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Hey guys I'm in the planning stage of building a 351w turbo kit. It will be a stock bottom end, 200 cc heads, super vic efi intake, with a S475 turbo with 1.10 A/R housing. Have the motor already, and parts are ordered.

A friend of mine will be fabricating the hot side out of mild steel. What diameter piping should we use? 2 1/2 inch? I read somewhere that the diameter can affect how quick it spools..

Thanks
Colin
 

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ditto.

ks
 

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Curious why dual waste gates ? I was planning a 80mm build 408 900 rwhp . Have a nice precision 66 mm at my disposal . Is 66mm gate going to hurt me?


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I think because they are using a divided housing and divided pipes.

Everyone around here seems to not like that idea. They all run combined pipes with a single WG even if the turbo is divided. A local shop that builds a lot of custom divided just ports the center to an edge and mixes the inlet exhaust. They were telling me it is impossible to balance the exhaust when it is divided and nothing is gained for all the work.

Same thing C&C Racecraft told me, and they do some real fast cars.

I've got no opinion, that just what two local shops and one other shop that builds some real fast stuff told me when we discussed turbos.
 

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Yes because he is keeping it divided he needs 2 gates. Will spool alot faster. If your not divided then the one gate will be fine.

I'm starting my s480/408w outside. I'm using 2.5 divided all the way with 2 jgs 40mm gates. Looking for high 8s. I'll post pics soon. Twin scroll t6 flange with twin scroll exhaust housing. Lots of guys switch from undivided with a merge to divided and say spool is night and day. Either way should be fine. This is my first turbo build so I'll post when I find out how it feels.
 

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Yes because he is keeping it divided he needs 2 gates. Will spool alot faster. If your not divided then the one gate will be fine.

I'm starting my s480/408w outside. I'm using 2.5 divided all the way with 2 jgs 40mm gates. Looking for high 8s. I'll post pics soon. Twin scroll t6 flange with twin scroll exhaust housing. Lots of guys switch from undivided with a merge to divided and say spool is night and day. Either way should be fine. This is my first turbo build so I'll post when I find out how it feels.
Will it really spool faster? Three places that do a lot of turbo stuff, although they are all self-taught, seem to think it is a PITA not worth doing.

I'm trying to recall exactly how one of them phrased it, but I think he cast aspersions on BW or someone about it. Two wanted to have me upgrade to a divided, but not divide the feed.

I'm real curious now. :)

Edit:

Some searching shows the Internet thinks no advantage either, unless the firing order is such that the pulses are 1-2-1-2-1-2 back and forth.

Like this thread:

http://www.yellowbullet.com/forum/showthread.php?t=292204
 

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I do alot of reading on yellow bullets and searches and that seems to be what all the turbo guys over there say. That's what I'm doing but like I say I have no idea what's better. I would think if the scroll is divided then divided hotside would work better. Depends on ci size and proper sized turbo too.
 

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Is this correct: If divided and using one gate on one turbo then the gases from one turbo are being bled off to slow it down while the other turbo is still spinning at full speed but I don't know if this is an issue or not..

ks
 

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My stock bottom end 351w s480 turbo motor went [email protected] first 1/4 pass

2.25" divided with 2 44mm gates.
 

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If you keep it divided the whole way to the flange, run a wastegate on each bank, OR run a section of pipe from each bank near the flange to a merge with a single gate.

Dual gates are more common

Don't put a single gate on only 1 side
 

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There is no question with a divided hot side it should have two gates, but I wonder how well balanced the two gates would be.

I just don't see how they could be made to reliably synchronize. Once either gate opens, the boost will limit. That would prevent the stronger gate from opening as far.

Seems to me it is exactly like the problem we have with dual exhausts, and would require a merge area to equalize pulses and pressure.

The local shop that builds a lot of turbos said they knife edge the divider and use one merged chamber with a single waste gate, and they never see any advantage to keeping a system split. This was pretty much parroted by a shop in Kentucky that does a lot of real fast stuff. They said something about divided being diesel truck six cylinder technology. :)

I wonder if the divided thing is just marketing by some manufacturers, or specifically an advantage with certain systems.

But how would you keep two waste gates controlling one boost source synced perfectly, when the instant one opens the boost stops increasing to both?
 

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Why not keep it divided all the way to a single waste gate like they do on the Ford Sierra Cosworth in the UK ?



Edit to add - the Cosworth is a 4 cylinder and the pic shows two manifolds for some reason
 

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Why not keep it divided all the way to a single waste gate like they do on the Ford Sierra Cosworth in the UK ?



Edit to add - the Cosworth is a 4 cylinder and the pic shows two manifolds for some reason
See, that makes a lot of sense. It looks planned. They do not run consecutively fired cylinders into the same inlet, and they use one wastegate equally tied to both.
 

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That setup would be killer for a twin setup. Either would be great. Their is no wrong way cause they both work. I'm doing it cause its easier and the 2.5 pipes fits great in the t6 flange. Keep the gates the same distance from the header on each side and let her eat. I mean if a stock 351w runs 155 doing it, it obviously works.
 

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Anyone have pics?
 

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I am waiting on my turbo from FI to get here. Soon as it does I'm starting my crossover and turbo mounting. Will have plenty of pics soon.
 

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I am in the middle of building my first turbo setup. I bought a stock block 408 with a turbo that has a ON3 kit. So I am trying to figure out if this kit is ok the way it is. I will be building a 363 real soon with a S480 turbo. So the more I can learn the better.
 
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