Has anyone got one of those engine analysis programs?

[Chassis 33]

As per the title, I'm looking for some guidance for designing the primaries and secondaries for a 4-2-1 exhaust. If you have one of these simulator packages or experience with RV8 exhausts could you get intouch. Basically I for a 3.9 RV8 running a Typhoon cam, the details of which lifted from the Real Steal website are 218 duration on both inlet and exhaust and .48" lift with 1.6 ratio rockers again on both inlet and exhaust.

Rolling road figures gave 245hp @ 5400rpm, and I forget the peak torque, it was something like 260 or 270 at around 3000rpm. The power figure is about right for the series (175hp/ton at the wheels), but I'd like a bit more torque.

Any thoughts on lengths and diameters, I haven't the funds to fit a cross over system in the space so the two banks will have to be treated separately.

Regards
Iain

[GavinPearson]

You'd be better off buying an exhaust from a Rover V8 tuner who knows what they are doing. Calculations get you 90% there, but experience gets you the remaining 10%. A good tuner will be at the 98% mark, and it is probably worth paying the premium to benefit from their experience.

[GreenV8S]

If you aren't balancing the two banks then it isn't going to tune worth a anyway, I fear.

[HarryW]

Can't remember the exact sizes, but if you are still running the standard TVR 4-1 manifolds they are probably over bore for the 4ltr imhe. I think they are something like 1 3/4", I went down to 1 5/8's on the V8S sticking to the TVR pre-cat layout (the large pre-cat volume and main cat volume will rob you of torque too) mine use to put out around 280lbs in that configuration (helped by mapped igniton too .
Ultimately packaging dictates what you can and can't do. Not sure there is much to be gained by going to 4-2-1 with the odd firing RV8 tbh. The unequal length of 4-1 TVR primaries can actually give you a better spread of torque too. I think good blending of the secondaries, rather than letting them mix straight into the center box will help with a decent equal length on them (over 30" (40" better) will yield more than the manifolds alone.
Speak to rob et al at V8D they did a lot of back to back dyno testing on RV8 manifolds a few years ago.

Editted to add if I was to do it again I think I might even take the primaries down to 1 1/2"

Edited by HarryW on Tuesday 26th February 00:25

[rev-erend]

Rob always advised that 1 1/2 inchs are optimal for nearly all RV8's.. with 1 5/8 being OK for the bigger engines (5.3 etc..).

As Harry says - packaging is the main issue - there in not much space as you know and that largely dictates what can be done.