Timing and/or Fuel adjustments per gear

[Black LS1 T/A]

The other thread about being leaner in lower gears is odd, to me, as my AFR is RICHER in lower gears, and leans out in the higher gears per RPM. This seems to be a natural occurrence of more fuel needed at that speed + the RPMs.

So, on a related question (I don't want to hi-jack his thread), if anyone can tell me how I could increase fuel specifically for each gear, I'd appreciate it.

Also, come to think of it, is there a way to change timing depending on the gear? I can handle more timing in the lower gears than the upper gears.

Also, I'd like LESS timing in 1st gear for a given RPM (to gain more street traction), yet full timing in 2nd (best pull), and a bit less timing in 3rd (more susceptible to KR). Though, I think what I REALLY need in 3rd gear is more fuel. :mrgreen:

Is any of this possible?

Thanks!

[J 98ta]

It is REALLY sounding like it's IAT related now. IE: With a blower, your IAT's are climbing, and mine are dropping. We have opposite porblems. Hmmm. I know the MAF will use IAT, but I am in SD.(maybe you are too) :?

I wonder if it has anything to do with the B4901 Charge temp blending ? I never knew what this table does.

Sorry, I do not know how you could vary timing based on gear. Probably needs custom OS ? :)

'J

[caver]

The other thread about being leaner in lower gears is odd, to me, as my AFR is RICHER in lower gears, and leans out in the higher gears per RPM. This seems to be a natural occurrence of more fuel needed at that speed + the RPMs.


Maybe you have a fuel delivery problem? measure your fuel pressure, in a turbo application the turbo doe'snt spool up as well in the lower gears and so the pump has a easier time supplying fuel.

Dont know if you have a turbo but it's a thought.

[Black LS1 T/A]

The other thread about being leaner in lower gears is odd, to me, as my AFR is RICHER in lower gears, and leans out in the higher gears per RPM. This seems to be a natural occurrence of more fuel needed at that speed + the RPMs.


Maybe you have a fuel delivery problem? measure your fuel pressure, in a turbo application the turbo doe'snt spool up as well in the lower gears and so the pump has a easier time supplying fuel.

Dont know if you have a turbo but it's a thought.

Thanks! :)

Check my sig... ;)

[caver]

Check my sig...


Promise to read all the way to the bottom in future :lol:

Centrifugal blower?

Seen similar things with Vortech blowers if the fuel pump is marginal.

[Black LS1 T/A]

At 6500 RPMs my IDC is about 80% to 85%. Even though I have two pumps and a boost referenced regulator, I still have some restrictive sections in my fuel route and I only have the Siemans 55# injectors.

That 422 at 12 PSI is thirsty! :twisted:

[kp]

I have 57lb siemans and I am at 95% DC at a solid 58psi so you have some room to go ;) My car actually gets richer at high rpm in high gear, I have to pull timing up top to stop detonation fom the increased IAT, not from being lean. It happens to work out well though..

Is your a/f diving on a wideband or stock O2s?

[Black LS1 T/A]

...
Is your a/f diving on a wideband or stock O2s?

On the dyno.

At about 6300 RPMs, I can't keep it from rising unless I increase my base regulator pressure. With a 1:1 increase (lb fuel per lb boost), I was trying to keep it from rising too high at 12 to 13 PSI boost.

I hold it at 11.4:1 or so until about 6000 RPMs, and it begins to rise. By 6300 it is above 12.1:1

Also, the 422's torque curve hits hard and immediate, then only goes down-hill. Admittedly, downhill from 700+ RWTQ is a lot, but it doesn't seem to be particularly helpful without slicks. :(

This isn't my best 549hp/757tq dyno run, but the graph is easier to see, and I can't find the other one to re-scan it better. My belt was slipping and I was only making 9 to 10 PSI peak, here:

http://www.blackls1ta.com/images/532_RWHP-679_RWTQ_Web.jpg

Heck, I'll put this other one up. I was about 11 PSI on this one. But, it's hard to read:

http://www.blackls1ta.com/images/549rwhp-757rwtq_RPM.jpg

[Black LS1 T/A]

A better cam choice might turn this aspect of my situation around for me...

[kp]

throw some fuel at it via the PE, your pump wont keep up above 60psi most likely. Since your dynos are with the converter unlocked your RPM is way off so its hard to tell exactly where you need to change it. If you have your dyno files or you can get them send them to me and I'll put them in the new dynojet software that will show the proper RPM and torque, dynojet finally fixed their software about a year ago.

I have the same injectors you do and at 12:1 a/f they are at 97% @ 61psi at 600rwhp through my drivetrain - thats all they are good for unless you can run the fuel pressure higher but thats hard on that pump and I wouldnt trust it.

Belt slip? Havent heard that for a while, the SDCE thing fixed that absolutely 100% Its the only reason I have a LS1 F-body procharger still :)

[Black LS1 T/A]

throw some fuel at it via the PE, your pump wont keep up above 60psi most likely. Since your dynos are with the converter unlocked your RPM is way off so its hard to tell exactly where you need to change it. If you have your dyno files or you can get them send them to me and I'll put them in the new dynojet software that will show the proper RPM and torque, dynojet finally fixed their software about a year ago.

I have the same injectors you do and at 12:1 a/f they are at 97% @ 61psi at 600rwhp through my drivetrain - thats all they are good for unless you can run the fuel pressure higher but thats hard on that pump and I wouldnt trust it.

Belt slip? Havent heard that for a while, the SDCE thing fixed that absolutely 100% Its the only reason I have a LS1 F-body procharger still :)

I broke my tranny when I solved the belt slip. Remember... I have TWO pumps. One runs all the time, the other kicks on at a couple lbs of boost.

I'll get the dyno's to ya. Thanks!

[kp]

If you can sustain that fuel pressure instead of raising the PE thats fine, but when you raise your base pressure everything changes. Dont be afraid to run those injectors up higher then 90% via the PE if need be though. These are still doing fine at 97% but thats about it, when it cools off I have to raise the fuel pressure - I just need bigger injectors..

[caver]

The curve is that way cause of the torque converter multiplying the torque at low rpm.

I use the bidirectional controls to lock the tranny in 3rd gear and lock the tcc.
That gives a proper rpm reading and a curve that makes sense.

Your fuel supply is definitely your problem I would run 2 pumps with their own 12mm pickups in the tank and join them into at least a 12mm fuel line all the way to the fuel rail. If you are running stock fuel rails that could also be a problem.
You cant go to big on the fuel supply side.
You also need a rising rate regulator I have run Bosch pumps up to 6.5 bar on blown M3's without a problem.

Running injectors above 90% duty cycle for extended periods is'nt very wise.

[Black LS1 T/A]

Unfortunately I can't lock my converter... I don't have the "Exetreme" version that is designed to handle that.

I have the Pro Yank 3400 (my Super Yank 3500 convertered to a higher STR to compensate for the 422 and Boost.)
So I didn't have the Kevlar material.

My engine builder told me even though I shouldn't do it for the strip, it should be OK for a few dyno runs, but Mike Senia at Yank adviced against me doing it at all. He said it might hold up to direct lock-up under WOT, but he wouldn't bet on it.. and that it would for sure fail if I did it at the strip. I would have to buy another converter if I want lock under WOT. :(

I have Speed Inc. Fuel rails and my return line is 8AN, but I have restriction thru the fuel sender and am using my stock supply line right now. I have a CAS Boost Referenced Rising Rate Regulator and I've flat-lined my IFR table.

Here are pics. (A little ghetto, I know... but it helped my fuel tremendously):

http://www.blackls1ta.com/images/BuieDP_Front.jpg

http://www.blackls1ta.com/images/BuieDP_Left.jpg

http://www.blackls1ta.com/images/BuieDP_Right.jpg

http://www.blackls1ta.com/images/BuieDP_Back.jpg

I'm using a Racetronix wiring to optimize current flow to the pumps and have the relays set up where one runs all the time and the other comes on when a Hobbs switch senses boost:

http://www.blackls1ta.com/images/fuel_sender_bulkhead_connector.jpg

[kp]

I thought you were still on the stock pump with the boost pump Mike, the dual 255s will be good to whatever you want to do. Could probbaly use a little bigger feedline though ;)

I have the same ghetto pump setup:

http://personalpages.tds.net/~kpevin/pic/fp.jpg

works for me..

[caver]

Is that an inertia dyno? Cant see whats the difference between a locked tcc on a inertia dyno and a hard pull on the road.

No way the std supply line can keep up with your demand. Make sure the non return valves in those pumps are working or you will pick up problems with fuel short circuiting through which ever one is'nt running.

You also need to join them with a y piece your connector is very restrictive.

Bend a 12mm piece of Bundy tubing drill a hole in the sender unit and silver solder or JB Weld it in.

[Black LS1 T/A]

Is that an inertia dyno? Cant see whats the difference between a locked tcc on a inertia dyno and a hard pull on the road.


While I might do a dozen quarter-mile passes at the strip, I would only do maybe three pulls at the dyno. :)



No way the std supply line can keep up with your demand. Make sure the non return valves in those pumps are working or you will pick up problems with fuel short circuiting through which ever one is'nt running.

You also need to join them with a y piece your connector is very restrictive.

Bend a 12mm piece of Bundy tubing drill a hole in the sender unit and silver solder or JB Weld it in.

Thanks for the advice... This bundy tubing comes in a Y? I searched and search for some alternatives. I'll give it another whirl...

[caver]

Bundy tubing is like brake pipe.
I have seen brass y pieces with tails that accept hoses at hydraulic shops locally so U should be able to find it.