Tried posting in the mopar section but can't seem to get any answers. So here's what I have- 4.315 bore, 4.25 stroke crank, eddy cnc ported heads with 2.14 intake and 1.85 exhaust, 8.7-1 static compression, I'm using an offenhauser tunnel ram base with new plenum all converted for efi witth dual 39 lb. hr. injectors per cylinder, using bigstuff three and running distributorless with chevy coil packs. Elevation where I live is 4500 feet. Want to run twin turbos and achieve 850 Hp. What turbos do I need and will any of the ones sold on Ebay work or are they junk? Thanks Pete

 

OK - I am probably going to ask more questions than give real answers so...

First - Search is still your friend...  What are you going to do with the car?  Street race, class race, cruise, show?  What are the rest of the components.  What is your budget constraint.  Answers vary by response...

Second - You stated 850 HP so need turbos capable of supporting ~425 HP worth of air each - there are many of these out there.  Search is your friend but I assume that most of the larger T04B types can get into this area.

Third - If my math is right that bore/stroke combo (assuming 8 cyls) puts you at just under 500 CI.  I know next to nothing about Mopar heads but I assume from the valve size that they will flow a decent amount of air NA.  Making 850HP under boost through big heads on a 500" motor might be considered underkill.   If the rest of the combo can handle more HP you might very well want to go to bigger twins and just wastegate them down to your HP level.

E-bay turbos are very hit and miss with a lot more mis than hit.  I have a $400 paperweight that I bought there before I started reading.  You will almost certainly be better off in the long run going with turbos from one of the resellers here.

Turbos do more in thin air than others....  Why are they the power adder of choice in small airplanes?

My advice - spend a lot more time digging before you spend time spending and you will get closer to what you want the first time.  Good luck...
Welcome....

 

oops - doubled....

 

the anwer to the first ? is during the first year or so it's going to see more show and street than anything else at least till the newness wears off then I will do more along the lines of strip racing. Answer to the 2nd ? is yes there is alot of stuff out there to read and I have alredy read the turbo bible here on this site as well as Hugh McInness's book Turbochargers. I have Maximum boost on order but there is still alot of variables to the formulas they give you and I'm not sure if I'm understanding all of it. I also wonder if all the formulas are or needed. It makes me a little nervous and I don't want to figure this wrong. 3rd ? Yes it's a 497 Callies crank, Oliver steel billet I beams, Ross pistons custom order dished with thickened tops ring pack mbved down, straightline custom grind solid roller. So yes the components could handle a considerable amount more but my block is the limiting factor. I eventually plan on a better block If I want more power as all of these components can be reused in an alum race block. M y budget is not unlimited but I will spend what I need to acheive my goal. But I do shop like everyone else I want to do it as cheap as is possible.

 

I think you'll like two T04S T66/P-trims on the car. Those are nice responding turbos and do well throughout the boost range.

 

Thank you for the responses. Do these spool fairly quick ,and what kind of boost are they capable of . Thanks Pete

 

Compressors in the range of T62-T66 would seem ideal.

P-trim turbines in the 0.69-0.96 A/R range would be good as depending on how soon you want boost and how much you want to eek out of the top end.