Exhaust manifold beast, what other adjsutments?

[christopherhenry]

I've obtained a beast of a 6 - 1 exhaust manifold for my Mk2 2000. I believe it's a TR6 manifold, but it may not be standard even for a TR6. It has 6 separate pipes that all come together to a single rather large pipe which splits into 2 for a twin exhaust. Fortunately as the car is a LHD, I have plenty of room on the right side of the engine. I think the steering would get in the way on a RHD.

We're going to fit the manifold and a custom exhaust system to the 2000 this week. My mechanic/friend in Germany that will be doing it has obtained some pipe which is about the same diameter as the output of the manifold (there isn't room for a twin exhaust, so we're sticking to a larger bore single) and also a couple of silencer boxes, a short one for the middle and one for the back, under the boot. The standard pea-shooter exhaust has a few minor holes and problems, so needs to be replaced anyway. The aim is for a few more BHP and of course a better exhaust note.

I think he's intending to come straight down with the manifold and then straight back, so not going through the chassis, as the standard exhaust seems to do in 2 places. It'll come out on the left where the existing exhaust goes. Ground clearance will be reduced, but apart from that I can't see it being much of an issue.

Is there anything we need to be aware of? Does anyone have any tips or pointers? What about carb (Stromberg) setup afterwards? Will I need richer needles or to make any other adjustments elsewhere? What about the extra heat, should we take measures to shield the manifold or wrap it in something?

Thanks.

[red2000chris]

HI. I would wrap the manifold in heat wrap as there will be a lot more hot surface area under the bonnet. As for the other possible issues, I would wait for more people in the know to comment but I guess there will be a big drop in back pressure for the engine and carbs to remain in standard tune.

[christopherhenry]

Can't do any harm to wrap it in heatwrap can it!

[TRPi]

@christopherhenry, thanks for notifying in similar thread: viewtopic.php?f=11&t=4910

As told by others, many would prefer 6-3-1 against 6-2-1 and 6-1 design. In Peter Collier's Triumphant Rallying book - "steel tubing exhaust manifold, 55mm outlet" - is mentioned about Triumph 2000 mk1 group 3 FIA spec. I would guess, that Standard-Triumph used 6-2-1 spec for rallying big saloons (when allowed by rules).

I have no practical experience on this topic, but I would assume loss of low-rev torque with 6-1 design.

If I am not wrong, 2.5Pi works rally cars had exhaust system running out of car's right side near rear door. Obviously it had only one silencer below the front seat on RH

JS

[christopherhenry]

Thanks. I've answered in the other thread, we may as well keep it all in there.