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Triumph TR6 - Exhaust manifold

I have twin stainless exhaust pipes on my car but have now noticed that the down pipe has corroded and got a small hole in it. It appears that there is no join from the manifold to the pipe. I am considering replacing it with a stainless sports manifold, I have been told that this is increases the BHP of the car and may stop the popping in the exhaust when I de-accelorate. Would welcome some comments or experience on this


Malcolm Wright

I doubt changing the manifold will stop the popping when you gear down...I've found that to be caused by the mixture too lean and /or the timing being off.

I understand a tuned manifold header will increase HP but how much??

Charlie B.

If the poppping is the result of secondaary combustion due to an exhaust leak, it will help with the popping. What happens is that residual fuel in the exhaust is still hot and will combust when given a source of oxygen, such as that introduced by an exhaust leak at the manifold / downpipe joint.

As for a horsepower increase, well there might be some small gain but the standard manifold flows rather well. The big advantage of the standard manifold over the sports manifold or what we would call headers over here is that they provide a fair amount of clearance between the exhaust run and the frame while providing access to the starter in the event that it requires replacement. With the header set ups that I have seen, there is little clearance between the frame rail and the header tubes. Any collapse of the engine mounts will allow the headers to contact the frame eventually damaging the header and introducing an exhaust leak.

Use really good engine mounts such as those heavy duty units from Revington if go with the headers to minimize the problem.

Your HP increase depends on the style or type of headers you use.

There are several types out there some of which are VERY different from others. Long run, short run, 6 into 3 into 1,,,,, or 6 into 2, all act differently.

IMHO check out wishbone classics. the owner Kai Radicke is a builder of performance engines. He knows these motors. He researchs and stands behind everything he sells.

Ive bought cheaper headers in the past and have been very disapointed with them. Here is where you truly get what you pay for.

And yes the popping is due to an exhast leak causing fuel in the exhast to burn. No leak, no popping. And the reason you have fuel in the exhaust is because there is some valve overlap when the intake and exhast valves are open at the same time in order to help fill the combustion chamber with the new incoming load, and force the old spent gases out into the manifold.

Hiope this helps,


This thread was discussed between 15/01/2007 and 29/01/2007

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