Dyno run sheet

[LGAFF]

Got my dyno info, they were unable to pull the tach so mph listed below. I did some calculating and w/a 4.09 rear end and looking at my peak power comes between 110-118mph, hanging at 389-391. I am estimating my peak rpm band to be only at 6000-6300rpm, which seems low for a car with 2.75" exhaust/X-Pipe/ported to 36mm, etc.

They did comment it was running lean, any thoughts,


http://i134.photobucket.com/albums/q115/lgaff/DYNO.jpg

Any thoughts

LGAFF
92 ZR1
#234

[jonszr1]

did they retune your prom since the porting? when corey ported mine it was way lean went from 372 to 409 after tuning. If not you could call him and have him down load my tune to your prom . it would put you very close anyway . really considering the temp not bad figures. get rid of the lean fuel and i think you might just hit 400rwhp:thumbsup:

[Aurora40]

Do you have headers? I sort of want to assume you do based on the fact you are pushing 390whp. If you don't, that might explain the peak being in the low 6,000 rpm range. However, it hardly looks like it drops off much from there on up.

Did they try to pull RPM with one of those induction clips over a plug wire? If so, I wonder if they couldn't account for the fact that it uses waste spark? A lot of GM (and other) cars are like that, but maybe not the kind that frequent dynos (I think the ZR-1 might be the only Corvette that used that type of ignition). I know the emissions shop I take my 'vette to seems to have a real problem with it.

[-=Jeff=-]

I thought the Buick Grand National was also Waste Spark

[Aurora40]

I thought the Buick Grand National was also Waste Spark
Yup, the Buick V6 had it before the 'vette ever did. But what I meant was most (none?) of the Chevy V8's never had it. I'd guess there are a lot more Chevy smallblocks out there than turbo'd Buick 6's. :)

[-=Jeff=-]

Yup, the Buick V6 had it before the 'vette ever did. But what I meant was most (none?) of the Chevy V8's never had it. I'd guess there are a lot more Chevy smallblocks out there than turbo'd Buick 6's. :)

True,

but for Dyno's the GN V6 is another popular motor to dyno...

also the TTA from 89

[XfireZ51]

4 dynos I've been to all had a problem picking up rpm from a plug wire. You're better off using a low inductance pickup on one of the pink wires at the back of the motor and under the MAP sensor.

[LGAFF]

http://i134.photobucket.com/albums/q115/lgaff/AFdyno.jpg


Here are my AF ratios on the car, ignore the blue line, the sensor fell out of the tailpipe at the end of the run, however you can see that the fuel curve leans after what would be 5100rpm which might explain my 6100-6300rpmmax power band vs the 6800 that Dominic saw.

I am sure Dominic can chime in to be more specific, but he was nice enough to check my DRM chip it is running 12% leaner than his tune at max hp, and fall off begins about 5000rpm.

LGAFF
92 ZR1
#234

[XfireZ51]

I compared Lgaff's High RPM Open VE table to mine. Beginning at 5000 rpm, his VE is lower than mine by 7% and by 12% at 7000rpm.

[-=Jeff=-]

Lee time to start tuning.. LOL

[jonszr1]

wow, you are lean , is dominic going to add more fuel for you. O would be very carefull till he or someone does . my car was like that till corey added more fuel and took out 1-2 deg of timing up top. the reason for the timing was californias wonderfull 91 oct fuel and special adiitives .id bet you would go over 400 whp easy with the right fuel curve.it shows you did a very nice job on the porting:thumbsup:

[LGAFF]

Sweet part is 390rwhp with a crap tune......this could be fun!

LGAFF
92 ZR1
#234

[-=Jeff=-]

Sweet part is 390rwhp with a crap tune......this could be fun!

LGAFF
92 ZR1
#234

Now you need to learn to control it

[Aurora40]

I'm no expert, but I've heard tailpipe widebands read lean by about half a point or so? So it might not be quite as bad as the 13.9-14:1 seems to indicate.

Also, wouldn't you lose a little power richening it up (though gain a huge margin of safety)? All I mean is a non-crap tune might not improve the power, though it certainly looks like it would be a good idea. :)

So do you have headers or what?

[LGAFF]

yes I am runnning Watson headers.

LGAFF
92 ZR1
#234

[jonszr1]

I think his car being that lean would cost power. it looks way lean , it would be fun to see what happens when they add fuel .if i had to guess 410to the wheels .but i am no expert :icon_scra

[XfireZ51]

I'm no expert, but I've heard tailpipe widebands read lean by about half a point or so? So it might not be quite as bad as the 13.9-14:1 seems to indicate.

Also, wouldn't you lose a little power richening it up (though gain a huge margin of safety)? All I mean is a non-crap tune might not improve the power, though it certainly looks like it would be a good idea. :)

So do you have headers or what?

A40,

The best place for a WB is in the collector next to the NB sensor. I think next time I go to the dyno, I'll have my ZT-2 hooked up. Be an interesting comparison between the tailpipe and the collector. My first run on thedyno showed a 13.4:1 AFR. Dropping that to 12.8 did nothing for power either way but a bit more peace of mind in case of bad gas for example.