Fuel Pressure Tuning

[Dadasracecar]

So I was tuning a customer's car last week using both versions of the SB software - the speedranker writes faster but Lou's version is what I'm used to. Anyway, I got the maps confused and ended up putting the meth values in the fuel pressure map. The car acted weird and when I had discovered what I'd done I knew that we could manipulate fuel pressure. In later discussions with our machine shop owner - builds Winston Cup engines so I listen to him - he indicated that one of the reasons he felt we were having problems making 5-600 hp was fueling. He wanted us to change the injector pulse timing. We can't do that yet - Lou's new standalone will be able to - but we can alter fuel pressure.

I'll be the first to admit that I have never believed the fueling arguments that Haltech, Lex, and others have made. Our cars were pig rich at the tailpipe and made power when we leaned them out. But, have dyno, will test.... I tuned Orlando's car using fuel pressure as one of the variables and his car REALLY responded. I don't have that dyno but I'm sure he'll post it soon.

I tuned Scotty's car - stock w/ cp-e nano, BOV, and flashes - and the results speak for themselves.[attachment=44395:111409_FP_dyno.JPG]


The solid line is the FP tune. The long dashes are a zeroed out standback. The short dashes is the track tune he came in with.

There is a surprising increase in torque when the pressure is increased. Caution, you can not just run amok with the fuel pressure adding. There is a limit and the car will stop running if it thinks it's pressure is too low or it can't get there. I use -40 as a max. Additionally, the car will run pig rich so you'll need to retune MAF. Finally, be careful about your timing. When lowering the MAF, you're decreasing the load that the car sees. It will consequently run more timing. That is likely responsible for much of the gains. It will add too much and the car will knock btw 4700 and as high as 6000. Finally, some pumps will not make this. Scott's car pulled nicely on the dyno but the pump couldn't keep up on the road. His pump is stock and we were able to hit 2000 psi reliably on the dyno. As soon as he took it out it was inconsistent and he was seeing pressure dropping to 1400ish after shifting. Orlando's car pulls like a freight train and has no issues. IIRC he's got a stock pump too and is fully bolted. It seems there is some variance in stock fuel pump performance.

We don't fully understand all of the aspects of this yet but it's pretty exciting and we wanted to share. The standback has had this functionality from the very first day. I can't believe we've never messed with it. Hats off to Lou for figuring out how to do it, Josh and Anthony for pushing him to do so, and cp-e as a whole for the product development.

Finally, Haltech, you were right. Man, that hurt...

[kore2000]

Like someone said on MSF.org, a giant round of facepalms if it was in the standback all along and no one, not even CP-E themselves ever mentioned trying it.

Dada, did you get this idea from the fuel pressure thread over on MSF.org or was it just some amazing timing, planets aligning, etc.

[Dadasracecar]

It truly was amazing timing. Our machine shop guy was at the shop on Wednesday and that's when we were talking about fueling and he convinced me to try it. I knew it could work b/c of the tuning error last weekend. Scott lurks on MSF and mentioned they were talking about it when we were talking with the machine shop guy. I'm IP banned there and never go there. Spend most of my time on BMW forums. Pretty crazy coincidence. I'm just thrilled we had the time to try it on Scottt's and Orlando's cars. Orlando is going to be happy we did...

[y2kc0wb0y]

That said, I've spoke with Lex about tricking fuel pressure with the SB per the new information arriving from the 500WHP ZZP Cobalt fuel pressure thread(s). I think this a great advance/discovery for the entire community to be able to advance the tuning abilities with a fuel pressure increase. Hopefully we can achieve more psi in the future to push even further.

[KoukiS14]

QUOTE (Dadasracecar @ Nov 15 2009, 06:34 AM)

He wanted us to change the injector pulse timing. We can't do that yet - Lou's new standalone will be able to - but we can alter fuel pressure.[/b]

We can now, SB or not, thanks to Dustin (djuosnteisn): How to scale the HPFP pressure sensor. It appears to directly affect the injector pulse width, in addition to increasing the pressure.

QUOTE (Zoom Zoom Bitch @ Nov 15 2009, 07:00 AM)

Like someone said on MSF.org, a giant round of facepalms if it was in the standback all along and no one, not even CP-E themselves ever mentioned trying it.[/b]

Once again, our friend and saviour djuosnteisn.

[kore2000]

So now the next task is to find a way to increase the pressure beyond the factory sensor. SSInstaller seems to think a BMW sensor would work nearly plug and play. Any comment on that dada being both a BMW and a former MS6er?

[Quakeguy]

I tossed out the BMW sensor idea, but SSinstaller linked a pic of it and it does not appear to be a npt sensor.

That dyno is dated yesterday btw, just wanted to throw that out there.

[SSinstaller]

Doesn't one of the P3 guys drive 335i? Why don't you snap a few pics of the high pressure sensor for us.... We need to see how it attaches to the rail. The picture I have isn't very clear.

[djmarkian]

This sounds very interesting, but does this only refer to ppl with upgraded CDFP and with an SB?...

[Dadasracecar]

the sensor is not the issue. The HPFPs, stock and cp-e, have a pressure release valve that is sprung at around 2000 psi give or take. We're looking in to modifying that atm to see if we can run higher pressure. About the most you can get the actual pressure up to is 2000 psi. And, btw if you're looking at the dashhawk, don't bother if you're using the standback. It's lying to the ecu.

QUOTE (Zoom Zoom Bitch @ Nov 15 2009, 10:00 AM)

Like someone said on MSF.org, a giant round of facepalms if it was in the standback all along and no one, not even CP-E themselves ever mentioned trying it.

Dada, did you get this idea from the fuel pressure thread over on MSF.org or was it just some amazing timing, planets aligning, etc.[/b]

Yet they had the forethought to include the functionality... They never wanted to be tuners. They only want to be manufacturers. They don't even want to do retail.