The V8 Owners Forum -

we had this posted on here somewhere but cant find it,

what size exhaust manifold tubes is ideal for the new motor,
4.6 block and crank with 4.0 pistons on 4.6 rods and stg3 heads,
think my present ones are 1-1/2
these a bit small?
should i be looking at 1-5/8? 1-3/4?

I think 1 5/8" is the best all rounder for modified RV8's Tony, if you were going to 5l or so then maybe the 1 3/4", but I'm sure Mike will confirm or shoot me down

1.5/8" is great. 1.3/4" could be made to work, especially on a high revving motor but you can comfortably run a 600hp small block chevy with 1.3/4" primaries so it's not neccessary for an RV8.

so if i upgrade from the 1.1/2" to 1.5/8" manifolds i'll be ok then mate,
thanks,

what about if i go ahead and fit the charger? 1.5/8" be ok still?

Hi Tony
1 5/8 should be OK with ported rover heads and a charger, 1 3/4 would also work, the smaller ones would be better for torque low down, 1 3/4 would be better for the top half of the rev range. If you were also going to use a centrifugal blower and a touch of nitous that you wound out as the boost came in then I would use the 1 3/4, it really depends on how much boost you were going to use. It would also depend on if you were to fit even bigger exhaust valves and where the red line was going to be.
If the plans are definatly for a super charger and to get the max out of it then go for the 1 3/4" ones, I doubt you would miss the 5-10 foot lbs below 3.5K and they should work well up top.
Sorry a bit of a rambling answer.
Best regards
Mike

Which manifolds or extractors would be best for a TR7 V8 running a 4.6 Rover with modified heads etc and used for circuit racing?
Any ideas?

Hi
I think the main issue will be what fits, however avoid block huggers you are better off with cast ones, especially the range rover type that are in 2 parts each side. If they will fit then a four into one with cross over or X pipe arrangement. . . but I think the issue will be what fits.
best regards
Mike