944 2.5 mild tuning - Any ideas ?

[carl4x4]

I have a 924s (le mans) with the 2.5 160bhp 944 engine, does anyone have any experience with tuning this engine or is it best left in factory spec?

Different companies recommend a number of different things, I was looking at adding the following;

-K&N airfilter
-ECu chip
-removing the centre exhaust box to improve throughflow
-Possible replacement of rear box with s'steel box?

The car allready has the throttle cam replaced.

Does anyone have any experience with any of these modds or any other suggestions?

Many thanks.

[williamp]

Oddly I am writing an article on 944 performance upgrades for the titanic web forum and PCGB Porsche Post.

With the 2.5 non turbo engine there isnt a great deal. You could remove the balancer shaft belts and shafts (more power, but not as smooth), or lighten the car: rear seats out, passenger seat etc etc.

From other peoples experience, the exhaust and intake mods do very little: as then engine is now about 20 years old, they will probably replace the horsepower lost through age.

Chips will do a little, but its important to make sure the engine is fit and healthy to begin with.

Hope this helps

Will

[ian d]

i have a 924S, great little car for its age and technology.

what do you do to the engine to get the 160bhp for the "le Mans" version?
is it worth doing to get the extra 10bhp?
or is it best left original?

[iguana]

ian d said:

what do you do to the engine to get the 160bhp for the "le Mans" version?

Normal 924S engine M44/07 & 08- 150bhp
compression ratio 9.7:1

1988 924S engine M44/09 & 10- 160bhp
compression ratio 10.2:1 (same as 1988 944)

Previous to 1988 944s were 10.6:1, later 944 lux = 2.7 engine.

[carl4x4]

Ian,

The LeMans version was the ltd edition Porsche used to sell the last 900 or so cars, only around 35 came to the Uk in RHD I'm told. Porsche fitted lowered suspension over the standard S, Gas shocks, stiffer anti-roll bars, and 7 inch rims on the back, along with bucket seats.
I'm afraid I haven't driven the standard S, but reading Peter Morgan's book on the 924/944/968 I believe the stroke was altered along with a couple of other engine internals to bring the engine up in line with the 944. (not easy stuff to do!)

I'm getting the impression that apart from a freeflow air filter there's not much to improve the 2.5 lump without spending a fortune on it !

One tip for any 924s owners out there;
I've changed to design 90 wheels which are 16 inch and therefore give me a lower profile tyre than the old 15.
If anyone tells you that the 16" Boxster wheels & tyres fit, they do but not well. The fronts need a 7mm spacer to clear the hub which brings the tyres outside the arches, and the rears were too close for my liking.
The guys at Porsche-apart helped me out by trying on a number of different combinations before we settled on the 6" and 7" design 90 wheels. these also give you 205 width tyres over the standard 185 or 195.

[ian d]

many thanks, i've got 15" rims with continental tyres on mine. i think they are fine, with good grip/ride balance. i couldn't find a "le Mans" 924S at the right £ when i was looking. just had the car since march and really no complaints at all. first porsche so hopefully a nibble at things to come, maybe.

it is certainly plenty quick enough and spending £££ to get a marginal % increase in hp is probably not worth the effort on such a low budget car. check out some of DeR's posts (much respect for his machinery) he is going through the same dilema i fear.

however i have done some mods with exhausts on my old classic, although the top end is unchanged the acceleration is noticebly improved (honest) by fitting a big bore tube, with an estimated extra 20hp at the wheels. now a big bore stainless tube on the 924, hmmm.

>> Edited by ian d on Monday 5th April 14:15

[dogsharks]

Dorget the K&N. Take a look at this, and think about Porsche engineering. Do you think they really undersized the air box in a sporting car, and do you really think you can increase the power with one of these things, breathing hot air from the engine compartment???? Now look at the stock configuration; it has an air intake from a cold spot in the tire well.

Sheesh, K&N marketing has done a great job, but the power you'll get from one of these foam filters will never be able to be seen without minute precision instrumentation, if that. What can be seen with instrumentation, is the added amount of silica that will be ingested into your motor. Sad but true.

The only place I'd ever consider a K&N would be for the race track on a modified motor. I'd never put on on a street driven car.

I did in the past. I bought one for my 944 and the 928, and didn't notice a thing, absolutely nothing. Then one day I actually recommended a K&N to a friend on a 928 forum and the whole forum jumped my case, along with a few well known experts in the field. So you live and learn. I have a photo of myself holding a cigar lighter under a K&N, so you can see what I think of them. Expensive, no increase in performaznce, let more dirt in, and a heck of a lot of nype.

Dogsharks

Dogsharks

[dogsharks]

Well, guess there's no edit feature here. That's supposed to be "forget the K&N"

Guess I need to do a better spell check next time too, sheesh, even sighed my name twice

DS

[ian d]

very interesting. as i'm new to porsches. i guess it is the "big question",

how much do you spend in tuning mods Vs the % hp increase Vs the value of the car.

a connnnnundrum?

a quick question to those with the knowledge, how much % increase does the increase need to be before you actually notice it while driving?

i suspect anything below 10% is not worth the effort on low hp(<200hp) cars.

[carl4x4]

so the K&N is out then ;-)

More and more I'm getting the impression that by the end of it's life the 924s was a pretty well sorted car. The people who prepped last years winning 924 race series car told me to not mess with the exhaust as it may actually result in giving me less power. they said that Porsche original exhausts are very well designed. They didn't rate chipping it, and said I may not notice the difference.

One thing they did say was that the best way of getting a car to go round a track faster was to fit propper seats and harness. Apparently most decent sports cars are capable of cornering alot faster than your average driver dares, therefore when you throw your car into a quick left then right hander, you back off considerably more in a production seat than in a harnessed bucket seat. A combination of perception of speed and being thrown around in your seat apparently.

Ian - I too thought the original 15" wheels were great on the road, until I tried the car on the track and spent a fun-filled time squeeling round corners in a four wheel drift :-)

[Thom]

dogsharks said:

I bought one for my 944 and the 928, and didn't notice a thing, absolutely nothing.

I guess all you have left to do is buy a K&N cartridge for your S2
I have put one in mine and have actually noticed an increase of torque in low and mid range.
The cone is indeed not quite the safest choice but the cartridge is fine.

dogsharks said:

]Then one day I actually recommended a K&N to a friend on a 928 forum and the whole forum jumped my case, along with a few well known experts in the field.

I believe that's because 928 have the "hot wire", unlike the S2. Nothing better than the stock unit for the 928 as far as I've heard.

>> Edited by Thom on Monday 5th April 18:04

[interloper]

I'm suprised Dontlift has'nt added his two penneth to this thread. His lux is powered by a lightened and balanced 2.5 built by EMC, was'nt silly money and apparently its considerably more potent than the regular lump.

For performance gains of a different sort, you could try looking at the suspenion. I've just fitted a thicker rear anti roll bar to my 944, the improvement in behaviour from changing lanes on the Motorway to attacking hairpin bends is remarkable !

[Dogsharks]

Well..............I was going to buy one for the S2, ya know, I'd like to have a "race car filter" in it. I seriously doubt if "I" could notice the difference, sheesh, I don't even know what fork to use first.

There's a guy here in the US by the name of Pasha, a contemporary of Mark Donahue, and they actually rubbed shoulders a time or two, or perhaps traded a bit of paint. Mr. Pasha writes a tech piece for Panorama, the PCA newsletter, and consults on speed and performance issues for a variety of cars, but the 944 was always his true love.

He is a huge fan of tuning the chassis. In fact, he is a "balance" freak. For US cars, he recommends lowering the rear of the car as they are generally set higher than the front,due to bumper regs. He also knows which coilover and sway bar to use, and is especially keen on spring rates which are specifically selected due to the intended use of the car. You could learn a wealth of info by looking up his publications, which sadly, I can not reference to you at this time, but I did have the pleasure of hearing him speak in person a couple months ago here in Nashville at a dinner program. Now that I recall, I think I used the inside fork first, for the main course, then I took on the desert, and backtracked to the main course. I think I actually interchanged forks during the dinner for no apparant reason, :-)

Regards, Dogsharks

[Dogsharks]

Here's an article from Jim Pasha, you don't wanna ask this guy about K&N air filters.

Happy reading





http://dspace.dial.pipex.com/town/pipexdsl/s/asco96/944t/SuspensionPreparation.htm


Dogsharks

[ian d]

what a great article. please excuse my ignorance but who is he?

reading it i think i will investigate the "low budget option" to level the car, maintaining the current ride height.

another question, what is the ISBN code for Peter Morgan's book on the 924/944/968?
clearly it is required reading for an owner.
found the code for those interested: 190143205x

>> Edited by ian d on Tuesday 6th April 16:52

[Thom]

Dogsharks said:

Here's an article from Jim Pasha

Good read, thanks.

There is just a couple of errors/intervertions in the suspension grid.
(Here's mine, for what it's worth ...)

[carl4x4]

An interesting article, although I think most of the stuff he mentions has been done by the factory on the Le Mans car I have.

One question though, Do you guys use any old tyres at trackdays, or is it important to have matched sets?

[diver944]

Carl,

I use full slicks available from Silverline tyres in Warwick or Hutchison Motorpsort. If you buy at the right time of year you can pick up 16" sizes for around £80 each.

They grip like stink, last a heck of a lot longer than road tyres and mask poor driver ability very well, than you very much

A set on scruffy spare wheels fit in the back of a 944 perfectly, and if it's a wet day just use your road tyres.

[carl4x4]

slicks eh? I was looking at getting either some toyo proxes TS-1, Yoko A539's or some Kumho KH11's which a friend uses on his Elise (he reckons they're cheap & great!)

[Dogsharks]

To answer the question "who is Jim", he is a guy who has tuned and raced cars most of his life, includig LeMans efforts and many other road racing venues in the US and Europe. He writes articles for Panorama, the Porsche Club of America's monthly newsletter (actually a book) and Excellence magazine. He's obviously extremely familiar with the 944 chassis, but he's also consulted on many other racing efforts, including cars he's driven personally.

An all around great guy, full of great stories and good information. Contrary to many automotive journalists who actually don't know which end of the wrench to use, this guy really has the hands-on experience.

Glad you enjoyed the article

Regards, Dogsharks