Hello all.. I am very near wrapping up my latest build, a turbo 400 low deck engine, and I am already wondering how far I can honestly push my luck.
I have read and learned from friends that turbo builds pretty regularly produce higher numbers at a safe and repeatable level than most power adders, but its all speculation at this point.
Anyways, I'd love to hear from, or be pointed towards anyone with some real world experience that I can draw from regarding turbo charged Mopar low deck big blocks.
Thanks in advance guys, much appreciated!
My friend Randy, that goes by
rdakota340 on TheTurboForums and elsewhere has been running a 400-based build for years, mainly on the street. He's lost a crank, and a few pistons in his 400/451, but the block has held up fairly strong. We both lost the #2 piston, that seemed to be the one that would let go due to fuel distribution in that cylinder with the Edelbrock Victor manifold (which was the best at the time).
My build ran around 8 PSI with a BW T6. Everything was a compromise however, and to me, the (safe) power levels with boost & 93-octane were similar to a modern 470" - 512" Chrysler N/A. Again, this was a street car, and not a drag car, there are many more variables involved. Over that period of time, I ran meth-injection as well as an air-to-water intercooler setup with a large ice tank in the trunk.
If I were to do it over again, it would be with a Procharger & E85. If you're already set up for the turbo build, definitely consider running E85 rather than pump-gas on the street [*Which it seems like you're doing!*]. My build was with a CSU Blow-Through carb [Gas].
I would run it fat also, 11.5-11.9 AFR @ WOT and make sure there are no lean spots under load. There is always a cylinder or two that will run leaner than the rest at peak torque, and does it really matter 'how many' pistons go when they do? Your tuning window is much shorter on a forced-induction build than N/A, can't afford to make mistakes and I would rather be down a bit on power tuning it safe, than trying to get more out of it.
In regards to gearing, I would go with either a 2.76 (26-27") -2.93 (29-30") gear depending on tire size. Converter around 2800-3200 stall speed.
