Inline 250 - T3 Turbo - w/ Video

[Driveway Dreams]

I just saw this thread for the first time. Very cool! I like the build over all. A lot like what I would like to do with my small block, a budget turbo set up. Very cool!

[rpmerf]

Just saw this engine in another thread. Very cool! The turbo almost looks like it was meant to be there. Any status updates?

how are you controlling boost? vac line straight from the manifold to the waste gate?

[boucher racing]

[/QUOTE]

how are you controlling boost? vac line straight from the manifold to the waste gate?[/QUOTE]

I am using the factory internal wastegate that is on the turbo. The only problem that it was a HD which means the PSI range was like 17-30 psi. So I was hitting 19 psi at times! I modified the wastegate to open earlier by designing a spring assist.

Check it out if you like:

http://youtu.be/rogCn4AJYsY

To control boost, there is a port on the intake side of the turbo that connects to the wastegate.

[boucher racing]

The truck is running great. I have set the wastegate to open at 10 psi. I drove it over 300 miles last week with no problems. The only issues is that my 1st gear in my T5 is trashed. It will not stay in, pops out everytime. I love driving it and hearing that turbo spool up and wastegate flutter out. Here is a pic of the finished engine as it sits. Possibly a intercooler set up this winter.

[MusicMan70]

sub scribed! Nice GMC!

[rpmerf]

Wow pretty cool mod on the waste gate! Could you not find a WG set at around 8 psi or did you want the HD one so its easier to push higher?

Are you doing anything for your PCV system while your in boost?

[boucher racing]

I wanted to use what I had, b/c a new one was a 100 bucks. Plus, I can always turn this one up.

There is no PVC system, I am running a crankcase vent though. I have two inline valve cover breathers connected to a 45 deg nipple port on my exhaust about 3' down the downpipe. It suprisingly provides alot of suction or vacuum to pull positive pressure out.
Posted via Mobile Device

[rpmerf]

oh cool venting into the exhaust seems to be the best way to do it.

[jiyrulz 1]

Awesome engine. Makes me wish I hadn't ditched my 250.

[kissingbug1978]

subscribed

[porter90]

this thread is making me have some serious second thoughts about gettin rid of my 250 as well...hrm where does the turbo start boosting?

[boucher racing]

Originally Posted by porter90

this thread is making me have some serious second thoughts about gettin rid of my 250 as well...hrm where does the turbo start boosting?

If you mean, WHEN?, It spools up quick around 1500 rpms. The engine is not a high RPM machine, so shifting is pretty quick. The psi's climb really quick, when my wastegate was not working correctly, at around 1500 rpm it was 1-2psi and at 2000 rpm it was at 15psi +! I had to get out of it quick.

I still want to put a intercooler on it this winter and swap the T5 out for one that 1st gear actually works. All in all, very pleased.

[c10hevy]

Subscribed! Im going to get my 250 rebuilt in december then follow exactly in your footsteps! 66 GMC and all!!

[VA72C10]

very cool! Love the engine bay vibe too!

[porter90]

yea thats what i meant! lol it was something i had always wondered because all of the turbo cars i have experience with seem to boost around 3000 and i dont really like to go much higher than that with mine. thats really awesome tho, if i knew how to subscribe i would! this is really cool and i think im going to look into it for sure

[awbrown]

Did you destroy first gear , or do you think it was on it's way out ??

[boucher racing]

Originally Posted by awbrown

Did you destroy first gear , or do you think it was on it's way out ??

i believe that is a synchro issue. It will not stay in first at all with a load. Also, this trans is loud! Mabey all T5's are noise, I dont know. I have a clean NWC donor (the tailshaft swapper) that I will install soon.
Posted via Mobile Device

[1963c-10]

Very cool build. The inlines are such great engines

[jbon64]

very cool set up !!!!!!!!!! one question , in your opening post it says GN T3 turbo . i assume that would be a grand national turbo ? as in a buick GN

[boucher racing]

You are correct. Its from a low mile 87 Buick Grand National, factory wastegate and elbow.
Posted via Mobile Device

[theastronaut]

The T5 in our S10 has started making alot of noise in the first three gears. The first three gears have seen alot of abuse though.

Posted via Mobile Device

[longbed67]

How's your fuel economy so far with this? I get my block and head back soon and am curious what to expect.

[boucher racing]

Originally Posted by longbed67

How's your fuel economy so far with this?

I actually just got my speedo / odometer back working with the 5 speed. I will a have to calculate it. I have always wondered also.

[krazy_texan]

wow that looks like it really wasnt that hard to do. what did you use for engine internals like camshaft and such.

[boucher racing]

Originally Posted by krazy_texan

wow that looks like it really wasnt that hard to do. what did you use for engine internals like camshaft and such.

I used the stock head that was cleaned up, rebuilt, Z28 valve springs.

Stock polished crank

Lunati cam- reverse duration efficiency design (212/202 adv dur, .465/.458 lift, 114 lsa)

.030 over forged NOS TRW pistons