jetech

I talked to a local automotive machine shop mechanic yesterday about what to do with my L48 this winter. I told him I wanted a boost in hp but keep good drivability and reasonable economy because it is a daily driver. He recomended keeping the stock intake and exhaust manifolds, adding a high lift/short duration cam, adding larger valves and flat top pistons if it doesn't already have them. I will keep the Q-jet but loose the EGR and cat. I know that I am beating this topic into the ground but with all the different ways to go I want to make the right descission the first time. What are your opinions? Keep in mind that I have to get the cost of the project past my wife and she is a Mustang fan :rolleyes: :chevy :flag

Smokehouse69

I agree with the cam and pistons, but a replacing the intake manifold with a quality dual plane aluminum intake will increase your hp for only around $120.00, and the thing that will give you most hp at no loss of drivability is a good set of full length headers. Dynomax ceramic coated are a good cheap choice at around $230.00 from Jeg's or Summit.
Without a good intake and exhaust, the bigger valves in the heads and the increased lift and duration provided by the cam won't be nearly as effective.

The Money Pit

Go with a short cam like the Edelbrock Performer,spring for headers and dual exhaust and with everything else stock you'll hit 320-330 hp that will idle like stock,pull like King Kong.I've used this combo many times in the past.

Ryan77

I would definately get the Performer intake, have them rebuild the Q-jet and tweak it for performance (not expensive), definately go with headers like the Dynomax ($230) or the Hedman thermal coated (what I have, $260), and if possible in your state go with true duals with a H or X pipe. The head work is good, but I would use a thinner head gasket and have the heads shaved for more compression. All these parts can be found from Jeg's. When all is said and done you'll a powerful motor that is also a great daily driver for a very reasonable price. Good Luck with whatever you choose :cheers:


[Modified by Ryan77, 10:00 PM 12/14/2002]

Crash Dummy

I disagree with your local mechanic about the stock exhaust manifolds. They serve no earthly purpose at all except to be a real pain in the butt to work around and down the road if you decide to do any more modifications they will have to go anyway as they will be a hinderance to performance. I agree that the stock manifold & Q-Jet will do anything you want to do with what you are looking for, so I see no reason to change them out. This is a budget minded post, so just take it that way. The stock heads can handle 300+HP and unless you are going to increase the compression to 10.0:1 or above then I personally think you are throwing money away putting larger valves in.
If your budget can handle it pistons, cam and double valve springs can do anything you want to maximize the engine you have.... and again... unload those stock manifolds in favor of headers.

jetech

Thanks everyone
Since joining this forum I have learned there are a lot of choices when it comes to building up an engine and I have learned alot. I think I have the cam narrowed down to a XE 262 after I talked to the Comp Cam tech. I will probably pull the engine before I decide on the rest. My plan was to have the engine out of the car by now but with this warm weather (near 60 tomorrow) I keep putting it off so I can keep driving the car. :D

redwingvette

Corvette Fever built an L-48 to hit 326hp by using a Crane Cam H-272 and openning up the heads adding larger valves. They said only 3-4hp gain came from changing the stock exhuast (true duals) to headers. I would go with Performer intake, heads,and cam for now. Go for the headers when your budget will allow it later.

dman535

Keep in mind that the design of the factory exhaust was longevity. Chevrolet didn't want to have customers complaining of exhaust leaks every 18 months becuase the gaskets failed. The rams horn manifolds are some of the best stock exhaust systems that are out there, expecially if you can find a set of the early LT-1 manifold with the 2.5" outlets.