Talk Morgan Forums Morgan Sports Cars Classic Morgans (pre-CX) Home again, home again...

Thanks. It sounds like it might be an option, after all. I think the best thing would be for me to try and take one fitted with the sports exhaust for a test drive.

Hi Peter, good to know you are back and happy with your trip and your car!

Your manifold looks about the same as my one. But there could be a difference in sound generation as the Plus4SS also has the single throttle bodies.
I had the experience with significant buzz sound in push operation. After some research my garage learned that the reason is the manifold´s design and structure itself (which is otherwise a piece of art).

One solution is to damp the manifold. Therefore I have let wrapped the manifold with heat insulating tape, similar to this one:

http://www.thermotec.com/products/11001-exhaust-insulating-header-wrap.html

The result is a clear reduce of buzz in push operation - and - as a free gift - a significant increase of torque and power in the mid rev band. The colour of the sound is a little bit reduced but you became familiar with it very soon. The car sounds more "dry" but the performance win is astonishing.

Later on I learned that a manifold wrap is common with racing cars. The effect of more performance is caused by keeping the air in the manifold hotter. Therefore the whole air flow works with lower resistance. Air speed in the exhaust rises up and accordingly the intake can suck more oxygen as well. Imagine how huge our manifolds are...they work as a cooler which should not be so.

Ah yes...your speed bumps.......I sailed over them without any problem!

Heinz, do you mean by "significant buzz sound in push operation" that you were getting a sort of metallic vibration at higher revs under acceleration? If so we are also experiencing that and I thought maybe a clamp was a little loose.

The manifold wrap is as ugly as sin but if it solves that problem and also makes the system more efficient I will consider adopting it too.

Peter...it may be worth easing off the clamps and retightening them. It works on my system!

Thanks Jay.
The car is going in for its first service on Tuesday. I will ask them to have a look at it.

Not when accelerating, the opposite. When driving without throttle the buzz sound appeared. Any other Plus 4 SS experiences about this issue? I talked to Günter who shares the same experience. Yes I´m aware that on an aesthetically level the pure manifold looks much better. But the increase of torque plus the suppression of buzz justifies the wrap around. It´s an issue between 3K and 4K revs.