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944 NA HP increase / How to be happy

Since somebody posted a "chip" question below I thought I'd roll out something I've been thinking about for a while. I've owned my '86 944 NA for 12 years now so I've had plenty of time to ponder this.

You can actually divide most "I want more HP" people into one of three categories:

1. People with the power craving. No matter how much they have, they generally want more.

2. People who like to tinker and are looking for a project.

Before I continue with the 3rd category, let me explain the first two and how each of these folks might be satisfied:

Power Cravers: There's a good chance you'll never be satisfied with any car and it's pretty definite you won't be satisfied with a 944 NA. Sell it and get either a 951, 968, or something with more power and less maintenance like a Corvette.

Tinkerers: Don't let Vulcan minds dissuade you; they don't understand you're not in this for the destination but the journey. The fact that it's hard to get power out of a 944 NA only makes you more attracted to the notion of doing so. The victory of achieving results will only be sweeter.

Okay, now for what I think constitutes many people (and myself). We post up messages asking about specific power adders because we think it's HP we're after -- it's not. What we really want is the engine to feel different. We want the powerplant's personality to match that of the chassis. We want an engine that feels like it wants to head for the hills and the curves. That bad news is that this is far more difficult to quantify than HP. The good news is that it's far cheaper to increase. BTW, the fact that most people spend a very small percentage of the time on the street at WOT should be a big clue that there's more to being happy than peak HP. Here are some things just about guaranteed to make you happier and transform the character of the motor:

1. Get or make the throttle cam if you haven't already. I drove a 944 without it and could have sworn the engine was breathing through a straw at light throttle inputs

2. Make sure your motor is in good running condition -- this sounds obvious but healthy engines seem 100% more willing.

3. Get one of the "proven" chips. In the 1980s Porsche was paranoid of expenses related to the 10yr emissions system warranty. As such, most of their US motors were programmed to run way lean to protect the cat at lower loads. In real life, this means incredibly "soggy" part throttle transients. It's like turbo lag on an NA motor. The chips remove that. Laggy reluctance is replaced with instant-on torque available with minor jabs of the right foot.

4. Don't be in a hurry when you drive (seriously). If you aren't pressed for time to get somewhere you won't get upset at not being able to shoot around other cars like they're standing still. Be in the right frame of mind to enjoy the car's strengths, not expose its weaknesses.

5. Install an exhaust with a sound you like. No joke. Speed is a psychologically sensation everywhere but at the track. An exhaust note you can hear which provides an aural answer to throttle inputs will make you a happier driver.

6a. Get a used airbox cover and grab 2-3" hole saw. Experiment with holes *on the sides* (the top is snug against hood insulation). Start with 1 or 2 holes and test the sound. Add more holes for more sound. Does it add any horsepower? Who knows (968 guys and C2/C4 guys have gotten results). But it definitely changes the induction sound and some people really like it.

6b. Wild version of above. Get a used airbox cover. Completely cut away everything but the frame. Grab some metal mesh metal and fashion a cover for the top of the air filter.

Speed and horsepower are really relative. There was a time when 150HP would have been enough to win the Indy 500. Driving enjoyment is not directly proportionate to the dyno numbers.

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86 944 NA
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09 BMW 335i 6MT
Old 07-19-2009, 11:16 PM
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Throttle cams are useless. They do nothing you can't do with your foot.

Cutting holes in the air box is a debatable modification which has been discussed elsewhere. All you really end up doing is sucking in hotter air from the engine bay than would normally be brought in via the inner driver's fender snorkel.

Exhaust systems can either gain or lose you horsepower. On an n/a the effect is negligible. On a turbo it can make a significant difference.

Agreed 100% about the "enjoy the car and drive it to its strengths" thing. Don't think for one second it's going to hang with today's performance cars that are 20 years newer and have more modern tuning, suspension, etc. It won't. Drive it and enjoy it for what it is. The 944 is a fine automobile sorted out. The n/a is one of the most underrated and underappreciated cars out there, IMHO. They can be an awful lot of fun.
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Old 07-20-2009, 06:13 AM
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If you want to improve the handling of the car, suspension modifications and new tires will add to the driving experience. We know by now the car is a slug off the line even with chips and the throttle cam.
http://www.dietersmotorsports.com/tech/2001/944_throttle_cam.htm

The car is best suited for the road. We get a rush when we see a curved freeway on ramp.

Replace or upgrade your bad rubber bushings and improve your suspension:
http://www.924.org/techsection/SuspensionPreparation.htm

GL & YMMV
John_AZ
Old 07-20-2009, 06:22 AM
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And check your ball joints and belts!
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Old 07-20-2009, 06:34 AM
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Quote:
Originally Posted by Porsche-O-Phile View Post

Exhaust systems can either gain or lose you horsepower. On an n/a the effect is negligible. On a turbo it can make a significant difference.


Removing the catalytic converter on a 944 and replacing it with a 'test pipe' section will increase horsepower and torque. (I want to say someone in 944 spec did a back-to-back dyno cat/no-cat and saw an 8 HP gain)...

Increasing the diameter of the exhaust will most likely result in only small gains in top end horsepower and overall loss in torque.

Increasing the diameter of the exhaust too much will most likely result in loss of power everywhere.
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Old 07-20-2009, 07:02 AM
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I find the easiest way to be satisfied with my NA is to have a slower car in the household. If your expectations are set by an economy car with a worse power to weight ratio and a slushbox, it's much easier to exceed them.

I don't think I'd enjoy driving with the "performance" throttle cam. When driving in bad traffic the extra control the stock came gives at low throttle comes in handy.
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Old 07-20-2009, 07:13 AM
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i agree with most of what's been said here, but there is more to the story on all of the mods - it's not as simple as "this does that"

airbox mods - reducing negative pressure is the key - whether or not a mod to the airbox increases power is entirely dependent on that - on the 968, using a K&N filter, the mod makes 11.8hp (about half that with the oem filter) - other cars may not see that much

removing the cat - a few things happen here that generally make for more problems than anything else - the emissions systems are tuned to the cat being there - removal may increase upper end power, but will cost low end torque and can ultimately cause other problems as it messes with the mixture

throttle cam - if the cable already allows your throttle body to open and close fully, the only difference would be geometry of the foot position - it won't add any power

chips - this is VERY car specific - chips are tuned to a particular car and condition when they are designed - different chips make different power, and get that power differently - one might do it with timing - one might do it with fuel - one might use a bit of both - you would have to know how they did it, and then try to determine if your other mods help or hurt that method - i did a chip shootout test on all of the 968 chips, and you would be amazed at the different results and why they were different

cat-back - again, this one is very car specific - a cat back could do one thing on one car, and something totally different on another, depending on what else is going on with that car - too big and you lose torque - too small and you lose horsepower - even the resonator placement affect things - so does the muffler design

the single best thing you can do for power is to make sure that your engine is in top condition - check your compression - there is a direct relationship between power and percentage of compression - you can bet that an engine with 100k on it is down at least 10% - that as much power as you would get from all the above mods combined
Old 07-20-2009, 08:20 AM
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I think that emissions/cat delete with a chip specifically tuned for use with such an exhaust would net a good deal of power and fun for those who live in states that can overlook those sort of things...

Sorry California..
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Old 07-20-2009, 09:55 AM
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Quote:
Originally Posted by Schumi View Post
I think that emissions/cat delete with a chip specifically tuned for use with such an exhaust would net a good deal of power and fun for those who live in states that can overlook those sort of things...

Sorry California..
It's no big deal. We have flanges here.
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Old 07-20-2009, 10:02 AM
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it would take quite a bit to build that exhaust, as measuring the gas velocity is difficult, but it probably could be done - you would probably have to reduce the primary tube diameter, and possibly even add anti-reversionary cones

i just put the factory cat back in on my 968 - i tried running without a cat, a hi-flow 100, 200 and 300 cell cat, two different double biscuit cats - all of them made less torque than running the factory cat

Last edited by flash968; 07-20-2009 at 10:05 AM..
Old 07-20-2009, 10:03 AM
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Quote:
Originally Posted by flash968 View Post
removing the cat - a few things happen here that generally make for more problems than anything else - the emissions systems are tuned to the cat being there - removal may increase upper end power, but will cost low end torque and can ultimately cause other problems as it messes with the mixture
The O2 sensor is located before the cat. The computer has no way of knowing what the exhaust looks like after it goes through the cat and so removing it will have zero effect on the fuel mixture (though your exhaust won't be as clean). The only impact on power/torque will be from reduced back pressure in the exhaust. I guess that could cost you some low-end torque for the same reasons a larger diameter exhaust is bad for the 8V NA engine, but it won't be because of the fuel mix.
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Old 07-20-2009, 11:08 AM
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Nice suggestions ScoobySteve, and I have to agree with you on most of these. I'm realizing this same thing with my 944 recently. So I'm focusing on getting the engine in excellent tune. It's hard to NOT want more when my daily is a chipped Audi 200 Turbo Quattro - super smooth power and turbo pull! But when it comes to corners the 944 chassis always puts a smile on my face
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Old 07-20-2009, 11:32 AM
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Quote:
Originally Posted by flash968 View Post
it would take quite a bit to build that exhaust, as measuring the gas velocity is difficult, but it probably could be done - you would probably have to reduce the primary tube diameter, and possibly even add anti-reversionary cones

i just put the factory cat back in on my 968 - i tried running without a cat, a hi-flow 100, 200 and 300 cell cat, two different double biscuit cats - all of them made less torque than running the factory cat
Bob, I know you have a penchant for actually testing your hypotheses. Can you give more detail on the results? Was it a loss of peak torque? Did your curve move farther up the graph? What testing methodology were you using?

I'd actually also be interested in the subjective feel. Unless I'm on the racetrack or being chased by aliens, I'd rather feel fast than be fast. Flat torque curves are fast, but they don't always feel that way. Sometimes giving up a little bottom end for high rpm "edge" makes you feel faster and rewards extending trips up the tach.
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Old 07-20-2009, 11:32 AM
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Yes, there's no power increase, just a different feel from hitting the pedal with a throttle cam...more "responsive" feeling.

A good chip (say 944 MAXHP NA chipset) will increase HP. Russell dyno tests all of his chips. I have the S chip, it does level out the power band, getting rid of the flat spot @ 3000-3500 RPMs.

Opening the exhaust to something like a full 2.5 inch will help top end, you may lose some bottom end torque if you go to 2.75 or 3.0 inch ID pipes. The test pipe idea is debatable, but as stated the O2 sensor is before the cat, so no rich running issues.

A nice sounding exhaust may make you 'feel" like you are travelling "faster"...as you are enjoying the sound you produce.

A good air filter is a help too.

All these things will increase your enjoyment of driving a NA 2.5 944...I think Scooby Steve made some valid points here.

A 944 was not designed for the 0-60 runs...it was designed for overall enjoyment of driving on curves, out braking and out-handling the muscle heads.
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Old 07-20-2009, 11:33 AM
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ScoobySteve, excellent observations and insightful post. A good post for newbs to read, too.
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Old 07-20-2009, 12:11 PM
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the O2 sensor is indeed in front of the cat - however, it still reacts to things beyond it - a quick before and after A/F reading will show this to be true - the mixture indeed changes - heck, it changes just based on cat-back restriction changes - it may or may not be enough to worry about, depending on a number of other factors

as for my testing, the process is usually on a dyno - sometimes it is in less accurate g-tech runs - the losses were different with each cat, and mostly down at 2.5k - 4k (where most driving is done)

again, this is on a 968, which is an entirely different animal

however, when i had my shop, we played with quite a few different cars, and the results were fairly similar - any time restriction was reduced, low end torque loss followed - the mixture also changed - sometimes it was worth it - sometimes it wasn't

the subjective "feel" issue is definitely there - a car might "feel" faster, but in fact be slower, or visa versa - it all depends on what is important to you

however, the biggest factor is going to be the condition of the engine itself - worn valves and guides will make a far greater difference in power and feel of that power than anything you could bolt up
Old 07-20-2009, 12:55 PM
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Good comments Steve, I'll add the one thing I did that made the car a lot more fun was the lighted flywheel. Car revs much quicker and feels quicker too. I've done a lot of work on the 924S but this was probably the most satisfying in terms of driving improvements, I haven't noticed any downside from the Alum. unit either.
Old 07-20-2009, 02:56 PM
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Old 07-20-2009, 04:34 PM
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+1. If there is any one upgrade I'd REALLY like to do, short of a 16v motor swap is run a Fidanza flywheel. The engine feels so heavy and slow to respond (and slow through 1st gear) as it is.

I love the throttle cam. I got it shortly after I got my car 3 years ago. Anyone that thinks it adds power is on crack, but it linearizes the low end throttle response very nicely and doesn't feel the least bit touchy once you get used to it. I HATED fishing for the right low rpms to match a 5th gear upshift on the highway. there's too much "space" down there, and combined with the mushy stock chip, it wasn't easy. I really like to do all the work, not make the clutch do it, so maybe for some it's not such a big deal. It really shines for rev matching and double clutched downshifts...stuff like that (I know...I like to take it easy on the syncros, too).

Russel's chips (944maxhp, or the Lindsey Racing 944max chip (same thing)) are awesome! That was the best thing I did to my engine besides changing the cam belt. It only gains about 3-4 hp max, but it adds like 15 ftlbs. of torque down around 2000-2500, gets rid of the plateau that stretches to 4500 rpms, and extends the usable power band from around 6200 to more like 6500 rpms (redline is 7000, but there's no power up there. It is useful for the occasional kamakaze merging operations where upshifting at 40 mph makes all the difference). I recently swapped my stock chip back in for a long road trip so I could run regular gas, and it really sucked after getting used to the 944MAX. I ran the MAX chip on the way back and it got nearly the same highway mpg as the stock did set -3% lean on the FQS.

I like the K&N filter mostly for the sound and the longetivity. The 944 NA has other more pressing restrictions than the air filter. The sound at WOT with the air box cover removed is to die for, though. I compromised and just removed the snorkel.
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Old 07-20-2009, 05:11 PM
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I did all of the above modifications mentioned to my 944 and after a few years still got bored of the power (or lack thereof). I'm the type who likes to constantly tinker on the car and after having not much else to do with the car for a while I decided to do the supercharger route. Currently I'm still in the final stages of the entire installation process, but I'm sure it will be a whole new animal when it's done. And aside from being a street driven car, I also compete in drift events and autocross, so I know I'll be using the extra power to its full potential.

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Old 07-22-2009, 10:23 PM
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