My combo is a b&g hotside with 38mm wastegate, trickflow tw heads ported, mpt70 turbo, vs racing intercooler, anderson b31 cam, trickflow streetheat intake, 70mm tb, 42lb. injectors, a1000 fuel pump, c4 4000 stall, and i'm sure i'm forgeting a bunch of shit. But what is the max power i can make with the 38mm wastegate? I would like to make around 5-550 rwhp. Does it sound like my combo will work? Any help is appreciated.

 

Waste gates do not have a max power, it depends on how little boost you are running. The more exhaust you have to run through the gate instead of the turbine housing to keep boost levels where you want them. Since the 38 is what Brian includes in his kits with the MP T70s I would think it would be fine. Hopefully someone who has more experience will chime in soon

 

38mm will flow enough to keep you in the 500-550 hp range with low or high boost as long as its located properly.

 

A 38mm is small for a V8 especially if you are running single digit boost levels.

The more boost you run, the less exhaust gas gets passed through the gate to maintain that boost level. So if you are running 20psi then you might be ok but I bet it will boost spike on you regardless.

Personally, a Tial 44mm is probably a more realistic choice.

 

My hellion setup with a 38mm would boost creep/spike when i was hitting 450rwhp. I'm currently upgrading to racegate.

 

plumbing plays a major role in the effectiveness of the gate, (as does the turbine size, housing size)>pre turbine/gate pressure, post turbine pressure if routed into the DP, screamer etc, the gate is only one piece of the puzzle, if the T70 has a small turbine housing like .69 the 38mm will probably work fine, as the backpressure is high, giveing the gate more pressure to work with, if you swapped the .69 for a 1.0+ it might not work soo good anymore. FYI I think many kits in the US supply tiny tiny hosuings to use on V8's, I cant understand why, its a waste IMO, like .96 on 4.1lt works good with auto, yet .63 or .69 whatever it is used on a 5.0?

 

The less boost the more gate you need, but I run a TiAL 38 on my low 10 second car and it works fine, but I also dont run low boost now either. But back in the day the car ran high 120s and would hold 5 psi of boost just fine.

 

I'm going to be running 10-12lbs. of boost. The exhaust housing on my mpt70 is the .68 Is 550 rwhp capable with this combo?

 

Yeah even my 4.2l v6 starts boosting at 2900rpm with a Holset 1.xx on the exhaust side. I forgot the exact specs, sorry. But if I had a smaller AR on the exhaust I would be into boost all the time and that would seem bad for a street car. Even my car makes plenty of torque off the line, so it would seem you wouldn't want to boost to early.

 

Yes. With 12#'s maybe alittle more.

 

I was able to get a T70 down to 9psi on a 302 with a 35mm tial but the it was right at the merge, not in the crossover like most kits. Just run it on a 9psi spring and see what happens. If it creeps and your not comfortable above that boost, then worry about it. No need changing things before you even get it together.

 

whoops