I did this on my Subaru but I dont know if any one does this with Evo's.

Basically, you take a 1/4" ratchet extension and a small hammer and tap the top of the FPR, you are pushing in the little dimple on the top a little bit further. This has the effect of raising your static fuel pressure a little bit (~5 to 10 psi).

This is helpfull if you only need a little more fuel and dont want to buy an adjustable FPR or injectors.

Has any one done this on an Evo or a DSM?

 

Raising your Fuel Pressure 10psi is a little more than a "bit"...

 

thanks for that very helpfull post.

 

This is a poor idea.

First of all, it's barely a band-aid grade fix for anything, as raising the FP is the least desirable way to obtain more fuel. Furthermore, it takes a lot less money to replace the injectors than it does to get to the point whereby the factory injectors reach their limit.

And finally, this mod risks damaging the diaphragm of the FP regulator. If the regulator is damaged, one runs the chance of sucking a stream of high pressure fuel straight into the intake manifold - an undesirable situation to say the least.

 

This is a fairly popular mod in the Subaru community, and I have never heard of any one having a problem. I understand and agree with your concerns. Which is exactly why I posted here to see if anyone has had a successful experience doing this on an Evo.

The fact that this mod is free is nice but not my main motivation. I would prefer to raise my fuel pressure a little bit as apposed to getting new injectors. I don’t want to have to worry about tuning injector latency.

Would getting an aftermarket adjustable FPR ease your concerns Ted?

Thanks for the reply.

 

you'd need to retune your fuel curve at idle and low injector duty operation, similar to what dropping in a Walbro does. Walbro plus crushed fuel regulator is going to add a lot of variability to the "tune", and possibly insane idle fuel pressures.

 

How do you know how much you will raise the fuel pressure? Why would you even try this?

 

Again, the cost of new injectors (<$300) is maybe only 15% of the cost of what it takes to get to the point whereby the injectors become an issue, so why resort to a band-aid fix?

And also again, it makes little sense to spend for an adjustable FPR when that's a good way toward the price of new injectors, and new injectors are the far superior option. Likewise, if one has the ability to tune to the point whereby the factory injectors are maxed, he has the ability to (easily) retune for larger injectors.

And finally, increasing the FP to 50psi only gives a 7% increase in flow and reduces fuel pump efficiency, while an upgrade to the next larger size (650cc) represents an increase of 18%.

There are all sorts of ways to jerry-rig things, but fortunately, such options are not popular here.

 

Thanks for the info.

 

Denting the top of the fpr increases the load on the spring that applies pressure to the flow valve in the fpr. If the dent is too large the spring could coil bind and limit the total possible fuel flow which would cause the fuel pressure to rise quite a bit. Without doing some flow and pressure testing, its impossible to say if the mod would be worthwhile.

 

That is a great Diagram thanks. I think that this mod would probably work and not have any ill effects as long as I did not dent the FPR too much. With that being said I think I may just upgrade to bigger injectors anyway.