True HP/Torque numbers from exhaust work

Good morning Guys.

1972 Skylark Custom 350 4bbl.

Stock motor, stock '72 single exhaust. Going to 2-1/2" dual exhaust with an "H" pipe. "H" pipe due to the lower end torque gains & actual muscle car sound.

Just wondering the ACTUAL HP/Torque gain to be expected. I've searched the net & see the age old 7-10% gain. I will not be doing any header work so it'll just be a header back system.

I understand that you guys cant give me spot on answers as everyone's motors, set-ups, etc are different but was just looking for some real world feedback fro people who have had exhaust work done & what to honestly expect.

Thanks,

Kyle

 

I don’t see it gaining low end torque as much as mid and upper rpm hp. 7 to 10 % seems about right. Figure about 10-15 hp above 2000 rpm. Get a distributer recurve kit, do a search for Larry’s “power timing” post. Follow that. Together you can probably see 15% for both changes.

 

I unfortunately have not gotten to the "power tune" yet.

Want to get my tach/dwell meter first. See one on CL for $25 though.

 

Get the electronic conversion kit. Or Ken at Everyday Performance can do the entire distributer.

 

It'll be louder. 10% would be a huge gain. Exhaust systems and stock exhaust manifolds get no respect. The engineers were not dummies. The stock exhaust is adequate for a stock car. If there was a 10% gain to be had from something so cheap and easy they would have done it!

 

I can understand where you're coming from Joe.

I would think that going from a "Y" pipe single exhaust with "creature friendly" muffler to a bigger diameter/better flowing true dual exhaust system would gain me something.

Quite possibly not 10% but as we all know 72 was a sad year for engine performance. Not 80's Detroit smog bag, lol but it was the start.

 

Don’t forget, they are still looking for profits, so a cost effective exhaust for 30,000 cars equals profit. And if the engineers where on the game, why is timing set a 4 advanced. When it easily takes 10-12

 

The .gov mandated the emissions standards and in an attempt to meet them before the engineers could design all the hardware to deal with emissions, like head design, lower compression, carburation, distributor baseline curves and all the other things, they adjusted what they could, with jetting, timing and the like.

The engineers in the business were some of the most brilliant and innovative.

Regulation and Wall Street helped kill that, and it it was a long a slow, painful thing to watch happen, as it happened.

And along that line was the "scene", when fuel was of good quality, and "dragging" the boulevards, and crusing the streets was the norm.

But, some die hards just won't give up.

 

I've worked on The General's vehicles for many years now & these engineers don't seem very brilliant when you have to work on things & they couldn't give you an 1/8" or more of space on occasion.

Firewall heater hose clamps come to mind when you switch over to worm clamps(yes I know I can stagger the worm clamps)

Front drum brake bleeder screws you can barely get a wrench or a bleed tube on.

In my opinion moving fuel pumps to inside the tank.

Having to remove tires or motor mounts to change plugs or wires.

Then again engineers don't have to work on the items they engineer. That's why they're engineers.

 

Yep. I doubt ease of maintenance was a concern. Just efficient and economical assembly/manufacturing.

 

That's what happens when train drivers think they can "design" anything!

 

Oh boy, is this where the thread runs off the tracks?!