THDP and Q-trim or PTE 68mm exhaust wheels

[Ed Valvo]

Can the 3" THDP's puck control the boost?

 

[jasjamz]

That depends on how much power you make. How much power do you plan to make?

 

[bison]

The 68 ex wheel is a turbonetics and is proven to 950hp. If you are running the turbo where it's using most of the mass flow potential you need less wastegate. The 7068 can potentially flow 85-90lbs/min which is good for about 900hp under the right conditions. I wouldn't want to try and run this at under 70lbs/min or about 725hp. If you did you would need more wastegate. The 3" dp will cover the ex outlet near the top. You can thin it out with a carbide burr. I'm running a t70 with 68 ex wheel currently and it's really happy between 25 and 30psi on a stock stroke with race ported heads and very aggressive hyd roller. 700whp@27psi on a 93 alky tune with a slightly rich 10.3:1 target and 21* timing. With better fuel and 2* more timing there is a little mire there. If you look at the map it all makes sense. Between 2.6 and 2.8:1 pressure ratio it has the highest mass flow potential. I have a 3.5" dp and heavy spring actuator. The wastegate hole is 1.05" and zero boost control problems. The t70 has a very narrow mass flow range where it's happy. It's tall and narrow so if you're engine can't flow the mass then it will run in surge since you will be heavy left of the surge line. Looks like about 500hp or less and you are running in surge if the boost is over 20psi. On the other side it drops off like a prom dress if not kept between 2.6 and 2.8:1pr when trying to get less than 75lbs/min or over 90lbs/min.