Big turbo on stock motor?

[YellaGN]

I have a Turbonetics 70mm BB p-trim 3 bolt turbo with an .82 housing on stock heads/cam car. Car has run some 11.30's at 120 mph at just 20 psi with 55# injectors. But...no matter what i do, I cant seem to get more than 20 psi. My question is can the .82 exhaust housing be too big for the amount of exhaust pressure that a stock motor can produce? I really love the top end that this .82 provides. Suggestions? Should i go with a smaller exhaust housing? Anyone run into a similar problem?

 

[salvageV6]

I have the Innovative DBB 70 P trim and smaller housing and have no trouble spooling to at least 26 psi. which is the peak I have tried on pump gas and alky.

160K heads and cam.

Never tried a .82 housing.

I'd suspect the boost gauge first, 20psi. is rather low for 120mph on a stock longblock.

 

[YellaGN]

Brand new boost gauge.

I see your point.....120mph is awful high for stock motor and 20psi, but this car just runs btter than most! It ran 11.40's @ 119 with a PT-51 @ 24-25psi.

???

 

[65vette396]

If you have an external wastegate, change the wastgate spring to something heavier. If you are using a stock style HD actuator, put a carb linkage return sping from the swing valve, to the acuator nipple or something farely close to get a decent tension on the wastgate. Good luck, Drew

 

[chris2316]

what kind of wastegate? im leaning on it being the spring being weak and blowing the flap open!

 

[tyrod]

Check to see if your fuel pressure is increasing only 20lbs. also. Calibrate your boost guage if different.

 

[Ormand]

What kind of IC do you have? Maybe the big turbo is putting out more air than the IC will flow. You may be dropping 5 or 6 psi across a stock intercooler, if that's what you have. Should have at least a "big neck" IC, if not a "stretch", to go with big turbo.

 

[YellaGN]

Running precision FM, and stock style actuator. Im thinking the wategate is where my problem may be.

 

[chris2316]

I think theres alot of stock actuator cars out there that are having problems get a racegate i love mine ! the boost goes anywhere i want it to and it also comes with three springs for adjustability.the car has =gtq71,gn1 heads.