Your experience foot brake vs. 2 step regarding ET

[Bobby Fazio]

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.

[dean ribeiro]

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! 😁

[StockerStang912]

We experienced a marginal performance improvement of .01 to 02 with a 2-step on a low hp Fox Body stocker. Would have to make a few more runs to have a better idea with reaction time, but certainly made staging easier/consistent.

To Bobby's point, we did not adjust fuel enrichment to accommodate the change so not sure if it's a true apples-to-apples comparison.

[Jack McCarthy]

my car hates it (as do i) kills me about .05 at least - more in bad air ....
and i cannot stand that sound ...

so im stuck in the 60s footbraking it

captain

[Robert Simpson]

Originally Posted by dean ribeiro

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 could you better explain to me about adjusting the secondary for a FB two step? I have a street car that I Foot brake. I leave around 1500 and it flashes to about 3800. I tried a two step one time and while it reacted quicker to stumbled about 10' foot out and then cleared up. You can IM me with any details if you would like. Thanks

[Rusty Davenport]

Maybe someone will see this and reply but has anyone experimented with low rpm 2 step ......will the motor respond ok on the 2 step at 2000 ????

[Rsmith38]

Don't know about 2000 but my R/SA Jeep 4.0 leaves fine at 2550 - down from 3000 because the brakes won't keep it from pushing thru the lights!
4.0 is FI so can't say about a carb reacting.

[Rusty Davenport]

I'm finding out little by little with experimentation, and it gets back a little to what some of you hinted around to, the quadrajet does not like "rich" fuel mixture when leaving on the mat with the 2 step activated by the brake. It will sit on the starting line and hold the RPMS but when you let go the "rich" will usually make it leave terribly, even though it will run great with the same carb setup when running with the footbrake only.
MAKING THE 2 STEP WORK WITH THE QJET IS A CHALLENGE in order to get it to perform at its best especially on a stocker that doesn't have a transbrake and has to leave at much lower RPMS......by what I am seeing testing the 2 step requires leaner setup to run at least reasonably well.
Does anyone else have similar findings ????

[Danny Ashley]

Plug the accelerator well tubes

Originally Posted by Rusty Davenport

Maybe someone will see this and reply but has anyone experimented with low rpm 2 step ......will the motor respond ok on the 2 step at 2000 ????

I used to leave at 2200 with my 455 Lemans. I did what Danny said. blocked off the accelerator tubes and it left great. Always to the floor.