Quote:
Originally Posted by bifrogifro
Currently have a J4, JP4 and JP4S. I'm scrapping the rust bucket C2 Code so taking a few parts from the JP4S.
Does anyone know what power is to be expected from a JP4 with either JP4S or J4 cams and JP4S alloy inlet manifold? If the J4 cams are more worthwhile, what other valvetrain components would it be prudent to swap over too?
Is remap a necessity?
Cheers
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the crucial thing on these engines, is to make sure the inlet cam and the intake manifold match.
If you're using a J4 plastic manifold, you MUST use the J4 inlet camshaft.
The plastic J4 manifold has better performance for intake temps too.
This isn't about peak power, this is about resonance. You'll have a much more consistent power across the board with these items matching. It's just not worth the hassle mixing and matching.
For the record, my standard j4 engine went from 122hp to 138hp in a short dyno session. Still probably a bit more to be had. That's simply with an old 4-2-1 raceland, with janspeed cat converter and system and a cone filter.
In short what I'm saying is if you fit the C2 manifold and cams, you will gain nothing.
By all means, feel free to swap over the complete engine, the valves are a bit different. There's a bit more torque in the mid range with the JP4S engine. This won't net you more hp though as it doesn't make the same power at high rpms but it's a better engine overall in terms of overall power output.