I am gathering parts for my first ever turbo build. It is going to be a 1972 dodge dart with a 5.7 Hemi. I have a couple questions. What determines what size waste gate is needed for a turbo system? and how to figure out the proper size? Also going on turbonetics website in their turbo matrix they recommend a super t-72 with .81 ar for the proper size for the 650hp goal I have in mind. Does this seem right? Also what cam companies are good to deal with for turbo grinds? This car will be a 99 percent street car and may see the track 2-4 times a year.
Thanks Bill

 

i would say in the ball park of of 70mm-80mm prob on the smaller side for the street,, dont forget about your needed fuel system upgrades as well

 

There are many variables in choosing a wastegate. Cubic inch, Placement, and boost level wanted are a few of the biggest, but intended rpm, hot side, down pipe, and turbine flow also play a big role. Error on the large side. With most street setups, it hard to go wrong with a 44mm on an engine of your size. The more info the better.

 

I plan on using flipped shorty headers. Im not sure of what boost level I will need to reach my goal HP. But i would suspect somewhere around 8 to 10 psi. I plan on maxing out rpms at around 6500. The turbo the matrix suggested is a 3 inch down pipe.
Thanks Bill

 

Depending on which turbine wheel your running, and placement, a 38mm may work for you at that boost level, but I try to go larger if in doubt..... or you can always add a second 38mm if you don't have the control you would like. Go as large as practically possible with the down pipe...... open dump, or recirculated wastegate also makes a difference.

 

Id say around a 76mm turbo. Im not that familiar with the newer Hemis but stock cams in general are pretty turbo friendly.I agree with Mnlx all of that plays a big role with your wastegate. you could have the right sized gat and if the placement is wrong,you could have problems with boost control.

 

how close to the turbo should the wastage be placed.
Thanks Bill

 

Ideally, you want both banks to have a good flow path to the gate (not always easy) so generally in the merge is good place, and that places it near the turbo. There are quite a few that have the gate on the crossover with good results, but typically run a larger gate (44-60 mm) Do a search, or check out the builds board, there is alot of info on the subject.

 

Would a s475 T6 1.10 ar be too big for a street car with the hemi and cnc'd cylinder heads or do I need more cubic inch?

 

I dont think so, I like that turbo for an engine of that size.......

 

im running an s400 with the t6 flange on my 5.7 hemi build