Forcefed86

iTrader: (4)

It's a sealed pressure system. All pressure in the system is equal before the bottle neck. The exit in the volute of a .96 T4 twin scroll is much smaller than 1 7/8". I'd assume an open scroll would be too but I'm not 100% certain. There is no location in the system that will reduce back pressure more than another when the turbo is the restriction.

Twin 38's are more than enough to control the system pressure. It's like having single 76mm WG. I run a 2" hotside on a 370" engine around 1000hp with twin 38mm gates. I can run 7lbs (or less with a smaller spring in the WG.) They are more than enough to control boost on a 700ish hp 5.3.

I agree spool-up won't be an issue either way. You are talking very minimal gains between 2" is and 1 7/8". Doubt you'd be able to tell a difference without some nice test equipment. But if you have the 1 7/8 piping to use for free I wouldn't hesitate with your goals.

Nathaninwa

Logging back pressure would still be neat on this system

And for reference, twin 38mm gates equals a single 57mm gate in surface area. I've seen single 60's control systems with great success

Forcefed86

iTrader: (4)

Was talking about running a divided system, each with it's own 38mm gate. This is going to double the WG capacity. More than enough gate for what he is needing. I've run 1 38mm gate placed properly on a 5.3 and was able to control boost just fine. Lots of folks place the gates in horrible positions and then think they need 60mm WG's is my point.

yenkomike

iTrader: (2)

yes I agree. I can hold 7 psi steady with a single 38 mm gate on a 6.0 /s480/83. placement is everything.

Ogoz23

I haven't been able to sleep thinking how I'm going to mount my Wastegage . This picture just solved my sleep problems . Thank you who ever posted it!

nick Ritter

iTrader: (3)

what turbo do you run and what rear gear ?

TURBOLSBIRD

iTrader: (5)

Wonder if it is divided all the way to the WG valve? Or if it merges just before and is open that few inches before the WG?

Nathaninwa

I'm running a billet S480 with the T6 1.32 housing. Custom intake with a Martin Smallwood cam I'm running a 3.25 gear with 27 inch measured tires with a 4l80e, however moving to a glide this winter

Ogoz23

Just wanted to pass this on to you guys. After reading this thread and with the help of other members I decided to go with 2" pipe for my hot pipes. I went to my local muffler shop and asked for 2 inch pipe . They gave me the pipe that's marked 2 inches and off I went .. I realized that the ID was smaller then 2" .. so if you decide to go with 2" pipe you need to buy 2.25" pipe.

Ogoz23

This is some of the work I did today with the 2.25 pipe

Nathaninwa

That's an industry qwerk. Exhaust, even though it's tubing with X wall thickness, we in general refer to it as pipe. So yes, 2 inch exhaust tubing is smaller and my 2.25 is just as you posted.

Same is true with headers, there measure od, so my 1-3/4 primary's are actually 1-5/8 and 1-5/8 headers are really only 1-1/2 id

Forcefed86

iTrader: (4)

Inside Diameter = OD – (2 x wall thickness) 16g is .065.

So 1.87" ID for 2" tubing

2.12" for 2.25" tubing


Using 2" 16g tubing on my 370 around 1000hp.

Ogoz23

Sorry this are the corrected measurements. Thanks forcefed86

nxfirebird

iTrader: (1)

your welcome! LOL
my buddy self fabbed his whole system/truck including the headers, except for that one piece. I've been doing that design on single systems for years, he brought me his merge and asked if i'd make that one piece for him. I sent him this pic while I was fitting it.

it is not, all I do is slice the 90's in half and just stitch them together.