I was able to run 11.02 at 121 15lbs 93oct, 9.5 degrees with the 70mm. Switched it out for the Turbonetics 78/75, ran 11.07 at 121.7 15lbs, 93oct, 50/50, 14.5 degrees of timing. The 78/75 lacked through the 8th, slower, and down on mph. Logs showed 78/75 not hitting max boost until 1k rpm later. I missed the fast spool. I switched out the 78/75 for a brand new BW 66/73. I know its small, but im gueesing it should be just as good as the 70mm, a little better with the bigger exhaust wheel. Going to try it out, now that i have the meth, I can keep the timing up over the 70mm and see how it does. Worst case scenario if it doesnt get me goals of 10.8-10.9s, (not going bigger on fuel system), It will be set up for a borg unit, and I will go a litte bigger. I got the turbo for 400.00 brand new, so its worth a shot to me.

4.8, just 214/218 562/562 111 cam, and dual, PTC 3500, and 3.90s. 70mm did a 1.54 60ft leaving at 8-9lbs
Truck weighs 4320 with me in it.

 

Were you ever able to dyno it? Interested in how that turbo works out.

 

Very interest to see how this works out too. My money is that S366 will blow the MP70 out of the water. I know it sure spool fast on my 5.3 in the 69 c10. Such a fun truck to drive with that "little" turbo on it and 12 lbs!

 

I just know my goals with truck, it has always seem to work. Im sure the bigger turbo would make more power, but I dont think I need it to reach my goal. People say do you want a race truck or street truck? The 70mm gave me balance with both, and I dont see why the 66mm wouldnt either.

 

Truck has never been dynoed. based off weight and mph around 550+ rwhp

 

How soon before you get to try again?

 

Rick, it may be couple weeks out. Need to mod the down pipe, and then retune. The 70mm had 10s in it with more timing, but wasnt running meth then. It trapped 121.2 on 15lbs, 93 oct, 9.5 degrees of timing, 10.8 AFR. I will try this 66mm with some more timing in it and see if how it picks up. I dont wont to put a cage in the truck, or redo fuel system, so goal is high 10s and call it a day.

 

In for results! Those 78/75 turbos are 400 bucks but it seems like I should be putting that toward a better turbo to keep instant spool time and still flow enough for some decent mph.

How did the turbo sound change going from the 70 to the 78? I know my little 70 screams when I'm not even in the throttle and I love the constant loud turbo sound.

 

Choda, I had the 1200 dollar Turbonetics 78/75 BB .96ar. It didnt have the instant responce of the 70, but when it did come in it came in hard. I have to wonder myself, with the 70mm, i was only commanding 10.5 degrees WOT with 15 psi. It started pulling timing by the 8th due to iats. 70mm would trap anywhere from 118 to 121 depending on how much timing got pull from 10.5. The 78/75 would only build 7 psi on 2 step at 3500, and the 70mm built 9 psi at same rpm, best 60ft with 70mm was 1.54, best with 78, I actuall got down to a 1.60. The 70mm was 2 tenths quicker to 330 ft, and had 2 mph over the 78mm at the 8th. but by the quarter the 78 almost ran as quick, and matched mph. If I were to turn the boost up and put the 78mm in its sweet spot im pretty sure it would have came to life. For around my area, and my goals, I dont need a turbo that can put out 1000hp, I wont ever get there, dont have the fuel system or desire to go that fast. I had 5 degrees more timing in the 78mm with meth to make it even come close. The 70mm just down right worked with my cam and converter/gear selection. Im pretty sure the 70mm with 5 degrees more timing and the cooler iats with the meth would have trapped 100+ in the 8th. The 78mm wasnt near as loud either. I did not pay full price for the turbonetics, I got a good deal and thought hell ill try it. Same with this BW s366, 400.00 bucks, couldnt pass it up, its brand new, never installed. If its anything like the 70mm, and can get me in the 10s, i will be happy.

 

Where are these $400 deals coming from? Starting to piece together turbo parts for whitney my 2003 4.8l $10000 truck so $400 sounds good.