Thinking of swapping to a 4wd one for a bit earlier boost, anyone done this, good bad thoughts ideas welcome.
thanks
tabetha

 

4x4 ex manifold gets restrictive over 450 bhp,and its hard to find one that hasnt cracked.

 

Graham goode says about 420bhp max for the 4x4 manifold, Mine not cracked yet and shes done 114k.

 

I have one but it has a hairline crack in it, be ok though I would think, thanks for replies.
tabetha

 

so to get boost earlier you want to use a manifold with a crack in it that will no doubt leak?

 

Earlier boost is caused by more airflow.. considering a 2WD manifold flows more than a 4WD one, then I can't see how you're improving anything

 

Actually, they flow the same for any given flow from the engine

And far more to boost building than that, an unequal length setup can result in short durations of higher pressure within the turbine housing as two pulses hit at the same time which can be useful for spooling a turbo (although typically will be counter productive higher up the rev range) especially if tuned to happen just at the point before the turbo would spool anyway.
Id hope that when ford designed the manifold for the 4wd they took this into account.

 

I had 425hp & 425lb ft on my old Harvey engine on a 4wd manifold no probs & had seen 432hp with it !

I'd go with Lloyd on the prediction of hp figures & when the manifold becomes restrictive. It is slightly less laggy than the 2wd item & the hair line crack shouldn't matter too much, they all do & it's inside, not all the way through !

Good luck

jb

p.s. I prefer the sound of Cossie's wit a 4wd manifold !

 

They have a much more compact design and offer less lag, as I drive a lot low down around 1500/2000 rpom this would suit me better.
I've never seen a problem with cracked ones actually breaking, or leaking to any degree that matters, so this is not a concern.
tabetha