twin setup?

[JoshH]

It will work either way just will affect how fast the bottom turbo lights, S400 can be had in both T4 and T6, personally for twins id use a t6 for a big single Id use a T4, a GT45 should work fine with a T4 also, It is similar to the GT42

Why is that?

 

[racinmike77]

Why is that?

I think the answer you want is because you could wastegate the top charger and keep Drive pressure to a minimum with a t6., however there are alot of other variables that effect the how the turbo will spool such as AR and even the compressor side.

 

[Turbo Buick 6]

I think the answer you want is because you could wastegate the top charger and keep Drive pressure to a minimum with a t6., however there are alot of other variables that effect the how the turbo will spool such as AR and even the compressor side.

This thread was started about a truck with a vvt, vgt or whatever you want to call it charger. Why would you want to put a gate on that

 

[bonescarolfi]

Most people use 3" tubing. 3" tubing has a surface area of about 7" sq. Most T4 flanges are around 5.5" sq. Most T6 flanges are around 8.5" sq. Velocity spools turbos. Why someone would want the gass to slow down as it enters the turbo is beyond me But to each their own, maybe its the bigger is better theory. As you add bends to a piece of tubing the flow goes down, so in all actuallity 3" tubing and a T4 flange are a perfect match. This all goes out the window if you use 3 1/2" tubing. But its pointless to use 3 1/2" tubing untill you have about a 90mm exducer on the turbine wheel of you small turbo. (That would be something like a GT45 as a small turbo)

Interesting. Thanks for the explanation. Im thinking about putting twins on my truck this fall/winter so im looking for all the info and options i can find. Sorry if i hi jacked this thread.

 

[racinmike77]

This thread was started about a truck with a vvt, vgt or whatever you want to call it charger. Why would you want to put a gate on that

Why not that is the whole idea of twins, if you arent gonna gate the top charger why bother building twins?

 

[dmaxvaz]

Why not that is the whole idea of twins, if you arent gonna gate the top charger why bother building twins?

the vgt doesnt need a gate for twins, it needs proper tuning for twins to work right. the gate would be good for the larger turbo in the twin setup

 

[Turbo Buick 6]

Why not that is the whole idea of twins, if you arent gonna gate the top charger why bother building twins?

Why would you gate the stock charger when you can open the vanes is this incase the vanes get stuck shut I have never in my life seen a vvt turbo with a gate

 

[Turbo Buick 6]

the vgt doesnt need a gate for twins, it needs proper tuning for twins to work right. the gate would be good for the larger turbo in the twin setup

Oh so hes talking about the bottom turbo? I guess I should go rip the twins off of about 8 trucks that I did without a gate and tell them there is no point in running them since they don't have a gate....no?

 

[racinmike77]

I though the idea was to keep the turbo in its efficiency island? Am I wrong? If I ran heavy Nitrous on a vvt I would also gate it. Dont confuse vanes for a wastegate.

I did not say there is no gain when not using a gate, but running a gate WILL improve efficiency.

 

[dmaxvaz]

Oh so hes talking about the bottom turbo? I guess I should go rip the twins off of about 8 trucks that I did without a gate and tell them there is no point in running them since they don't have a gate....no?

idk what he is talking about on that one, some gated the big turbo some didnt. i gated mine. these twins you built what turbos have you used and what a/r on the exh did you use?

 

[racinmike77]

idk what he is talking about on that one, some gated the big turbo some didnt. i gated mine. these twins you built what turbos have you used and what a/r on the exh did you use?

I am talking about the small turbo, it should be gated in to the hot pipe.

 

[dmaxvaz]

I though the idea was to keep the turbo in its efficiency island? Am I wrong? If I ran heavy Nitrous on a vvt I would also gate it. Dont confuse vanes for a wastegate.

I did not say there is no gain when not using a gate, but running a gate WILL improve efficiency.

you can do that with careful tuning, and not need a gate

 

[Turbo Buick 6]

I though the idea was to keep the turbo in its efficiency island? Am I wrong? If I ran heavy Nitrous on a vvt I would also gate it. Dont confuse vanes for a wastegate.

Don't worry, I'm far from confused. Have you ever done any tuning on a truck with twins and a stock vvt turbo? If so you would see that opening the vanes does more than enough to drop drive pressure and control turbo speed.

Keeping the turbo on its map is very easy. Run both turbos a a 2to1 P/R (which is very low and efficient) and you'll end up with 45lbs of boost. To run off the map you would either need to have mismatched turbos or be trying to run crazy triple digit boost.

 

[dmaxvaz]

I am talking about the small turbo, it should be gated in to the hot pipe.

on the vgt it doesnt

 

[Turbo Buick 6]

idk what he is talking about on that one, some gated the big turbo some didnt. i gated mine. these twins you built what turbos have you used and what a/r on the exh did you use?

I have gated some large turbos and some I have not. The turbo sizes have been all over the map as I have built them for D-Maxs, CumminGs, Powerchokes, and a few on Peterbuilts (they were neat).

I agrees that it is both common and sometimes requred to gate the bottom turbo. What I can't seem to grasp is this radical new idea that it is pointless to build twins if you not going to put a gate on a vvt turbo

 

[racinmike77]

you can do that with careful tuning, and not need a gate

I agree, but go back to my other post, a gate will allow you to push the bottom charger harder with out overspeeding the top charger.

This is my only point sorry for the coufusion and long debate.

 

[dmaxvaz]

I have gated some large turbos and some I have not. The turbo sizes have been all over the map as I have built them for D-Maxs, CumminGs, Powerchokes, and a few on Peterbuilts.

I agrees that it is both common and sometimes requred to gate the bottom turbo. What I can't seem to grasp is this radical new idea that it is pointless to build twins if you not going to put a gate on a vvt turbo

me too. it is hard for someone that has not built twins or has not studied this subject enough to understand whats going on.

 

[Turbo Buick 6]

I agree, but go back to my other post, a gate will allow you to push the bottom charger harder with out overspeeding the top charger.

The assumption your making is that people are overspeeding a vvt top charger. Can you post any tech to back this up? Most setups I've seen have been running that bottom charger at a higher pressure ratio that the top. That would put the bottom charger at more of a risk for being oversped

 

[racinmike77]

me too. it is hard for someone that has not built twins or has not studied this subject enough to understand whats going on.

You have no idea if your turbo is in its efficiency island because I guarantee you have not done the math nor do you have a compessor map. I hope you have a drive pressure gauge, thats a start.

 

[dmaxvaz]

I agree, but go back to my other post, a gate will allow you to push the bottom charger harder with out overspeeding the top charger.

This is my only point sorry for the coufusion and long debate.

doing that will make drive psi go to a 2:1 ratio and that is what we dont want. we want a 1:1(50 psi boost, 50 psi dp) or close to it.