Hello all! I'm starting my first attempt at a turbo engine. I have been building and racing Pontiacs all my life, my last car was a tube chassis 1965 Pontiac LeMans with a 455 Pontiac engine, than car ran a best of 9.14 @ 146 on a bad track in bad air. I didn't enjoy the tube chassis thing much as even with a 1.24 60 foot and running 146 mph the car felt like it had 1.50 60 foot times and felt like it was going 155 mph, I guess that was because the car was doing what it was supposed to do. I missed the street scene and always wanted to build a turbo engine so now I am doing both, a turbo charged streetcar. I still love Pontiac power but just the cost of the block alone is half of would I can build a complete turbo charged small block Chevy for. My motor is going to be a 4.125 bore Little M block 3.875 stroke 414 with Patriot 225 heads, I have 6" Eagle H-beams w/L19 bolts and Mahle coated nitrous/blower pistons, the compression will be 10:1. I bought a set of OBX 1 7/8ths ss headers, I have a Holley HP EFI system, a set of 120 lb injectors coming, a 6061.com throttle body adapter and a 92 mm throttle body. The last piece of the puzzle is the turbo itself. For a while Cecil County was thinking about adopting the RS 275 class from down south which had a 76 mm turbo limit so bought a BW S475, well Cecil is not going with RS 275 but will adopt either Ultimate or Ultra street which allows an 80 mm with a minimum weight of 3250. But I'm thinking just build what I want to go have fun, run fast as I can with no regulatory rules. I'm currently looking at C.R.T.'s 88 and 91 mm Garrett based turbo, I talked to Chris and he is recommending that I go with the 91 mm with a 1.39 A/R tubine housing, I forget what size wheel he told me but i'm thinking it was 112 mm... What do you guys think? that turbo also comes standard with the T6 1.23 A/R housing with a 96 mm wheel. As for BOVs and wastegates I'm thinking 60 mm for both. I'll have tons more questions as I move into the details of the build... D. Miles

 

Don, couple questions, what cam, solid, hydraulic? How fast do YOU want to go. Set a goal and build around that. I learned from a member on here (thank wantabe) that the trend now is to go large turbine and tight ar to aid in responsiveness. I would call forced inductions or reed at work turbochargers before settling on one option.

Anthony

 

Thanks Anthony. I'm going solid roller, I was looking at a grind Herbert has 278/286 adv. 242/246 @ .050 .378/.390 which will give me .604 and .624 @ the valve with a 1.6 rocker with a 114 lobe sep. My goal is 1000 HP at the wheels so I figure aim for just past that to make sure. I read Slammed98GMC's build and saw what he accomplished with an S480 first then an S488, ET/MPH wise, 8.70's-8.80's @ 155ish, that's my goal. Now I think I follow you when you say "large turbine, tight A/R" you mean like a 100+ mm turbine wheel with say a 1.00-1.10 A/R. C.R.T.'s HP 88 and HP 91's are both mid frame units that come with either a 1.08 or 1.23 A/R and a 96 mm wheel while the upgrade is a 1.39 A/R with a 112 mm wheel (I Think!). When I asked Chris about spool time right away he said FAST very fast and definately quicker than a standard 96mm/1.32 A/R S400 series BW, he said it has an extremely aggressive turbine wheel. I did talk to Jose @ Forced Inductions, that's who I bought my S475 from, he said for my goals, an S480 with a race cover would be right on the edge, he did recommend an S488 but still with the 96mm/1.32 turbine I just don't have $1649. My budget was built around the S480 w/race cover which is $1187, I figured an extra $150 for 200 more HP is a small price to pay so I can work around it. D. Miles