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The mkiv Supra Owners Club

Hybrids on a bpu j-spec ?


Mcgoo

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Hello again,

As you may be aware I popped a turbo yesterday :( and am now considering my options.

 

So would it be safe/ok to fit some j-spec hybrids to to my BPU soop if I was to keep it down to 1.1 / 1.2 bar ? ie could the j-spec fuel system/ injectors cope ?

 

I could then add bigger injectors, fuel control etc at a later date when I want more power and money permitted.

 

Already fitted I have FCD, walbro, full decat, Nur spec, HKS BOV, WB AFR, Boost gauge and an EGT to fit when fitting the tubbies.

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From a car with 550's and strong hybrids, 1.2bar boost requires 80% duty cycle at 6000rpm to maintain 11.8:1 afrs (stock fpr). That means 1.2bar with 440's needs 100% duty cycle and that is with nearly 1000rpm to go. So I wouldn't run 1.2bar. I wouldn't even run 1.1 as that would leave the injectors flat out and any squeak above it would start leaning things off.

 

1.0bar should be OK but again I'd only be comfortable if it was checked out, you have a wideband sensor yes? That will help you a lot with peace of mind if you start at 1.0bar. It should be pretty strong even at that level if the hybrids aren't mickey mouse ones. And you'll feel a fat improvement at 1.4bar once you have the fuelling in place to handle it.

 

-Ian

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From a car with 550's and strong hybrids, 1.2bar boost requires 80% duty cycle at 6000rpm to maintain 11.8:1 afrs (stock fpr). That means 1.2bar with 440's needs 100% duty cycle and that is with nearly 1000rpm to go. So I wouldn't run 1.2bar. I wouldn't even run 1.1 as that would leave the injectors flat out and any squeak above it would start leaning things off.

 

1.0bar should be OK but again I'd only be comfortable if it was checked out, you have a wideband sensor yes? That will help you a lot with peace of mind if you start at 1.0bar. It should be pretty strong even at that level if the hybrids aren't mickey mouse ones. And you'll feel a fat improvement at 1.4bar once you have the fuelling in place to handle it.

 

-Ian

 

Thanks alot Ian, I do have wide band and will have EGT to keep an eye on things.

Would a set of hybrids at 1.0 bar feel any better or worse than my stocks did at 1.1 bar?

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