Recently had my car chassis dynoed and tuned at a local speed shop on the Dynojet.
The car is an 87 IROC Z28, I had the engine custom built at Bowtie Performance a local engine shop which included all new internals, a brand new custom rebuild which now has around 1.2k on the motor. The car and motor includes the following.

350 bored .30 over (355)
Stock 350 crank
Mild street/strip roller cam
Vortec heads (L32 I believe)
Edelbrock RPM Air Gap intake
MSD HEI Street Fire distributor
MSD 8.5MM Super Conductor wires
ARP hardware
Quick Fuel Hot Rod series 680cfm vacuum secondary carburetor
9.2:1 compression
1 5/8" Hooker shorty headers w/ 2.5" y pipe w/ 3" Flowmaster catback
14" K&N air cleaner
700r4 trans
3.73 gears
1800-2000 stall converter
Dual electric fans
Aluminum pulleys (Vbelts)
Stock power steering


I THOUGHT the engine would blueprint around 375hp 400tq at the crank.

The car made 225rwhp 271rwtq

Less than I expected, but seems to be a GREAT street car, with very reasonable gas mileage considering the motor.

They set the AFR around 13.1

15 degrees initial timing
37 degrees total timing
On 92 octane
The 9.2:1 runs great on pump gas.

Any advice or input? What do you guys think? The car feels like a rocket ship coming out the hole. Just not the numbers I expected.

Thanks for reading, I hope this helps someone else with their build as well

 

What head casting #? What cam?

 

How about hitting the strip in Kent and make a few runs?
Mph would confirm or deny the chassis dyno run.

 

yea, run it. your torque converter could make the numbers seem off.

 

That does seem a bit low. I would have guessed about 40-50 higher than that, assuming about 350 or so at the crank.

Is 37* really where it made best power? Vortecs usually only want or need about 32*.

I'd also wonder about that converter, especially if it's a bargain-brand like out of the Summit catalog or something.

Now, the offset to this is that not all dynos are the same. Mustang dynos in particular can spit out some fairly odd numbers sometimes if it's not calibrated or run properly. Your MPH across the stripe at the dragstrip will tell you more about your real HP than second-guessing dyno numbers.

My brother's old GTA made only 260HP on a Mustang dyno but ran 110-111 at the strip, and it was a HEAVY car.

 

The cam is a mild custom grind. I told the builder street/strip and he built the cam. I don't remember the casting # for the heads but they are the better Vortecs out of the two. The converter is from a local transmission shop the engine builder got for me, the trans shop is his friend who's been building tranmissions since highschool (these guys are old and grey now) the converter stalls perfectly between 1800-2000 rpm

 

So does it meet your expectations other than a low dyno number?

 

i trashed my vortec heads and picked up a pair of dart iron eagles and gained 64 hp on my 383.

 

Can't help you if you won't tell us what heads and cam you have.

That's where power lives. Vague descriptions like "mild" and "better" tell nothing about how much untapped potential there might (or might not) be.

 

friend of mine was dynoing a guys car one day when i was there hanging out. it had a "custom cam" that wound up being some sort of circle track cam. it made "bleh" power up to a point, and then it flatlined.... FOREVER. i think you could turn that thing 10k and it would make the same power it did at 6k. (if the engine held together)

basically, that combo didnt make much peak power either.

 

I said they are L32 Vortec heads, stock, just cleaned up. The cam is a mild street strip cam. I don't know the specs