Correct injector for E85

[metro094]

Hi. I have a 94 metro xfi and would like to convert to E85. I need to find some compatible throttle body injectors I can use to get the right mixture. Later, I plan to increase compression with new pistons, but for now will work with stock engine.

Can somebody help with this?

[tjts1]

If you are going to run E85 exclusively, you want injectors about 30% larger than stock. If you plan to use either E85 or straight gasoline some tuning will be required.

[dremd]

Also check that your fuel lines are compatible with E-85.

In theory your pump must be E-85 rated as well, but I "THINK" most pumps work just fine with E-85.

[dcb]

I can envision a $10 circuit (per individually fired injector) that would lengthen an injector pulse by 30% at the flip of a switch. If I were more of an ethanol fan I'd run off and try it.

[metro094]

As far as extending the pulse width goes, I think there are reasons to not have the duration of the pulse too long. Likely it would be fine, but I thought it would just be easier to have an injector with sufficient capacity.

I have heard estimates anywhere from 15% to 50% increase, but are all throttle body injectors alike and interchangeable? I need to know how to find one that will fit. Can I pull one off an old cavalier or corsica? I don't think I can go to the junk yard or the parts store and say I want an injector with 30% higher flow rate.

I'm aware of the lines issue, and will check that no rubber is in the line. Does anyone know if I will have enough fuel pressure and volume, or will I need a supplemental pump and new regulator?

[dremd]

I have never worked on TBI, but I can tell you that 95% of port injectors fall in to 2 categories Top Feed or side feed.

[metro094]

So do they mount and connect the same? Even different brands? Would something off a 1.8 or 2.0 liter engine be suitable? Any recommendations? I thought Bosch, ND, Delco, etc. would all have unique mounting and connection harnesses. If they are the same, that would make life easier.

[tjts1]

All fuel injected vehicles after 1990 have fuel lines compatible with E10 and therefore E85. The quick and dirty way to check is pull a bit of fuel like off a similar car at the JY and store it in a jar full of E85 for a month or so.

[Rower4VT]

Instead of messing with the injectors or pulse-width, just increase the fuel pressure. My stock pressure was 36 and at 65psi I can run E85 with no issues. Do not go above 65psi however as that is the generally accepted upper limit for injectors.

In terms of tanks and fuel pumps, you shouldn't have to do anything. I converted a '94 Acura Vigor with 200K miles on it. Been running E85 for a year with no problems.

[dremd]

Originally Posted by Rower4VT

Instead of messing with the injectors or pulse-width, just increase the fuel pressure. My stock pressure was 36 and at 65psi I can run E85 with no issues. Do not go above 65psi however as that is the generally accepted upper limit for injectors.

In terms of tanks and fuel pumps, you shouldn't have to do anything. I converted a '94 Acura Vigor with 200K miles on it. Been running E85 for a year with no problems.

2 things
1) TBI runs at very low pressure (like 10psi.
2) Injectors do hit a wall on running higher pressures, some more than others.

[Rower4VT]

Originally Posted by dremd

2 things
1) TBI runs at very low pressure (like 10psi.
2) Injectors do hit a wall on running higher pressures, some more than others.

Okay, good to know. The theory would still hold true. If your stock pressure was 10psi and you wanted to increase your fuel flow 30% (for E85) then you would need your fuel pressure to be 17psi, which the TBI injector should not have a problem with. For flowrate vs. pressure calculations, to increase the flow rate by 30% you need to increase pressure by 70%. So, bottom-line, take your stock fuel pressure, and multiply it by 1.7 to get the fuel pressure needed to run E85. You can definitely get away with less, as the O2 sensor and ECU will pick up the slack, however for cold starting (open loop running) it's better to go with the 30% flow increase. I was running ~17% flowrate increase for a few months with no real problems, however when I bumped it up to ~30% increase cold starts were much smoother.

[Lazarus]

Here's a thread that long and tedious but there is some good info in there.

[tjts1]

Its a lot easier to change a TBI injector instead of FPR or varibla FPR.