Fastest Pump Gas / Alky 1/8th mile (updated 10.07.18)

[NY Twin Turbo]

The problem with the pa enable is when the pa line is dropped it. It goes into closed loop instantly and this can cause a big issues. cause the a/f ratio is not correct and it takes a split second for the exhaust to clear out to get a true a/f and not have any large corrections based the incorrect a/f .....




I use the same tune on the street as when I race ...I do a zero corrections in the area where I'm on the 2step.

This is done in the +/- correction tables and I just zero out the area where the two step rpm and boost is at....I leave all the other closed loop stuff alone ..

My alky starts spraying in the 9-10 psi and I leave at 3k rpm and that's about 6-7 psi boost ..

If you have any questions in box me a way to contact you ..I can explain better than typing it all out ..

So, what your saying is simply don't allow correction at your launch RPM?

Tune the launch area of the VE map as normal, with it being dead-on for your desired AF. Then as soon as it leaves those few "0 correction" cells (when you release the two-step/trans brake) correction will begin again if needed. Just allow one cell more for the exhaust to clear the un-burned fuel.

Am I understanding this correctly? I installed the 2-step in the fall and haven't tuned for it yet. This info is appreciated.

 

[SloGN]

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[Sydwyndr]

I was wondering if anyone was doing this. I was looking at the PA enable like I said in the post, but there is so much in the power adder area that I'm worried I'll screw something up. Good info seeing what everyone is doing.

This is the way Cal set mine up years ago and I've had no problems, Lemme screen shot the setup and Ill send to you so you can see what to do. I think is much better than changing the +/- correction tables myself. You would have to have the tune correct while it is on the 2 step when you adjust the +/- correction tables. Once you got the car close so once it comes out of the correction tables to have the car not go very rich / lean once it leaves the zero correction

 

[Sydwyndr]

So, what your saying is simply don't allow correction at your launch RPM?

Tune the launch area of the VE map as normal, with it being dead-on for your desired AF. Then as soon as it leaves those few "0 correction" cells (when you release the two-step/trans brake) correction will begin again if needed. Just allow one cell more for the exhaust to clear the un-burned fuel.

Am I understanding this correctly? I installed the 2-step in the fall and haven't tuned for it yet. This info is appreciated.

You assumption is correct. The only issue is for a quick moment it may fluctuate as it comes off the 2 step depending on how "lean" the actual A/F is ONLY due to the 2 step turning the ignition on and off. It may try to richen up then lean right back out to get to your actual A/F ratio. All this will happen before the car gets to the 60 foot mark (1.4 seconds into the actual run) so it shouldn't affect how the car runs.

 

[pacecarta]

on the classic i set the row at launch boost and just above to 0

on the fast i set the cells right around launch at 0

i on chip used to do the alky delay with the wire to the brake , it doesnt kill the alky it just slows it down ,

and slogn's explanation is sorta right, the sensor reads air not fuel
2step stutters the cylinders and the o2 that wasnt burned is seen by the o2 and if correction is running it applies correction , the af seems to be fine because thats the correction doing it job maintaining the af but can assure you its rich because every skipped cylinder dropped by the 2step will dilute the a/f by atleast 10percent , once 2step is released correction will have to work to pull out what it added and you will be rich right off the hit add that the alky will also be dumping in
but on pump gas you are safer having the alky then to hit double digit boost off the launch with out the alky there
this is where we logged on murphsters and tweaked the PAC box to sort of coordinate the alky pressure rise (flow) with the boost rise after the release , so far so good but hes looking for the key to 1.2s and that might not be doable without more timing, the that race gas allows , trying on alky and if the alky doesnt get there the high timing could loosen gaskets .


edit , clint you beat me to it on slogns post , was typing out when you replied

 

[murphster]

Good info here and interesting to see the different ways people are doing this. And Paul is correct in that I am trying to get a 1.2 and also that we did spend some time dialing in the PAC settings so that the alky comes in smooth with boost on the launch.

I agree with Clint that using PA enable seems good in that its only active with the transbrake and you can add in things like playing with timing to help spoolup, etc. Using PA enable or zeroing out the VE correction both accomplish the same thing where you are going to open loop, so your base VE must be correct either way to get the desired fuel. Patrick, from what I understand in Power Adder you can have a delay set for a second stage with correction enabled, which would come into play after you release the transbrake. The delay time can be used to give time for the O2 to recover after coming off the 2 step.

The only issue I can see is that there is still the variable of how much alky is actually coming in. Any change to the alky settings or pump means a different amount of alky would be coming in while launching and there would be no correction. Just something to keep in mind. No leaks and fully primed is the only way to make sure it comes in consistently each run. I've got so many logs over the years showing how different the alky comes in when there are leaks, or not primed recently enough, or tank not full enough with the conventional overflow tank setup, etc.....

 

[jdsgnx]

Well just like anything there seems to be a dozen different ways to get the same thing done. Keep us posted on your progress and wish you the best of luck

 

[pacecarta]

you know if he ever gets a 1.2x ..the day after he will want a 1.1x

 

[jdsgnx]

you know if he ever gets a 1.2x ..the day after he will want a 1.1x

Isn't that always the way it is we all want more we all said once we get a 1090,a 990 and so on and so on it never ends that's when you know you got bit by the bug

 

[murphster]

Just to post up something interesting.... Here are examples of the different ways alky comes in with boost. These are screengrabs of XFI logs from 3 different cars (bottom two are from same car), all 9 second passes and 60fts of 1.4x or better....

Even though the scales are different the max alky pressures are pretty similar for each log. The turn on points and initial gain differences are clear in the logs. No knock recorded on any of these logs either.

 

[jdsgnx]

has the top two logs had the pump checked recently. Big difference between the top two in the bottom two logs on the smothness of pressure.Great info thanks for Sharon Murphy

 

[murphster]

The top left one was turned down some for that pass, good pump though and made great pressure. Top right one a little weak and new one bought after. Bottom one was brand new, Initial gain turned up higher than most.

 

[jdsgnx]

Just out of curiosity ,I know it's a long way away, but do you think there will be any chance you will be coming to Bowling Green this year?

 

[murphster]

Definitely a chance. Would likely drive the truck down, but would be nice to run the white car in TAI. Might have to throw a couple rednecks in the trunk to make weight though.

 

[pacecarta]

the two on bottom ...needs more boost

and scott says rednecks ..he means kinfoke

could put a complete lc2 in the trunk and he still would have to throw some spare parts in with it to make weight

 

[jdsgnx]

You can do whatever it takes as long as he shows up the more the merrier to talk to you soon

 

[murphster]

The truck runs on alky.....

 

[pacecarta]

...and if you dont get carried away with the fiberglass parts catalog it might make the weight

 

[jdsgnx]

 

[jdsgnx]