alright, so lately i've been trying to learn ALL that i can about the lnf, as i'm getting one in a few months.

HOKAY so, about this 400 whp.....i've been wondering about that.
then i saw this post in a trifecta vs gms1
- "I dont see how you can compare custom tunes from trif and htp to the GM stage 1. They are soooo different, your talking a custom tune to get the absolute most out of the car to a tune from the manf. that keeps things very safe. Now trif vs hpt is comparable, they are after a very similar market.

Even as Bill said, once they get the fueling tables unlocked...400whp and up should be pretty easy. "


I was just wondering what you thought of that statement. Is it true that once those are unlocked there is no need to wait for a di upgrade?


So I emailed vince about it as I normally do when I have any questions involving tuning.

This is his response.







"Which part? LOL

If you are referring to the comment about the fueling, here’s what I will say about that:

1) People have told me if you try to go past about 400WHP you have fueling problems because the injector pulse is too long

2) A guy on LNFPerformance forum that claims to be a GM engineer alluded to the fuel issues being related to fuel rail pressure and that the stock injectors are good to 700HP

3) The fuel rail pressure is ECM controlled on the TC and can be modified in the ECM calibration

The fuel rail runs at a maximum of around 2200psi on these cars without “fueling tables unlocked”. I don’t know what the maximum rating on the fuel rail equipment is, but in theory more pressure would give more fuel per degree of time in the pulsewidth, which would allow more horsepower without fueling problems. I have been approached several times about making fuel rail pressure changes but not by anybody serious about actually needing it yet (e.g. I am NOT giving fuel rail pressure tweaks to someone who believes the reason he’s not making power at 6600RPM on the stock turbo is because of fueling).

I am also hesitant to put anything out there that modifies the fuel rail pressure until I’ve tested it well. Imagine what would happen if you had a fuel leak under the hood with the fuel at 2500psi." - vince from trifecta




discuss

 

what if they made a custom larger diameter fuel rail? would that allow more volume of fuel at a the same pressure? hmm.. idk if it'd matter.

 

vince is really looking to do this .. but as said he needs someone with a turbo swap to come forward

and as of right now not many people have done it .. partially because you can hit 350 whp on stock turbo and only 400 on a swap lol

this is not a bad idea though bump fuel pressure to like 2500 then use a larger rail so it drops back down

 

where would we get that fuel rail lol?
hmm, well once i get my tc, i'm really interested in getting that synapse turbo kit, but with a gt30 instead.
i guess i'll see

 

I don't know about the fuel rail but on the mazdaspeed 2.3l engine they fixed (or at least helped this problem greatly) by replacing the stock fuel pump with an aftermarket high pressure pump. The only thing we need is for a vendor to come out with one. They aint cheap though on mazdas they sell for like $650 + a $300 core charge. And its a mechanical cam driven pump so it aint easy to replace. But I wouldn't count on them making it because it does essentially the same thing as unlocking the fuel table (raises pressure) so if they invest all this time and moneyinto making a fuel pump and then hpt finally gets the tables unlocked then who will buy the pump when tuning via hpt is so much cheaper. Its just a big risk.

But unfortunetly whether we raise the psi via electronically (hpt) or mechanically (fuel pump) it raises the question of how high can you raise it. Nobody really knows if that rail can hold 2300 or 4300 psi. And if its somewhere around the former we may run into some issues with those guys looking for really high hp. Some of the vendors may want to look into an aftermarket intake manifold with its own auxillery port fuel system that sprays a predetermined amount of fuel for each psi increase based off a second map sensor or the OEM GM sensor.

 

Having a larger fuel rail will decrease the pressure lost, friction pressure, to push the fuel throught the rail. This will help a little. The real way to get more fuel through the stock injectors is by increasing the fuel rail pressure. When the injector fuel rate is in critical flow through the injector, there are two ways to increase the smount of fuel going through the injector, one is the increase the fuel rail pressure, or two, increase the size of the openings in the injector.

 

How much is an LNF fuel rail?
Couldn't someone just buy one and using an adaptor (maybe custom) and pressure gauge, Pressurize the fuel rail with Nitrogen and see if it will hold like 2500-3000 psi?
This would give an idea of safety when increasing the pressure before you actually risk hurting a car or a person?

Raising the pressure via HPT (ECM tune) when it's finally unlocked sounds like the answer to most people's fueling issues. Trifetca is at it again!

Also, for really extreme fuel needs, couldn't a solid block of aluminum be CNC'ed into a larger diameter fuel rail? Use a lot of material in the side walls and keep everything very precise and I don't see why it wouldn't work and be safe with 2500 psi or more.

 

hmm how well will spraying fuel into the air going into di work?
i had heard some vendor talking about that actually, and that it wasn't right.
someone correct me if i'm wrong but i don't know if it can actually function as well as it sounds.

i would think that increasing the fuel rail is best, cause if you increase the pressure like vince mentioned who knows how much it can handle without bursting

i wonder what italianjoe would think of this.
he was gonna do some machine for me before.
interesting...
either way maybe we should start pitching this to some vendors for those power hungry lnf guys. it would also be badass to include this say....a synapse kit or maybe a future kit from zzp.
that way the swapped turbo could be taken advantage of

 

Thats probably how a vendor would test it. The only thing we would have to see probably with the aftermarket rail would be fitment issues but thats a good idea.

 

sub'd

 

It's not optimal getting the fuel via the DI would be best. But there will eventually be a limit to the volume and pressure you can put thru one rail stock or otherwise. And once we start getting into race applications there is the matter of dealing with the injectors themselves. I'm talking about really high hp built motors with gt35r or bigger turbos on race gas of course. Raising the psi or getting an aftermarket rail would be great for alot of guys with stock motors and less high hp goals.

 

Not trying to step on your toes but this really isn't a good/safe way of testing the fuel rail. (I am a Mechanical Engineer before people start flaming me). They have a Safety Factor on any pressurized piece such as this, I can't say for sure but it could be as little as 1.1 all the way up to 2.0 (2420-4400psi). The reason that safety factor is there is because the the absolute maximum pressure the fuel rail can withstand is tested under optimum circumstances the fuel rail in our cars is not always under optimum circumstances ie. temperature, pressure, bumps/shocks/vibrations..... So if someone where to build an adapter and pressurize this fuel rail until it reaches burst pressure (which can be dangerous) they would most certainly get a number higher than 2200psi but then running over 2200psi and not necessarily as high of a pressure as the test determined in a real-world situation could have some serious consequences.

 

I have some information I can share on this topic.

1. I'm not sure where people are getting the idea to increase the size of the fuel rail. At over 2000psi, the factory rail is capable of supporting well over 1000 HP.

2. Swapping the pump won't increase the fuel pressure since it is electronically controlled.

3. Raising the fuel pressure by means outside of the PCM will quickly set a DTC.

At ZZP, we have been testing fuel pressure changes for a few months. I'm running ~2700psi on my 08 and have not run into any issues. On the stock turbo, power increases of about 10whp were seen at 6500 RPM. Peak HP did not increase as much, but power definitely carried out further. This was pretty much what we expected based on the injection pulse widths.

Here's where it gets interesting... We are currently working on our Borg Warner 256 extended tip turbo upgrade which should be available in a couple months. The kit is nearly complete and we should have it on the dyno very soon. We will finally have the opportunity to go well past 400whp on the DI setup. I'm expecting 450whp to come pretty easy, with an eventual goal of 500whp for this kit. I will keep you guys informed as we make progress.

 

 

getting more hp should be just raising the FP .. like vince will try to do a boost referenced fuel pressure or something along the lines of infiniboost..

I think the reason the new rail was brought up is because so far not many people have tested the system over the stock 2200 so we don't know how it would react to another 500 psi... so increasing preasure and increasing rail size would get more fuel to the injector while maintaining the a lower pressure

raising rail pressure to 2700-3000 should make alot of head room for bigger turbos

 

That doesn't make sense. The pressure is either higher or it isn't. Pressure is equal throughout the rail and would not change if the rail size was increased.

 

ok 2200 PSI with a larger rail would push more fuel is the essence of what i was saying because making the rail larger would need more pressure relative to a smaller rail .. you of all people should know this.. thats like ok the m62 puts 12 psi on the ss/sc but like 7 on a 2.4... larger ci = less psi at same flow.. THUS.. keeping a consistent commanded 2200 psi will result in more flow basic fluid dynamics..

i know i might've worded it confusing .. but i'm also slightly intoxicated LULZ

 

Observer name for larger turbo info.
I"m tuned by vince, even made some data logs for him last night.

I'd love the attention needed to get this done so i can make more power. I've actually been attempting to get more power out of my setup for awhile with Vince.

Precesion Turbo 5457ball bearing
3 inch catless down pipe
Hahn intercooler
3 inch cat back
Synchronic bov
Soon to be hahn cai intake.

My last dyno run, trifecta tuned, had me at 26 psi and only putting down 325whp. Given, there were some issues preventing a higher number, but i feel it should have still been better.

I've been working with vince for over 5 months, with a turbo swapped cobalt. He's never once mentioned unlocking anything for more fuel, which would greatly benefit my car.

 

Increasing rail size doesn't increase injector size. 2000 psi in a thimble or a drum makes no difference when the outlet is the same. It's not like we have gravity acting on the injectors or anything. As long as the stock rail can handle the increase in pressure (which ZZP has pointed out that it can), then a pressure increase is all that's needed.

 

325whp out of that turbo @ 26PSI? Something is definitely wrong - I would have guessed at least 375-400whp. Would you mind elaborating on the issues that were preventing the higher number? I can't believe it was totally fuel related. Was the throttle plate closing on you?

 

this is what i like about you guys.
you are not afraid to test stuff out on your cars, and ensure that its gonna work.
im glad you guys do what you do.
can't wait to see what you guys come up with

 

Believe there was a tad of spark blowout, and the air/fuel mix was really, REALLY bad due to the car not being warmed up.
The dyno was reading low. I mean, VERY low, for everyone.

However, i still feel that there should have been more from the car than that.

Throttle plate shouldn't have been closing. I'm using a mbc, but the tune is set to open the factory boost controller at 28psi so i can have room to play.

 

As Tom said above, if the fuel pressure is consistent, the rail size does not affect injector flow whatsoever. Your example of running an M62 on two different size motors does not have any similarity to the flow characteristics of a regulated fuel system.

 

The issue on the ms3... it was not fixed or helped much actually at all. The only thing the new internals on the cdfp helped was keeping the pressure at WOT to full psi. I dont have time at this minute to explain the issue as its exactly the same as the ms3 but I will after my work. It has to do with the amount of time you have to inject the fuel/air mix and cam timing. There isnt enough time during a cyle to inject enough in to get more power. Look at vw's they found a way to tune to get more time and they are (on DI engines) able to get 600+whp.

To the OP why didnt you quote the person saying those quotes on post 1? They look familiar to me

 

We fired up my '08 SS today with the new turbo setup, and I had time for a few dyno pulls. I will post the news in another thread. You guys are going to like the results.