Reducing Exhaust Diameter

[DeeElle]

Hi all. Just after some advice. I have a 4 branch manifold that has a 2.5 inch pipe diameter exit. My current exhaust is 2 inch diameter. I am looking at keeping my original exhaust through using a reducer (or 2). Has anyone done anything similar and were there any adverse side affects, or does anyone have an opinion as to why this would or wouldn't be suitable? Cheers.

[stevieturbo]

If you're sticking with the 2" system, then really cant see a problem.

[davepoth]

stevieturbo said:

If you're sticking with the 2" system, then really cant see a problem.

Shouldn't be an issue, but you won't get as much of the benefit of the new manifold. Make sure that the reducers don't cause turbulence in the exhaust.

[SMGB]

I had to have an adaptor made to connect the mild steel manifold to the stainless system on my MGB, they were both nominal 2" but were out by about 5mm. A specialist outfit up at Silverstone put the car up on a ramp and dug out a stainless tube that fitted the smaller one, the exhaust, and then cut a short lenght and then stretched one end until it fitted the manifold. The resulting change in diameter is radiused and I dont think it causes many problems. It isnt bigger is better with exhausts, you need the right gas velocity Anyway find a local custom exhaust outfit and they will fix you up.

[DeeElle]

Appreciate your responses, thanks.

[PaulKemp]

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