Twin turbocharged 350 Chevy project

December 2004.

Twin T34's

After an extensive search, Ive ended up buying a brand new pair of the original T34 Garrett turbos as fitted to the Escort Cosworth. Even finding a rebuildable pair proved difficult, I also looked into importing a pair of T3's from the states. The only company that was kind enough to reply to my enquiries was Vecco High Performance - everyone else ignored my contacts - Unfortunately a pair of turbo's with wastegates and shipping would cost close to $2000 Even with a strong pound, that's still around £1200. I ended up getting this pair from Giles at Turbo Technics in Northampton.

Comparison of the GT32's against the T34's

Here's the compressor map plot, for 8,12 & 14psi respectively. The purple line represents max torque, all within 68-70% efficiency.

Also got my DIY weld yourself header kit now - plenty of mandrel bends to make my turbo headers, The header flanges are a decent 10mm thick.

Beware of Fake / Low Quality turbos

There appear to be alot of turbos for sale, especially on ebay that claim to be t3/t4 hybrid turbo's - although the word "Garrett" is never mentioned. Have a look at this Honda forum thread it shows pictures of turbo compressor housing split in half. Also read This thread which discusses turbos from Custom Chrome / Stone racing.

9th Jan 2005 Fixing Jig

No car over Christmas due to gearbox problems meant that no progress was made at-all. Now the car is back, I managed to make a turbo fixing Jig that places the turbo exactly where I need it in the car.

This enables me to use a spare cylinder head on the workbench to create the manifolds, without having to constantly go back and try it on the car.

The turbo is centered on the two middle exhaust ports at exactly 90 degrees, making fabrication easier (I hope!!)

Jan 17, 2004

Finally made some reasonable progress, thanks to the 'Missus letting me have the whole day in the shed and helping hands from my dad. The cone shaped collector took a few hours to make and the headers themselves took all day - You always need to be thinking a few steps ahead; Consider the following when laying out your pipes:

• Where will the Oil drains go?
• Where will the exhaust go (Mine will route between the gap between the outer and middle pipes)?
• Can you get a spanner on the bolts to actually fit the turbo?
• Do you clear the spark plugs and will you be able to remove the plugs?

Here's the mock up; welding those collectors should be an fun...

I Couldn't get the collector to meet the turbo exactly where i wanted it, so I just tacked in on and tried it in the car. It fits, but its too close the the master reservoir and steering shaft. So I need to fettle it some more.

A hour's worth of fettling later, I got the collector to align with the turbo in the Jig, notice that the turbo is further away from the heat critical master cylinder and the suspension turret. Basically its exactly where I wanted it, the Jig is defiantly the way to do it. (The brake pipes will be rerouted anyway)