modyfying stock fuel pressure regulator

[mops]

Hello.

I heard there is a way of modyfyinf almost any stock fuel pressure regulator to give higher fuel pressure. But I'm not sure how. I dont know anybody that did it, but i heard severl confilcting theories:

-it has to be open and spring inside has to be crushed (compressed ?)
-it has to be open and spring inside is mounted on some rod and severl washers have to be added to compress it
-might not work on all FPR's but aparently some of them allow pressure/vacum to be applied to the other side of the fdiaghgarm creating some effect on fuel pressure.


anyone here is familiar with procedure ?

basically i got stock ecu which holds fuel pressure at 3 bar abouve menifold pressure. that should be enough for my turbo project, BUT it would be cool if I could incerase it bu, say 1 extra bar (even across the range).

Thanks in advance.

[Mk1rocco]

Here are instructions for modifying a Buick grand National (Bosch) regulator, I haven't tried this myself so can't vouch for the technique.

[PSIG]

EDIT: I mis-read and you have a manifold referenced FPR already. I'll leave the rest for other's reference, but have not done the 'crush' mod myself. I did talk to another who said he used a split section of pipe to support the FPR flange and a ratchet socket on the top to crush it in a press to "get a few pounds". That's all he mentioned.

For modding to get manifold referenced fuel pressure regulator output:

A lot depends on the type of FPR, but most can be modified for manifold referenced pressure - which is what MS actually expects. It will allow your 3 bar at WOT to rise with the boost pressure increase as well as decrease with the vacuum towards idle at roughly 1:1 ratio. If you can't find an OEM model to adapt directly I have done both the following, the first is modding a particular FPR (adjustable Bosch 001) as is done by MSD and marketed as the #2222 :
http://www.dune-buggy.com/turbo/fuelsystem.htm

If you want to mod whatever FPR you have now for MAP reference, you can simply drill and tap a small hole in the upper spring section (the section on the other side of the flange from the fuel ports) to thread-in one of

these tiny nipples which are sized for 3 to 4mm (1/8 to 3/16") line. They are fuel and pressure fittings for gas-powered models. I suppose you could solder a tube in like the first example, but this is neat, quick and cheap. Although the threaded section of the nipple is short, try to position it where the internal spring won't rub or hit it, commonly on the top. I use a dab of silicone sealer as well as the gasket.

Hope that helps,
David

[Ferret]

I understand that you have a stock FPR with reference to the manifold pressure.
What I have read (not tried) is that you put the regulator in a vice and crush it slighly, so that the spring inside is more copressed. When the spring is more compressed it has higher resistance and raises the fuel pressure.

Avner.

[16vconvert]

I have crushed 2 FPR on a turbo dodge , (1) 1/16 of an inch crush netted me 5-6lbs across the board, (2) I have also cut off the end w/ the vac nipple and made a new can out of exhaust pipe and nuts and some long screws from a Q-jet ,some epoxy, a centering ring for the spring, result adjustable FPR from 0-100 now.

it's definite doable, but i want a rising rate of gain regulator like 1.25 lbs of fuel for every lb of intake pressure

Just my 2 cents

Jeremy

[mops]

I have crushed 2 FPR on a turbo dodge , (1) 1/16 of an inch crush netted me 5-6lbs across the board, (2) I have also cut off the end w/ the vac nipple and made a new can out of exhaust pipe and nuts and some long screws from a Q-jet ,some epoxy, a centering ring for the spring, result adjustable FPR from 0-100 now.

it's definite doable, but i want a rising rate of gain regulator like 1.25 lbs of fuel for every lb of intake pressure

Just my 2 cents

Jeremy

any pics of the (2) ?
I'm really keen to try it out.

so basically, you have removed the 'backcover' with the pressure nipple, replace it with a custom version that includes a vacum nipple AND and screw for adjusting fpr pressure spring, right ?

[gofastant]

This should help: http://www.snstuning.com/DIY/FPR/fpr.htm

Put a socket over the nipple that reads manifold vacuum/pressure. And crush away.