Exhaust sizing
superhatch
Moderator
I haven't had to size an exhaust for a FI application before so I was looking for some input from someone with more experience.
I'll be running 8-10psi from a jrsc on a z6 which will have a 10.5:1 compression ratio. Any input would be appreciated.
I'll be running 8-10psi from a jrsc on a z6 which will have a 10.5:1 compression ratio. Any input would be appreciated.
Comments
this will help you really calculate what you need.
http://dairally.net/daihard/chas/MiscCa ... iPipes.htm
Mandrel bent was the plan.
then you can order from the nearest distributor once you get the package.
you'll love the power.
that calculator helps really fine tune your exhaust so that you can maximize your power.
the guys i talked to here quoted me $650 for mild steel, mandrel bent, but i guess thats on par with other places. its just a shame when you can get an exhaust for other cars in stainless for less than half that...
Those steel exhausts are just coated, and eventually rust... I'm pretty sure there is a guy around me that bends aluminum for exhausts, but I could be wrong... I had one ran for my integra, and it was only $280, I'll look into it further
this is EXTREMELY not true and a common misconception!
honestly ANY high horsepower you must use 3'' or bigger..
i know this from experience. i have cars come into the shop daily with 2.5'' exhaust and the flow restricts them from making the power they could and it chokes their engine out. basically the engine cannot get rid of the exhaust fast enough and it slows the rest if the process down.
i had an n/a car come into the shop on the dyno, built motor 85mm pistons 95mm stroker crank custom pistons custom head porting. 2.5 exhaust only made 220.
same car with 3'' made over 240 thats a built b series.
i can sit here and tell you story after story but that would be redundant.
just because someone suggests it doesn't make it true. call any REAL tuner and ask them they preferred exhaust sizing and use what they tell you..
ill give you two places to call and ask them instead.
1) NRG Tech Racing on Long Island NY 631 243 6674
2) t1 race development in Houston TX (214) 607-902
wait till weds. (we have a grudge race in baytown TX and both shops wont be back until then)
those are the two fastest people in the industry (if you dont know who these guys are you tube em)
in addition, if you use mild steel (which is fine its just less expensive) spray paint over the welds and the flanges b/c thats where it will rust. nothing wrong with mild steel, DONT do aluminum if you plan on driving this car actively. aluminum is weak and one bad bottom and your exhaust is crushed. mild steel is fine but seriously, don't go less than 3''. ANYONE who says ANYTHING about back pressure needs to be up' doesn't know what they are talking about. you want zero or negative back pressure if anything. (btw to get negative back pressure one would need to create a scavenger effect on the exhaust system. google that its what circle track guys do to get lift on the pistons)
not trying to start a huge debate, i honestly want to know your experience.
that setup will be flowing a max amount of 24lbs/min which would run through 2.5 will almost zero back pressure.
I would go 3'' for this set up, you'll need the extra flow for your SC. This is my opinion.
I agree.. I installed mine a 2.5"
D16Z6
JRSC 8psi pulley
Hondata S300
DSM 450cc injectors
Walboro 255 fuel pump
Skunk 2 valves
Supertech valve springs/retainers/seats
ARP Head Studs
Crower Stage 2 cam
Skunk 2 Cam gear
Bisimoto V2 header
CP 10.5:1 pistons
Eagle rods (std length)
Full OEM gaskets/bearings/seals
New OEM pumps,sensors.
If I remember correctly the K20A's in the CTR have a 2.25" exhaust. My thought process was that I also don't want a loud exhaust so finding a balance between sound and power is going to be my concern. 2.25" was my first thought, maybe 2.5".