twin turbo project

[Todd King]

     >out 320 hp with mostly bolt ons. Initially I'll limit the intercooled
     >boost to 6 psi since I don't think the stock lower end can take more
     >than 450 hp anyways. I assume I'll need larger injectors and a bigger
     >fuel pump too. This might force me to abandon my stock MAF system and 
     >go with a DFI unit. You can follow the project at
     
     Ahhh, a project after my own heart :-) As for the bottom end, blown 
     cars are known for being easy on rods due to reduced tensile loads. As 
     long as you don't let it detonate it should easily live at much higher 
     boost levels than 6psi. Personally I know of several GN's (including 
     my own T-type) that live with totally stock v6 blocks and bottom ends 
     well into the tens (23-28 psi boost, 550-650 hp). Again, *don't* let 
     it detonate; I trust that the IROC's have some sort of detonation 
     detection that you can tap a beeper into(?). If you rely on your ears 
     it's too late under boost... Don't try to save a few bucks by messing 
     around with suspect octane rating fuel when you turn up the wick; go 
     with a tankfull of C16 or Maximal only. As for injector size, use the 
     2x rule of thumb; if you want say 500hp then you need (500hp / 2) / 8 
     = 31 lb/hr injectors. To size the fuel pump, take the gal/hr rating at 
     max psi, multiply by 6 lb/gal to get lb/hr then apply the 2x rule 
     again. 500hp would require about 250 lb/hr of fuel capacity at max 
     pressure, which will depend on your boost level of course. I have a 
     used in tank EFI pump that easily supports this power level if you are 
     interested; I went 97 mph in the 1/8th with it my first time out. The 
     stock MAF should work fine; maybe remove one of the screens (if there 
     are two like in a GN MAF). On my car the stock MAF immediatley pegs at 
     255 grams/sec (8 bit system) out of the hole but surprisingly you can 
     still go plenty fast with no air metering taking place. You just have 
     to tweak the PE tables, starting rich (safe) and working your way 
     down. Of course a DFI would also work great if you can get it close 
     all around, plus you lose the MAF sensor which is fairly significant 
     once you start flowing alot of air. Another thing, you can greatly 
     simplify things (and save alot of coin) by going with a single turbo 
     setup; in fact twins are sort of "out of style" with the fast v6 crowd 
     thanks to the tremendous progress made recently with compressor and 
     exhaust side choices. A big single from the GN stack, like say a TE63 
     (I run this one) or TE70 (I hear that several 5.0's run this one) with 
     an .82 exh side would be excellent for you to below the 10.50 level. 
     Also, see the new book by Corky Bell on turbocharging ("Maximum 
     Boost"). It's a pretty good one. Good luck, keep us posted, and hope 
     this helps.
     
     Todd       todd_king at ccm2.jf.intel.com