Sueden was nice enough to send me the cam lift specs for the 928. I think this will be enlightening:

 

Yeah, all that is available in the manuals too.

Remember my thing about hallways?
-If you open ALL the doors ALL the way, you can run from one end to the other at the maximum speed.

any one door that isn't all the way open, and you end up with a delay. Delays compound themselves- that is, their average delay tends to increase the more of them that there are.

Adding a Euro intake to heads that are not designed for them seems, in my eyes, to get seriously into this realm. A wide open intake that binds up with a head that has smaller ports and valves...

I suspect my S2's probable 270 rear wheel horsepower comes from its cams. The fact that nothing happens until 3000 rpm tells me this...along with the 13.8 second quarter mile times at 106 mph.

Have fun-

Normy!
'85 S2 5 Speed

 

cool. that looks like it would be better than what i started it out with . by the way, the 117 looks like the air tool bit i used with the air tool set up.

Ill have to buy a 115 for my dremel
mk

 

I think 928 specialist talks about using one damper and one fuel regulator( adjustable) in place of the two stock fuel regs.

dont worry about the o2 sensor. you want it hooked up for idle mixture regulation, and fuel mileage. however, it is not required. since you have it, I would use it. even with the regulators, the vacuum at idle pulls fuel pressure out , and it doesn matter anyway, as the o2 sensor fights to keep the ave mixture as lean as possible (hunting between rich and lean for an average around 15:1) without the o2 sensor, you run around 12-13:1 with a regultor all the time.


MK

 

So w/o the O2 sensor the mixture is perfect for the Euro setup all through the power band for now, I'm still going to get the set from 928 specialists.
I'm going to start pulling intake parts off my car tomorrow, and I was wondering somthing beforehand. When the runners meet up to the heads, the ports on the runners are bigger than the ports they meet up to on the heads? If so will that have any major affect on flow?
Is it a difficult task for the average mechanic to take heads off of a928?

Thanks
Cory J.

 

runners fit heads fine. good enough for our uses. heads do not come off easy!
Mk

 

not a great analogy, but there is some truth to it. the answer is, "it depends" there are pressure drops along the intake system. we dont know if the throttle body is the greatest pressure drop in the system, probably not, the AFM technically should be. however, even with that door partially closed (as you say), there are still pressure drops along the way to the heads. for example, put 8 throttle bodies on each intake port, and watch a 4 .5 liter scream!! (even with aneamic cams and valve sizes)
also look at those cam comparisons. euro 82vs84 vs US 79 or 82 are differnt, but they are still mild cams. there is not a tremendous amount of hp lurking there. however, the euro spec 84 was rated at 310hp with bigger valves, larger ports, and the entire intake sytem, plus 10% higher compression. us to euro was 242 to 310hp for 1984. how much of that was the cam is your question. it was everything. (but no headers) with headers, we have gotten close to the euro spec with the smalller valve, lower compression heads, and the 82 300hp euro cam. All going through a tiny AFM, but with a good set of headers. (lots of trade offs as you can see)
the top CIS part euro 5 liter engines are running 290hp . I built a 5 liter part euro that put out 290 as well. BUT, with the 2x1.5" AFM opening vs the much bigger CIS inlets or the euro MAF 3.5" unit.
Lots of factors here. Johns problem could be due to the exhaust system. we wont know until he changes and puts on a set of headers.

my US head 928 with euro intake and cams went from 200 documented hp to 243hp at the ground. I dont think that 43hp was all cams. also, we did an 82 that had JUST the intake. the dyno shows good hp and we saw comparitively more acceleration, faster throttle response, and it hangs with my S4 now, when my old 79 would smoke it. big change, nothing other than intake changed. John, didnt see the gains, but there could be a million other factors. in looking at that US throttle body, it was a clear limiter for the HP produced for the US. sure, the heads and valves are another factor, given that I was able to take the 243hp and take it to 292 with 300ccs more, and higher compression and bigger valves.

Mk

 

just an elbow as it (the U ) is not attached. then you just tap it, and fit any 90degree metal elbow to it. then, you can fit the part that you pull out of that press fit hole, and leave it attached to the breather hose and the new hose set up. you just cant go straight up with the breather hose off the U with the euro TB. it wont fit, without the microswitch housing removed. so, the elbow is the answer. Not a big job by any streatch.

Mk


[QUOTE]Originally posted by Weissach1982
[B]Mark- about threading the hold for the breather, is there a certain kind of fitting or pipe i'll have to buy in order for the breather line to fit?

 

Mark you said that ''we did an 82 that had JUST the intake. the dyno shows good hp and we saw comparitively more acceleration, faster throttle response, and it hangs with my S4 now, when my old 79 would smoke it''. Were the 82 and S4 both autos? Because my acceleration time on my car is around 8.1-8.5 secs, that is kinda slow but i know 928's weren't draggers. What do you think my times would be after the Euro intake only? But keeping up with an S4 would be great, seeing an old 4.5 keep up with that a 5.0 32V!
I have another question but its not about the Euro intake, its about my tranny. Is it true that the 3spd auto with the 2.75 ratio gets off the line quicker than the other auto 928s with 4spds?

I forgot to mention in my last post about fuel pressure. Being that my car runs open-loop w/o an 02 sensor, when I get my adj fuel pressure regulator and damper, what is the best pressure setting for power?
Thanks,
Cory J.

 

Mark- You deserve some total thanx for all of your support! The info that you've provided is invaluable-

B safe and Please Don't Convert To Any Other Sort Of Porsche!

N!

 

Yes I totally agree with Normy on your support, without it I'd sure as hell be lost! Thanks Mark.
Cory J.

 

I love to help anyway i can. this stuff is pretty exciting, but frustrating when things like what happened to John F, happen. I hope it is just a matter of the fact that he doent have headers , and just a stock exhaust manifold. if the manifolds are as bad as we all think they are, maybe its the reason, especially, with the type of cam profile the US cars have.

Generally, i always thought, they were independent. (intake and exhaust mods) all I can say, as I have so much empirical testing with 60-100mph runs in all my cars, i know when we have an improvement. generally, 12 seconds for a stock 84. modified with headers, 9 seconds. modified with intake and cam 7.5 -8 seconds. modified with 5 liter bottomend, 6.5 seconds. Stock S4 with headers and exhaust 6 seconds. 6 liter stroker stock, no changes, 6 seconds. stock S4 with headers and exhaust, and gutted !! 5.75 seconds. 60 to 100mph is a great test, as it rules out shifing and grip issues, and its a long enough time to compare. now, dont get a ticket doing it, but im sure you can find a place to do this safely. use a car phone and call out your speeds and time it later, or video tape , or just use a plain old stop watch.

we will certainly know a heck of a lot more when we do Scots fuel regs this weekend
mk

 

we are talking about scots 82 converted race car and my old converted race car 79. the 79 was faster than his for a long time, until he did the intake. we raced on the highway all the way to buttonwillow one morning 3 hours of 60 to 100mph all the way there. he was upset that my 79 was so much faster. we later found that he had his vacuum advance disconnected. (one problem) later , still the 79 pulled faster, and he has the headers. (cis vs Ljet) now, with his intake, advancing the timing a bit , he is much faster. my 79 was pretty fast. the reason Scots 82 is as fast as my S4 race car on the street was because of gearing, and i was carrying over 600lbs of track equip from the track when we did the test. the S4 slightly move ahead of the 82, but it was close enough to see the improvement vs before the intake.


gearing of the 2.75 will not be that great of a diff of the line. porsche keeps all the ratios pretty close in all models. even though you have a 2.2:1 vs a 2.75 in a 84 to 79 comparison, porsche changes the transmission ratios so the difference is much less. only 4 to 8% in most cases. the automatic makes the comparison almost unmeasureable

as far as the fuel regulator goes, the come set already at 15% more pressure. I think one full turn clockwise, will do the trick. R (rich) L (lean)

Mk

 

I keep following this thread with great interest.

A few friends of mine that have experience with 928's said my 81 feels tired, especially over 4k rpm. Its a 5-speed. I came out of turn 3 at Road America next to an automatic 84. We were side by side long enough to be even, I was in 3rd (I think) we raced down to turn 5. By the bridged (not even half way) he already pulled at least 2 car lengths on me. Speed wise I only know I was at 4k rpm in 4th when I braked before 5. 85mph speedo sucks.

i'm putting the newer style exhaust manifold on in spring along with a cat bypass. No smog testing here, no worries! Not sure what muffler yet. I'll run her wide open for at least one auto-cross just for fun.

In January I'm taking the intake off. Initially my intention was to clean it up. Have it powder coated and put a new emblem on it. While its off, replace any common wear items that will be easier to get at.

Mark (or anyone else), is there a list of what emmisions equipment I won't need on the car anymore? Also, with the intake and runners off, anything you would do to the car if it were in your hands? I'm open to any suggestions at this point.

Right now she's running wide open after the CAT, sounds sweet. I didn't notice any increase of power though. Didn't expect to, just wanted the noise level cranked up. Took her touring twice this year at Road America with the loud exhaust. Even my Corvette buddies were impressed, even though I wasn't going very fast.

Mark - I found a picture of your car at the IMSA Camel GT at Heartland Park Topeka race back in the late 80's in the full support gear. I'll scan it in when I get a chance.

 

I remember, when i had my 79, my car was really feeling sluggish. it would surge above 4k. found out when I put on the straight pipe and remove the cat, that the cat was all broken up in side. totally clogged!!!! after a 3" cat was installed, it was so so much faster, and accelerated smoothly.

As far as mods when the intake is off. if you are not doing a euro intake, there is not much to be done. the big gains are in the euro intake.

as far as smog, i pulled it all off. its not needed and its just extra weight.

the only gotcha is the air pump runs the mechanical fan. i would install an electric fan , and remove the mechanical fan. if you dont want to remove the mechanical fan, you can also use a different belt.

MK