Injector Size

[Shibby]

I am currently building a RB30 with 26 head and will be using a T88

My aim is around 800hp at the fly or around 700rwhp, what size injectors would be best, I know rule of thumb on 6cyl is hp equals cc roughly but say with 800cc injectors would that leave the duty at 80%

thanks

[IanH]

1000cc Inj's would be fine (800's are a little close to maxing out if you make a little more than 800hp).

[Guerilla]

Yeah I agree... 1000cc

[Sydneykid]

My 20 cents worth, 800 cc = 800 bhp after allowing for 85% duty cycle.

Every new aftermarket injector I have tested flows more than their rating. I have seen 850 cc injectors flow 875 cc's, 550 cc injectors flow 568 cc's etc.

I have found it to be quite safe to add ~10% to the flow with fuel pressure increases.

I would be surpised if you couldn't get 900 bhp out of 800 cc rated injectors.

That said, if you have to buy them, 1,000 cc injectors can sometimes cost less than 800 cc injectors.

Hope that helps:cheers:

[BMCGTR]

I think going by that rule is about 90% duty.

[Sydneykid]

More clarification, OK..........BHP per cc is not exact, the more appropriate calculation is by using the mass of the fuel rather than its volume. So the specific gravity of the fuel used is an important requirement. Most cars running 800 bhp won't be using "normal" fuel. Elf Turbo Max for example, has a higher oxygen content matched to a higher calourific value. So using it, 800 bhp out of 800 cc injecors would be a snap. Similar would apply to other fuels typically used in that application.