4g61t.org

Im in the process of swapping a rebuilt 91-94 non turbo throttle body onto my original 61t colt. (Steve at dsmthrottlebodies is awesome and so fast). In this process im finding out i have to use the shorter non turbo mani bolts and studs but also that the 91-94 style tps on my rebuilt throttle body wont clear the 61t or 90 style fuel rail. Now i have the non turbo 91-94 style fuel rail to solve the clearance issue since all these parts have come from my 91-94 complete non turbo parts motor..

my question is that ive read the non turbo fpr has a higher pressure something like 48 psi vs the turbo at 37psi?
Also that some people consider this an upgrade. I would have the perfect oportunity to use the higher rate non turbo fpr since its connected to the fuel rail i have to use to clear my new tps. Anyone try this? Have experience?
Or thoughts on why this might be good or bad etc? Should i just stick with the turbo fpr? Etc.

My car is pretty much stock high mileage 61t with 14b, 450cc, and megasquirt fuel injection running speed density
i really appreciate the insight from guys who have been doing this awhile. Thanks

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Black 1989 Colt GT with 4g61t. 200k miles and climbing. Rebuilt 2.0 in the works.....
14b, 450cc's, 3" exhaust, small fmic, all running on megasquirt version: DIYPNP
White 1992 colt-vista wagon 2.4, awd, auto (daily)
Keane

Just go with a remote AFPR and whichever rail fits, that's what most of us do.

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Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

You have to make sure the stock non turbo FPR is a rising rate model like the turbo ones are.

As you hit boost pressure, you need the FPR to raise pressure 1 PSI per pound of boost.

If the FPR does not accomplish this, you go crazy lean.

The End.

* Okay, so maybe not the end but you see where this is going.

A good aftermarket unit (as Mechacode suggested) is rebuildable and guarantees consistent fuel pressure at high fuel volumes.

Stock FPR on the turbo mitsu's were easily over run, because they weren't designed with the needs of the flow of an aftermarket high flow fuel pump in mind; they didn't need to be for the HP

window they were built with.

Can someone confirm the stock Mitsubishi Non Turbo FPR can be used and is a rising rate unit or not ??

Rising rate.... ok so i learned something. I did know that the fuel pressure increased with boost. I have no idea if the non turbo fpr would also do that. Since no one really seems to have experience with doing this swap or can say its a great idea i will just stick with thefactory turbo fpr for know.

Is there advantages to hoigher fuel pressures? If so What is the ideal fuel pressure? Is it dependent on horespower levels?

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Black 1989 Colt GT with 4g61t. 200k miles and climbing. Rebuilt 2.0 in the works.....
14b, 450cc's, 3" exhaust, small fmic, all running on megasquirt version: DIYPNP
White 1992 colt-vista wagon 2.4, awd, auto (daily)
Keane

I'm curious to know if there is a vacuum nipple on the non turbo FPR's, as this is the source to allow pressure to apply to the mechanism/diaphragm in the FPR.

Just like AFPR's (aftermarket fuel pressure regulators), with a vacuum nipple, your FPR will have to have this to operate properly.

Higher fuel pressure will allow the injector flow more up to a point.

More fuel pressure allows for less chance of boiling in the fuel rail and anywhere it may experience heat soak in parts of the system.

The fuel pressure solenoid is there on our engines because of the tendency for the fuel to boil and cause a hard start/no start when hot enough.

Delete it and a no start or finicky long crank starts in hot weather can be a real dose of reality.

I can't tell you much more than that, but lots of tuning gurus here can enlighten you on the merits of slightly higher fuel pressures above the 37.5 PSI range.

Higher fuel pressure is how PTE gets their extra 30cc's on their injectors (ie, 580/680/780s). You have to go from the the base 38 to 42psi.

_________________
Had a:
1991 Eagle Summit ES Hatchback - 4g15 12v 5spd
1991 Dodge Colt -4g15 12v 4spd
Have a:
1978 Oldsmobile Cutlass - 468BBO TH350
Round 3:
1990 Dodge Colt-4G63T 5spd

This was a common upgrade 20yrs ago. I've run several turbo DSMs with non turbo fpr. It still works well for that little extra fuel capacity if you need it. However, higher base fuel pressure means higher total fuel pressure under boost. The higher the fuel pressure the more work and lower output from the fuel pump. And to really be able to tune it properly you'll need to be able to compensate for the extra fuel.

All in all, my advice is if you have a fuel pump, aren't running more than 15psi boost and need just a little more fuel capacity than you have now, go for it. If not, an adjustable fpr is the best way to go.

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'89 Colt GT w/bigger than stock turbo
'91 Talon AWD w/bigger than stock turbo
'05 Dodge diesel w/bigger than stock turbo