[JohnnyC]

How much difference in performance will be noticed between the origianl ram air manifolds, which are 2.25, and the r.a.r.e repo. manifolds that are 2.5? Will there be a drastic change? Am going to put one or the other on my 462 when its done, but need a little help making my mind up. Thanks

[69lm69gp]

A while back HPP did a test of headers and ram air manifolds (Dec 2003). They tested both the PY and RARE manifolds. In the first 455 test the PY manifolds used compression bent pipes and the RARE manifolds used mandrel bent head pipes that RARE sent with the manifolds. The PY pieces produced 19 less HP and 13 less lb/Ft of torque. In the second test they adapted the RARE head pipes to the PY manifolds In that test RARE manifolds only produced 2 HP and 1 lb/Ft of torque over the PY manifolds.

Hope that helps.

Mike

[JohnnyC]

69lm69gp,

Thanks for the info,,,, but they py manifolds and r.a.r.e are both aftermarket repo's, correct? Or am I wrong? The reason i created this post was because i'm looking at some original ram air 3 exhuast manifolds on ebay that have 2.25,,,, wanted to compare what that would cost me power wise as compared to the r.a.r.e 2.5 repo's... thanks

[69lm69gp]

Yes both manifolds are reproductions. The PY manifolds were a stock replacement with 2.25 outlet.

[racerboy]

Don't know if this matters to you, but the R.A.R.E manifold bolt bosses and flanges more closely match the original production RA manifolds than the other repros out there (PY, AMES, YO).

Frank

[JohnnyC]

so how much of a difference in power loss am I going to see if i use a pair of original ram air 3 manifolds at 2.25, compared to the 2.5 r.a.r.e ones.......There is a big difference in price also

[7T2]

there is enough meat on an original set of oe ra3 manifolds to open them up to the 2.5" headpipes. you have to do the flanges too. a endmill would be best, but you might be able to use a big drill press with the right accessories.