vh41de headers

[mak3]

hi everyone.just wondering if has anybody has had any exsperience during enging swaps,with fabricating new better flowing headers for the vh41/45 iv just finished a set hoping theyll help gain a little pwr. taking one look at the origonals when i got my vh41 n thought there pretty restrictive

[Q45tech]

The headers are designed the way they are to accomplish QUICK cat light off to meet emission standards. Changing anything from the last cat back to engine is a violation of Federal and State laws.

Measure the backpressure at the first O2 sensor bung* to determine which might help more............exhaust, higher flow but limited life cat, or manifolds.

The exhaust cams are probably more a limiting factor than the manifolds.

Again the design is there to make sure the CATS function to at least 100,000 miles as required by EPA.

* Graph the pressure rise vs RPM at WOT under acceleration load to redline. You will see little until you start to exceed the torque peak rpm.Modern engineers try to achieve maximal torque [efficiency].

The rise in pressure is the converse of a flow bench test but very useful.

[JimmyMethod]

hi everyone.just wondering if has anybody has had any exsperience during enging swaps,with fabricating new better flowing headers for the vh41/45 iv just finished a set hoping theyll help gain a little pwr. taking one look at the origonals when i got my vh41 n thought there pretty restrictive

You custom fabbed headers? Wanna make me some?

[mak3]

i understand what your saying thankyou but the engine in question is for a transplantinto a classic older car. there aint going to be any cats trust me. New zealands a great place to modify cars. ive seen a few transplanted nissan v8s over here an everyone ive seen has slightly larger dia an better flowing headers.including a vh41 into a nissan safari by a nissan parts dealer who mensioned that the stock headers were one of the ways which nissan used to help restrictpower to keep it under the 208kw. So he suggested that any better flowing headers of the right design should unleash a little moor power within.i jst wanted to confirm if he had sent me down the right track.

[Q45tech]

Again the cams are matched to the headers................little overlap at TDC to avoid reversion.

[maxnix]

Might want to take a look at the Impul ones for the VH41DE as they are obviously designed fro RHD.

Don't recall seeing any camshafts for the engine, but in Japan, all kinds of things exist that we don't see.