jetech

Sorry for the :beatdeadhorse: but I am still not sure what size exhaust to put on my 77. I am going true dual with probably Flowmaster 40's and no cats. I have ceramic headers to install also. The engine has a Performer manifold and comp cam so its not totally stock. From what I have read 2.5" with a H pipe should be about right and 3" would be overkill. What are your opinions and experiences.
:seeya

lowvette

Have you considered Hooker headers with sidemount exhaust? I believe they open up to 4". The mufflers can be glass pack or a slightly quieter variety.

Downside
Legs can be burned on the sidepipes.
I don't believe they fit under 1969 fiberglass sidepipe covers.
Some people just don't like the looks of sidepipes.

From a performance standpoint, has anyone had experience comparing header/sidepipes against header/dual exhaust and/or header with cross-over pipes?

:auto:

In racing, the only thing better than cubic inches is cubic dollars.

Lowcountry Corvette
www.LowVette.com

bkarsten26

Hey I don't have any idea what size exhaust you need, but I was wondering what comp cam you have? Sorry for getting off of the topic!

inqbus383

In my opinion, 2.5" dual with an h-pipe is an excellent all around size. Plenty large to make 500 hp, but still small enough to promote easy routing and good ground clearance. :chevy

jetech

I will look it up tonight, have to get to work now.

Torcher

This is just my opinion... your mileage may vary!! If you run a true 2" to 2.25" with mandrel bends, it would be more than enough with true duals and a crossover for a small block. With that, I run a true dual 2.5" but i do not have mandrel bends, so the restrictions in the bends aren't enough to limit the flow I need for my small block. I run headers, true duals, no cats, no crossovers, and Dynomax Super Turbo's. I like this set up because before I ran the Flowmaster 2.5" 2 chamber (same as what they call 40's) and they were LOUD! I like loud sometimes.. but they snapped and popped alot! What I have now sounds excellent at open throttle yet has a slight rumble at cruise that does not create any popping or resonance. Mine is a 4spd Convertible.. so I could control the resonance to a point, still it was very loud. NOw, I have a Harley too... and THAT is LOUD! :eek: :lol: :seeya

Jvette73

Im runnin 2.25 without mandrel bends, crossover and 2.25 flowmasters. I dont think its restricting me but I could be wrong. Bigger pipes will help a high reving engine put out more in the higher rpms. But if you have a mild to moderate cam with and rpm range that doesnt go over 5500rpm or so 2.25 is plenty. If the exhaust is too open for the given application it can reduce low end tq. Theres a correct amount of backpressure for every application. Theres a sweet spot for everything. Bigger isnt always better.

Vesa

definitely no bigger that 2.5" :chill:

jetech

The cam is a XE262H-10. I can move the idle speed up or down to smooth out the lump. At around 600 RPM at idle the car lumps and shakes like a dragster. At around 700 to 750 RPM the idle smooths out with a lot less shake.