Exhaust Pipe Size
- Thread starter LukeZ
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I was also going to say that 3" pipe on a stock 305 is way overkill. I personally wouldn't go larger than a 2.5" pipe, maybe even 2.25". As it was pointed out, anything larger will kill low end torque...and a 305 needs all the torque it can get...😛
I don't think a 2 into 1 system going into an oval pipe would be a bad setup either. I've seen that setup in an older issue of Popular Hot Rodding on an LT1 powered Malibu. It seemed to work nicely.
I don't think a 2 into 1 system going into an oval pipe would be a bad setup either. I've seen that setup in an older issue of Popular Hot Rodding on an LT1 powered Malibu. It seemed to work nicely.
I personally like my exhaust to be symmetrical on the exterior even if it is a y pipe to a single pipe and splitting into dual exhaust but on any performance applications I would use true duals.
I also prefer the tailpipes to exit behind the rear tire similar to a GN, this not only gives you the opportunity to aim the exhaust more towards the ground but I feel it gives a cleaner look since you don't have to see a couple feet of tailpipe hanging below the quarter panel.
I also prefer the tailpipes to exit behind the rear tire similar to a GN, this not only gives you the opportunity to aim the exhaust more towards the ground but I feel it gives a cleaner look since you don't have to see a couple feet of tailpipe hanging below the quarter panel.
Another thing to keep in mind is backpressure of the exhuast. Gotta keep the balance just right based off how the engine is built. If the engine is stock, going with a 2.25" true dual set up would do fine to keep enough of a balance & give a few horses. I wouldn't go over 2.5".
How does shorty headers to a single 3in pipe sound to you guys? It would have a catalytic converter and muffler. Exit in front of rear passenger tire. I was thinking 2.5in, but if I ever do an engine swap after I get out of college, Id want an engine that makes at least 300hp, so I dont want to have to buy a new exhaust system all at once. Id rather have one that will suffice until I can afford a super nice one, hence the 3in single pipe.
Yes, why do you ask? I would be removing the smog pump and all associated hardware such as the AIR tubes to the manifolds and the tube that goes to the original cat. I talked to DMV of Delaware to see if this is all good, and they said that as long as the engine runs clean enough, they dont care what you do to the hardware. So as long as the new cat I get can clean my emissions to meet standards, I should be Ok.
To avoid any possible issues with testing maybe consider a factory replacement dual exhaust set up.
I installed a new cat back Walker set up for a 442 on my 86' Regal with a 307 and gutted the original catalytic, it bolted right up with no fitment issues and is sized correctly for a stock engine, for yours if there is not one for an El Camino a Monte SS would probably fit with little to no modifications.
Mine definitely sounds healthier without being overly loud.
I installed a new cat back Walker set up for a 442 on my 86' Regal with a 307 and gutted the original catalytic, it bolted right up with no fitment issues and is sized correctly for a stock engine, for yours if there is not one for an El Camino a Monte SS would probably fit with little to no modifications.
Mine definitely sounds healthier without being overly loud.
All I can say is, around here the price is the same for 2.25 or 2.5 so I would go with 2.5. It is hard to get 2.5 or 3 inch over the rearend without mandrel bent tail pipes.
FWIW I have never had luck with shorty headers. Every set I installed, new and used, have leaked at the collector.
Also, I am a child of the 80s, I grew up with the Flowmaster sound, I prefer it, the warble of glass-pack and straight thru style mufflers...not so much. I also dig the tone from Super-Turbo or Hemi-Turbo style mufflers. I just did 2.5 with smaller long tubes and MagnaFlows straight thru mufflers on my current big block Malibu... sounds deep and great at idle, has that glass-pack warble sound under full acceleration....its gonna get some Delta 40 FLowmasters real quick like. Personal preference and opinions may vary.
I had the 2.5 inch Thrush chamber mufflers and true duals in service on a Regal with a small cam (268), sounded great also, it was with stock exhaust manifolds (Buick 350).
My former daily driver Malibu (its waiting on a heart transplant to be back in service) has Flow Tech small block Chevy long tubes with 2.5 and Flowmasters...been in service for about 8 years with winter driving...no issues, not even a collector gasket. Best money I ever spent! It is a stone stock 180K mile, worn out, TBI 350 from a pickup with a cast iron Q-jet intake and carb swapped on. Sounds great...would be cooler with a small cam....hence the heart transplant.
We are blessed here in Oklahoma, no smog tests.
FWIW I have never had luck with shorty headers. Every set I installed, new and used, have leaked at the collector.
Also, I am a child of the 80s, I grew up with the Flowmaster sound, I prefer it, the warble of glass-pack and straight thru style mufflers...not so much. I also dig the tone from Super-Turbo or Hemi-Turbo style mufflers. I just did 2.5 with smaller long tubes and MagnaFlows straight thru mufflers on my current big block Malibu... sounds deep and great at idle, has that glass-pack warble sound under full acceleration....its gonna get some Delta 40 FLowmasters real quick like. Personal preference and opinions may vary.
I had the 2.5 inch Thrush chamber mufflers and true duals in service on a Regal with a small cam (268), sounded great also, it was with stock exhaust manifolds (Buick 350).
My former daily driver Malibu (its waiting on a heart transplant to be back in service) has Flow Tech small block Chevy long tubes with 2.5 and Flowmasters...been in service for about 8 years with winter driving...no issues, not even a collector gasket. Best money I ever spent! It is a stone stock 180K mile, worn out, TBI 350 from a pickup with a cast iron Q-jet intake and carb swapped on. Sounds great...would be cooler with a small cam....hence the heart transplant.
We are blessed here in Oklahoma, no smog tests.
I've been kind of tip toeing around the issue for years......but thank you.....I think?
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