Dyno Run Data
#16
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Originally Posted by Ben in Plano, TX
I did a Dyno yesterday as well - here is the text of a post I made to our local PCA board. My car is a 97 Carrera S - with ~70k miles.
and here is the graph
Let me also answer Steve's earlier questions:
1) 3 runs made - all have similar numbers with minor differences in the appearance of the traces.
2) This chart is run #3
3) Dyno was in a bay in a shop - shop was ~40' x 60' x 20' high.
4) A large high flow fan (about 42" diameter) was blowing directly across the motor (they new to put it in the back!)
5) Don't know precise temps but I warmed up the car to 9 o'clock on the gauge before the runs.
Ben
and here is the graph
Let me also answer Steve's earlier questions:
1) 3 runs made - all have similar numbers with minor differences in the appearance of the traces.
2) This chart is run #3
3) Dyno was in a bay in a shop - shop was ~40' x 60' x 20' high.
4) A large high flow fan (about 42" diameter) was blowing directly across the motor (they new to put it in the back!)
5) Don't know precise temps but I warmed up the car to 9 o'clock on the gauge before the runs.
Ben
BTW, another clue we had was that the HVAC airflow direction "flaps" would work properly sometimes, other times not......
#17
Thanks Bob,
Vacuum leaks are where we're going first - and my A/C does act up on Max A/C setting. Funny thing is that 4 vacuum leaks were found about a year ago - guess we needed to keep looking.
Ben
Vacuum leaks are where we're going first - and my A/C does act up on Max A/C setting. Funny thing is that 4 vacuum leaks were found about a year ago - guess we needed to keep looking.
Ben
#18
Three Wheelin'
Join Date: May 2001
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Damn Steve, you have to temp me like that. I wish mine wasn't a '96 with the funky box that can't be chipped. I don't feel like shelling out for another ECU. Maybe one day and I'd definitely send it to you.
I don't want to get into the exact numbers of the air/fuel mixture, as I think they are not extremely accurate, what I want to know is why our curves are so different? Could it be that they just didn't place the probe properly in the exhaust?
Scott, I don't remember if I asked but did you get the dyno run files electronically? BTW, it was nice meeting you.
Deltawedge, your rev limiter didn't kick in, it was the shop that stopped it at 6K. They did that to me on my first run and I had to convince them to rev it up to 6750. Remember, these guys are use to dynoing small/big block cars that don't really go over 6K.
George
I don't want to get into the exact numbers of the air/fuel mixture, as I think they are not extremely accurate, what I want to know is why our curves are so different? Could it be that they just didn't place the probe properly in the exhaust?
Scott, I don't remember if I asked but did you get the dyno run files electronically? BTW, it was nice meeting you.
Deltawedge, your rev limiter didn't kick in, it was the shop that stopped it at 6K. They did that to me on my first run and I had to convince them to rev it up to 6750. Remember, these guys are use to dynoing small/big block cars that don't really go over 6K.
George
#19
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Originally Posted by Steve Weiner-Rennsport Systems
Eric: ... Above 5200-5500, these things are the same...
#20
RL Technical Advisor
Originally Posted by George A
I don't want to get into the exact numbers of the air/fuel mixture, as I think they are not extremely accurate, what I want to know is why our curves are so different? Could it be that they just didn't place the probe properly in the exhaust?
#21
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Steve, my question is not about my car running leaner, it's about why the shape of the curves looks so different. Mine looks almost linear, while Ben's looks concave.
But since you mentioned my car running lean, I’ll ask one more question. Wouldn’t my engine run hotter if it was running lean? The reason I ask is that my engine never gets close to the red mark on the engine oil temp, even on the track, and 110 degree days are not uncommon during the summer here. Also, I don’t have the additional oil cooler. I’ve helped a couple of my 996 friends put third radiators on their cars and always tease them about how cool my car runs.
George
But since you mentioned my car running lean, I’ll ask one more question. Wouldn’t my engine run hotter if it was running lean? The reason I ask is that my engine never gets close to the red mark on the engine oil temp, even on the track, and 110 degree days are not uncommon during the summer here. Also, I don’t have the additional oil cooler. I’ve helped a couple of my 996 friends put third radiators on their cars and always tease them about how cool my car runs.
George
#22
RL Technical Advisor
There are many factors that influence the shapes of the curves; some are environmental and some are mechanical. We've found that cam timing disparities can account for the reason why some 993's run harder than others. Engine running temps account for some differences as well.
Running lean doesn't ALWAYS result in a hotter running engine. Once again, its a question of degree,....... I've seen a good number of these cars with partially obstructed front oil coolers from road dirt, grass, leaves and things like that. With the lower third of the cooler partially blocked, these cars will run hotter. I like to pull the front bumper cover and clean the whole cooler to ensure that its doing the best job it can to keep the motor cool.
It would be interesting to be for you and some others to have compression & leakdown tests performed at the same time to see the differences.
Running lean doesn't ALWAYS result in a hotter running engine. Once again, its a question of degree,....... I've seen a good number of these cars with partially obstructed front oil coolers from road dirt, grass, leaves and things like that. With the lower third of the cooler partially blocked, these cars will run hotter. I like to pull the front bumper cover and clean the whole cooler to ensure that its doing the best job it can to keep the motor cool.
It would be interesting to be for you and some others to have compression & leakdown tests performed at the same time to see the differences.
#23
I have preliminary information from my tech on leakdown & compression.
Cylinders 1-5 all have < 10% leakdown and compression of 185 (units?).
Cylinder 6 has 18% leakdown and compression of 160.
Cylinder 6 is not happy - any chance this valve spring or lifter issue (valve not making good seal). I'm not using much oil (quart every 1000-1200 miles) so piston rings don't seem likely.
Ben
Cylinders 1-5 all have < 10% leakdown and compression of 185 (units?).
Cylinder 6 has 18% leakdown and compression of 160.
Cylinder 6 is not happy - any chance this valve spring or lifter issue (valve not making good seal). I'm not using much oil (quart every 1000-1200 miles) so piston rings don't seem likely.
Ben
#25
Rennlist Member
Ben,
The units are psi. I'm not convinced that the magnitude of the numbers are all that meaningful because my previous 1996 C4 measured about 240 psi with one about 10% lower. Although the numbers were high, the car pulled 215 hp on a 4-wheel dynojet, which was disappointing. Some have said that you want numbers at 200 psi or higher, but I don't think that's a rule to live by. My current car measured at 200 psi on all but one cylinder which measured 190 psi. This car feels much faster than my prior.
But still, your numbers DO seem low, and your weak cylinder surely doesn't help.
The units are psi. I'm not convinced that the magnitude of the numbers are all that meaningful because my previous 1996 C4 measured about 240 psi with one about 10% lower. Although the numbers were high, the car pulled 215 hp on a 4-wheel dynojet, which was disappointing. Some have said that you want numbers at 200 psi or higher, but I don't think that's a rule to live by. My current car measured at 200 psi on all but one cylinder which measured 190 psi. This car feels much faster than my prior.
But still, your numbers DO seem low, and your weak cylinder surely doesn't help.
#26
Eric,
I'm sure I don't understand the compression test correctly but it seems to me that it would measure the maximum pressure attained during the 4-stroke cycle. Atmospheric pressure at sea level is 14.7 psi and the compression ratio is supposed to be 11.3:1 (optimistic) so that would either be 14.7 + 11.3*14.7 (psia) or just 11.3*14.7 (psig) for a maximum pressure of ~180 psia. So it seems like the cylinders registering around ~180 are good and the one down at 160 is definitely low.
I suppose the slop in the magnitude of the numbers could simply be pressure gauge calibration. I'm betting most shops don't use annually NIST certified gauges ;-)
Ben
I'm sure I don't understand the compression test correctly but it seems to me that it would measure the maximum pressure attained during the 4-stroke cycle. Atmospheric pressure at sea level is 14.7 psi and the compression ratio is supposed to be 11.3:1 (optimistic) so that would either be 14.7 + 11.3*14.7 (psia) or just 11.3*14.7 (psig) for a maximum pressure of ~180 psia. So it seems like the cylinders registering around ~180 are good and the one down at 160 is definitely low.
I suppose the slop in the magnitude of the numbers could simply be pressure gauge calibration. I'm betting most shops don't use annually NIST certified gauges ;-)
Ben
#27
Originally Posted by George A
Deltawedge, your rev limiter didn't kick in, it was the shop that stopped it at 6K. They did that to me on my first run and I had to convince them to rev it up to 6750. Remember, these guys are use to dynoing small/big block cars that don't really go over 6K.
George
George
P.S. From the looks of their shop they are used to the Civic and Celica crowd (Japanese auto tuner). They did ask which end had the motor(to hook up the tach) on my C2, amusing.
#29
Originally Posted by George A
Sorry Ken, I thought your experience was like mine.
I would definitely change out that chip. 6K is where all the fun begins.
George
I would definitely change out that chip. 6K is where all the fun begins.
George