Clintock77

I have a 98 4runner supercharged with high pressure fuel pump. Had someone tell me that high pressure fuel pump means nothing if the fuel pressure regulator is not upgraded. Is this true and do I need to get a variable fuel pressure regulator? Also, any recommendations on a brand/model to go with?

wyoming9

iTrader: (1)

My question is how does the engine run??

Do your big injectors starve for fuel at higher rpm.

just what pressure do these injectors need??

How about some real world fuel pressure numbers ??

Texas_Ace

You need to read up on how the fuel system works and how to mod for the supercharger.

What you need is some form of fuel mod, aka, something that will give the engine more fuel under boost to keep it from running lean and possibly melting something.

An upgraded fuel pump flows more fuel, pressure is determined by the FPR. Your stock fuel pump could have run quite a bit more pressure on the stock injectors. Your friend is right that the new one is not doing anything BUT he is wrong in how to make it do something.

simply upping the fuel pressure is a very bad way to add more fuel. It is not only very precipice but it also is very limited in how much more fuel it can add along with changing your whole fuel map, thus larger injectors would be a better choice.

Just tossing in larger injectors is not really a viable option for toyotas though since the ECU can not be tuned and larger injectors will just screw up the tune it came with. Generally more headaches then it is worth if using injectors large enough to matter.

So that leaves you with the only real viable options for your situation.

Best bang for the buck on pump gas is a AEM FIC piggyback with either larger injectors or an extra set of injectors.

Best option for a TRD supercharger is a larger shot of meth injection with a quality kit that includes a failsafe. BUT you need to be able to buy 100% methanol by the barrel for this to work. So not an option for some/

Next option is a prebuilt 7th injector system from URD, it works but is a nightmare to tune.

The last option is pricy, takes a lot of know how and is way overkill for the TRD supercharger. You can go full standalone. This is only for high powered turbo applications IMO though. Sub ~400hp, a piggyback and meth should work fine. With a TRD supercharger you will be lucky to have 250whp on a smaller pulley.

Clintock77

I've read a lot about what is needed to change when doing the supercharger and I know a fuel upgrade is necessary. I am going to get the 7th injector from URD which I'm hoping is a good route. I haven't found anything in regards to the FPR so wanted to see if anyone else any experience with it. I also have read about the methane injection, just wasn't sure how necessary it is. I didn't install the supercharger, was done by previous owner. I'm now fixing what all he didn't do right. Thanks for the info.

Texas_Ace

Don't worru about the FPR, the 7th is all you need.

Also it is methanol injection, not methane. While it is great, it does require you to be able to buy pure methanol for optimal performance and thus is not for everyone.

If you have the 7th injector then there is no need for a good meth kit, a small cheap kit for a little cooling is more then enough.

Clintock77

Thanks Texas_Ace, I really appreciate the advice. And I meant methanol not methane lol, stupid auto-correct. It's been a lot of work fixing the previous owners screw ups on this truck, but I think I'm almost done fixing it.

One other thing I'm curious about is if I do the 7th injector is there a need to get bigger injectors for the other 6? I would think not from what I've read on URD.

Texas_Ace

No, just use the 7th by itself. It's a big enough pain to tune as it is. Oh yeah, and you need a wideband as well.