Ferocity02

iTrader: (60)

I am going to be installing a ATI D1SC soon and will be ordering the fuel system soon. I will be getting a Racetronix pump and Mototron 60# injectors. I plan to only run about 6 lbs of boost for starters. So as the title says, is a boost referenced fuel pressure regulator, or any FPR needed, or can the stock one be used? Thanks.

slow

iTrader: (7)

to tune a car right you need to know what the injectors flow.

Since the stock map sensor is used to determine the pressure delta of the injectors, 58 psi static rail, + the value of the manifold pressure, to get the pressure drop, this is why the injector flow rate table has manifold pressure in it.

The stock map sensor does not go into boost, so once you boost, your 58 psi rail pressure stays the same, but the manifold becomes boosted, so that 58 psi pressure drop, becomes 57, 56, 55, 54, 53, 52 drop. This will lower the output of the injectors some. 95% of people just alter the calibration of the comptuer tuning to acount for this and are just fine. But to be 100% correct, I would want a boost/vac referenced regulator setup. However, my point of view is do it like the factory would have done it.

Ryan

MelloYellow

I prefer static when you can.
Higher pressure reduces pump flow specs.

02BlueFirehawk

I bought a boost ref. reg... not using reference... doing it in the pcm.

stevieturbo

Depends on boost pressure you intend using. At only 6psi boost, its hardly worth worrying about.

At higher fuel pressures, yes the pump may flow less, but then at the same time with static pressure, and boost in the inlet manifold, the injectors will flow less, as the pressure diff across the injector is less, possibly requiring larger injectors ( 60lb would be more than ample ).

slow

iTrader: (7)

right.

60's will support a huge amount of power, more than you will see with 6# of boost, so i would not be worried about it.

Ryan

MelloYellow

Depends if you are more worried about max'ing your injectors vs. max'ing your pump and what each can handle.

Shinobi'sZ

We yanked the Boost Reference off of my car this weekend because it was making the tune look like a roller coaster (AFR). If I had the bosch 310lph pump it would probably go 1:1..but it would go to 70 then drop to 64...with it off it was 62psi on every run with various boost levels from 9# - 17#.

I am using
60lb Motos
LPE 255lph (walbro)
KB BAP
Return System

For the 17# dyno runs, I stood outside the car with a FP guage and only watched the FP...my eyes never left the guage and the FP never left 62psi...it made tuning very easy.

I know that boost reference is supposed to be good, but with 60 motos at 62psi FP will support almost 1000hp...so I don't have a need to have a boost reference system. But I have seen them work well..you just need to make sure you have enough pump to support it. A 255lph pump will flow better at 62psi then it will if its forced to try and flow at 70psi..it just runs out of its pumping capability..thats why you need a FP that can pump more fuel.

For Fbody's, two pumps can be used and you can get a 1:1 boost reference to tune with. Y Body's can too but it takes a lot more fuel system mods, it was not necessary on my car and shouldn't be on most other Y body's too.

stevieturbo

If you have a non-boost ref setup, running 62psi static, and using 17psi boost, that effectivley gives you only 45psi of fuel pressure across the injector, reducing its flow abilities. The FPR may stay at 62psi, but thats not how much actual pressure you have to inject the fuel.

Virtually every turbocharged factory car uses a boost ref reg, so its not a big deal. Ive mapped a few Subarus and my own car all with boost reference regs, and again, its no big deal ( all aftermarket ecu's, speed density ).

Having said that ive never worked with the LS1's factory ecu, so cant say what it would be like.

Ferocity02

iTrader: (60)

So is a FPR only needed if you are close to maxing out your fuel system? I am not at all worried about that. I think the components I am putting in will not be maxed out before the bottom end gives out

CorvetteAndy

iTrader: (4)

I tuned Shinobis Z as well as a 408 F1R Corvette this weekend. I took off the boost reference on both cars and the AFR was much easier to straighten out.
I prefer not to use it.

nick y

iTrader: (1)

andy thanks by the way for today
when you say you remove your referring to the referenced part of the regulator? you still use it its just that you arent ref. to boost pressures?

MelloYellow

Agree also re: easier to tune with static setup.

Racetronix

iTrader: (2)

This is due to the way the factory LS1 parameters are set up.

Given the correct calibration, manifold referenced fuel pressure can extend the operating range of the injectors and in some cases the fuel pump's capacity to maintain volume. It can make tuning a large injector at idle much easier. This is because the pressure differential across the injector remains constant which means the injector constant itself is static.

Everybody has their own unique way of tuning a motor so no one way is right or wrong.

Since Delphi disc injectors and Mototron 60's are fairly fast injectors it lets one adjust for a very narrow and stable PW at idle in order to target the desired A/F ratio.

Whether you chose to have your FP manifold referenced is up to you but relocating the FPR to the rail for high HP motors is always a good idea.

Shinobi'sZ

Stevie,
I am/was inclined to agree with you and do about the Boost Reference. But if it were completely true I don't think my car would have been able to have been tuned the way it was. At 16lbs of boost with 60lbs injectors @62psi I can easily support the 820 (approx) bhp that my car made. I will go back an recalculate but I don't think the 60 mototrons could support that much hp at 45psi fp.Now if my fuel pump had the capability to go 1:1 all the way up then boost reference would work fine..because for every 1 boost pressure you would get 1 fuel pressure...then tuning would be as easy as when the fp just stays at a set psi...however it would support more hp and the injector duty cycle would be lower.


Even at 17lbs the fp was stable at 62psi...it just started to misfire because of the spark plugs. The AFR was 11.7 and it had 0 KR...so I think we had plenty of fuel.

slow

iTrader: (7)

I don't see how tuning a car with injectors that get smaller under boost being a "right" way to do it, your lying to the computer somehow, either telling it the injectors are smaller than they are, or your telling the computer that it is seeing more air. Or the even worse way of tuning, commanding a stupid rich air fuel ratio, ie 9:1 when you want a 11.5.

if the ls1 was designed for a factory fi setup, I am sure the fuel system would have been different.

Ryan

ls1290

iTrader: (20)

Isn't the BAP working basically the same as a boost referanced regulator?

Keith

stevieturbo

Most FPR's do rise 1:1 boost reference.

If you have 62psi base, with 17psi boost inlet, then you can only have 45psi to inject the fuel. There should be no confusion about that.

If you had 62psi boost pressure ( wow ) then there would be no pressure difference across the injector, and no fuel would be injected, regardless of duty cycle or pump used.

Racetronix

iTrader: (2)

No, this only increases the pump's output volume so that you can maintain pressure under WOT. In many cases on the C5 it is used to overwhelm the factory regulator and return line so that a pressure rise occurs at the back of the car which helps offset the pressure drop at the rail. The pressure drop across the feedline still exists.

'97-98 C5 owners with FM FPR's are lucky in this respect.

John_D.

iTrader: (2)

When I wire up my BAP to run at all times, and then slowly turn up the dial at idle, I can see the fuel pressure gauge rise... It's slight though, only a couple of psi. That was when I was using it to overdrive the v6 pump when I was running a 150 dry shot. I could also see my trims change slightly while logging the car around town, depending on where I had the BAP dial set. That was with the stock v6 fpr and return line setup.

I kept it after the v8 swap, while I still had the v6 pump in the car. This past weekend I finally took out the v6 pump and put in a walbro, since the turbo install is finished. I'm still keeping the BAP for insurance.

I am running a 97 vette rail and fpr with my new setup, since I already had the v6 return lines to work with.