924Board.org

[mantise]

hi i had a question what is the best way to increase accelaration on a 924s 1988 automatic. my car runs like a bullet but got beaten by a 97 volkswagen getta in acceleration. so what would be the best perfermance upgrade to increase accelaration. thanks in advance guys

[edh]

less weight, smaller tyres
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current - '90 944S2, '00 986S,
ex - '90 944 turbo '86 924S, '88 924S

[gohim]

Get rid of the automatic transmission.

The automatic transmission is soaking up about 20% of the hp output of your engine.

The Jetta actually weighs more, and has more hp (if he has the V6) than you have with the 2.5L 944 engine and automatic transmission.

[ESC944]

After you loose the AUTOMATIC add BOOST!

[CBass]

Switching to a 5 speed transmission should make your car considerably faster.

You can add little boltons to the motor such as a header, cold air intake, aftermarket exhaust, chip, etc, and see little if any gains, for a great deal of expense.

Since you have a 924S, any 944 or 968 engine is a simple proposition to swap in. Find a 3.0 DOHC motor from a 944S2 or a 968, clean up the head and throw in some cams and a header, and you'll have one serious quick little 924S. A 951 engine would also bolt in. There would be some minor wiring differences, but this sort of thing has been done before with 944's, which are essentially the same as a 924S.
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'81 931 in various states of assembly

[Min]

Just a note, no engine swap is a 'simple proposition' .... I strongly recommend against that upgrade path. Cbass just makes it sound so easy.

Min

[Llamaguy]

Has anyone try nitrous? I'm thinking about it but I'd have to find a universal kit for about $300. I don't really want a huge increase, just the 50 shot or possible the 75. I saw the "sneeky pete" kit that looked good, said it fits in a briefcase and is removable, but it would only be enough for one or two shots.
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1987 924S Guards Red
1997 Suzuki Tl1000 Supersport

[Helstrm]

[ESC944]

Ok bottle size has nothing to do with how much HP you add. Its about the jets and nozzle.

You can run dry or wet. With an EFI setup and if you had a way to increase fuel when you injected the Nitrous you could go with a dry setup.

The best setup would be simple, bottle, 2 solinoids, one for fuel one for Nitrous, tap fuel line, run nitrous line to a single injector that blends the two together or two injectors place the fuel down stream from the nitrous, you want the nitrous to spray at the fuel and mix with it as it goes into intake. Get best mix.

Simple I can set it up in a few hours, so can you. You just need the parts.

Jet size, either at the injector or at the solinoid determines how much you are injecting when you hit the button or trigger.

I prefer to install the jet at the solinoid and that makes the injector a simple affair, nothing expensive or complicated.

You would want the mix injected into the intake stream as close to the TB as possible to ensure adequate distribution between all cylinders. Its not an exact science.

I use small bootles usually, since I rarely use nitrous and I like to conceal things. Anthing from a 7 oz to 20oz is fairly small, although anything over 12 oz does start to get fatter(wider). So you jet it for 10, 15, or 25HP, thats what I have run on the 944. Even a 10Hp shot can make a difference... depending on when you use it, you can use it again and again, as long as the bottle last, but you should give the engine some breathing room in between shots.

I have never been a huge fan of nitrous, but it can be fun to play with.

Remember Nitrous doesnt make power by its self, it lets you burn more fuel.

Of course in my opinion you are better off with boost, cost more to setup, but their is no bottle to fill, and you underdrive a supercharger to keep boost low or even use other means to control boost, same with a turbo...

You will find that at 3 PSI you see significant gains and almost zero risk to the engine, all the way up to 5 PSI, in fact on the 944, I have seen her run fine with just alchy and water up to 5 PSI, but that is marginal... she starts to run lean, bad buisness. With the CIS setup on the 924 well your in good shape.

heck even compressed air injected into the intake can generate positive boost, provided you configured it right and any positive boost will result in more power, just got to have fuel to go with that possitive boost.

Heck the big three built quite a few land speed cars and drag racers using compressed air for boost and made some insane power, so much so that it was banned from competition :under the guidelines that it was unsafe... hemm go figure.. compressed air vs. nitrous... which is more dangerous.

Not to get off track, but a quick study of pneumatics offers up quite a few cheap home brew solutions for just a little more power... but what do I know?

As for engine swaps... well before I would go to the trouble of swaping in something like a 3.0 or a 951 motor, I would just build what I have.

An engine is an engine is an engine. More fuel and air, more compression, more displacement, boost, all simple solutions compared to an engine swap.

Cost is the only thing about owning a 924, 944, 968 or 928 that typically discurages modification. I say think outside the box. As you can see if you look at the various posts over the years, you can use parts from different engines. Think of it as more of a hot rod that is just waiting to be woken up and less of a german sports car.

Offset grind the crank, use some other pistons and rods, massage the head, or use a 931 head or something else.. if you can figure that out. Build a motor that breathes or help it breath.

I prefer starting with a 931 engine, better internals as far as the 2.0 goes. Deal with machine shops and other locations that dont care if its a porsche, so you dont pay porsche prices.

Now back on to the 944... you can build a stroker using later model cranks and bore engine slightly, thermal coat the parts, build a hybrid 924S/951 motor and add some boost. Of course this has been beaten to death, most people will tell you its cheaper to buy a different car, since you have two strikes, one its an auto and two it didnt come from the factory with a turbo.

Purist will tell you with some sort of cult reverence for the porsche not to do anything radical to it, sell it and upgarde to a later 944 S series, or the turbo model or a 968 and modify that.

IF you are looking to hot rod your car and have experience hot rodding cars, well its a CAR, figure out what you want and go for it.

The trans swap will make a serious difference, but its some serious work, not for the inexperienced. And forget paying to have it done, unless you have money to burn.

The real short comming in the car is the limit of its components to handle more power, that is even if you can get more power out of the car and hince go faster, their is only so much the transaxle, especially the automatic can take before it goes south on you.

Put the car on a diet, that helps quite a bit, run with less fuel even in the tank.

KEEP in mind you car isnt built to shine in all out acceleration or drag racing or going in a straight line. Change the discussion to the track or curves and its a different ball game, although you will always take a hit using the automatic, it wasnt the best design and go luck finding parts when it does give up the ghost.

Heck if you want a super fast car for going in a straight line, then lose the transaxle and the porsche engine, drop in not only a V8 or some other more powerful engine, but also a live axle and transmission, be great for going in a straightline, heck build a drag car, toss in a ford 9" or some such, and of course the v8 and trans and their you go... great for all out acceleration or going in a straight line... but I dont think thats what you are going for.

The 924, 944, 968 are balanced cars, not just in handling but in overall design. They have their limitations.

Their are things you can do to increase performance, engine mods, suspension, etc... but it all cost money and time. I am not trying to discurage you from making modifications and improvements, I encurage it. Just keep in mind its not a muscle car or a hot rod, it can be hot rodded, in the spirt of that you can modify it... you just need a plan, money and time.

Decide what you really want, do the research, plan and execute...

Keep in mind in most cases, these cars do not give huge gains for the more basic investments.

I think that two of the biggest limitations is the Engine management system and the engine design, you improve on both... many have, but its never cheap when you include the word porsche. So avoid Porsche based solutions....when you can.

Look at the serious 944 turbo guys, they spend truck loads of cash on parts and they get serious performance, their modifications come from established sources, but they pay through the nose, becuase the parts are dedicated porsche parts.

Step away from that and you can save some money... For example you can get a supercharger kit for the 2.5 liter motor, but be prepared to pay over 5k for an entry level system you could build for less. But that requires skill, knowledge and the will to do it.

You should look through the archieves and also check 944 sources for performance tips on the 2.5 liter motor.

[ESC944]

Here is a thought:

If you could get a 924 turbo (931) motor and trans, install that. Gets rid of the automatic and give you more power. The 931 motor is cheaper to maintain and can easily reach 944 turbo levels with basic modifications.

Of course as I mentioned their are loads of other choices and that is strictly a porsche based solution... but rather cheap, if you are switching from a an auto to manual... or stick just changine to a manual and enjoy some spirited driving.

[-nick]

No offense, but you want to suggest to someone to install a 931 drivetrain in an '87 924S? How exactly would fabbing up engine mounts (where there are none), adding an entire CIS injection system, dumping the Motronic and rewiring the entire engine bay for the 931 ignition, be more cost effective than just buying a 931 (or 951 for that matter)? That's a ridiculous undertaking for anyone. Sorry to be so blunt, but you have to be joking?

Short answer to the original question- you will spend a significant amount of money to make even slight acceleration improvements to the 2.5L engine. Nitrous appears to be the most cost-effective method, but few seem to mess with it.

If you just want to drive a fast car, then buy one. If you like to tinker and spend money (they aren't separable!), then the sky is the limit.

nick

[ESC944]

Nick, first of all yea I am only half serious... mostly joking about the 931.

I SAID HERE IS A THOUGHT... I never said ok go do this! Or this is the best thing to do, my previous post offered some possibilities and advice about not listening to anyone tell him what to do or not to do or accept that just because its a porsche you can improve on it.

I take no offense to anything anyone says, unless its tell someone that their is only one way to make more power or that you have to loose what you have to get what you want. Or sell your car is a POS get one with a manual oh and you want more power sell that slow thing you own and go buy the 931 or the 951 or some such. Please! Give me a break thats so old. Sounds like the list more than something you should see on here.

I did not say it was cheaper, read a little closer their bud. I said its cheaper to maintain. And who said anything about the CIS? I said the engine and trans... would be cheaper to maintain... gessh. But again only half serious, as in sarcastic, makes about as much sense as telling him to swap in any other engine.

Go back and read my larger post... their are tons of options to go faster. Little bolt ons may not add up to huge gains, but you can build up to something nice, besides NA mods work well with a supercharger, let the engine breath better in and out and you wake her up.

Suggesting the 931 setup makes about as much sense as telling someone to swap in a 951 setup, sure lets grab a different engine, swap out the mounts so you have the support for the turbo, change the radiator, etc... get the engine in, then you have to install both the DME and KLR and all that. Just not easy solutions or cheap, especially not a 951 trans. For the average cost of a 944 turbo trans I can build a supercharger setup, add a MAF instead of the AFM, tune, add IC, water injection, dyno the car and still have money for a shake down road trip.

Of course you can build a stroker, etc... my point in all this madness is that sure of hand you can suggest change the trans, change the engine, blah blah,

How about just go lighter and add some more power. Simple and direct.

Of course the Auto trans is limited in what it will tolerate for power, but if you ran 5 PSI of boost, sure a manually powered car would be better given equal levels of power, but 5 psi is still 5 psi.

As for motor mounts so? Oh Please, you can building anything with a welder raw materials and determination. We are not talking about moving the fire wall adding a tube chasis and dropping in a 928 motor. <-- Again only half serious. If he has an engine and trans handy then great, go for whatever floats your boat and that you can tackle on your own.

As for rewiring, screw that. You dump everything porsche, in my other post I said one of the limitations to these cars is the engine control. Their are a lot of cheap solutions their as well. Mine, others, etc... piggy back, stand alone, etc.

I also didnt tell him to sell his car, I said others would say that.

How about you dump the trans and use a different Transaxle setup... their a thought... hemm lets keep it automatic, lets go get a C5 Automatic, we can fabricate a custom torque tube, with gm on one end and porsche on the other end, then modify the vette axles to work with the stock porsche rear hubs and their you got a bullet proof automatic that would proably spank most stock manual cars provided you have the power. You even pickup more gears and better gearing, cheap? Nope sure isn't but its radical and different. Do able sure... biggest hurdle is fitting the unit, fabricate some tubular crossmember to hold it in place. It isnt much different in size by the way!

So to answer his question, to improve acceleration, well to go faster go lighter and add more power.

Use a better throttle cam, to give better response. Do the simple stuff, better exhaust, header, etc.. Custom chip, etc... other things would be loose anything that isnt needed to shave some more weight.

Got a little more money, swap on a MAF with a chip that works. In fact I would get everything together and do it all at once, let Danno over a guru racing know what your plans are and he can set you up with a chip.

You can wake up the head and intake as well, anything that would work on another engine will in most cases work on a porsche, provided something else isnt holding it back, like the engine management system or intake or head restrictions.

The engine isn't the best it isnt the worse, it just doesnt show huge gains from little improvements, it wasnt exactly undertuned from the factory.

Most cars coming out now a days are not tuned for performance, they make reasonable power and are tuned with the idea that some idiot will own them and never get them properly serviced, so they are setup to perform under those conditions.

SO:
--- Automatic or no, more power makes a difference, to optimize improvements a manual is a better way to go, plus the automatic imposes more of a limit in how far you can go with power than a manual.

--- I say lighten the car, add some more power and drive it, when and if the trans lets go, its not like rebuilding or replacing the auto with another auto is even a possibility. Thats when you swap to a manual.

Their are a hundred suggestions of what will and will not make power on a 2.5 engine, I saw look at the people making power and see what they did, figure out a way to do that simply and cheaply without name brand parts.

Its amazing what you can do if you stop looking at your engine as porsche and start looking at it as a engine, just another engine with its own weak points and strengths, exploit the strengths and work around the weaknesses.

[ESC944]

Nitrous is a cheap solution and works well. Few porsche people mess with it cause a mistake gets super expensive.

I think you have to look at what you can go and group things into two lists:

FIRST list is what you can do to your already running motor and have it continue to perform without a rebuild. You are limited in what you can do, even with boost. Especially with a stock head gasket in place, not to mentione the timing chain etc...

SECOND list is what you could do if you are going to do a rebuild. If you are building a motor their is a lot more you can do to get more power. Even if you kept the motor stock, you could thermal coat the pistons and other parts, this would let you raise the boost level, yes even on a NA motor. You are still limited in what the stock non-forged internals can handle, but my 944 has run up to 12 PSI on stock internals on a 84 NA motor, no rebuild, just new performance head gasket.

Can you run that kind of boost on every motor, cant say, I think anything over 8 PSI on a non-modified NA is pushing your luck.

[Mavfan]

NOS is the best way to go, i know. go check out my main website in my signature. my car is essentially the same except with a manual tranny. right now a 75 shot (the highest you can go with a 4 cylinder engine) is in there, and it all has to do with the nozzles, not the tank. if your only going to get 2 or 3 shots from that one bottle you talked about, then nos isn't even worth it, i have a 15lb bottle that holds 10lbs of nitrous. if i kept it on continuously it would stay on for 3 minutes, so if each use is in the teens, then you can see how this will last a long time. so visit my website or visit the post i have set up where people have commented on it.

http://www.924board.org/viewtopic.php?t=15394
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Black 1988 924S SE
Red 1985.5 944

http://mavfan72.tripod.com/
http://www.cardomain.com/id/mavfan

Video:
http://video.google.com/videoplay?docid=-5193982457901018136

[CBass]

Nitrous is a good choice for racing or for freeway onramps I guess, but it's not really sustained power.

As for putting a 3 liter or a 951 motor in the car, it is a pretty simple proposition granted that you have everything you need and you make sure you learn everything you need to know to do it. Keep in mind, as far as the engine mounting and wiring goes, an '83 944 is largely the same as a '90 944S2, and a 924S is pretty much an early 944 mechanically.

Physically, the engine bolts in. Best approach is to take the entire drivetrain assembly, from engine/clutch/driveshaft/transmission and swap it in. All you really need is to find a wreckers.

While buying a different car is always a good bet, often people end up becoming attached to one particular car, for one reason or another, often because they have an awful lot of money and time invested in that car that they know they will never get back. Telling certain people "just buy a different car" can be considered condescending and even insulting. I can't tell you how annoyed I was when discussing building up a V8 RX7 as a street/strip/autoX project, and a number of people said "just buy a camaro!", or "just buy a turbo RX7!". Sometimes ya gotta have it your way
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'81 931 in various states of assembly