I have 86 S10 that I ran last year with a n/a 355 w/flattop pistons, small valve 300 horse heads, holley contender dp intake, lunati brakt master II cam-246* @.050-.515" lift-108*lsa, preform 750 race carb, 1 3/4 headman fenderwell headers, turbo 350 w/3000 converter, 9" ford w/4.56 gears, 28"x10.5 hoosier slicks....fastest time was a 7.051 @90 mph w/ 1.56 60' . I have bought a ON 3 7875 turbo and have built my own log style headers, 2" crossover. I m changing intake to a old torker intake...keeping everything else on the engine the same for now...I know the compression and cam is a bit much for turbo usage...thinking of changing to a summit cam that is 228* @ 0.50, .480" lift, 112* lsa hydraulic. I m curious as to weather this 7875 turbo will carry a 355 to 6000 or even 6500 rpms and what rear gears shud I change to... 3.25 ?

 

turbos like the taller gears like the 3.25

i think the 7875 will work pretty good with your combo, depending on what heads you have it may be a little small on the turbine

 

.....thanks for the reply M&M....I got my fuel pump, regulator, some AN fittings, charge pipe and intake gaskets today from Jegs...hoping csu hat comes in the next couple of days and some parts from treadstone...

 

http://www.hangar18fabrication.com/blowthru.html

if going to mod a carb yourself

 

My fastest ET's have been with the gear set for peak RPM crossing the finish line. Less ratio slowed me down.

 

is your engine setup to make peak power at that rpm tho? just curious is all. i've found on my own setup it likes the load from the gear.

 

My peak power is pretty broad. The peak is about 6200-6300 and about 1240 or so, but HP is over 1200 even at 7500+. I do have a tighter converter coming. This one only drops to 6700 or so now with my HP increased, and it should probably drop to 6200-6300 on the shift.

I don't know how other people's cars are, but my car's boost is essentially the same from 4000-7500, light load or not. If I am on the transbrake at 4300 with a stage RPM limiter, far below stall of 6400, it goes to 23 psi (or whatever I have the wastegate at). When I let go and it flashes to 6400 or 6500, it stays at 23. When I shift, it is pretty much at 23. I have not eased the boost up beyond 23 with the present turbo.

To my thinking, if a turbo needs a high gear to load the engine to spin the turbine and make boost, something is wrong. I can get 20 psi when stuttering with the limiter at 4000 RPM.

The only reason I would reduce my car's rear gear ratio would be if I was blowing the tires off or running out of RPM on the big end.

 

....I have done those mods(hanger 18) on a friends vortech charged s10 blazer....he and I are goin to send our carbs to kevin at csu...ive done all I can do to his with out major surgery...it does alrite but I think it cud be a lot better, and I have heard nuthin but good about kevins work...

 

i have totally different setup and requirements are a bit different. along with a very narrow power range. it is cool to see the differences in the power range and boost levels. once i get mine ironed out boost should be around 80-100psi depending on how i have the gate and fueling set up. 65psi was the highest i saw but with a major hot pipe leak. peak power should be right around 4k rpm and around 1k hp to the tires. i was leaving the line anywhere from 15-20psi last time i had it at the track. balancing act to keep the trans alive.