3" Cutout Enough?
01-23-2020, 01:36 PM
#23
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I noticed that strange flare looking design. Before I order anything I'm gonna stop by a local import shop that just opened up and is only 15 minutes from me. They are the only shop within 20 miles and their instagram weld photos look top notch. Just spoke to the owner and he said come show him exactly what I want because he may be able to make make a merge out of stuff he has cheaper and nicer. I'm hoping he can get me V bands and stuff cheaper and possibly measure and order drive shafts for me.
01-23-2020, 02:56 PM
#24
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He's going from dual 3" header collectors to a single 3" pipe that he has right now, to a dual 3" inlet Y pipe merge with 4" inch
So dual 3" to single 3" changing to dual 3" in single 4" out.
Dual 3" into single 3" is basically just running a single 3" and killing the point of having 3" collectors on the headers if you're gonna slam both of them into one 3" pipe. And even with 400 rwhp you'll see a gain going dual 3" or single 4" over single 3".
He's got a heads, cam, supercharged 6.0 if I recall correctly without going back and looking. That's gonna see a gain.
So dual 3" to single 3" changing to dual 3" in single 4" out.
Dual 3" into single 3" is basically just running a single 3" and killing the point of having 3" collectors on the headers if you're gonna slam both of them into one 3" pipe. And even with 400 rwhp you'll see a gain going dual 3" or single 4" over single 3".
He's got a heads, cam, supercharged 6.0 if I recall correctly without going back and looking. That's gonna see a gain.
01-23-2020, 03:05 PM
#25
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Yes I agree dual 3" cutouts would flow more than a single 4" but I don't know If I have that space or want to complicate the setup that much. From my googling 4 should support my power level (600ish) and the difference between single 3" and single 4" is big where Single 4" to dual 3" Isn't that much difference.
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
Last edited by dantheman1540; 01-23-2020 at 03:11 PM.
01-23-2020, 03:35 PM
#26
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Yes I agree dual 3" cutouts would flow more than a single 4" but I don't know If I have that space or want to complicate the setup that much. From my googling 4 should support my power level (600ish) and the difference between single 3" and single 4" is big where Single 4" to dual 3" Isn't that much difference.
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
01-23-2020, 03:36 PM
#27
That's why I was saying that it would be the easier, and probably better performance wise, to do dual 3" cutouts. When the cutout is closed in the 4" system you open up and then immediately neck back down to 3". Dual 3" open cutouts should flow more than dual 3" pipe into a single 4" cutout.... no?
but where constraints come in a single 4 is FAR better than single 3" and not too bad of a compromise at his power level. Hell on a 500 whp vehicle I'd like to see at least a single 4. If you read up on pipe size vs hp calculators/charts, it's shocking to see what they recommend for minimums and you'll come away thinking none of us have large enough exhaust
I just assumed two cutouts would be complex and pretty expensive compared to one in a 4" merge. Plus the 4" merge will always be there and in use. Exhaust can actually neck down in size as it goes along in length and still flow well. But yes dual 3 flows more than single 4
But there's also length, venturi, velocity considerations. If you watch testing videos a lot of power is picked up from header extensions, in other words you want length of pipe pretty much as long as possible to take advantage of scavenging. If you place the 4" merge in there you're slightly reducing overall diameter but keeping a good size flow capability and lengthening the pipe then place the cutout well behind that then neck down to 3" and you've got a pretty nicely designed setup.
Yes I agree dual 3" cutouts would flow more than a single 4" but I don't know If I have that space or want to complicate the setup that much. From my googling 4 should support my power level (600ish) and the difference between single 3" and single 4" is big where Single 4" to dual 3" Isn't that much difference.
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
Plus not sure why but I feel like single exit sounds rowdier at high rpm than dual. What do you guys think?
But from reading I've done on people that look into it's usually due to a y pipe setup vs a X or H pipe that gives a bit more rasp/scream/higher pitch. However, a better merge actually is supposed to help with some of the rasp. That came from people that have fooled with it. I have not personally done back to back testing.
01-26-2020, 10:08 PM
#28
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Spoke to my local fab shop and they are down to do the single 4" setup so parts have been ordered and hopefully in a week or 2 I can post pics and sound clips.
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01-27-2020, 07:34 AM
#29
I still have the same exhaust setup with the turbo only now it’s a 4” DP into the 4”. I haven’t measured exhaust back pressure yet but my turbine back presssure is only 1.75-1 at 17.5psi so my exhaust back pressure can’t be to high. Once weather breaks I’ll test with and without the cutout open to compare.
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