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z28 and 9th gen impala

3K views 8 replies 4 participants last post by  Markemery 
#1 ·
I was at a stop light turning left with an ninth gen impala behind me when i made the turn I opened up the car and pulled away from buddy who also stepped on it but i was pretty disappointed with how fast i pulled away i mean i really started pulling in 3rd gear but I stopped at 120 km. im thinking with my mods i should be close to 400 whp i should have obliterated that guy..don't get me wrong I know it could have been an SS but still that shouldn't have mattered.
I dynoed the car with longtube headers/tune/cai/underdrive pullies and it made 310whp, i was planning on dynoing it again this summer but the dyno in my area is closeed as there rebuilding there garage. The car hooks up pretty dam well i really only break loose in first gear the rest of the time she grabs and pulled pretty hard. Anyone with a similar build mind letting me know how yours runs?
 
#2 ·
400whp on a dyno of any sort would be ridiculously impressive with such a set up. I am guessing M6? Even though dyno numbers are really cool and seem to give you an absolute the only real truth is the 1/4 mile. Once you get the tune you are satisfied with take it to the track and use MPH/weight calculator, that's the best bet for how much power it really makes.
 
#3 ·
I have to agree. A little 224 grind usually makes 360-380 whp on an LS1. I'd imagine a LT with ported heads would be in the same area.

Several years ago we had a kid in a LS4 Imp with loud mufflers pull up to a meet and want to race. He kept asking to race the C5's and f-bodies. All very well modded and capable of low 7 to high 6 sec 1/8 mi ET's. The guys kept telling him," No, you don't want to race that." I was in my wife's stock TBSS at the time so they told him to race me. I obliged by walking him from a dig, roll, and even a pull where he left while I was slowing down to get next to him. He came back to the meet for a few minutes afterward and looked a bit dejected.
 
#4 ·
I mean im hoping for 400 not expecting it but i sure as **** expect an entire top end build be worth more than 50 whp.

Shit last time i dynoed the thing the guy at the dyno was trying to bet me the car would make 260 at best, altho i think they were fox body guys.
 
#5 ·
Stock with full exhaust on my A4 I pulled 278 rwhp on a Mustang dyno, so not bad at all. With a cam, competition grind on the heads and beehives I was 320 to the wheels on the same dyno. If I remember correctly most LE2 H/C/I 350CI cars run 380-420 depending on a few things including the dyno itself.
 
#7 ·
For an example: My 383 was slightly disappointing with 390 rwhp finalized on a Dynojet after fixing the first tuners errors. It wasn't a glory run by any means as the trans and engine were at running temp so if I'm lucky maybe I could achieve 400 rwhp on that same dyno but who knows. I'm more interested on the trap speed down the 1/4 mile but the car may not see that for awhile.
 
#8 · (Edited)
Some dynos are very generous too. There was a local shop that all their builds made over 500whp for a while, but on other dynos they were 50-70 whp less and the cars are slow for the inflated HP levels. They have some odd dyno that is supposed to read lower too. On the flip side, another shop dynos a good 30-50 whp lower than most other shops on their dynojet.

Dyno numbers are just that. I've outran cars that made 70 more whp than my car, so they don't necessarily translate to a faster car.
 
#9 ·
Fellas its been years...and i appreciate the info you all left. After this many years of hardly driving the car i moved back to a place that had a dyno tuning shop capable of tuning the LT1....with the tune i currently had car made 311whp. (i figured it was the tune) This tuning shop did some work and the car made 370WHP without nitrous(i have a 75shot) Tuner said he can get some more out of it so tomorrow ill see what it makes.

I posted this story to another thread but i figure i would just give a quick many year later update here.
 
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