Scrildo

Hi there thanks for the reply I will PM you so i won't clutter up the OP's thread still waiting to hear from them though.

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iTrader: (14)

PM sent.

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iTrader: (14)

I tackled the 3.5" down pipe challange....

There is just not enough room to come out of the turbo with a 3.5" pipe. The reason for this is the transition between 3" (turbo outlet) and 3.5" in a very short distance. So the next best thing is this....:





Two 45 degree elbows at the turbo, going to a 3" flex coupler and then 3.5" after that. The distance is so short that the difference in performance would be negligible/non measurable. This also works out because of ground clearance....as it is not an issue at all with this configuration. If I was to use a 3.5" down pipe, the flex couple would have a much larger outside diameter..... and the ground clearance would be compormised.

This kit will go out and will get the 6766 T4 twin sroll 1.32 a/r turbine. From what I understand tuning will be done with E85, so the numbers should be impressive.

binder

iTrader: (8)

custom transmission cross brace. get your head in the game sasha

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iTrader: (14)

I don't know that it would change anything really. The issue is right at the turbine outlet (if you are refering to the 3.5" DP).

I will look at that when the Tial flanges come in, and I am able to complete this kit.

RudeG_v2.0

iTrader: (1)

3" turbine outlet? I thought all of Precision's T4 turbine outlets were 3 5/8" in diameter (including the divided 1.32 A/R housing you mentioned), so I looked it up and confirmed that for both the 6266 and 6766.

http://www.precisionturbo.net/Street...-CEA%C2%AE/479

http://www.precisionturbo.net/Street...-CEA%C2%AE/480

So you've been attaching a 3" downpipe to the 3 5/8" turbine outlet on your kits due to space constraints and clearance issues? It didn't dawn on me until now when I read your post. You apparently haven't had any negative results with back pressure by doing that, so I guess the top mount ST kits could have had a T4 production version attached to their 3" down pipes all along. Interesting.

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iTrader: (14)

Yes, all these turbos have the 3" down pipe as intended by Precision.

The 3 5/8" is the V-band flange outside diameter, and not the actual down pipe size suggested/intended. There is no clearance/space constraints issues with the mid mount kit at all, as I can run a 4" down pipe on that if a customer wanted it. Unlike the top mount, I am also able to run a 3" up-pipe if needed for the 76mm turbo kit version I offer...again two things that would not be possible with a top mount design without major modifications.

You would have to be pushing a lot of power (700whp +) for the 3" DP to become a concern (back pressure). Also, remember that with the mid mount the 3" down pipe/exhaust after the turbo is much shorter than with a top mount, so the exhaust gas does not have to travel the full length of the car (headlight to tailpipe) before exiting at the back.

And yes, the top mount kits could easily have the T4 turbine housings and make more power than they are now. Like I said many times before, the key to making solid power on a single kit on a VQ is the turbine housing size. As soon as Momentum went with the larger (than T3 .82 a/r) housing they were able to hit the 600whp mark on pump gas. The motor had a lot done to it too though, cams, cossworth IM, head work ect. This is something that is not needed when you have the larger T4 turbine, as I have customers making over 600whp with simple short block builds on pump gas. No need for aftermarket IM's, head work, aftermarket cams..ect. It just shows that a lot of the flow issues are overcome by the large turbine housing.


Also, as you can see, the twin scroll has a 3" DP for the first 10" or so. After that I can go to 3.5" without any issues at all. The 10" long 3" diameter sectioin of the DP will not be an issue at all when it comes to flow. It is so short, that the difference in performance betweeen it and a complete 3.5" DP from the turbine may not even be measurable.

I will add a picture to this post of a 3" piece of pipe mated to the outlet of a 66mm turbine.

RudeG_v2.0

iTrader: (1)

Oh I see. The 2JZ cars normally run 3.5" or 4" down pipes from those Precision T4 housings, but they don't have the space constraints of the VQ. The cars that have PL kits with the 7675 turbo as well as my build have 3.5" down pipes from the turbine. It just requires aftermarket headers for extra clearance, and you'd be running headers with such a setup for that power level anyway.

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iTrader: (14)

If anybody ever maxes out the mid mount kit with a 6766 T4 .96 a/r, or the twin scroll 6766 T4 1.32 a/r, with 3" down pipes, I will look at larger down pipes for sure. Although, the customer with a 3.5" down pipe (shown above) will do his best to run the 6766 T4 1.32 to the max on E85.

Here is a 3" pipe inside the outle of a T4 twin scroll turbine:



and the flange outside diameter (3 5/8"):

jerryd87

iTrader: (4)

thats because the exhuast flows along the walls of the exhuast first when first exiting a turbo, got a book around here somewhere think its one of corky bells books, optimal exhuast is a mega phone, starts as the same size as the outlet on the turbo and has a 15 degree angle from there for 18 inchs will be the optimal exhuast setup for any turbo.

str8dum1

iTrader: (11)

rude, the supra guys have to use an expander at the flange to mate to a 4" downpipe on alot of the t4 turbos as well. they dont come out of the housing as 4"

like this

RudeG_v2.0

iTrader: (1)

I already knew that Rich. Obviously, if the turbine outlet is listed as 3 5/8", an expander would have to be attached at the flange to go 4" on the down pipe.

MI 35th

iTrader: (16)

I am in freaking florida on business. This is killing me not being able to take the old parts off and get the car to Hal. Home in 2-3 weeks. In the meantime it lets me pay down my cc from bribe spending. Every dollar spent on a car parts must be matched to a Happy Girlfriend fund. These upgrades mean vacations and shopping sprees... Not to mention new clutch, more fuel, tuning... The latter I don't mind.

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iTrader: (14)

Don, I think you need a new GF...

binder

iTrader: (8)

Ya, my gf is excited when I talk about upgrades to the car. She doesn't care what I do with my money.

suprasam

^^THat's what I'm talking about!

I know girls get excited when their man has a job!

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iTrader: (14)

Forgot to update this thread with the twin scroll 3.5" DP. It is all complete, just waiting for some tial wastegate flanges to show up (taking forever to get here, USPS is very slow)



3.5" down pipe to OEM (like) exhaust system:





There are also 4 K&N air filters that will work with this application, here is one that I happen to find at a local store. Perfect fit:

binder

iTrader: (8)

looks amazing

Christian824

Finally I've been waiting for the right kit to come along and here it is!!!!!!! Was going to pull the plug on the original bp kit a year ago but something told me to wait and my Patience and reading has paid off Ready When You start production!!!

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iTrader: (14)

Sounds good. I need to make a jig for that manifold first, hope to get that done this week. Once that is done, I can move on to production. This kit will cost more (than the mid mount) due to the additional fabrication (manifold is a time consuming part to build).