Hi,
I`ve just fitted two 1200cc injectors on the seconderies,and I`ve got two 550cc on the primaries.
How much hp will these injectors support?
The engine is a Street/race ported 13bt with a kkk k27 turbo and a huge fmic (31"x10"x3")
And how much boost can I run safe?
Thanks
Ronny

 

Hard to give exact numbers, but they can probably support some fairly high boost levels. I would estimate they should be good up till the 22-26 psi range.

 

You really need to have some instrumentation telling you what your specific motor is doing. Nobody is going to be able to answer that question other than in generalities...

You'll need: Air/Fuel, Exhaust Gas Temp., Fuel Pressure at the minimum to answer your question.

 

I`m aiming at 400+rwhp.
Will the 1200cc injectors provide enough fuel for that,or will I have to get even bigger injectors?
Thanks
Ronny

 

They will most likely be able to do the job for you. You might have to upgrade to 1600cc secondaries, but probably not. Get it all set up, strap it on a dyno and tune it watching the air/fuel ratio closely.
I have seen guys with over 500 rwhp using the 550/1200 injector setup, but I suspect they would be getting pretty close to maxing out the injectors and running them over 80% duty cycle.

 

550ish HP at the flywheel

 

Your setup shouldn't be pushed over 22lbs of boost. I ran 1600cc secondaries with 550 primaries and started maxing out the primaries at 23psi. You have smaller secondaries which means you may max out even sooner. I'd upgrade if you plan on running more than 18psi.

 

Nobody can accurately answer this question without testing YOUR car.

You need to get a wideband oxygen sensor in on the action; that will tell you a lot about what you need to know.

I am using 550/1600 right now and my car dynoed at ~400 rwhp on a 105 degree day at 14 PSI. At the time, the injector duty was only around 85%...

But now that the temps here are down in the 20s and 30s, my duty cycles are maxing out around 98% at high rpms (7700-8000). If I had to take a guess, I'd say th at I'm doing better than 425 rwhp on these cold nights at the minimum. I'm running about 15 PSI right now and because of the high duty cycles in cold weather I'm going to put in 850/1600 to keep safe.

So... now that I've rambled on... I'd say start at around 10 PSI and figure out your injector duty cycle % and your AFRs. Then you will know if you can move up to say... 14 PSI... then try for more if you like.. Go slow in steps so you don't blow it up

I don't think there is any way you will safely get over 400 at the wheels with 550/1200. I would consider 550/1600 to be the smallest that I would want.

Brian

 

650cc per fuel per min injectoer rating per 100HP in a turbo'd rotary is the usual method

that mens 540-550HP at the flywheel, or 460RWHP on a typical US dyno, it will support a tad more HP than that, but you will be maxing out your injectors.......

I have 800cc pri and 1600cc sec ready for my new motor. more than enough fuel for my target HP range. but should i feel the need for a bigger compressor and more boost at a later stage i'll have the fuel system there for it

 

Ok,then I guess they should be ok to start with.
I have one more question.There is a rubber hose,going from the tb to the inector mounting on the manifold.
It looks like it feeding air to underneath the injectors some how.What`s the purpose of this?
If the hoses is just blocked of,can it result in bad gas milage and bad idle?
Thanks
Ronny

 

This should help:
http://www.maxcooper.com/rx7/how-to/...tem/calcs.html

The BSFC will change based on tuning. Richer means a higher BSFC.

-Max