different story.

if you're going for max-effort power you can only get so much before it makes sense to use the 16v head.

 

I'd think that with modern engine management, high compression, a different cam and a lot of head work 175 WHP should be achievable.

Stock NA engines usually do around 120 WHP, give or take 10HP for year, DME, compression, etc.

 

The answer to your question is the 16v 2.5 head from a 944S, it flows about double what the 8v head does (300cfm iirc). This head and a little more compression is the reason that the S makes 188hp vs 152, the rest of the S motor is the same as the 8v except the pistons and intake.

 

How do you even answer that question.

Under what conditions are you going to put the head through?

your hp and tq will change through different cam profiles and intake runner length and plenum volume.
It'll also change with different compression ratios and fuel types.

 

It depends on the specs. The RoW 944 got a 10.6 CR, so the engine should have 163 fwhp, whereas the USA type just got 9.5 CR, which results in 150fwhp. Plus don't forget the different ECU settings.
If you get rid of the restrictive AFM, then it should be pretty easy to get 190fwhp out of the engine, provided you have a RoW Type. The cam Porsche engineered was made for emission reasons and that the intake creates a big enough vacuum to operate the AFM (barndoor) properly. That means pretty late intake opening/nearly no overlap. When the AFM is deleted I don’t see big obstacles to come close to the 190fwhp. Just doing the proven and tested head work, install a matched camshaft and fuel management. I’m working on it.

As for the 2.7L engine, this engine was obviously severely detuned. 165fwhp from 2.7L is a ridiculously low number, considered that Porsche calls themselves a Sportscar manufacturer. Even in 1973 Mercedes was able to pull 185fwhp from a 2.8L engine. Check out http://en.wikipedia.org/wiki/Mercedes-Benz_M110_engine
The camshaft of the 2.7L is different compared to the 2.5L type. The 2.7L was made for low down torque.

 

2.7L has the same cam as the 85.5+ 2.5 does it not?
the torque improvement from the displacement was a substantial gain.
i bet the real limiter on that engine is the AFM of course...would be fun to see what that does with a MAF.

i hadn't thought about the camshaft vacuum relating to the AFM door...big cam could be nice.

 

The camshaft is different, hence the numbers ...05=944/I; ...09 =944/II whereas ...10=944/2.7L. Basically the timings of the 09/10 are the same, but not the shape of the lobes, escpecially the intake lobe.

Some camshaft science. The lower the CR the shorter the camshaft duration sould be. But Porsche equipped all the engines, no matter if the CR was 8.0(Turbo); 9.5(N/A, USA); 10.2(N/A, 1988); 10,6 (N/A, RoW) or 10.9 (N/A, 2.7L) with basically the same camshaft (intake) duration. So if the above mentioned science is right, this means that the OEM camshaft can't be the ideal (universal) solution for all that different types of 944 engines. Particularly if you consider that a +4° camshaft key helps to improve the power output.
It appears to me that Porsche, in this case, just took what it already had in their shelves.

 

Wow. Great responses from everyone... I forgot to specify the 8 VALVE. But please continue to include info on all related configurations! Cheers.

 

have you measured the 2.7 vs 2.5 cams?

 

meanwhile I took my 2.7l motor apart (click link). But the installed camshaft is marked as 155 09. That's weird, the manual tells something about ...155.10. Probably the previous owner changed the camshaft some time ago.


Below is the camshaft with 15509 on it. Above is the 9R cam from a 1986 NA and above that the 05 camshaft from a turbo/early NA. Between 09 and 9R there are no significant differences visible.
But, as far as I know, on the 155.10 camshaft there was just a sort of smoothing technique applied. These smoothing routines lead to 'reduced jerk' which is actually 'lesser impulse' on the valvetrain and that means reduced stresses and lower valvetrain noise without diminishing the performance-related characteristics of that valve lift profile. This does not affect the camshaft timing. If you like, on http://www.profblairandassociates.com/RET_Articles.html you can read a bit about that and even more topics.

 

SO performance-wise there's no real benefit using say an 05 or 09 cam in a 2.7 engine originally with a -10 cam?

 

I think so, but as we know, 09 is a bit better than 05.

 

the ends = 1 big giant boat of kissing your sister and endless mediocrity.

*gutless should hurt.


















*not trying to post full turd/just putting it out there.

 

Headwork alone, idk.

Custom work on the whole engine, from internals to management, can net about a max of 275 fwhp.

No, I don't have the dyno sheets to prove it.

...........Yea, I'm that guy who randomly posts in these threads claiming these numbers. I'm sure no one believes it anyway, so whatever!