dastallion951

just curious if anyone has the specs on the fuel system for our 8's.......unfortunately i dont have a manual in my posession, with such knowledge.....im curious if anyone has information reguarding the CC's min injectors for both primary n secondary, if the injectors r either Saturated circuit or Peak and Hold...... what the fuel pressure is comin through the injectors n if anyone has any experience using an after market fuel pressure regulator, with a booster pump that is used to the stock fuel pump................
any help would be appreciated, if u have REAL knowledge........

Jaguar_MBA

With the engine underload, the fuel pressure should be ~58-60PSI.

rkostolni

They are saturated circuit injectors.

If memory serves I believe they are:
P1: 280cc
Secondary: 390cc
P2: 390cc

Although I might have the 8's and 9's backwards. In which case they're
P1: 290cc
Secondary: 380cc
P2: 380cc

Either way is close enough, there's a significant tolerance in that spec anyway.

dastallion951

ok now i was also curious do either of u two guys know what the BSFC is, or the brake specific fuel consumption is for our 8's.............which is the amount of fuel used per hp, per hour........... reason im askin all this is i wanna setup a fuel system for my car get all the right parts so i have my fuel system taken care of for when i go FI, i should hit the 400 hp mark....now just out of curiousity has anyone bothered to lookup the specs on the primary n secondary injectors from the FD rx7..............i believe they were like 550cc for primary n 660 for secondary??? anyone know if there saturated circuit injectors if so might be able to make those work???

rkostolni

BSFC for a rotary is relatively high, 0.6 or so.

Koma

does RP midpipe fit to stock exhaust?

zoom44

i think the using the 4port secondaries would give enough fuel for 400 bhp. i havent done the calculation but the stockers are good for 300 plus bhp

Red Devil

Where did that come from?


Zoom, I assume that 400bhp number is with keeping the factory primaries in place?

zoom44

yeah if you changed them all you'd definetly have room for 400bhp and probably 400whp. dstallion should talk to ptp about pressure. i know the return;less system is good for over 300bhp maybe even 350 bhp. but you'll probably want to change it to a return type for over that.

rkostolni

I wouldn't push the stock fuel pump over 300whp. There have been a significant amount of failures even below that hp level. For the relatively cheap cost of a fuel pump, you should change it before it blows your expensive motor. Now, I just need to heed my own advise!

400bhp should require 2500cc's/min worth of fuel assuming a bsfc of 0.6. Now assuming you only want to run your injectors at 80% duty you'll need 3150cc/min of fuel. Keeping the stock P1's and P2's, leaves you needing 1800cc/min of fuel, or 2 900cc injectors assuming stock fuel pressure. But, no one says you have to keep the stock P1's, P2's or stock fuel pressure. But, those are also fairly conservative estimates. You could do it with smaller injectors, you just wouldn't have as much headroom.

dastallion951

well that is a good point what u make rkolstolni, but, the way ive been taught if u go good enough size injectors, n a fuel pump with enough flowing capabilities, as well as a really thick return line, u control ur fuel system for forced induction, with an aftermarket pressure regulator, if u have big enough injectors n pump with return line, then u dont have to run high pressure in the system, there fore, when it comes to tuning, when i have all my parts ready for the turbo, i could in theory flow enough to exceed 400whp, i would have to have the ignition system capable of flowin that high voltage n current.....

rkostolni

I wasn't saying you have to run higher pressure. I just meant that is a method to get a little more fuel through a given set of injectors. If you have large enough injectors, then you obviously wouldn't have to worry about that.