How do we know what FP to tune at?

[TYTILIDIE]

Ive started my tuning journey and ahd a thought. I read through Jeffs Fuel tuning 101 and a tthe part abotu fuel pressure I wondered, hwo are you supposed to knwo what FP to tune aorund? I am running ATR stock injectors? 33/hr I think. A 20g turbo, 3K stall. those are the main things. I want to run more boost obviously so Im just wondering, what are 11.9 stock turbo truck guys tuning around? Or how do you make that decision?

 

[nallj92]

Re: How do we know what FP to tune at?

whats your duty cycle look like on DM? i was running 22-23boost and had FP at idle around 55psi if i remember, and was sprying alky with a 20g, but my duty cycle was 110%

 

[TYTILIDIE]

Re: How do we know what FP to tune at?

I have no idea. I was just wondering where to start. I have it at 50 right now and the truck is great. A/FR is 13ish at 18 psi and it feels far faster than when I was running the Ultimate chip at 20. But I am concerned about things like gas milage and system wear. Or should I not be? Basically, if I want to eventually get 25 psi, could a chieve that with my FP set at say 45?

 

[nallj92]

Re: How do we know what FP to tune at?

didnt you get the ostrich working? could just add more fueling there instead of changing the FP, 50 should be fine, but ideally the injectors are going to run out, gotta watch the duty cycles at WOT
i would add more alky and get the WOT afr's down to 12's, but it all depends on what the engine likes. just have to mess around with it.

 

[TYTILIDIE]

Re: How do we know what FP to tune at?

Yeah I got the Ostrich working. I dont run ALky. I was just wondering what is a good FP to tune aorund is all.

 

[Don W.]

Re: How do we know what FP to tune at?

:2cents: One source I have says 42 at idle with vac line disconnected. The manual I have says 35-38 engine off. (You can test this by turning the key on. The pump runs for 2 sec when you turn the key on.) This will give you base line with stock injectors. Don't know anything about Ostrich so the above may be all wet. Get used to pulling and reading plugs.

HTH

 

[4C FED]

Re: How do we know what FP to tune at?

:2cents: One source I have says 42 at idle with vac line disconnected. The manual I have says 35-38 engine off. (You can test this by turning the key on. The pump runs for 2 sec when you turn the key on.) This will give you base line with stock injectors. Don't know anything about Ostrich so the above may be all wet. Get used to pulling and reading plugs.

HTH

You can also use the grey wire with black spade connector located by the fuel pump & IC relays.
Put 12 volts to it & it will drive the fuel pump. Also works great for emptying fuel tank if you need to replace the pump.

 

[Don W.]

Re: How do we know what FP to tune at?

You can also use the grey wire with black spade connector located by the fuel pump & IC relays.
Put 12 volts to it & it will drive the fuel pump. Also works great for emptying fuel tank if you need to replace the pump.

Just for the heck of it, one of these days I'm gonna check and see if there's any difference between the above (engine off) and engine running.:roll:

 

[turbodig]

Re: How do we know what FP to tune at?

I have no idea. I was just wondering where to start. I have it at 50 right now and the truck is great. A/FR is 13ish at 18 psi and it feels far faster than when I was running the Ultimate chip at 20. But I am concerned about things like gas milage and system wear. Or should I not be? Basically, if I want to eventually get 25 psi, could a chieve that with my FP set at say 45?

13:1 WOT AFR = soon to die motor.

On pump gas, I rarely get above 11.5. Race gas rarely over 12.4. I have run leaner, but not for long...

You'll need at least 60 psi base to go much over 22 psi. I ran 65# base at 24 psi.

 

[dgoodhue]

Re: How do we know what FP to tune at?

Since the stock injectors are on the small side you need to run more fuel pressure to make the injector seem bigger than they are. I have read that the stock .bin's can have an injector duty cycle of 100% if that give you an idea about the stock injector size. This is one of the reasons the Ultimate chips were tuned with more Fuel Pressure than the stock injectors. So essentially you have to run more FP if your running out injectors. Their is only som much FP that you can run though, before the fuel pump runs out of capacity (the higher the FP, the less capacity) and I have heard some stock injectors locking up (maybe that is a good thing, I remember reading about it with FMU's & certain GM injectors, but I don't remember if locks on or off.)

If you had 50# injectors with the stock turbo 40psi of base FP would be more than enough.

 

[gjp]

Re: How do we know what FP to tune at?

is that based on stock injectors?. With 50#'s I was running 38# FP and seeing 10.6 WOT on the wideband?? without the alky

 

[TYTILIDIE]

Re: How do we know what FP to tune at?

Ouch!!! I didnt know that. I will have to do some tuning I guess. I thought 13 was decent. The Ultimate I got back from you was running about 10-11 @ WOT. I wonder if this is why my oil preessure has been slightly decreasing. I also hear at part throttle, a pinging sound but hte A/Fr is at 14's and Its usually under very light acceleration.

 

[It's just a six]

Re: How do we know what FP to tune at?

When I dynoed my Sy, most of the runs, the A/F ratio were in the 13's.
Peak HP & torque was around 13.4 A/F ratio. 386 HP, 550 FT. lbs.
10 -11 A/F ratio is way too rich.
A/F 14's part throttle is OK, maybe go a little richer or try maybe pulling some timeing out? Is this under boost,part throttle, the pinging?
I'll state it again for others 10-11 A/F ratio is way too rich!!!
There is a point of fueling too much will hurt it.
Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13.
BTW, the A/F reading from the Dyno were the same as I was getting with my LM1

 

[gjp]

Re: How do we know what FP to tune at?

When I dynoed my Sy, most of the runs, the A/F ratio were in the 13's.
Peak HP & torque was around 13.4 A/F ratio. 386 HP, 550 FT. lbs.
10 -11 A/F ratio is way too rich.
A/F 14's part throttle is OK, maybe go a little richer or try maybe pulling some timeing out? Is this under boost,part throttle, the pinging?
I'll state it again for others 10-11 A/F ratio is way too rich!!!
There is a point of fueling too much will hurt it.
Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13.

The only way to get the A/F to 12's is to run 33# fp??

 

[It's just a six]

Re: How do we know what FP to tune at?

is that based on stock injectors?. With 50#'s I was running 38# FP and seeing 10.6 WOT on the wideband?? without the alky

Need to lean that baby up.
Way, way too rich.

 

[berzerker]

Re: How do we know what FP to tune at?

Mike U Need To Get Your Truck Up Into Denver One Of These Day's . Let Me And Cheatham Show U Around The Nightmare Of Tuning, And Let Cheaty Give U Some Pointers On Using The Software . Will Get Your Truck Running Awsome In No Time !

 

[Six-is-Enough]

Re: How do we know what FP to tune at?

On my race chip (more aggressive timing) I run 52 psi F/P. Now that is with Methanol injection. The AFR on my 11.9 run were 10.8 to 1. On the street I run 48 psi of F/P with AFR's in the 10.8 - 11 to 1. Also with Methanol Injection.:tup:

 

[TYTILIDIE]

Re: How do we know what FP to tune at?

Mike U Need To Get Your Truck Up Into Denver One Of These Day's . Let Me And Cheatham Show U Around The Nightmare Of Tuning, And Let Cheaty Give U Some Pointers On Using The Software . Will Get Your Truck Running Awsome In No Time !

How much will htat run me? Last I talked to Dan, he wanted betweem 2 and 500. Ofcourse I think that was for him to do it alone but I have since decided to tackle this crap myself as I feel total control is my best benefit. Let me know. I can get up there whenever.

 

[turbodig]

Re: How do we know what FP to tune at?

When I dynoed my Sy, most of the runs, the A/F ratio were in the 13's.
Peak HP & torque was around 13.4 A/F ratio. 386 HP, 550 FT. lbs.
10 -11 A/F ratio is way too rich.
A/F 14's part throttle is OK, maybe go a little richer or try maybe pulling some timeing out? Is this under boost,part throttle, the pinging?
I'll state it again for others 10-11 A/F ratio is way too rich!!!
There is a point of fueling too much will hurt it.
Most engines produce maximum power (with optimized ignition timing) at an air-fuel-ratio between 12 and 13.

Dyno AFR != road AFR. Run a WB02 truck on a dyno, and watch the AFR, then run on the street, and watch the AFR. You'll be at least .6-1.0 richer on the street. Also, I don't trust the calibration of most WBo2s that dyno shops have any futher than I can throw them.

Over the years, I've tuned about 30-40 trucks for pump gas. The leanest I ever got one was about 11.9, and that was my own. And it ate 2 piston ring lands.

I find some trucks that won't run more than 14 psi unless you fuel 'em up. 10:1 is a bit excessive. Typically 11.2-11.5 works, sometimes leaner if I can get by with it.

And, that's on the cheapest 91 I can find. I stopped tuning pump gas trucks on "ringer" 93-94. The quality of pump gas varies dramatically, so you need to tune for the least common denominator.

Race fuel is an entirely different beast. I've run as lean as 12.8:1 intentionally. And it got faster. It also started to knock a couple degrees on the shifts. So, I pulled it back to around 12.5. I don't consider a tune that knocks a good tune. (Even if it is faster)

There is power to be made from a certain degree of leanness... but it comes at a price. I know people running 13.8s to 14s at WOT... but they're ok with the parts failures that come with it.

 

[nallj92]

Re: How do we know what FP to tune at?

Dyno AFR != road AFR. Run a WB02 truck on a dyno, and watch the AFR, then run on the street, and watch the AFR. You'll be at least .6-1.0 richer on the street. Also, I don't trust the calibration of most WBo2s that dyno shops have any futher than I can throw them.

Over the years, I've tuned about 30-40 trucks for pump gas. The leanest I ever got one was about 11.9, and that was my own. And it ate 2 piston ring lands.

I find some trucks that won't run more than 14 psi unless you fuel 'em up. 10:1 is a bit excessive. Typically 11.2-11.5 works, sometimes leaner if I can get by with it.

And, that's on the cheapest 91 I can find. I stopped tuning pump gas trucks on "ringer" 93-94. The quality of pump gas varies dramatically, so you need to tune for the least common denominator.

Race fuel is an entirely different beast. I've run as lean as 12.8:1 intentionally. And it got faster. It also started to knock a couple degrees on the shifts. So, I pulled it back to around 12.5. I don't consider a tune that knocks a good tune. (Even if it is faster)

There is power to be made from a certain degree of leanness... but it comes at a price. I know people running 13.8s to 14s at WOT... but they're ok with the parts failures that come with it.

yeah thats the way i understand it too,
also people should note that with alky the stoic. values are richer than gas, so its ok to have 10.0's while spraying lots of meth.
i was running 11.0 afr's with my bin, and with your bin when we tried it up in sabin it was more like 12.6's, and ran about the same, each truck is different too. i rather replace plugs more often than rings and pistons