Help, only dynoing 300RWHP

[Kevin]

is the duct collapsing?

[EvanZR1]

Not sure, the dyno was an above ground unit, so I wasn't able to get up next to the car while they were doing the run.

[Kevin]

do you have a reinforced duct, if no, then it is collapsing

[Corvette95]

A pre-93 stock LT5 with mild porting and a chip isnt going to produce 380 rwhp. You are only about 20 to 30 hp off, the dyno could be a little out of calibration.

[EvanZR1]

Considering that a stock 92 dynoed 345RWHP just before me, I think their is something wrong. Considering stock is 375, I'd expect about 310-320RWHP for a stock car, and then at least an extra 30HP from the chip and porting. Corey Henderson has offered a free update on the porting, and can fix the issue while he's got the top end off (obviously not free for the work other than porting, but still too good to pass up). I think I'll probably just have him pull the secondaries completely if that's what the problem is. Will probably be mid January or even February before I have time to get it down to him though.

[Corvette95]

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.

[Paul Workman]

Originally Posted by Corvette95

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.

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.

Originally Posted by Nacho_ZR1

(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

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) - 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!

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

P.

[Locobob]

Originally Posted by Paul Workman

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) - 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!

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

P.

I agree with Paul, 345rwhp while on the higher side is not unheard of for a close to stock ZR-1. My old 91 made 351rwhp with just a Power Effects cat back and a DRM chip which increased to 371rwhp after I ported the intake - dyno graph is posted on page one of this thread. A car with port work coming in at 300rwhp says to me there is something not quite right. Headers and exhaust do wonders for making the most of top end porting but to say that porting alone won't make a difference is erroneous.

[EvanZR1]

Yeah, we're kind of wondering what's up with NachoZR1's car. From all appearances, it's a stock car with just an open air lid and Dynomax mufflers.

[mgbrv8]

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