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turbo crossover pipes changes in tuning?

740atl

Gear acquisition syndrome
Joined
Apr 17, 2010
Location
USA
So I've been back and forth with supercharger/rear mount turbo/low mount twin turbos/single turbo/bigger heads/snakes on my v8 and I've seen most people do the standard flip the manifolds up or forward and join the exhaust from each side into a common t3 or T4 flange, then hero/success/boost/instant 9 second 1/4.

Like what's shown below....

623753d1501365935-truck-manifold-turbo-set-up-faq-s-000_1836.jpg


PROBLEM.....I don't have room for any of that.

I've been looking at pictures of the old buick grand national and they did it differently... In case you didn't know, they take one bank from the driver's side, feed it under the engine and then send it back into the header on the passenger side. Well, it looks like this.

ta-v2009-jpg.106286


My brain likes option 1 with two sides merging into one. I like it better from a tuning aspect. I don't know why, my brain just likes it.

Option 2 seems like the passenger side is going to see something different than the driver's side. The entire driver side exhaust gets dumped into the passenger side while it's coming out of the head.

My brain is telling me it should make no difference 1 or 2 because pressure is pressure, but I wanted to ask the question anyways. Do buick GN people have special tuning considerations because of the way the exhaust combines or is it not anything to worry about? I mean it obviously works because GNX's ruled the Earth..
 
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Thanks guys.

Andrew, that's very similar to what I'm thinking of doing except I might make a log manifold instead of using the stocker (lt1). I'm thinking of this. The LT1 accessory drive takes up so much room compared to the LS setup. I think I have enough room to do this and make the crossover pipe go under and behind the engine.
663660d1501791986-lt1-turbo-manifolds-dsc01529.jpg


Andrew, what size turbo are you working with?


What will a single 3" exhaust v8 sound like?
 
Andrew, what size turbo are you working with?

I have the VS Racing 7875 non billet wheel. Billet vs non billet wont change the physical size at all. Just a bit more airflow from the compressor.

The sound varies depending on how you run the exhaust and with yours being an LT1 itll be difficult to give you an example of sound. Turbo V8 IMO almost always sound awesome.

Andrew
 
Thats is pretty damn big it appears. Wont be hurting for flow thats for sure.

my awesome merge right there at the turbo probably kills half of whatever I gained by going that large (which, I think, was largely because it was the same size as the manifold after the flange was cut off...)
 
my awesome merge right there at the turbo probably kills half of whatever I gained by going that large (which, I think, was largely because it was the same size as the manifold after the flange was cut off...)

Lol that merge isnt that bad at all, really.

I used 2" vbands welded straight to manifolds and then it necks down a smidge to 1 7/8 for the majority of the crossover. Hopefully velocity stays up without choking. Should work great for my goal (550whp to 600whp)

Minus the vbands themselves the crossover is 100% reused exhaust off the Volvo haha

As a huge bonus it was very easy to package
 
I have the VS Racing 7875 non billet wheel. Billet vs non billet wont change the physical size at all. Just a bit more airflow from the compressor.

The sound varies depending on how you run the exhaust and with yours being an LT1 itll be difficult to give you an example of sound. Turbo V8 IMO almost always sound awesome.

Andrew

I guess because I have a dual 3" exhaust right now, I was curious as to what it would be like with all of it crammed into a 3" single exhaust.

The 3" dual gets noticed... even by police.


just looking at the specs for the 7875. That's probably more turbo than I need... (or sadly... afford). I hate to say it but I think I'm going to try to use this old holset I have lying around... he351cw and see what happens.
 
Yeah 3" duals are probly very noisy. A single turbo with 3" straight pipe will probly be quieter than what you have now.

The 7875 is a great budget turbo, check the sloppymechanics classified facebook page. People are dumping the cast wheel 7875 for super cheap now that the billet 7875 is out.
 
Yeah 3" duals are probly very noisy. A single turbo with 3" straight pipe will probly be quieter than what you have now.

The 7875 is a great budget turbo, check the sloppymechanics classified facebook page. People are dumping the cast wheel 7875 for super cheap now that the billet 7875 is out.

I just came off that page and did a double take. That's probably more what I'm looking for.
 
Yeah crazy cheap 750whp turbo because people want the new hotness when the old version is still an excellent turbo lol

Take advantage of other people needing the newest and "best"
 
Yeah 3" duals are probly very noisy. A single turbo with 3" straight pipe will probly be quieter than what you have now.

The 7875 is a great budget turbo, check the sloppymechanics classified facebook page. People are dumping the cast wheel 7875 for super cheap now that the billet 7875 is out.

mine's actually a turbonetics unit, not the china clone. I kinda want one to play with on the gold car though, I may get one of the VS billet ones for it
 
mine's actually a turbonetics unit, not the china clone. I kinda want one to play with on the gold car though, I may get one of the VS billet ones for it

They are really impressive for the money and Vren at VS Racing has bitchin customer service. Cant recommend them enough. The china s480 he carries pushed a gen 4 6.0 to 1076whp.
 
I made this setup with a stock ls3 manifold on the drivers side and a 2.25 crossover under the torque converter, made for a super compact setup.


cnWURNCl.jpg

Do you have any other pics of this? Is the crossover tucked under the passenger side manifold?
 
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