The SOHC engine is a nice little engine, but like most things with me, I needed something with a little more power. SO. . .I bought an Isuzu Impulse RS that was completely rusted out. The engine was totally trashed, turbo blown(the shaft was broken in 2 spots) and the compression was a joke.
One thing to do from there, Rebuild time!
The Cylinder walls were etched with rust and needed to be bored out. I search high and low, but could not find Stock overbore pistons...Isuzu, Lotus, nobody had a set. That meant that I had to go Custom. I got a set of Forged pistons from Ross Racing Pistons made for $600: 9.35:1CR flat top with valve reliefs, .030" Overbore, Ross Racing Molly rings ($75), 4340 Chrome Moly Tapered Pins($22each), Reinforced pin bridge($27 extra)
Since the turbo was scrap metal, I needed a replacement. I found out that the 1989 Ford Thunderbird Turbocoupe used the same center cartridge as the Impulse RS, but has a larger compressor wheel. (IHI RHB5) So I found one, rebuilt it, and ceramic coated the compressor housing/center cartridge/exhaust shield/turbine blades.
I also ceramic coated the exhaust manifold and O2 sensor housing
After the head got a 3 angle valve job, I ported the intake and Exhaust, opened them up to match the gaskets- an extra 2mm per port
I couldn't stop there, so I ported the turbine housing, wastegate, exhaust manifold, secondaries, and intake plenum.
