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I'm thinking of doing like one of the guys on our Forum and just pulling my stock shortie setup and cleaning em up. Apparently there are stock obstructions to exhaust gas flow within them. This may be a good compromize till I see if I need long tubes to get into the 12s.
WHRITZY, I think you need to add at least another choice..."leave it alone". If the motor is stock, going to the Hookers (1 7/8") is noticeably going to cost you low end torque.
I'm thinking of doing like one of the guys on our Forum and just pulling my stock shortie setup and cleaning em up. Apparently there are stock obstructions to exhaust gas flow within them. This may be a good compromize till I see if I need long tubes to get into the 12s.
This was one of the things that I checked while in Carlisle. There were a number of vendors selling used exhaust manifolds. I looked at several and found that all had the air injection tubes penetrating into the exhaust path to varying degrees, some as much as a 1/2 inch. The EGR was another story. I blocks about 40% air flow for that cylinder. Mine are coming off this winter for a clean-up. Another trick is to weld the flange and pipes on the outside (currently welded on the inside) and then gasket match the inlets.
You're right as usual vettenuts. I saw a factory set that was port matched after being welded up on the outside. BIG difference. When I took mine off to go to the 2149's, it was surprising at *how much* the stock headers blocked the bottom of the exhaust ports. BTW, cleaning up the stock headers is a real *&%CH. Have a very good ($$$) carbide cutter, mask, gloves, longsleeves and glasses. They are made from type 409 stainless, work harden as you cut it, and give off some super sharp chips.
Andy1983,
It's all about quality and appearance:cool:. You get these headers fitted right. If anything must be banged on it's alright. Then weld the O2 bungs and the EGR fittings. Then take them off and sand them smooth and get them coated at a speed shop. The Hooker coating isn't too good. And they aren't fully coated
(only coated on the outside). A speed shop can do the inside and outside of the header. Have them put on and you have a flawless set off headers. :cheers:
I don't think there are any emission legal longtubes for the Vette. So get #2151 that has no coating, no O2 bungs and no EGR fitting. It will cost around $40 more (total) than part number #2149 but the quality and appearance will be far better.
The Hooker 2149's have all the air & EGR tubes, and are therefore legal. (ex for the Calif. smog *****)
WHRITZY, I've picked up enough on the top end to offset what I've lost down low. My car has a .373 rear and an abundance of WRTQ, so event though I felt the loss, I still have a ton. I haven't dynoed it since the change, so can't quote any new numbers. I used to have 367tq. @ 3150, at the wheels, and it used to die at 5,000. Now it pulls hard to 54-5500. So I'm making more hp. A fair trade off.
You can clean up the stockers, but they won't even come close to allowing a mild motor to exhale. I opened mine up as much as possible and they're still killing a ton of power. I gotta break down and fit and coat my Hedmans.
I am using the Lingenfelter 1 5/8 inch headers. They were HPC coated from the factory and I had no problems with fitment or scratching on instalation. Any one who thinks they can "clean up" their stock manifolds to flow like a header is nutz. When you remove the stockers and see how pitifully small the tubes are compaired to a header system you will agree.
I wasn't suggesting that stock L98 manifold cleanup was an equivalent to headers, but certainly is a low $$ improvement for those who may not be ready to do headers (or have the Ca smog ***** to contend with).
Anyway, for the cost of a set of gaskets and a weekend I'm going to try it; I'll post the track results (though maybe not this season).
I agree. Some of us can't put in headers due to visual inspections during emissions checks. Cleaning up the stock unit will provide some boost (I am convinced based on what I have seen so far) and allow the car to pass the visual check. I agree that headers flow better, but in this case it is any port in the storm :cool: