Freshly built 383 tpi in a 1988 GTA

10 to 1 cr
dart aluminum 180cc shp's
hooker 2055 into 3" performance exhaust
extensively ported stock base
heavily ported slp runners
58mm tb with ported plenum
stock intake with K&N filter
comp 502 roller

Dyno tuned for correct AF ratio thru out RPM range
Timing did best at 38* all in by 2500 rpm.

Results are best 213 hp at 4586 rpm. 281 torque at 3684 rpm.

Tuner says he has a stingy dyno. The car does run well, but Me thinks it's time for a carb.

 

Mild heads and smaller cam, but still should make more hp and boatloads more torque on most dyno jets. If its a stingy dyno then its extremely stingy.

I would expect closer to 280-300 hp, 350-375 trq

 

It's a PowerDyne Mustang Dynamometer. He says another 1000rpm would get me another 100 horse.

 

I believe it is the wrong combination of parts.
A 383 needs air to make power.
Those parts will not supply what it needs.
It's all about cylinder filling.

Flow #'s on those heads

Lift INT EX
.200 139 114
.300 190 145
.400 218 164
.500 222 172
.600 218 174

 

If you're not sure of what I am saying read this:

http://speedtalk.com/forum/viewtopic.php?f=1&t=29421

 

These are the Dart #'s they gave me before purchase

lift Int Ex.
200 127 103
300 175 143
400 217 170
500 248 186
550 249 190
600 250 195

 

See if its making vacuum at wot.

 

A carb probably wont gain you much either. Your heads are too small for a 383, your stock intake is too small for a 383, and your headers are too small for a 383.

 

Still should make more than a bolt on L98 but being a mustang dyno there is possibilty to be alot lower than dynojets.

Find out what other known cars have been dyno'd there. Like new vettes, new ls camaros, 5.0 new mustangs. See what they dyno stock or mostly stock and compare to other common numbers for those cars on dynojets. That may give you an idea how stingy dyno is

 

That's..... pretty stingy. The worst I ever saw personally was on an older Mustang Dyno. My brother's mild 400 combo (TPIS MiniRam, small cam, half-decent heads, same headers as you) that laid down a whopping 256 HP. It still ran 13.000000000000001 @ 110.5 in a 3700 lb. GTA on street rubber. Quite a bit more real-world power than the modest dyno numbers would have indicated, in my opinion.

If you have a smart phone you can download an application that basically does something similar to an old G-Tech. (Or just take it to the track and see what it runs). Vehicle weight and your MPH across the stripe are all you need to calculate what your real HP is. (Online calculators abound to do that math for you)

 

Just take it to a drag strip and get a clean run. Write down your trap speed and weigh it right afterwards. I'd trust that more than some dyno. Thats real world results. Not a calculation based on a bunch of assumptions. Its at least worth trying before you start buying parts.