PCA SDR

Had great access to a dyno last week and learned a lot. My car did many pulls, sadly peaking at 123.1 RWHP. I guess the 250K miles with no internal repairs is finally starting to take their toll. Guess a rebuild is in the not too distant future.

The learning occured as a result of the exhaust system. It is MSDS header to 2.5" tubing through a magnaflow resonator and ending in 19" supertrapp resonator. Car has an FR Wilk chip and a K&N air filter, all the rest is stock. Peaks all were 6000-6100 with the curve droping like a stone afterwards. With the cap off and no restriction HP was 123.1 torque 127. With 6 diffusers and endcap on, HP 116.4 and toque 123. With 12 diffusers and endcap HP 121.6 and torque 125. Mixture remained fairly consistent and well within acceptable ranges in each of three different configurations. And the shape of the curves is pretty consistent as well.

harnishclan wrote:Had great access to a dyno last week and learned a lot. My car did many pulls, sadly peaking at 123.1 RWHP. I guess the 250K miles with no internal repairs is finally starting to take their toll. Guess a rebuild is in the not too distant future.

The learning occured as a result of the exhaust system. It is MSDS header to 2.5" tubing through a magnaflow resonator and ending in 19" supertrapp resonator. Car has an FR Wilk chip and a K&N air filter, all the rest is stock. Peaks all were 6000-6100 with the curve droping like a stone afterwards. With the cap off and no restriction HP was 123.1 torque 127. With 6 diffusers and endcap on, HP 116.4 and toque 123. With 12 diffusers and endcap HP 121.6 and torque 125. Mixture remained fairly consistent and well within acceptable ranges in each of three different configurations. And the shape of the curves is pretty consistent as well.

Brian:

If you take the "rated" HP at flywheel of a 944 and calculate out the roughly 15% drive train loss, you come up with about 126 RWHP. So, 123HP and 126HP ... I'd say you're about right where you should be. Of course, someone more techie than me might tell you otherwise. I don't think you're really missing out on any power per se, and it shows how long-lasting those 944's are.

I've always believed a 2.5 944N/A to be around 125HP to 129HP at the rear wheels depending on air temp, tire and wheel configuration, etc. That was my experience with the "great white wonder" ... which had about 230K miles on it, too.

"Typical" 944 N/A engine should have 129-138 at the rear wheels depending on environmental variables and early vs. late engine from all the information I have been able to gather in total stock form. I was hoping to be a little closer to that range, but the real surprise was the difference in the exhaust. All the marketing for supertrapp says increased torque with the cap on due to backpressure. But there was no appreciable difference in torque across any configuration, only the HP changed. And while 8 HP doesn't sound like much to most, that is about an 8% change for my particular engine on that particular day which is a lot of change.

harnishclan wrote:"Typical" 944 N/A engine should have 129-138 at the rear wheels depending on environmental variables and early vs. late engine from all the information I have been able to gather in total stock form. I was hoping to be a little closer to that range, but the real surprise was the difference in the exhaust. All the marketing for supertrapp says increased torque with the cap on due to backpressure. But there was no appreciable difference in torque across any configuration, only the HP changed. And while 8 HP doesn't sound like much to most, that is about an 8% change for my particular engine on that particular day which is a lot of change.

Not sure what you are saying here: HP is simply torque times RPM, so the only way to change HP with the same torque to rev higher.

Torque X RPM divided by 5252 = horsepower

harnishclan wrote:"Typical" 944 N/A engine should have 129-138 at the rear wheels depending on environmental variables and early vs. late engine from all the information I have been able to gather in total stock form. I was hoping to be a little closer to that range, but the real surprise was the difference in the exhaust. All the marketing for supertrapp says increased torque with the cap on due to backpressure. But there was no appreciable difference in torque across any configuration, only the HP changed. And while 8 HP doesn't sound like much to most, that is about an 8% change for my particular engine on that particular day which is a lot of change.

Interesting. I'm not sure where you got your numbers, but I was only working on the 1987 year engine, so my info was a bit limited. It just seems that 138 at the wheels (roughly 159 at flywheel) is a bit high except for maybe the 2.7 or S engines. Again, I'm no expert. As for Supertrapp's claims ... well, that's marketing, right? I'm not sure how much work Supertrapp has done with 944N/A's

what I do know from countless resources is the 944N/A comes "out of the box" with as optimized an engine as Porsche made at that time(regarding water-pumpers). All the shops, tuners, and anecdotal info I got said the same thing: you're "optimized" now, go drive the thing.

I tried a chip. Nothin'. I tried different exhaust systems . Nothin' (Just pi$$ed-off the neigbors). I tried cat on and cat off. Nothin'. I tried playing with the Motronic rich, mid, lean settings. Nothin'. I tried fuel and oil additives. Nothin'. I tried air-boxes. Nothin'. I could have tried an advanced cam, but would have never passed smog, so nothin' doin'. I tried lots of things... all $$$$$$$, and no improvements.

Based on your exhaust experiments, you may have found that "improved" exhaust systems gave you ... well ... er ... nothin'.

I don't want to sound too cheeky (I'm just trying to be entertaining), but I really don't think there's much you can do to optimize your HP (from an engine point of view) without tearing down the engine, and starting from scratch with some very, very expensive parts (titanium rods, Mahle pistons - modified .... skirted or whatever, modified crank and cam, polished and ported head, larger intake valves, different crank and bearings, lightened flywheel and clutch assembly, ad nausium). And from where I stood 18 months ago, I couldn't see building an 8, or 10, or 15 thousand dollar engine for a ... a .... how shall I say this ...... ah, yes ....... a budget-based sportscar that weighed in at over 3000#. I even had an opportunity to drop a 1992 944S2 engine in my car for what could have been fairly reasonable (less than $5K), and opted out. Yeah, a 212HP (about 180 RWHP) engine. I don't think gains in speed will be in the engine. It probably lies in parts originally designed as a touring/cruising/entry-level street car that can be switched for higher performance driving (suspension, brakes, etc). Seems to me you've already done most if not all of that.

Again, I didn't really see the benefit of it all for a 944N/A. I know, you've heard this before, if you want a truly powerfull 944 get a Turbo (951). Yeah, I know you're sick of hearing it. However, the fact that N/A944's are still so cheap ... sorry ... inexpensive, and their optimization has pretty much already been done, I'd have to reiterate the value may be in looking into other parts of the car for improving speed. Lightening the weight, and improving the brakes (which are also faily optimized from the factory). If that's been done, well ... I think you're done for now.

On the otherhand, if you start finding more performance with bolt-on and other "mild" optimizations, I'll gladly observe and learn. So, I don't want to discourage you from trying. I just don't want to see you as frustrated and penny-punched as I was. Also, you might talk with Ralph Linares, Jad Duncan, Jerry Mize, Doug Briggs. These guys all know 944's very, very well. They've owned them and worked on them for years. They taught me heaps and were very helpful. Also, Steve Grosekemper can enlighten you beyond your ability to see as far as this topic is concerned. At least he did for me. Corner him sometime and see what he may suggest.

Just my views, Brian. Good luck with it.

Dan

My 88 had 132/134 in dead stock form at 180K. Now I have a web cam, MSDS w/test pipe, Wilk chip, ~10.5:1 compression, and stock everything else. I am dying to dyno it to see if anything changed. I can feel that there has been a shift in power but hard to tell if I gained anything. I got all the parts dirt cheap from a wrecked car however, so little was invested. The biggest change is that it sounds like a race car at idle.

Now I was putting down some good laps at The Glen. Even 944 turbos had a hard time pulling away out of the boot (steep uphill) but I think most of that was exit speed. I did manage to keep with a Lotus Elise on slicks, couldn't gain any ground though.

I thought that 944's were about setting up the suspension and learning to drive the best possible line as mistake free as possible. I've heard from quite a few people that you really can't do much with the NA motor except drive the hell out of it. The biggest difference seems to be to dial in your suspension and tire pressures. The good news is that you don't have to spend a lot of money. The bad news is that you have drive better (at least I need to. ) Of course I could drop an S motor in ours and not have any excuses when Jackie beats me.

A few years ago (I think around 4), we had a tech session at a Dyno shop in Santee. There were a LOT of 944's there. As I recall, they ranged in HP from around 125 to 132 (Greg's post above - his is an 88 which has a few more HP). This included several of the Spec 944's of the time before everybody started chipping them, etc. So, the range is narrow.

The absolute highest Dyno HP that I know of for a reasonably stock motor (a 1988 at that) is 142. This was chipped for race gas, etc. with headers. If 10 HP is all you can get without going crazy, then, as was mentioned earlier, spend your time on learning to drive and getting the suspension dialed in. It will make more of a difference.

When I was a kid we called hot rodding an engine with 180,000 miles on it building a "Shot Rod".

Freshen up that worn out old beater.

In the history of the world, no engine ever ran well with a ragged valve job......a crispy sharp valve job sharpens the intake "pop" (sonic wave) starting intake flow in less time, increasing intake velocity (the holy grail of horsepower)/charge density/brake mean effective pressure......rougn carbon buildup on the piston crowns inhibits rapid burn promoting (power making) combustion chamber turbulence......loose fitting pistons have to run hotter to fit the bores, reducing charge density and promoting power robbing detonation.....worn rings heat the pistons further by leaving a feeble heat path from the piston crowns to the bores (that's where the pistons shed most of their heat, through the rings-not the skirts, they're too far away from the crowns, the heat path's too long and interrupted by the ring lands) and leak intake charge pressure down the bores before the combustion event pressurizes the worn rings making them finally (sort of) seal.....carbon fouled exhuast ports increase back pressure increasing heat absorbtion in the exhause ports which cools the gasses prematurely, increasing cooling system load while reducing gas velocity in the exhaust tract, and also rob power through inhibiting combustion chamber scavenging.....poorly fitting manifold gaskets inhibit gas flow......weak ignition coils/old sparkplug wires/worn mis-gapped plugs cause minor misfire you can't hear....run the thinnest oil you can get away with.....if your fuel mixture isn't spot on the money you might as well stay home.....clean that air cleaner EVERY time you run the car......home made intake setups that breathe hot engine compartment air are foolish intake air density reducer systems......are your calipers dragging.....when were you wheel bearings last looked at.....do you have a drop more fuel in the car than you need to finish the event? 6 pounds per gallon........
And so on.

You i've left well enough alone? The motor was fully rebuilt last summer with all new bearings, gaskets, seals, rings, valves, machine work done my Motorworks, including refreshing the '83 forged rods I put in with new wrist pins, that and cross-drilling the crank. So the motor only has about 10K on it. I put the aftermarket parts on it because I got everything for less than a set of 15" RA-1s. (cam-tower with perfect low milage lifters and hot cam, custom light under-drive pulleys including an early 90A alternator, MSDS header and test-pipe, and other parts I'm forgetting about) The chip was more about broadening the power band and smoothing the return to idle, not about HP.

To make the car faster I removed weight. Thats the secret to 944 speed. A worn out tired motor and a fresh hot motor might have 15HP difference and that can easily be made up with driver and weight reduction. My favorite is when people come up to me and ask, "it's a turbo right?" and I get to answer "NOPE".

Ask chuck about the yellow 944S/S2 running Victoracers that he passed, driver is still the biggest factor.

Some day I'll get it back down to SD for a weekend. I miss the competition.

944 Boy, I'm not pointing at you in particualr, rather at the (seeming majority of) racers who complain about the power output of 250,000 mile engines, or spend zillions lightening and improving cars with worn out engines that aren't making the power they should in the first place. The same criticism goes for worn out gearboxes, shot suspension bushings, fragged brake rotors, etc. Basic stuff.
It's like building up the running muscles of an athlete with a bad heart. Fix the primary things first.

I think we're all talking apples here. It's pretty-much agreed by most 944 owners that the engines/transaxles are about as good from the factory as they get ... even the higher-mileage ones. Monkey around and you might get a tic more. Maybe. I know Tim Comeau and John Chambers have experimented with 944's a bit. So has Huntley and Anderson. When the fat is boiled down, if you want a reliable endurance engine you're back to square-one with a 4-cylinder N/A engine that will put out just around 130 RWHP + or - a few ponies. Just the way the factory built them.

It sounds to me like Brian is trying to squeeze a tad more power out of his engine. However, I'm not sure how much more blood he can squeeze from that turnip. Freshening the engine as Dave says will definitely optimize a worn-out unit and give a slightly "more crisp" responding engine, however it sounds like Brian's up in the mid to high 120's for RWHP ... about right for that engine. So a couple of grand $$ to freshen the top end ... for 3 or 5 more RWHP and a 1/100th better response time?

Pretty-much I think we're all saying the same thing: it's suspension upgrades, weight reduction, good brakes, and ... oh yeah, what Mark said ... driving skills.

There's only so much you can do with a 944 as far as power goes....the manifolds you could fix,(throw away and start over) and the ports could be welded to decrease their "too big for velocity" size, but the combustion chamber design is terrible. Seriously high compression ratio without severly masking the valves isn't possible with the existing configuration, and you can't alter the intake/exhaust cam timing independantly on the dyno without having a bunch of custom ground cams in your pocket to experiment with.
Engine development would be very expensive for what you get. 400+ hp is hiding in that block, but.....
I'm willing to bet a BUNCH more power could be made fairly easily if you started with an S2 head however. It's far more modern/tuner friendly in design.

The HP is/was never an issue for me. It was dyno tested as part of a project my son was doing for his High School auto shop. I am quite proud that my car cost me $700. out of pocket as it sits. Competition and placing is completely irrelevant to me, I am not looking to be the next McLaren driver. Just to have fun in the car I built from the ground up.
I just found it interesting how much (in percentage terms) changing the exhaust diffusers on the resonator turned out to be compared to what the marketing claims were. To a lessor extent, that I am down on HP most likely due to a tired engine.
As a result of my son welding the #2 main bearing on his 944 while doing his own experiment (how long can a 944 go without oil), we now have 2 motors I will freshen up and merge into 1 in the fall.
So in the end, I will drive it til she blows or the rest of this year, whichever comes first. Oh and the answer to my sons experiment? Three days of school commuting plus several extraneous trips totaling about 65 miles !