Originally Posted by EvanZR1 (Post 103916)

Yeah, I'm thinking about just removing the secondaries completely. Corey has already offered to update my top end porting for free, so I think I'm just going to have him pull the secondary system completely and burn a new chip while he's doing that. He thinks I'm probably down about 80HP from where it should be, which would be great. Now I just have to figure out when I can get the car down to him for a couple of weeks.

Originally Posted by Locobob (Post 103921)

Here is a dyno of a 91 before and after porting, no headers. If you compare this to your dyno you will note that yours is down on power over the whole rpm range - not just at the top. So whatever issue you are having is effecting the whole curve, probably not a collapsing air duct as that usually just shows up at the higher rpms.

http://www.pnwzr1.net/Robert/Misc%20...ortingresz.jpg

Originally Posted by Pete (Post 103922)

Peaks at 5600 :icon_scra
Some details please.

Pete

Originally Posted by Corvette95 (Post 103939)

a stock 92 will not dyno 345 , what mods did it have. Porting and a chip is being optimistic looking for 345, especially with no exhaust work, at least none was mentioned. Porting and chip with no outlet will do little with everything else stock
345 rwhp from 375 crank hp is less than 8% total output loss.

Originally Posted by Nacho_ZR1 (Post 103901)

(posted on CF as well)...

Ok so here go some more updates. When the first run was complete, the technician yelled out "346.5" and I became awash with excitement! He mentioned that these were raw numbers and the printout would contain the SAE corrected figures. The printout shows the following:

Run 1 - 342.49 hp and 316.80 tq
Run 2 - 340.23 hp and 318.81 tq
Run 3 - 337.57 hp and 321.27 tq

Originally Posted by mgbrv8 (Post 103956)

Mmmmm 4.10s? What gear did you pull in??

Originally Posted by Paul Workman (Post 103958)

I'm just making "conversation" here (over a cup a 'nog' :)) - not casting dispersions, but you seem pretty emphatic about a stock 90-92 not making 345 RWHP. You may be right...maybe. I believe he (Nacho said) the raw hp was 346.5 hp but we see that after correction for air temp, etc, the strongest pull was 342.5, and averaged approx 340.



Give or take a couple hp for conditions and dyno calibration AND whatever "standard" is being applied to make corrections, 340 has been recorded on several similarly equipped 90-92s. But, my point is cam timing can make substantially more than a 5 hp variation at the rear wheels - as Dominic just learned (from Pete's inspection of his 92 motor):jawdrop: - So, again, not impugning your experience, I don't think I'd be quick to make a flat statement that a stocker wouldn't make 345 ish rwhp. I'm just sayin.

Nacho's car aside, as for Evan's ZR-1 making 300 IN SPITE of having some top end porting, he's short a lot more than 20-30 hp. There are many examples of 370 + for other cars; LOCOBOB recently posted one; Evan is missing 70 - 80 hp somewhere. And, by bolting on headers and a free flowing exhaust, he could be up against 390-400, according to examples by others...mods being mods, of course.

Bottom line...I'd just like to see the expression on Evan's face when he whacks the throttle after a 70+ hp boost!:dancing

Merry Christmas / happy holidays...(lifting my 'nog' to you and all the 'Brotherhood of the Beast").

P.

Originally Posted by Locobob (Post 103921)

Here is a dyno of a 91 before and after porting, no headers. If you compare this to your dyno you will note that yours is down on power over the whole rpm range - not just at the top. So whatever issue you are having is effecting the whole curve, probably not a collapsing air duct as that usually just shows up at the higher rpms.

http://www.pnwzr1.net/Robert/Misc%20...ortingresz.jpg

Originally Posted by rhipsher (Post 104070)

Hum! interesting to see the difference between Locobobs dyno results and my dyno results with top end porting an my totally stock exhaust. Bobs increase shows up at about 4200rpm,s. And the increase in my dyno shows up right from the beginning all the way up. Interesting to see how different they are. I'm not sure which results are more typical. I guess it all comes down to porting technique.
http://i301.photobucket.com/albums/n...0/P1010024.jpg

Originally Posted by rhipsher (Post 104088)

HOG there was no tuning done at all. That was simply the result of the top end porting alone. Corey simply laid down the before porting run done 4 years earlier over the after porting run so I could see the improvement over the before porting run. Im still running stock cats and exhaust which doesn't compliment the top end port at all. Once I get the proper headers x pipe and a more free flowing exhaust system with a fantastic Corey tune I'll be curious to see what kind of numbers it will produce then. But even with stock exhaust, top end porting makes a difference either way