Best header for JRSC?
 

Trying to source all my parts for the grand install and was wondering if people have any experience with different headers? Function > Form

It’s probably the Ace A350.


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Ace is the best.
Many people will say get a tomei or invidia or maybe even a jdl because of cost and bang for buck.
But the ace is the all around best in performance.

Ace definitely seems like the make for highest HP. Best could mean a few different things for headers though. JDL makes great headers, I'd be sure to get some headers that come with ceramic coating to insulate heat in the headers for efficient evacuation. You also need to decide if you want UEL or EL. I'd stick with EL for pure function.

JDL UEL performs like a EL header according to most people.

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My thoughts are that there are limits to NA power, which dictate the size of the exhaust. Typically, if you go too big then all you get is top end and too small and all you get is low end. A properly sized diameter and runner length 4-2-1 header seems to allow for the best NA gains, but does that mean it'll have the best gains for forced induction? Not necessarily, especially if there is significant increase in power.


Many people say for turbos that no exhaust, or the bigger the better, is the way to go because there is no sense in limiting the exhaust flow, as the turbo is flow dependent. A supercharger is not dependent on the exhaust to generate boost, so this idea of bigger is better just doesn't hold water with superchargers, as long as the exhaust is not the bottleneck to engine output.

With a roots supercharger like my Harrop SC, the power delivery is linear, meaning it build boosts linearly with rpm. The JRSC, like other superchargers, build boost exponentially (X^2) with boost, which is why they have late power gains, but really big gains when that power finally comes on.


So it begs the question, what would be the best header? Well, if the goal is to not limit the flow then the header should be large to support top end power, which is where the JRSC has most of its flow. If the goal is to try and flatten the torque curve a little then the header could be designed for low end power, but then it may be restrictive to those high rpm gains, which is kind of what the JRSC is all about.

more than highest HP, i would say ACE is best for torque gains under tge curve, and good gains on top end. if i m not wrong jackson racing is a centrifugal sc, so you really want to gain more under the curve

also don't go UEL for forced induction, i have it and i'm down more than 20hp on higher rpm compared to a friend with identical setup as mine (hks v2) with a EL catless header

I agree 100% with what you've said, I'm going EL as well for my FI setup. They may be trying to have their car embrace the boxer rumble more and be willing to sacrifice overall performance for it, which is as long as they know what they want. At least a header can be changed out relatively easy.

Performance is not being sacrificed.

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Cosworth says that just a more free catback net more than 10whp on FI cars, do you think UEL can go the same as EL on higher rpm with a centrifugal supercharger?
i understand JDL makes UEL with quite big primaries but they sure can't go the same as EL, since uel are more inefficient per nature.. talking about pump gas of course, not E85

How much power at 3k and at redline is a header realistically going to yield? Get the s/c on, that's the important thing. I would only go changing heads, over/front pipe for noise and flames. I'm on jrsc and catback. Stock head. Already pushing luck with neighbors lol. I have a fetish for subie rumble for uel all the way.

Ace is king.

A good header is additive or multiplicative with a supercharger!

I'll be running my A350 with the JRSC!