Any how tos on modifying stock exhaust manifold
#1
Any how tos on modifying stock exhaust manifold
I seen somewhere in some of the header threads that it is better to modify the existing manifold to flow from the stock size to a 3" outlet to mate with my Racing Beat midpipe. Does anyone have any recommendations on materials, where to cut or have any pictures or How Tos on this?
Thank you in advance.
Thank you in advance.
#2
Registered
It makes sense to have a wider opening if running an aftermarket exhaust. However, you wont see a lot of HP gains from it with the Renesis engine. Because the stock manifold is cast iron, I would be very careful if you are going to attempt to bore it out. There is no real way to repair the manifold if you bore it too thin. Also, you may need to tune the ECU so it can make use of the extra exhaust flow.
All in all, unless you are running a turbo or supercharger it's really not necessary.
All in all, unless you are running a turbo or supercharger it's really not necessary.
#3
I am not talking about ‘boaring’ or posting the exhaust manifold.
I actually found the thread I was looking for.
https://www.rx8club.com/series-i-aft...thread-266914/
scroll through and you’ll see team RX8s modified stock manifold
I actually found the thread I was looking for.
https://www.rx8club.com/series-i-aft...thread-266914/
scroll through and you’ll see team RX8s modified stock manifold
#4
Registered
Yea, I wouldn't copy that. He has the time and resources to build more if something goes wrong in construction, or over time as the car is driven. Unless your car is strict racing application, this won't really be worth your time or money to do. Looking at a slight HP gain on a stock engine. If I were running a turbo racing setup, I would just buy a set of stainless steel headers.
Last edited by CaymanRotary; 08-01-2019 at 03:59 PM.
#5
My car is not a daily driver, it is about to go thru a Pettit racing stage 3 build. I’m sticking N.A. for now.
This isnt that much work, and a trustworthy header that I’d buy (racing beat, black halo) are $500, so in your opinion you don’t think the fabricated stock manifold will be in the end cheaper and more free flowing? The aftermarket headers only exit at around 2”...
thanks for your reply
This isnt that much work, and a trustworthy header that I’d buy (racing beat, black halo) are $500, so in your opinion you don’t think the fabricated stock manifold will be in the end cheaper and more free flowing? The aftermarket headers only exit at around 2”...
thanks for your reply
#6
FULLY SEMI AUTOMATIC
iTrader: (9)
pretty sure teamrx8 has a very detailed thread on the renny manifold fyi
#7
Registered
Well in your case it is a viable upgrade then. Aftermarket stainless steel pipes pretty close to 3". Most are 65mm to 70mm. The thread seems pretty detailed but it doesnt show how he constructed those pipes. It's really not something that should be attempted unless you have background in that type of fabrication. For me, it would be cheaper to just buy an aftermarket header than to attempt to modify the stock header yes.
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Rexy84 (08-01-2019)
#8
#9
Well in your case it is a viable upgrade then. Aftermarket stainless steel pipes pretty close to 3". Most are 65mm to 70mm. The thread seems pretty detailed but it doesnt show how he constructed those pipes. It's really not something that should be attempted unless you have background in that type of fabrication. For me, it would be cheaper to just buy an aftermarket header than to attempt to modify the stock header yes.
Can you point me to a trustworthy RX8 header with a 3 inch outlet? I prefer not to have a “bundle of snakes” or “matched length tubing” and I’m not seeing any mainstream headers with an exit of 3”...
i currently have a racing beat dual resonated midpipe and HKS dual day back exhaust.
#10
Registered
Cant really help with that. However, you could buy a cheap stainless steel header and modify it so it gets the 3" you want. Would be 100x easier than trying to modify the stock one. Cast iron is such a crappy material to work with.
#12
Registered
It's time consuming, risky and expensive either way you go really. I like the idea, but its gonna be a lot and I still doubt it will give you huge HP gains even if you did it correctly. I'd save that mod and put the money elsewhere. Headers should be the last thing you think about if you are unable to get the power you want. You are better off just going the forced induction route to be honest. Money is better spent there.
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Rexy84 (08-01-2019)
#14
Water Foul
Really take your time and research what is available to be gained from a header. Most of the restriction is in the ports themselves. You might get 3 to 5 HP above 7500 RPM. Worth it?
#15
No respecter of malarkey
iTrader: (25)
Unless you want to spend between $1500-$2000, just take a Racing Beat header and put a good straight 3” collector on it. Even then it will still cost up near $1000 if all new parts. If you can find a used header it will save you some money.
Here is an example, longer tubes not necessary, do not put a reducing collector on it like he did
https://www.rx8club.com/rx-8-racing-...rx-8-a-220741/
Here is an example, longer tubes not necessary, do not put a reducing collector on it like he did
https://www.rx8club.com/rx-8-racing-...rx-8-a-220741/
The following 2 users liked this post by TeamRX8:
CaymanRotary (08-03-2019),
Rexy84 (08-01-2019)
#16
So, to be clear... in all of your opinions... after I’ve exhausted (no pun intended)” all available and efficient porting, balancing, blueprinting, (stage 3 Pettit) and bolt ons (midpipe, Catback, ignition, AEM intake etc) you’d still not get a header? Stock is still the best option, even tho it would be the only “stock” piece left ?
#17
Unless you want to spend between $1500-$2000, just take a Racing Beat header and put a good straight 3” collector on it. Even then it will still cost up near $1000 if all new parts. If you can find a used header it will save you some money.
Here is an example, longer tubes not necessary, do not put a reducing collector on it like he did
https://www.rx8club.com/rx-8-racing-...rx-8-a-220741/
Here is an example, longer tubes not necessary, do not put a reducing collector on it like he did
https://www.rx8club.com/rx-8-racing-...rx-8-a-220741/
I really like this idea of lengthening the Racing Beat header ❤️! See I’m successful with no kids and an awesome wife. I need something to spend my money on 😬
#18
Registered
Nothing the bolt on, unmodified stainless steel aftermarket header couldn't handle. As mentioned before, the real restriction is in the ports, not the header. You could run a supercharger no problem with the stock header.
#20
Haha stop. Don’t make me leverage my life savings for that magnificent mid engine masterpiece.
But, seriously...I’m going to make my RX8 as beastly and fun as possible and then most likely get a 2009+ 911 with PDK tranny. Or... a mid engine vet in 2-4 years
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CaymanRotary (08-01-2019)
#22
#23
Whats even weirder is you’re the whole reason I’m seeking this mod in the first place. I love your modified stock setup. Why not just appreciate the hunger you inspire in others rather than judge? You’re no one, in comparison to anyone else. Happy Thursday
#25
Touché. However, Either way, sir. Noob or not, it’s my money, my time, my efforts. I’ll still be happy either way. I appreciate your input and the amazing thread and research you put into your original post that I cited and loved. Thus, provoking my entire thread in the first place.
I found a thought I liked, from you coincidentally... and somehow you’re still judgmental? I don’t trust someone or myself modifying a 15 year old iron manifold when I can buy something from Racing Beat and do a similar modification to with more longevity and similar results to add on to my existing and to be modified setup.
Thanks for your 2 cents.
I found a thought I liked, from you coincidentally... and somehow you’re still judgmental? I don’t trust someone or myself modifying a 15 year old iron manifold when I can buy something from Racing Beat and do a similar modification to with more longevity and similar results to add on to my existing and to be modified setup.
Thanks for your 2 cents.