Captain Morgan

Here are the results from a dyno run today in my '79. Horsepower and torque are on 2 different scales, so the graphs don't cross at 5250 on the chart. This chart also shows two runs, both fairly close to each other. I'll also give a little background as to another run and mods.

In Utah (elev 4400 ft) I had a dyno run and had timing set up properly so that full mechanical of 34 degrees came in by 2500 RPM. The baseline before the setup, was 152 RWHP at the wheels at 4000 RPM. After distributor was recurved, I had 170 RWHP @ 4000 RPM. An increase of 18 RWHP. This was run on an analog dyno so I don't have a graph. I'm not sure why the operator chose to stop at 4000 RPM.

I then moved to Indiana (elev 400 ft) and replaced the stock exhaust with true dual, no cats, H-pipe behind tranny, and Flowmaster DeltaFlow 50 series mufflers. My dyno run today showed 224 RWHP @ 4000 RPM, an increase of 54 RWHP over the stock exhaust setup used in the previous run in Utah. Peak RWHP was shortly above 4400 RPM, at approximately 230.

Now, the problem with these comparisons, is that the tests were not run under the same environmental conditions. However, the dyno operator in Salt Lake City said that I should see an increase of about 30 - 40 RWHP by changing to true dual. That seems accurate from looking at these results.

Enough jabbering, here is the chart:

Eddie 70

I gotta get out and try this someday. They had one at the Fall Corvette Expo in Knoxville last year. But I was on my truck and the vette stayed home. Imagine that.

Blues77

:cool: Thanks for the chart! Keeps me motivated. :D

Carl in LA

Keeps me feeling like cra* that I live in Cali where I would be an outlaw if I went to a no-cat system... Your gains are just killing me thinking that I've got 50-hp plugged up in that single cat and dual stocker mufflers!!!!

Captain Morgan

Carl,
If you really want to spend the money for gains, you could probably go with 2.5 that Y's into a 3 inch high flow cat, and then 2.5 after the split. Don't see any reason why you have to keep the stock mufflers, but I've heard Cali has some strange laws.

That will definitly outflow the stock setup, just maybe not quite as much as true duals and no cat.

Avery

SuperFast80

Congrats! We are making the exact same numbers! :cool:

Captain Morgan

:cool: If you go to the Cruise-In, we'll line 'em up at the dragstrip. :D Toronto shouldn't be too far of a drive. ;)

Avery

SuperFast80

It only 10 hours! :lol:

We should line 'em up before the cruise in because by then, I should be sporting a 500hp 454. :eek: