Power Curve Flattens out at 4500 RPM

[95BlackTan50]

I went to the dyno a few weeks ago and noticed that my power curve is flat from about 4500 RPM to 5700 RPM. My MAF and Injectors are not maxed out, so I was wondering if anyone had some ideas if this is normal for my combo or not. I would have expected the power to climb for a few more RPMs with the 2031 cam. Thanks.

Dyno Chart

 

[donkey_punch]

thats does't seem right. when i read the title i was going to reply welcome to the world of stock cam. but a 2031 cam power curve is to like 5600-58000 one of the two i can't remember. now your scaring me cause i'm ready to put my 2031 cam in. somethng ain't right there.

stupid question. did you buy the car with the cam in it already? or did you buy the cam and have it installed?

 

[AUcobra94]

Its not the cam, its probably the heads. Do you have the stock h-pipe?

 

[final5-0]

The e7's really hold you back at the upper rpm's.

I'd also say the e7's are making your tb & maf be not very effective as well.

Notice that the bulk of your tq is in the first 1/3 of your power band and that is due to the heads starting to make the combo run outta breath.

Another thing is that from about 3300rpm and more your at 12 to 1 or fatter and from 4krpm your in the 11's. Thats too fat and you could pick up some gain with a little tweecing on the old fuel table.

btw ...... what does your highest load row in your spark table look like as far as total spark, and how quick its all in, etc.

Later
Grady

 

[95BlackTan50]

donkey_punch - I installed the cam myself. I aligned the cam dot to dot. I did not degree it if that's what you're asking.

AUcobra94 - Stock H-Pipe.

Grady - I think that I was still in my fuel startup table during the run which caused me to be richer than expected. I noticed that my lambses were commanding 11.8 - 11.9. It turns out that the W4H0 calibration has a stabilized_min_time of 210 seconds which I think means that even though my ECT is warm, I still wait 210 seconds before going to my stabilized fuel tables. I have my stabilized fuel table set to 13 in the top row so that should help. I also TwEECed my MAF curve based on commanded versus actual AFR and that should help as well.

The spark table runs from 21 deg (2500 RPM), 22 (3000), 24 (4000), 25 degrees at 5000 RPM in the top row with a 6 degree global spark adder and the dizzy at 10 degrees. The actual spark ran from about 31 to 35 degrees which would be closer to a couple of rows down the table for a load of 0.7. My load scaling switch is set to zero so I should be using loadx for load(?). I should be on the top row since loadx is greater than 90%. Maybe I'm missing a spark adder?

If you want to look at my tune or the log file I have them posted as well:

Dyno Log
Dyno Tune

Sounds like heads and exhaust will free up the top end.

Thanks for the help.

Barney

 

[final5-0]

Grady - I think that I was still in my fuel startup table during the run which caused me to be richer than expected. I noticed that my lambses were commanding 11.8 - 11.9. It turns out that the W4H0 calibration has a stabilized_min_time of 210 seconds which I think means that even though my ECT is warm, I still wait 210 seconds before going to my stabilized fuel tables.

I think that is exactly what caused the fat ratios.

I looked at the scalars stab_min_ect & stab_min_time for the t4mo, u4p0, and j4j1. I saw 120 and 210 for the t4m0 & u4p0 but 160 & 1 for the j4j1. Those values would have to be seconds as no way they could be minutes and I don't see how they could be milli seconds. I've seen you and Rick talk a bit about this subject. What are your thoughts about those values Barney?

I have my stabilized fuel table set to 13 in the top row so that should help. I also TwEECed my MAF curve based on commanded versus actual AFR and that should help as well.

I did not see data in the AFR column of the raw data so I assume you don't have a wb.

The spark table runs from 21 deg (2500 RPM), 22 (3000), 24 (4000), 25 degrees at 5000 RPM in the top row with a 6 degree global spark adder and the dizzy at 10 degrees. The actual spark ran from about 31 to 35 degrees which would be closer to a couple of rows down the table for a load of 0.7. My load scaling switch is set to zero so I should be using loadx for load(?). I should be on the top row since loadx is greater than 90%. Maybe I'm missing a spark adder?

Yes I looked at the raw data and saw spark values like that.

The dlog shows a rpm range of about 3100 to 5700 but the dyno chart shows about 2500 to 6200. Whats up with that?

I don't know if the iron heads can take it but ............................
if you can get about 36 and get it all in by 2500 ...........................
you will pick up a good bit of power.

Later
Grady

 

[95BlackTan50]

I looked at the scalars stab_min_ect & stab_min_time for the t4mo, u4p0, and j4j1. I saw 120 and 210 for the t4m0 & u4p0 but 160 & 1 for the j4j1. Those values would have to be seconds as no way they could be minutes and I don't see how they could be milli seconds. I've seen you and Rick talk a bit about this subject. What are your thoughts about those values Barney?

I think the stab_min_time numbers need to be in seconds. I've changed my numbers since the dyno to 5, but haven't had a chance to verify the result. Rick told me about some "extra" variables in the CL flag in V1.20B, but I haven't had the time to reload the old version and try it out.

I did not see data in the AFR column of the raw data so I assume you don't have a wb.

No, I don't have a WB. That was one of the reasons to go to the dyno was to get a reading of lambse vs actual. The other reason was that it was only $30 during dyno day!

The dlog shows a rpm range of about 3100 to 5700 but the dyno chart shows about 2500 to 6200. Whats up with that?

I truncated the log. I chopped off the low end because there was a jump in the ratio between mph and rpm due to the converter unlocking. I was able to keep the AODE from downshifting at WOT but couldn't keep the converter locked for some reason. There must be some kind of unconditional unlock at WOT or something like that. I don't know why the dyno goes up to 6200 on the high end. My un-truncated data log still only shows a max rpm of 5800.

 

[final5-0]

Hey Barney

You can't go wrong with a pull for only 30 bux, lol.

I find it so strange that you bring up the topic of a dyno pull being skewed because of the pull being made before the pcm has made everything stabilized or normal, if you will.

I've been thinking about that for some time now and I'm gonna do a little datalogging myself and see what I come up with.

I'll let you know what I find when I can get around to having enough time to check it out. If you come up with anytihing please let me know or put it up on one of the sites.

Later
Grady

 

[95snoozer]

do you have stock heads? that is why,

get heads