What Is Difference Between Normal & Total Inj. Duty Cycle

[Mark...]

I think I may have maxed my Toyota 315cc injectors at ~7.5psi in a 1994 1.8L MX5 with EManage Blue.

Question is on datalogging the "Normal inj. Duty cycle" is fine as maxed out at ~80%

but the "Total inj. Duty cycle" is maxed out at 100+%


Whats the difference between Normal and Total?



Should I up the fuel pressure?

[Kennymp3]

Sounds like you may need to upgrade to larger injector's.
I'm running 295cc injectors(stock)on a 1.3L, 315's on a 1.8L maybe a tad too small.
I don't think upping the fuel pressure with help.

[Mark...]

Surprising you have 295's on a 1.3L, is it a starlet?

From Miata turbo's messiahx: "I think normal duty cycle is more or less what the stock ECU is putting out. Total shows what the duty cycle is with your additions to it from the INJ map." I think that makes perfect sense now.


I think raising the fuel pressure as some have done will probably be the way I will try for now. However the cost of a rising rate FPR seems really costly from BEGi or Vortech at about £120+ !

Precision Turbo injectors could be about £175 for 390cc's. By my calculations the standard injectors were 265cc x 150% = 397.5cc so the EMB can handle 390's. This might give me enough fuel at low enough total duty? How do I calculate that I'm wondering?


Unfortunately I don't really have £175 at the moment. So can I not just buy a cheaper adjustable FPR, increase the EMB injector change to suit with upping the pressure till the total duty is ~80% max?

Or will the engine not like this, so is a rising rate FPR a must?

[Accord2nrz]

A rising rate FPR is highly encourage but it can be done in other ways. You just have be diligent in your calculations and keep an eye on the motor to see how it's reacting as your building up to your target HP and boost levels. Start with the low level adjustments and see how the engine takes to it. If it gives you a hard time at the lower levels then I'd wait until you get stronger injectors.

:)

[Mark...]

Well doing some calculations raising the fuel rail from the stock 43.5psi to 68psi will let the 315cc's flow as 393.84cc's at a safe 80% duty = good enough for potential 200bhp and the EMB can handle it. (Much safer than the standard 265cc's at 96psi).

Therefore as its unlikely to make 200bhp, a FPR that can increase the rail by 24.5psi ideally with a gauge and fitting kit, should do.

The two unknowns at the moment are:
Finding out how high a pressure the 315cc's can run at safely?

Finding what max psi the OEM fuel pump can cope with safely?
I have read the pump tends to max at 85psi on MiataTurbo but is it the same for a 1.8L Eunos roadster?