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There have been several threads on comparison of the early vs late 32-valve manifolds. Searching will get you the info - not many folks will want to start over on the discussions.
If you look at Porsche's specs on the various MYs . . . here: http://www.928s4vr.com/ then "resources" and "model info"
but those figures are just HP improvements year by year, and Porsche's numbers are subject to lots of considerations before they published, not the least, EPA regs for that year.
You are asking if someone has run a dyno on an S3 intake; then fitted an S4 to the same engine and run a dyno and compared. Could be, but I haven't seen that. If someone went to the trouble to do that, they were usu polishing and coating the intake. And looking for better #s based on changes they made.
There was a thread last week that showed computer modeling of airflow rates based on different shaped orifaces of intakes, and what was or would happen around the oriface. Heavy duty airflow studies. But I don't think he was building a new one, so it was all theoretical.
I have an 86 928 with an 89 S4 long block. I am using the 86 intake and computers on the 89 long block. It has dyno'd 275 rwhp, and 300 rwtq. with this setup. I'm not sure of the 87 and newer rear wheel torque and horsepower figures with the stock intake but maybe this helps a little?
I have an 86 928 with an 89 S4 long block. I am using the 86 intake and computers on the 89 long block. It has dyno'd 275 rwhp, and 300 rwtq. with this setup. I'm not sure of the 87 and newer rear wheel torque and horsepower figures with the stock intake but maybe this helps a little?
Are you using '89 heads with the '86 intake? How did those two marry together, given that the intake port shape is quite different? Photos and explanations would be appreciated.
Off the top of my head I'd say the 85/86 has hotter cams, much more detuned ignition and fuel brains, and the S4 a better intake torque and HP. Replace the 85/86 chips in the brains and performance is much closer, but the S4 has knock detection to be safer highly tuned, and replacing the S4 cams bumps it out ahead again.
Size of the intake doesn't tell the story, many early intakes were larger, but the modern intakes are very small and make the most torque and hp.
Off the top of my head I'd say the 85/86 has hotter cams, much more detuned ignition and fuel brains, and the S4 a better intake torque and HP. Replace the 85/86 chips in the brains and performance is much closer, but the S4 has knock detection to be safer highly tuned, and replacing the S4 cams bumps it out ahead again.
Size of the intake doesn't tell the story, many early intakes were larger, but the modern intakes are very small and make the most torque and hp.
Interesting, as I would have thought the volume and length of the runners of the early 32v cars would have an advantage.
Like an L98 TPI 85-91 Vette had torque vs. 92-96 Vette w/ LT1 had more hp. Compression ratio was higher on the Corvettes w/ the LT1, too, but the intake w/ short runners made more hp at a sacrifice of torque.
Actually, I've read (without seeing any actual proof) that the S3 intake is in fact superior...but I don't know if anyone has really proven it one way or the other. Since I have an S3 I'm partial to think of it that way...there has to be some trade-off for the fact that it blocks access to damn near everything...
ptuomov, I've not had the intake off the car, I bought the car with this setup. I had no idea until I did timing belt and water pump and the 85-86 tensioner was not correct. 928 Intl. asked me to verify engine year by the number on the front of the block and it turned out to be an 89 S4 block. I've been told that 86 heads will not work on an 89 block so i assume the heads are 89 as well.
I've been told that 86 heads will not work on an 89 block
They will work if studs from '78-86 block or shorter bolts from early S4 are used. It is possible to id the heads by checking some features in them. For example casting numbers might be visible even with S3 intake.
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How much difference in torque does this intake deliver?
