rxse7en

I want to upgrade my Series 5 TII secondary injectors to 720cc injectors. Anyone know where to buy them? Does manufacturer matter? Are they a direct drop in for the high imp. system or will they need a resistor pack?

Searching brings up a lot of answers for Series 4 cars, not much on the Series 5 and just adds to my confusion. RX7store et al do not state whether they are high or low!

Thanks for your help all.
B

SonicRaT

iTrader: (6)

Send yours to rc egineering and have them bore(sp?) them to 720cc

Scott 89t2

but boring them out is like $200+ vrs $100 for new ones...

nobody makes one for S5's or 88's. only 87's

you'd need to add resistors and change the injector harness plug. (or cut something I think to make it fit)

SonicRaT

iTrader: (6)

I think someone was selling a set of s5 1000cc injectors for about $200 or so not too long ago, i think they were venom injectors or something like that.

Blue13B

Hey i'm going add on a question since i dont want to start a whole new thread. Why in the hell do RX-7s need such big injectors?

Scott 89t2

umm cause power requires fuel...

NZConvertible

What are your mods? Are you sure you actually need them? Do you have a fuel controller to fix the pig-rich, power-killing mixtures this will cause?

darkwaveboi

how much do they need to be detuned (720cc secondaries) for full intake/exhaust? (enough so that reducing the fuel flow by 5% from 4k up wont hurt it..or leave it alone till a wideband session is held)

fstrnyou

Well, 13B's actually displace 2.6 Liters of air per 2 revolutions. With a lot of air you need a lot of fuel.

Craig

NZConvertible

I would never spend money on larger injectors and fuel controllers until I'd had the car dyno'd to verify that the mixtures are actually too lean.
Some people slap on a big exhaust and get too much boost, so that add lots of fuel to kill any detonation caused by the high temps from the boost. It works but it's crude and inefficient.
I'd prefer to sort out the overboost problem so that all that extra fuel isn't required. The stock injectors can handle at least 300hp, which is more that the stock turbo can make.
The fuel pump is a different story and should be upgraded first.

darkwaveboi

a rotary has a power pulse every 60º of revolution of the eccentric shaft (360º) while V8's have a power pulse every 90º of the 720º the crankshaft has to move to make a complete piston revolution.

fstrnyou

No, not really. Rotaries have a "power pulse" every 180 degrees of shaft rotation. It takes the eccentric shaft three turns to spin the rotar around once. From that, there is a combustion cycle once per rotar per shaft revolution, 360 degrees. The other rotar is clocked 180 degree apart. Making two combustion cycles per 360 degrees of eccentric shaft revolution. If you don't believe me, download some animated video of a rotary.

Craig

ForsakenRX7

Wouldnt it be more like every 120 degrees or am I seeing the math wrong?

NZConvertible

fstrnyou is right, but the number of pulses has absolutely nothing to do with the amount of fuel (injector size) required, and this thread has nothing to do with rotary power pulses.

fstrnyou

Ya, sorry. Guess I got a little excited when I had the chance to correct someone. I've already given my lecture on the rotary displacement thread. Anyway...

Craig