Author Topic: fuel/ignition timer  (Read 4643 times)

Offline noslin

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fuel/ignition timer
« on: November 04, 2016, 06:11:17 PM »
looking for a little education on fuel and ignition timers on a mechanical setup.   would like semi-indepth info on how say fuel timers are used in a blown (or n/a?) setup.   how is it different then say using pills and pop-off's (or bleed valves?).   do the timers whether electric, c02, or ? operated take fuel away or add fuel?   how many would be typically used.   

ive been trying to do some research and dont find much information.  see people discussing whether electronic solenoids are legal to be used in certain classes vs c02.   ive read where (i think) a timer or solenoid would be used at burnout to limit fuel so the motor doesnt load up (is that correct?)

on the ignition side, are the timers controlled by rpm or time?   i know from my experience with my old car that had a turbo, take timing out till peak torque then you can start to add some back in.  is that the case with electric timers on blown/mechanical setup? ive looked at Electrimotion site, i see the leahy box and misc timers and ways to hook up etc depending on how many you want.

anyways, just looking to learn something. 

ty
dean


Offline Spud Miller

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Re: fuel/ignition timer
« Reply #1 on: November 08, 2016, 04:53:44 PM »
 I'll take a quick stab at this and if you have other questions, just ask.
 
 Timers are a much nicer, more consistent and repeatable way to control lean out/enrichment than check valves which are dependent on system pressure. Anytime you change the main pill, the system pressure on a pass changes and everything will be different for those check valves. Timers don't care...they do their thing when the time comes regardless of RPM, pressure, pill, tide, phase of the moon...  :)  If you partially (or completely) plug a nozzle on a pass, all your check valves will be wonky and come in WAY too early for example.

 "Normally open" and "Normally closed" valves can each be used to bypass fuel (lean) or stop bypassing fuel (enrich) when they are activated.

 A normally closed electric valve can be activated with the transbrake to lean a system out when on the converter or against a launch rev limiter. It slams shut and the system goes rich and ready to make torque when the brake is released. A clutch car can lean the system when the clutch pedal is depressed and go rich when released (maybe with a switch on low gear so it only happens at the starting line).

It's pretty common that a blown system in a heavy car wants to eat more fuel for the first 100' or so to get the car moving and once rolling along, fights better a bit leaner. That might be your 2nd stage leanout valve...what I call a "low speed bypass" that kicks in 1.5 - 2 seconds out.

When things are motivating along pretty well and HP (not torque) is needed for the top end charge, another bypass can take fuel away at the top end 1.5 - 2 seconds from the finish line.

 In a nitro situation, an electronic valve can be used for a high-side/low-side setup. You could even make it go to the high-side automatically when the throttle is even slightly depressed or the clutch pedal comes all the way out.

 Anywhere you can route a wire and mount a switch, logic could be added. Using a series of micro-switches and/or RPM switches, a lean out could be setup to only work after a certain number of seconds, only if in high gear, and only if engine RPM is above a certain value.
 
 Someone wanting to control the staging volume, the low speed and high speed will need at least three different valves.

 Because most folks don't want to spend $1,000 for simple on/off control of fuel and timing changes, FIE offers a 4 channel timer that's worth looking at: https://fuelinjectionent.myshopify.com/collections/tuning-parts/products/4-channel-timer-controller  It'll change the state of each channel twice per pass if desired. Here's the valve we like to use for these purposes: https://fuelinjectionent.myshopify.com/collections/tuning-parts/products/electronic-lean-out-valve-assembly It comes in an enrichment version as well.

 People use a channel to activate a timing controller to retard the timing at the starting line for the first second or so. Or shift the car (one channel will shift twice for you). If you have a channel left over, you could use it to activate a shift light by time.

 Some classes don't allow electronic valves or even simple timers. For some reason, air controlled valves are usually considered ok in those cases.

 I'd prefer to use time vs. RPM to change fuel or timing. If traction is an issue or converter temp/slippage is a bit different from pass to pass, the RPM will differ a little each time causing your events to be triggered differently - which in my mind only amplifies the error and inconsistency on the lap.

Time waits for no one!

 Spud


 

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Offline hotrod316

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Re: fuel/ignition timer
« Reply #2 on: November 08, 2016, 05:16:43 PM »
thanks spud, it always nice to read your posts
steve m.

Offline noslin

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Re: fuel/ignition timer
« Reply #3 on: November 08, 2016, 05:47:10 PM »
thank you for your reply, really appreciate it. 

Offline 69427

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Re: fuel/ignition timer
« Reply #4 on: September 30, 2019, 05:47:11 PM »
.....
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Offline 69427

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Re: fuel/ignition timer
« Reply #5 on: October 01, 2019, 08:38:33 AM »
I'll take a quick stab at this and if you have other questions, just ask.
 
 A normally closed electric valve can be activated with the transbrake to lean a system out when on the converter or against a launch rev limiter. It slams shut and the system goes rich and ready to make torque when the brake is released. Spud

N/A speaking here, Looking at last years logs, at about .5 into a run, it looks like there is a little to much fuel pressure sending the O2's richer. It's all bundled with a small dip in ERPM DSRPM.

My question: has any one held their launch leanout valve open after the trans brake release for X amount of time?

I have a Digi-Set "delay on break" timer I can use to delay the lean out after trans brake release.
1.29 5.97 @ 114.00 @ #3251 Better in 2022
427 BBC by S&S Speed Center, AFD, Enderle MFI by Spud Miller
Trackside Products, Sepanek Racing T400, Dynamic converter, Autoweld, Santhuff, Smith Racecraft, Dick Fords Body Shop