Just so i get an idea the engine has a street port and t70 just wondering
Whats the max power these 850s can deliver at 100% i no combind its 56.666 cc a sec
But im looking for a hp is their a calculation im wondering why peope always upgrade to 1600 and 2000 it sounds like overkill
Say u want to acheve 450rwhp

 

On pump gas, around 360-385 at the wheels but your injector duty cycles will be in the high 80s-90s%.

I wouldn't recommend running idc's higher than 80%.

-J

 

http://www.rx7.com/cgi-local/3rdgencalc.cgi

4x850's @ 80% would flow ~410hp @ flywheel

 

Ok, 410 - 10-15% drivetrain loss, let's call it 12% ~ 410x0.12=49.2 ~ 410-49.2 = 360.2WHP @ 80% duty cycle!

looks right on to me...


And if you had a calculator like that to begin with, why did you even ask the question in the first place?
-J

 

I hit 84% when tuned for 327-rwhp so depending on how rich you run it can be even lower than the calculator says. Save the head ache of 850 primaries and go with 2000 secondaries or 725/2000 combo.

Jack

 

Precisely Or, if you are concerned with running an aftermarket sec rail, bore the 850's to 1300cc. But ultimately, I recommend going with either 550stock/2000ID or 725ID/2000ID.

-J

 

hell even 550/1600's or 550/1300's would be better that doubling up on 850's

and, supposedly they don't idle all guud

 

No, just "some people" can't get them to idle... Not everyone has those tuning issues
Also, you have to machine the primary rail to accept 850's anyway, so going that route is pointless with all the other options out there.

-J

 

I asked due to my tuner told me he can get 420 whp from 850s all round he the 1 that told me i can run 100%
Thins is why i ask all you guys

Its running fine on idle with 850 primry I was just thinkin im not sure what pump im runnn but i think its the 255
Do you guys run duel pumps or inline wen goin to 2000s

Thanks

 

Yea just calculated the 255 pump can only deliver 4250cc min so if i wen with 1600 or 2000 injectors i might have to go duel pump
walbro sell a 400lph pump has any 1 used it ?

 

Do you guys go to 550 only due to idle or is their another reason?
Might have to 550 and 2000 sounds like u guys used them and had no problems
Thanks guys

 

You can get 850 primaries to run fine as long as they are setup properly. Make sure you get the injectors cleaned by WitchHunter.com first and then use these settings in the PowerFC.

FR-PR %65.0 -0.04
FR-SC------- +0.00
RR-PR %65.0 -0.04
RR-SC------- +0.00

PR 850cc
SC 850cc

Most cars run fine after just using these settings but any decent tuner could adjust things further if you need more fine tuning.

Also, the machining is not that big of a deal. All you have to do is remove 1/8" of a inch of material off the top of the rail so that the injectors sit lower in the rail. I did this with a belt sander in 10 minutes. I once read on the forum that a guy did this with the sandpaper like material on the top a skateboard!

I ran 4x850's years ago and on stock twins the most boost I could safely tune for was 13psi and that was at around 80% duty cycle. I still run stock side-feed 850cc injectors now.

I haven't heard much about the new Walbro 400lph fuel pump but I run 850 primary/1600 secondaries and use the Aeromotive 340lph Stealth in-tank pump. Fuel pressure has been rock solid and I'm making 452whp.

 

Psst, I didn't ask the question in the first place!

Its a handy calculator though.

 

Thanks balljoint

Thanks m8 mice info you may have changed my mind might leave the primry 850 and upgrade 1600 sec
Also is the 1600 limmiting ur power in any way i mean if u wanted 500 whp would they hold up,
And will have to check the fuelpump proply and check if it is 255
And what psi boost u running at the moment and what turbo to get that power

 

This should be a huge red flag to you... you NEED a new tuner.

-J

 

My bad sir...

-J

 

This is only true if you were going to be pushing the fuel system to it's limitations. for 400hp, a walbro (though I personally don't recommend them) will be more than enough for pump fuel.

The smaller the injector, the more resolution you have. They are easier to tune and usually run a lot better. With that said, I personally recommend ID injectors to all my customers and have had NO issues getting them to run/drive/transition. Runing just as smooth(er) as a lexus

-J

 

The 850/1600 injector combo has been proven good for 500whp with some making more than that. The Injector Dynamics ID2000 injectors have newer technology behind them and obviously flow more then the 1600's but the 1600's are cheaper and 850/1600 combo has been proven on high HP cars. So if you have the money for ID2000's then do that, but if not there's nothing wrong with 1600's.

The Walbro 255 usually max's out at around 400whp. People used to run two Walbro 255's when they wre going for big power, but with new pumps like the Aeromotive Stealth 340 and Walbro 400 you should have enough flow out of the one pump to hit 500whp.

I run BNR stage 3's upgraded twin's non-sequentially at 21psi. Made 452whp. Except for a better intercooler (and a few other tricks ) I've pretty much maxed out the turbo's. I'm more then happy with the power already but I want to see how far I can go.

 

What tips u running and the power u have i would be over joyed with your power
You running pump gas and no hidden nitro or meth injection