M758

Guys..
There is always lot of talk a performance mods for 944 NA 2.5L motors. I have collected dyno charts from the 3 spec cars that have won races this season (in Az and SoCal). See for yourself some typical HP numbers!

Check my website here for the information.

<a href="http://members.rennlist.com/m758/944SpecDynoCharts.htm" target="_blank">http://members.rennlist.com/m758/944SpecDynoCharts.htm</a>

If anyone else has a Dyno chart of their car they would like to list let me know.

"Fancy engines don't win races, Drivers win races!"
- Me

Ken

I've got one, I still haven't scanned it in. I'll try and get it up to you soon. I'm not sure about it though, only 120 max HP. When I scan it I'll ask some questions. Thanks for sharing!

M758

Ken,
All the data I can get is good. The charts I posted are common for the 944-spec cars. I heard of street stock cars making 123 rwhp so 120 is about right. Maybe ditching the cat is worth some hp? Lets see if we can get the data to prove it!

97xray

I continue to be willing to put my car up on a dyno if someone else will pay for it!

I'm really interested in the functional significance of the Euro compression on RWHP.
I'm very happy to see you posting dynos though, thanks!

Ken

Ok, so here's my dyno sheet:

<img src="http://boards.rennlist.com/upload/Ken944NADyno.jpg" alt=" - " />

This run was done on a dynopack hub dyno. Part of the Deman Dyno day, if you caught that thread.

My engine specs are:
Freshly resealed engine, original rings and pistons(130K), new rod bearings, new clutch, freshened stock head. Cone air intake, factory tube headers, stock cat, Bursch cat-back, MSD Blaster 2 coil, stock chip.

Questions:
What's up with the torque curve at the beginning of the graph? I'm guessing it's just an error on on the dyno, but it seems really wierd. This skewed the readings on the bottom of the graph as the computer thinks my torque peak is in a completely different spot. It also appears that my torque curve is about 5-15 ft/lbs below the other graphs.

It appears that the HP keeps rising near the end of the graph. They only took it to 6000rpms which they said was 120HP, the bottom of the chart states 119 at 5900. Perhaps it would be more if I spun it to 6300-6500? Although it appears that most of the peak HPs on the dyno charts you posted occur shortly before 6000rpms.

So let me know what you think!

M758

Ken,
The curve shapes look fine. It is odd that your torque curve starts out so high. Also odd that you did not go to 6400 rpm fuel cut off.

You are about 10 hp & 10 ft-lbs low compared to the 944-spec charts. None of us have the cat in the car still so this might be the difference.

I'd would need to do more comparisons to see if you really have a problem of if the cat is really worth 10 hp.

Ken

I don't know how old my cat is, it looks pretty original. Could it be so clogged as to cause that much of a power loss? I might eventually replace the cat with either a high flow or a straight pipe but funds don't allow that now.

The other concern is that the dyno was incorrect. The 968 owners who were there got very strange numbers and their torque peaks did not line up with the RPM that Porsche provides(about 1000rpms off). Any idea what type of dyno the other charts were from?

M758

Paul and My charts were from a dynojet 248C. It is the inhouse dyno at Technodyne.

Not sure on Tim's Chart, but it matchs mine pretty well.

Now your curve shapes seem ok as the have much the same dips and such. Only thing is the 120 hp or so. This hp level is consisent with your torque out put so either they dyno is 10 hp low or your car has less hp. I remember hearing a 944 NA making 123 rhwp on the Technodyne dyno so I think it may be the cat that is making the differnce. Honestly I don't know and I would need more data to be sure. If you have 110 hp I'd be worried.

Ken

M758, thanks for all the help and opinions. I'm pretty happy with the results, everything looks healthy for my car. I'm gonna start looking more into replacing my cat, I'll report back and let everyone know if it makes that much of a difference. Thanks again and feel free to put my dyno chart up at your site.

M758

Ok Ken, Just remember that you cat may be just fine. Replacing it may not get you any power. Removing it might.

Geoffrey

Ken, on the day you had you car dynoed, your car's clutch was slipping. We began your dyno run at about 3000rpm so it was easier to get the dyno spinning. I believe this is why you see the chart the way it is. We've since dynoed a 944 race car with a cam, headers, etc. and it only had about 140hp. No disrespect meant, but with the overall condition and higher milage of your car, 120hp is not unbelievable. Additionally, the dyno was NOT incorrectly set up as you previously stated.

Ken

Geoffrey, I am rather shocked that you say my clutch was slipping. No one told me that during the run, all anyone said was "You're car sounds good." and "That's about right for a stock 944." I'm more shocked because my clutch has less than 1000 miles on it. Are you sure you're not confusing my car with another as I believe there was another Ken there with a black car?

Also, I can understand that the exterior and interior of my car are not in great condition but that in no way reflects the condition of the engine. Nearly everything on it has recently(within 1000 miles) been either replaced or rebuilt except for the pistons, rings, and crank. I didn't go that far as the compression and leakdown tests both came back very well. I can understand that the engine might still be down on power compared to a fresh race engine, but when making the comparision to the spec cars that are in very similiar mechanical condition to mine, I find it confusing that I could be down so much power.

Regarding your dyno, I only stated that I suspect it might have something to do with my numbers as the 968 guys are also confused with their results. I am not blaming you or your dyno, I am just trying to examine everything I can.

Geoffrey

Ken,

It's been a few weeks since then so I could be mistaken on the clutch. The graph looks like the run was started at a higher rpm than the normal 1500. We had to do that with the cars that had slipping clutches and that skews the torque reading until the dyno is loaded. I aplogize if I am incorrect and no disrespect meant. I'm just concerned that everyone is blaming the dyno for the numbers. Also, as I've stated before dyno numbers will change from day to day, dyno to dyno, mfg to mfg. Even the turbo magazine article that compared 2 dynojets on the same day were about 10hp apart.

Damian in NJ

Geoffrey, I've posted several times about my confusion over my charts. I still don't know why the Dynapack shows every 968 you've tested as having a torque peak almost 1000 rpms away from where Porsche says it should occur, as well as the horsepower peak not being where it should be as well. Shouldn't the dyno show max torque and hp peaks where the factory says it should? If the peaks were in the correct place, but off by a certain percentage, I could understand. But they're not, and no one can explain this to me. Can you understand how I'm questioning the results?

Geoffrey

Damian,

Yes I can see why you would be questioning the results and I believe there is probably a reason for it, but I'm not sure what it is without doing some digging. I like to deal with facts so without setting up a controlled test I don't know. Remember the dyno day was just that, run a number of cars through the dyno. There wasn't the controlled setup and testing that would have been done during a tuning session. The time and costs associated with are vastly different.