Inliners International Forums General Discussion Blown and Injected Turbo for my 250

Ive been reading lots, and am thinking I need a turbo with a turbine A/R somewhere between .63 and .80

I'm not looking for smashing top end speed for my 71 C-10, but i'd like her to be able to get from a slow roll to 60-70 PDQ.

I have a complete donor 250 for parts modification as well. I'd like find something used preferably from a production car if it suits the purpose, rather than buy a new one from a perfromance joint.

I'm thinking the GMC Syclone Mitsu turbo would work.

Any advice?

I'll assume from your avatar you're in the Navy so thank you for your service, there have beeen lots of different posts on this subject so use the search function at the top of the page and look for discussions like this one, https://www.inliners.org/ubbthreads/ubbthreads.php?ubb=showflat&Number=69201&fpart=1 .

Thanks, it was my pleasure. Just finished 20 years in May. Thanks for the info I like the 302 Jimmy manifold.

JStew,
I'm DEFINITELY no expert on the matter, but I have aquired a used turbo from a Buick Grand National to use on my injected/turbocharged 250 project. I'm not looking for BIG horsepower numbers, would be happy with 350hp which I think is easily obtainable. I'm not looking to twist this thing up past 5K either.
Do a search for 'Boucher', he is a user here that used a GN turbo for his build. I'm sure he can give good feedback.
There are LOTS of other turbo combos going here as well, and all of those individuals have more experience and knowledge than myself.
Just thought I'd throw that out there for you.

Copo-rat,

Thanks! Are you going to run a blow thru or draw thru setup? What type of injection are you using TBI?

JStew,
I will be using a throttle body (throttle by wire) and electronics (sensors, wiring, ecm etc), from an '08 Trailblazer (4200 I6). I'm going to adapt cam and crank reluctors to my motor so I can run the ignition distributorless (like the 4200 I6, LS series V8 etc etc).
Here is a pic of the intake with the throttle body on and a couple of injectors in place.....

Unreal! Where do you mount sensors to give it the inputs that the fuel injection system needs?

I've been playing with a similar set-up as has TLowe, I have a problem with it running rough up to the 1200-1300 rpm level before it starts to smooth out, so I'm making some port dividers to fit into the head and intake manifold to try and seperate the flow to each cylinder. TLowe has done it with dividers in the head.

Are you using a Clifford intake also? 292 CI engine?

I am thinking FI would work a little bit better w/an Offy intake, just me thinking out loud.
The way the Clifford has a nice long smooth radius into the # 1 & # 6 ports, most of the air goes to them.

W/a sharp 90 degree turn the Offy has, I am thinking it does not distribute the air/fuel the same way.

Plus I have alway said, the smaller intake volume & runner size the Offy has, it will create better bottom end responce, especially on 250 & smaller engines.

MBHD

Jalopy,
Did not realise you were making progress on your project. Please start a new post and tell us about it!

I'll have some time after Christmas when I'm home to take pictures and play with it some more. I made some aluminum plate dividers that go in and twist to seperate the ports and fit into groooves in the Clifford intake to hold them in place.. Still using a V6 TPI sytem with an ECM and dizzy from the same car.

I don't know how you can separate the runner passage all the way beyond the valve seat.

Like TLowe, I also own a Sawzall, a mill, lathe and drill press, I'll find a way.

You GO Jalopy!