HOME FORUM RULES CONTACT
     
   
   

Go Back   CLASS RACER FORUM > Class Racer Forums > Stock and Super Stock Tech


Reply
 
Thread Tools Display Modes
Old 08-08-2016, 02:01 PM   #11
FireSale
VIP Member
 
FireSale's Avatar
 
Join Date: Feb 2014
Location: Lakewood Washington
Posts: 1,407
Likes: 29
Liked 236 Times in 127 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

Here's my take. If you floor the pedal on a two step set at 3000 or so, the butterflies go wide open and the pump shot from a double pumper is expended with the car on the line. If you rev until you just hear the stutter kick in you still have throttle travel in reserve and get the pump shot when the engine goes under load at launch. I haven't raced enough to tell the difference but I feel more like a racer when I mash the pedal on the last yellow...I mean green light...

Dale
__________________
Dale Shearon
68 Mustang 6394
FireSale is offline   Reply With Quote
Old 08-08-2016, 02:10 PM   #12
HandOverFist
VIP Member
 
HandOverFist's Avatar
 
Join Date: Oct 2013
Location: Gulf Breeze, FL
Posts: 1,655
Likes: 8
Liked 33 Times in 16 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

Quote:
Originally Posted by FireSale View Post
Here's my take. If you floor the pedal on a two step set at 3000 or so, the butterflies go wide open and the pump shot from a double pumper is expended with the car on the line. If you rev until you just hear the stutter kick in you still have throttle travel in reserve and get the pump shot when the engine goes under load at launch. I haven't raced enough to tell the difference but I feel more like a racer when I mash the pedal on the last yellow...I mean green light...

Dale
Kind of how I used to think about it as well Dale, but according to those in the know the engine does not care about that pump shot because of the airflow with all the butterflies WOT. I see them leave fine so it must have merit. -
__________________
Rich Taylor
I/SA - 321

Last edited by HandOverFist; 08-08-2016 at 02:21 PM.
HandOverFist is offline   Reply With Quote
Old 08-10-2016, 09:06 AM   #13
Eric Merryfield
Senior Member
 
Eric Merryfield's Avatar
 
Join Date: Apr 2008
Posts: 846
Likes: 1
Liked 467 Times in 113 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

On a two barrel beast like the Gremlin, there is a noticeable difference. With two step the extra accelerator pump shot, can help with reaction time, and car launches tamer, a tick quicker .01 for same launch RPM 60 foot. 1/4 mile no real difference. However the car launches much harder off footbrake and mashing it, and you can adjust your RPM up and down as needed for reaction time.

My fuel injected cars/trucks seem to really like 2 step. Test with dakota a couple of years ago was .02 quicker in 60 foot and .03-.04 quicker in 1/4 mile.

For real accurate data, you would want to datalog the throttle position just to make sure you are at 100 WOT especially if you have wheelstand or hard landings going on also.
__________________
Eric Merryfield 1883 STK
Eric Merryfield is offline   Reply With Quote
Old 08-12-2016, 05:38 PM   #14
impstocker
Member
 
impstocker's Avatar
 
Join Date: Dec 2008
Location: Wingdale, NY
Posts: 302
Likes: 27
Liked 54 Times in 16 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

I find this a interesting subject as I have never raced a "real automatic race car" I learned to race with my 68 Impala stocker with the Jerico 4 speed which I just floored the pedal to the desired RPM set on the 2 step (usually 5500 - 6500) So in building my 65 Impala I wired 2 step through a Brake pressure switch with a on/off toggle to activate the system. I assume with a 2000-3500 rpm range I will mash pedal on 2 step.

I will also be running the Holley version 396/325

Building motor now, can't wait to race. This "bench racing" gets played.

Will Lamprecht
1965 Impala I/SA almost finished.
impstocker is offline   Reply With Quote
Old 08-15-2016, 01:42 PM   #15
Rusty Davenport
Senior Member
 
Join Date: Jun 2005
Location: Nashville N.C.
Posts: 505
Likes: 4
Liked 100 Times in 26 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

[QUOTE=HandOverFist;511057]Not by intent, but rather by design Rusty. As you can see in the image the activation button is in the brake pedal itself...I know some use a micro-switch.

[/QUOTe

you almost answered my question.....why aren't you putting the gas pedal on the WOT on the floor instead of stopping when you hear it break up ???? Is it any faster not to mat it ???
__________________
NHRA AND IHRA STOCK ELIMINATOR 2772
Rusty Davenport is offline   Reply With Quote
Old 08-15-2016, 01:54 PM   #16
HandOverFist
VIP Member
 
HandOverFist's Avatar
 
Join Date: Oct 2013
Location: Gulf Breeze, FL
Posts: 1,655
Likes: 8
Liked 33 Times in 16 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

[quote=Rusty Davenport;511598]
Quote:
Originally Posted by HandOverFist View Post
Not by intent, but rather by design Rusty. As you can see in the image the activation button is in the brake pedal itself...I know some use a micro-switch.

[/QUOTe

you almost answered my question.....why aren't you putting the gas pedal on the WOT on the floor instead of stopping when you hear it break up ???? Is it any faster not to mat it ???
The correct procedure would be to mat the throttle and come off the brake pedal to launch...just the opposite of what I normally do. I have never taken the time to adjust to this method so I can't answer which is better. Some TNT time would answer this I'm sure...just have to make myself re-learn lol. In simple terms I would be controlling events with my left leg instead of my right leg if that makes any sense.
__________________
Rich Taylor
I/SA - 321

Last edited by HandOverFist; 08-15-2016 at 01:57 PM.
HandOverFist is offline   Reply With Quote
Old 08-15-2016, 02:12 PM   #17
Rusty Davenport
Senior Member
 
Join Date: Jun 2005
Location: Nashville N.C.
Posts: 505
Likes: 4
Liked 100 Times in 26 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

[quote=HandOverFist;511600]
Quote:
Originally Posted by Rusty Davenport View Post

The correct procedure would be to mat the throttle and come off the brake pedal to launch...just the opposite of what I normally do. I have never taken the time to adjust to this method so I can't answer which is better. Some TNT time would answer this I'm sure...just have to make myself re-learn lol. In simple terms I would be controlling events with my left leg instead of my right leg if that makes any sense.
So if I am getting this correct......you are actually foot braking and using the 2 step to tell you where you are on RPMs and hold at that point ???
__________________
NHRA AND IHRA STOCK ELIMINATOR 2772
Rusty Davenport is offline   Reply With Quote
Old 08-15-2016, 02:26 PM   #18
HandOverFist
VIP Member
 
HandOverFist's Avatar
 
Join Date: Oct 2013
Location: Gulf Breeze, FL
Posts: 1,655
Likes: 8
Liked 33 Times in 16 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

[quote=Rusty Davenport;511603]
Quote:
Originally Posted by HandOverFist View Post

So if I am getting this correct......you are actually foot braking and using the 2 step to tell you where you are on RPMs and hold at that point ???
Not intentionally Rusty. I would run across this more often with the Stocker engine combined with the 200 metric trans and 8" ATI converter...with the four wheel discs on the car I could hold it on the line easily upwards of 4000 rpm. The two-step has always had a 3000 rpm chip in it. I normally try to stage just below 3000 rpm.

I see this less often now with the current 383 engine/PG combo as the converter installed is not really optimal for this set-up.
__________________
Rich Taylor
I/SA - 321
HandOverFist is offline   Reply With Quote
Old 08-22-2016, 10:44 AM   #19
Bobby Fazio
VIP Member
 
Bobby Fazio's Avatar
 
Join Date: Nov 2009
Location: Egg Harbor Township, NJ
Posts: 1,371
Likes: 1,122
Liked 3,449 Times in 420 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

I don't know how much about two-steps on a carb motor but an EFI motor must be tuned to do both. Footbraking launch RPM puts you in a lower load cell section on the fuel map and the transition to the high load launch must be smooth and have that accel enrichment stuff all tuned properly. The two step puts you in a high load cell as soon as you drop the pedal to the floor so all accel enrich stuff is finished before actual launch so you are transitioning between high load cells.
__________________
'65 Mustang SS/L & L/SA
DriverInterviews.com | App.DragInsights.com
Bobby Fazio is offline   Reply With Quote
Old 08-22-2016, 10:30 PM   #20
dean ribeiro
Member
 
Join Date: Oct 2003
Location: candia, nh
Posts: 494
Likes: 53
Liked 214 Times in 66 Posts
Default Re: Your experience foot brake vs. 2 step regarding ET

Rusty-
My experience has been .008-.012 quicker in 60ft ET with a two step switch (same launch RPM) This equates to .016-.024 improvement in 1/4 ETs. It should be noted that to leave matted off of a 2-Step, the carb requires a different set up (think secondaries). My experience with fuel injection stockers mirror Eric and Bobby ( you stand to pick up a little more ET). I suspect this has to do with the amazing starting line efficiencies with FI (compared to the "quadra-bogs")

Feel free to call with questions buddy!

PS- I surround myself with much smarter people than myself! 😁
dean ribeiro is offline   Reply With Quote
Reply


Thread Tools
Display Modes

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off

Forum Jump


All times are GMT -4. The time now is 08:54 AM.


Powered by vBulletin® Version 3.8.11
Copyright ©2000 - 2024, vBulletin Solutions Inc.
Copyright © Class Racer.com. All Rights Reserved. Designated trademarks and brands are the property of their respective owners.