Omixeo

iTrader: (1)

So I'm about to buy an rtek so I can raise the boost, but I'm not sure which to get. Is the 1.8 really needed for 12lbs of boost? Do I really need 720 primaries? I know Digi7ech has the 1.7 and I think he's running 10-12lbs. The only diferences I see in the 1.7 and the 1.8 are the primary injector sizes. I'm wondering why that is, and at what point do you need that extra fuel?

I have a rebuilt and street ported motor, not sure if its all s4 or mixed parts internally, 3" full exhaust, 3" tid, and an fmic being mocked up at the moment. With a boost controller running 10-12lbs would I need the extra fuel that the 1.8 supports? Given more fuel is always safer, I still don't want to be wasting it. Any opinions?

Black Knight RX7 FC3S

iTrader: (7)

1.8 is ONLY for 720s and higher injector.
If you try to use anything lower then 720ccs on a 1.8 engine damage will occur from running lean. 1.8 has maps based on 720cc.

If you are running 10-12psi I would suggest someway to actually tune the fuel with a rtek 1.8.

Anything more then 8 psi to me, and you will need 720cc injectors to be on the safe side. And if you are going to run 720cc, get the rtek 1.8 and a fuel controller like a safc to fine tune it.

Omixeo

iTrader: (1)

Well yah....That's pretty much obvious. My question is why is the 1.8 needed compared to the 1.7? At what point do you need to put 720's into the primaries as well? If the 1.7 can support up to 14lbs on the stock turbo with 550/720's then what changes or what are people doing that need a 720 in the primary?

RotaryRocket88

iTrader: (7)

Answered your question in your 2nd gen tech section thread: https://www.rx7club.com/2nd-generation-specific-1986-1992-17/rtek-1-7-vs-1-8-a-850392/

It basically comes down to injector duty cycle. 550s are pretty easy to max out with even the stock turbo.