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1QuickS's Avatar
 
Join Date: Feb 2008
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944S engine performance

Apparently the 944S engine is limited to tweeking. A serious effort would include: increasing displacement, installing camshafts with overlap, replacement of hydraulic lifters with solid ones, upping the redline & installing ITBs with new engine management system.

Common 8V performance upgrades include:
  • MAF kit (not available for twin cam motor)
  • Performance chip (adds 4 HP to the 944S)
  • Tubular header (the tubular header on the 944S is somewhat better than the 8V header so minimal gain there)

Questions:
  • Can camshafts be re-indexed for performance enhancement & stay within the 6800 RPM redline limit?
  • How about milling the head to gain compression? What amount to remove & still use pump gas?

Last edited by 1QuickS; 02-26-2018 at 10:08 AM..
Old 02-26-2018, 10:02 AM
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no need to change lifters, no need for ITBs, upping redline will just spin a rod bearing faster. stock compression is 10.9:1, no need to up it anymore and compression gets you VERY LITTLE in terms of power the higher you go.

the stock 944S cams (and tune) are very mild for emissions reasons. putting hotter (more duration) cams in will really wake it up and you don't need to change lifters or springs.

look through the catalog for the 944S cams:
Web Cam Inc. - Performance and Racing Camshafts

next big step is to ditch the AFM and stock DME - there's no commercial MAF conversion but there are 2 plug-and-play MAP conversion aftermarket ECUs for your car...pulling the AFM out will REALLY wake up the low/mid-range of the engine.
more power all around is found thru tuning. the guy who does VEMS (below) got +30hp on a totally stock 944S2 engine just by ditching AFM and tuning it well.

Megasquirt (contact them to buy)
https://www.diyautotune.com/support/tech/hardware/diypnp/available-models/

VEMS (which I use and it is excellent)
https://www.stuttcars.com/part/2027/
Old 02-26-2018, 10:25 AM
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v2rocket is right on the mods.

One more trick to improve the 944S is to upgrade the intake to an S2 configuration. You won't gain a lot (10-15 HP) but that's the cheapest per HP you can get.

VEMS will also up the HP since you will no longer have the AFM, but you will have to consider visual smog inspections if you live in an area where it is required, or be sneaking and hide the goodies.

Webcam in Riverside can grind some good cams if you want to send yours out.
http://www.webcamshafts.com/

Don't forget that you are dealing with a 2.5 L block, not the 3.0 L S2 block, so that's another limitation of the S engine.

Last edited by Pauld_94S2; 02-26-2018 at 12:11 PM..
Old 02-26-2018, 12:05 PM
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I would think twice about intake swaps: S and S2 port matching
Old 02-26-2018, 01:26 PM
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Excellent! Mostly bolt-on stuff. I live in Salem, Oregon which does not require my car is smog exempt.

So, either MegaSquirt or VEMS replaces Bosch DME?

How about the AFM? It sounds like a replacement DME uses a MAP sensor and the AFM is removed. This would then leave the intake manifold with an air cleaner on one end and intake ports on the other, right?

Am I right to assume tuning of the system is a chassis dyno effort?

Last edited by 1QuickS; 02-26-2018 at 04:30 PM..
Old 02-26-2018, 03:29 PM
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And a couple examples of maybe so:

https://rennlist.com/forums/924-931-944-951-968-forum/981532-944-s2-intake-manifold-on-944s.html

944 Forum - 944S With S2 Intake Swap
Old 02-26-2018, 06:25 PM
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yes both megasquirt + VEMS would replace your DME, and yes with the AFM removed you could hang the air filter off the throttle body directly if you wanted.

VEMS will come with a spot-on tune out of the box and has the ability to self-tune fueling as you drive "fine tuning".

MS I think you will have to DIY a little more but not certain.

..
..
re: manifold swap and that linked post, the location of the 944S2 air filter box was a matter of convenience/fitment rather than any performance boost. there just was nowhere else to put it, to fit the redesigned manifold. the AFM flapper door in the way would kill any high velocity air coming in quickly at anything under WOT and ~4000rpm.

I happen to have both a 944S and 944S2 intake manifold handy and the runners are all the same length within about 1/2" of eachother, and the diameter and port size where the runners meet the head are completely identical. so "tuning-wise" the 944S and S2 intakes are identical for both peak power airflow (though the S2 should make it at a lower RPM than the S due to displacement) and torque-boosting resonance wave tuning.

my guess is that the switch to the 944S2 intake was based on material cost (mag vs alu) and service - the 944S intake was a really nice design but having the throttle at the very back and the long tube feeding it really makes maintenance frustrating...
Old 02-26-2018, 07:10 PM
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