Trying to decide what turbo to run on my new 370ci motor.... Found a decent deal on a Garrett GT47-88 turbo and was wondering if anyone is running one, and how it does? The specs on the one I'm looking at are T6 .96A/R exhaust housing. At first I was gonna get a precision CEA 7675, so I wouldn't have to change any of my piping, but I figured it would be a little small? Any thoughts or suggestions are appreciated!

 

How much power do you want? That is a considerably larger turbo than the 7676.

 

I'm just shooting for around 800 to the wheels. And on the precision CEA 7675 I was just worried about to much back pressure, because I'm going to be running 823 heads...

 

I need to write an article to help clear up these backpressure misconceptions...

 

So you think a CEA 7675 with a t4 .96 A/R housing would be adequate on the 370 with some ls3 heads? This would be the best option for me, as I wouldn't have to change a thing on hit or cold side piping.

I love my precision 7475 turbo on my 5.3, and I was gonna try to run it on the new motor if I was sticking with my 799 heads...

 

If that's your goal I would stick with the 7675. Backpressure is not a boogie man, that turbo should make 800 for you just fine.

 

The different ports will change some aspects about how the cylinder fills, but its not suddenly going to create massive backpressure issues. I feel like the whole turbo aftermarket jumped on this backpressure bandwagon and started pointing fingers at it whenever a turbo setup doesn't run the numbers, when the reality is that the problems are a little more complex.

Think of it like this... If a number of other people have made 800 and up with that 7675 and your setup tops out at 750, can't get a single more pony out of it....it doesn't make sense to blame the turbo, right? Even if you have a set of $10,000 heads on it with the best and biggest intake ports possible, the turbo is still going to be capable of the same 800 and up like others have done. The bigger ports won't suddenly eat up more air and create additional backpressure without a corresponding horsepower increase.

If it were me I wouldn't bother with the bigger heads. Lower port velocity and bigger intake valves for more strain on the valvetrain...meh. I made retarded power with completely stock 317s. Like wasting tuned liter bikes with good riders with my truck at 5500lbs kind of power. When you start feeding an engine with a turbo, suddenly it cares a lot less about what heads you run.

 

True True.... I have a complete 799 top end, complete ly6 823 top end, and some 317 heads laying around.... Maybe I'll just see what a 7475 precision is capable of! Would be nice to beat up on bikes around here!

 

Well, I talked to my dude Mario down at Spike Performance and Tuning yesterday.... I think I'm gonna go with the Bullseye street billet 80mm turbo with a t4 1.10 exhaust housing 83mm turbine! These are some nice looking turbos! I'm gonna try and swing the v-band SS exhaust housing if I can! Also gonna do the new Gen IV tunable race cover, with the v-band/ slip on! These things are super nice and spike swears by them to be the best... So I may just give them a try!

 

Dont forget that salesmen are always trying to sell you stuff you don't need. They're in the business of making $$

Don't overturbo
Dont mismatch turbine and compressor wheel (80mm wheel on 83/74mm turbine doesn't make sense)