js racing exhaust manifold

[blueguy]

My 4-2 is in transit (2-1 is already here), and should be fitted/mapped along with some other bits by end of August.

I'll keep you posted mate.

 

[sinbad]

did anyone else get this manifold in the end?

If so, how does it perform on your car (and more importantly, what other modifications do you have)?

I'm having a heap of difficulties getting the power extracted from my K20A. will be trying a old DC sports race header instead of the J's today. there is something seeeeeriously wrong with my setup at the moment.. might have to start a new thread..

Please explain?

 

[Kinli]

did anyone else get this manifold in the end?

If so, how does it perform on your car (and more importantly, what other modifications do you have)?

I'm having a heap of difficulties getting the power extracted from my K20A. will be trying a old DC sports race header instead of the J's today. there is something seeeeeriously wrong with my setup at the moment.. might have to start a new thread..

Please explain?

here you go:
viewtopic.php?f=4&t=31794

 

[Kinli]

My 4-2 is in transit (2-1 is already here), and should be fitted/mapped along with some other bits by end of August.

I'll keep you posted mate.

So, did you get the manifold and did you map it?

 

[blueguy]

So, did you get the manifold and did you map it?

Hey Kinli, yes Mase mapped it at the same dyno I've had a dyno run on before.

For reference, the first two graphs are when the car was OEM so:

• Stock at the fly
• Stock at the wheels
• J's 4-2, 2-1, 60RS, Tsuchinoko intake, RBC, 70mm TB, Kpro at the wheels

At the Fly - Stock

At the Wheels - Stock

At the wheels - J's 4-2, 2-1, 60RS, Tsuchinoko intake, RBC, 70mm TB.

If I take the same drivetrain loss it's pushing just over 258bhp at the fly. So that's a gain of 41.4 bhp at the fly.
In addition my induction pipe fitted to my J's intake needs sorting out to be perfect. The only way would be a custom job from the likes of SFS or Samco.

More importantly though, it drives very well and the difference in bhp and torque was very noticeable

 

[wayne_teggy]

I have had the j's racing manifold fitted now for roughly 7 months. A beautiful looking manifold but I made sure the engine mounts where done first. I didn't want £800 going down the drain due to cracks.
I had the manifold fitted along with a 2-1 decat and a smaller 3.4" supercharger pulley ( down from a 4")
Before , it had standard manifold , standard cat and bigger pulley and it was dynoed at 279 at the fly.
With the new exhaust and smaller pulley it produced 279 at the wheels so roughly 335ish at fly

 

[Kinli]

Hey Kinli, yes Mase mapped it at the same dyno I've had a dyno run on before.


If I take the same drivetrain loss it's pushing just over 258bhp at the fly. So that's a gain of 41.4 bhp at the fly.
In addition my induction pipe fitted to my J's intake needs sorting out to be perfect. The only way would be a custom job from the likes of SFS or Samco.

More importantly though, it drives very well and the difference in bhp and torque was very noticeable

Very good. Thanks for the update!
I've had the car sitting in the garage for about two years and I'm just strarting over again...
Do you have any memories about the tuning? I'm just wondering about the longer primary pipes. Was the j's header somehow trickier to tune than a "normal" header like toda, dc, bc, etc.?

What diameter is the 60RS b-pipe at the front? I'm running a mugen twinloop at the moment and it makes a not so nice bottleneck as it's smaller than the j's 2-1 end.

What is yout target AF at WOT?