My 69 4 speed coupe has a non original 350. I would like to increase performance, but do not want to use headers. Is there a limit with original rams horn exhaust manifolds as to HP and torque? Any suggestions to how far to go with an engine re-build or replacement with the goal of a pump gas, streetable torquey engine? Thanks for any advice.
-
-
Re: exhaust manifolds
Patrick -
The "ram's horn" manifolds are pretty efficient, especially the '65 and earlier 2-1/2" outlet versions; I'd stick with those and avoid all the PITA problems that come with headers. -
Re: exhaust manifolds
Patrick and John-----
Without a doubt, the 62-65 2-1/2" outlet Corvette ram's horn manifolds are the best for small blocks. However, none of these were/are manufactured which have fittings for the AIR system. If maintaining this system is important to you for emissions compliance, then the 2-1/2" outlet manifolds cannot be used.
If you do wish to use them, you can use GM PART #3846563 for the left side. This manifold has the forward attachment points for the 69 alternator bracket.
For the right side, use GM PART #3814970 or GM PART #3797901 depending if you want the unused pre-66 style alternator bracket on the front or rear of the manifold. You can also obtain a reproduction manifold of the 2-1/2" outlet style which had no brackets, but these cost about $250.
If you do need to keep the AIR (which, personally, I would recommend doing), then the 2" outlet original 69 ram's horn manifolds with AIR fittings are still pretty good. The ram's horn style manifolds were the most efficient small block cast iron manifolds ever used by Chevrolet.
Forget headers!In Appreciation of John HinckleyComment
-
Re: exhaust manifolds
The best bang for the buck performance improvement would be to install the LT-1 cam, but if you don't want to deal with mechanical lifters install the L-46/82 cam, and advance it four degrees if you want to trade off a little top end for more low end grunt.
Both these cams were designed for the OEM exhaust manifolds.
There is no practical limit to horsepower, but if you focus on nothing but the top end you won't have any useable torque or driveability in the rev range for normal driving, which is idle to about 3500 to 4000. The name of the game for a high performance street engine is torque bandwidth.
An 750 HP unlimited NASCAR engine would not work very well for normal driving!
DukeComment
-
Re: exhaust manifolds
Duke: sure would be fun to have one of the 750 hp Nascar engine for a weekend of two. regards, mikeComment
Comment