4inch Exhaust
Originally Posted by dirtytrucker+nurse05
how about single 5 inch?
MAF sensor restrictions On an interesting side note, you can prove that the stock 75 mm MAF sensor is a restriction, using the above formulas:
Code:
75mm = 790 cfm = 359 hp 85mm = 1007 cfm = 458 hp 90mm = 1131 cfm = 514 hp
Originally Posted by lsx24
Is this fwhp or rwhp?
Originally Posted by lsx24
On an interesting side note, you can prove that the stock 75 mm MAF sensor is a restriction, using the above formulas:
Code:
75mm = 790 cfm = 359 hp 85mm = 1007 cfm = 458 hp 90mm = 1131 cfm = 514 hp
This means that for every cubic inch of incoming air, there is FAR more molecules than in one cubic inch of exhaust. This formula only applies to exhaust systems.
That makes sense since I didn't take into account the density of the incoming air....to bad there isn't a formula for cold air I'd be interested to run some numbers through it. No wonder I was already loosing faith in the stock MAF sensor. 
Thread Starter
Teching In
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This was origianally posted in "small block, big block specific". I didn't get any responses for a few days, so I tried in here. Specifically for a FI BBC 468 in a tube chassis trail rig. I don't have room for duals and I have a 3" exhaust kit but, I didn't think it would support the HP I will be making. That's why I asked about single 4". Thanks for all the responses, Mike
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Originally Posted by TheBlurLS1
Exhaust gas is a *slight* bit warmer, and less dense than incoming air wouldn't you say?
This means that for every cubic inch of incoming air, there is FAR more molecules than in one cubic inch of exhaust. This formula only applies to exhaust systems.
This means that for every cubic inch of incoming air, there is FAR more molecules than in one cubic inch of exhaust. This formula only applies to exhaust systems.
Originally Posted by lsx24
woops nevermind I realize you have to divide by 2.2 in the final step...it's 2.2 cfm per hp not 2.2 hp per cfm...so here are the hp support numbers I get:
Is this fwhp or rwhp?
Code:
single 3" = 369 hp single 4" = 656 hp dual 2.5" = 512 hp dual 3" = 738 hp
Is this fwhp or rwhp?
for every hp produced the pipe needs to flow .4545.. cfm
1cfm=2.2hp
1127cfm=2479hp
I assume that formula holds true for only na?
Looking at the numbers a 4in pipe is absurd.
Originally Posted by dirtytrucker+nurse05
Thanks for the input. I was hoping someone would know some formulas to figure that out. TheBlurLS1 if your bored how about 5"? I think 656 will be over what I will be making but, I didn't think the Flowmaster 3" kit I have would do it, I was thinking Flowmaster said either 350 or 450 HP. I am hoping to be in the 500-550 HP range. Thanks again, Mike
Revised my 3" exhaust to 4" (lost 2psi). Made a more efficient inlet hat and gained back the 2psi + 1 deg timing. Gained +58rwhp/+63rwtq
Figure roughly +40rwhp/+40rwtq without the degree of timing.
Same boost, more efficient, more power.
614rwhp/537rwtq to 672rwhp/600rwtq
https://ls1tech.com/forums/forced-induction/626013-procharger-346ci-58rwhp-63rwtq-new-inlet-hat-exhaust-1deg-timing.html
Last edited by SSmokin 01; Dec 29, 2006 at 03:13 AM.
Does it make a difference if you're talking about the ID of the exhaust as opposed to the OD? The exhaust gases are flowing through the inside of exhaust, not the OD.
I would think you'd take into consideration the thickness of the material and subtract that from the OD. Figure for 16GA tubing you lose ~.130" (.065" wall thickness) of the cross section.
I'm only mentioning this because I was figuring out the same stuff not too long ago.
I would think you'd take into consideration the thickness of the material and subtract that from the OD. Figure for 16GA tubing you lose ~.130" (.065" wall thickness) of the cross section.
I'm only mentioning this because I was figuring out the same stuff not too long ago.
Originally Posted by lsx24
You're going to be restricted by your header collector at this point. Since most (if not all) header collectors come in at 3", that is going to be a bottleneck of any system even if the piping is larger behind it.
Originally Posted by greysteel_M6
I think you were right the first time. From Theblurls1's post he's saying that each cubic foot of air that flows through the pipe supports 2.2hp, thus
for every hp produced the pipe needs to flow .4545.. cfm
1cfm=2.2hp
1127cfm=2479hp
for every hp produced the pipe needs to flow .4545.. cfm
1cfm=2.2hp
1127cfm=2479hp
Originally Posted by lsx24
Actually this is not true. There are two header collectors, therefore it would be 2 x 3", or 6" exhaust before the collectors become a restriction in this system.
Originally Posted by lsx24
Actually this is not true. There are two header collectors, therefore it would be 2 x 3", or 6" exhaust before the collectors become a restriction in this system.
Originally Posted by ss1
As far as what is the equivilent pipe diameter that the start to become a restriction...
Just like 3" True Duals is 3" + 3", 2 header collectors are 3" + 3".
Yeah, the math doesn't come out the same. You could almost fit two 3" OD pipes side by side in one piece of 6" OD pipe, and still have a bunch of area left over. I don't feel like doing the math right now though.
Maybe I just misunderstood what you were trying to say. No big deal.
Maybe I just misunderstood what you were trying to say. No big deal.