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I beleive you, but I'd also like to get some insight on the subject as I am considering a street port for my rebuild and I was also considering headers so if they're not necessary even with a street port I can focus my money elsewhere
but I don't expect anyone to start listening now any more than 10 years ago ...
Originally Posted by TheRedRotor
im seeing some strong opinions in this thread.....however if the motor in question has been streetported, would everyone still be opposed to an aftermarket header setup or is it more practical for the application?
So this hasn't made much clear to me regardless of how many times I read it, Is there an aftermarket header that would be better than the stock one? I.e has the most gains over the competition/stock? Or should I get a shop to make one and if so, In what shape/style? Some legitimate answers would be nice.
Anything that claims to improve power using equal length runners or helping with scavenging is full of crap. Those concepts don't apply to the Renesis like they did on previous 13B's or piston engines.
Taken from the link... Essentially since the motor has no overlap, exhaust manifolds do nothing because there's no such thing as exhaust gas savaging if there's no open port to pull it out of the engine...Hope that makes since to you, and why this whole Idea is chasing ghosts. If you want something that sounds a little different or looks better... go for it. Expect no gains though. As Team recommends, just make it as free flowing as possible. That's all you can do.
Originally Posted by TeamRX8
In summary, no overlap = no exhaust tuning. For all intents and purposes I view the Renesis as a slightly supercharged naturally-aspirated engine. All the pulse tuning is on the intake side to provide a slight supercharger effect at certain rpm ranges. Exhaust tube length, diameter, etc. is mostly irrelevant. All you can do is make it as free flowing as possible to get what ever you can out. That’s why I recommend going straight to 2” OD tubing, smoothly collect into 3” as soon as possible, and then have 3” back to the rear muffler area and then split into two 2.5” or a single 3” with some type of center muffler/resonator for the most benefit at the least effort.
My searches turn up very old posts. I wish there was a sticky on the header for comparison.
I plan to buy a header pretty soon, so I've been looking around. Currently for exhaust I have the HKS single exit, and racing beat non resonated test pipe.
BHR long tube looks amazing, but its cost accounts for the test pipe/ catalytic that it eliminates. ($1625)
Racing Beat ($536) has my favorite pipe design. Looks like the runners are simple and equal length.
And then there are other headers that look decent with a low price like obx($270) and turboxs($250).
Is racing beat the best way to go second to BHR?
go with racing beat. they know what there doing, never been disapointed with there work, i have all there parts and the gains are in the pudding.
Did anyone else notice that BHR changed their header offering from equal length to just 1 7/8 primaries and CNC'd manifold port transitions? I want to upgrade from my revision.
Make that 13 years now and still counting, lolz ...
maybe this will help, but I doubt it ...
Originally Posted by TeamRX8
but I don't expect anyone to start listening now any more than 10 years ago ...
Originally Posted by TheRedRotor
im seeing some strong opinions in this thread.....however if the motor in question has been streetported, would everyone still be opposed to an aftermarket header setup or is it more practical for the application?
Make that 13 years now and still counting, lolz ...
Care to weigh in on the apparent revision to the BHR header? Design wise, as it's still a pretty expensive piece. Charles seems to have made notes on what you were talking about in your theory thread. If you want to say it there, or take it to PM feel free, I'd just like to hear others thoughts on it.
Well you can nitpick all day long if you want, but it’s all for nought wrt engine output.
Otherwise 2” primaries merging smoothly (15* or 12* collector) into 3” single and minimal restrictions is all that matters performance-wise imo and is my recommendation. I don’t really see an issue with 1.875” tubes, but how you fit them up to the actual exhaust port shape might matter more.
If you want to play the length game then knock yourself out, but again, everyone is so tied into overlap valving engine methodology they just can’t accept that you can’t get anywhere near the resonance strength or powerband range on a zero overlap timing engine. Which a Renesis is unique among almost all engines in this regard. Otherwise I recommend individual flanges & tubes with slip fit connections for thermal expansion/contraction. T321 tubing is also best also due to high exhaust temps, especially if going thin-wall to save weight. If you were building a true resonance manifold the siamese center port would need to be a much smaller diameter and different length than the two main end port tubes too fwiw.
so while I did build a tubular header for this next go around, I have zero performance gains expectations over the extremely short length primary ultra-lightweight manifold race header that I originally built back in 2006. I had to retire it due to thermal stress fracturing finally taking it’s toll since it has no allowance for expansion/contraction. So the new header is built for that purpose with everything split apart into individual components with slip fit connections. The length is only for expansion allowance using thin 18 & 20 Ga. thickness T321 tubing.
I actually have a 3” extension piece to elimnate the three straight tube sections and locate the collector on the main primary connections just because it’s a bit lighter.
Again, the RB header with 1.75" 14 Ga tubes is only a 1.584" ID, that's less than the flow area of the smaller siamese port, let alone the larger end ports.
but I don't expect anyone to start listening now any more than 10 years ago ...
matching up tube diameter to port area is a manufacturing decision. a real header is designed for the intended power. 1-3/4" is MORE than enough for 250 bhp (on the large ports, no less). 2.5" cat back is also more than enough. I'd like to see pressure drop numbers to prove otherwise, or acceleration tests. dyno test procedure won't show squat.
the most likely reason they go with 14 ga is because they use 304, which doesn't like heat, and makes it a little more durable. so if they don't add much hp, they'd darned well not crack.
scavenging has two purposes - starting intake flow, and reducing exhaust pumping, which I'd say it's the more important function. it just just as much to do as when you open the exhaust port as header size/length. people on this forum keep saying that intake porting does nothing...which tells me it doesn't need more intake overlap (i.e. scavenging). that would also mean bridge porting just encourages raw fuel out the tail pipe without much power gain (with the typical configuration). we need more investigation into intake pumping and intake ramming (between tdc and port closing).
Last edited by Chris Stavropoulos; 04-28-2019 at 12:02 PM.
Have Racing Beat and felt no difference. Just louder. Also, it was a pain in the *** to install. I had to disconnect both motor mounts and put the engine on a host and shift it to the driver's side to get enough clearance to get the header on. it was a waste of time and money.
My take on the header controversy - a $140 alibaba taiwanese header, I chopped off the stock collector and welded on a 3" ID pipe with a v band. Cheap, not sure how effective though.
01-14-2018, 01:47 PM
