Yellow Bullet Forums banner

1 - 20 of 21 Posts

·
Registered
Joined
·
129 Posts
Discussion Starter #1
If your Tryn to make sure the car doesn't leave violent off the line should u pull timing an ramp it back in or lower 2 step? I won't to no with one wont hurt your ET the must....
 

·
Registered
Joined
·
1,627 Posts
I havent noticed a huge difference in my car moving the 2 step around, the nitrous still hits real hard. Maybe yours will act different but I would try killing it with timing or a progressive controller. Or try other things, taller gear maybe
 

·
Registered
Joined
·
6,825 Posts
Good question, as we are always needing to kill power on the Launch due to less than tight track conditions.

Here are the options as I see it (to reduce power @ Launch)...

I will leave out the obvious items such taller & wider tires, higher rear gear, higher 1st gear, better suspension or suspension adjustments (shocks, ladder bar or 4 link adjustments, tieing the front end down more or less, etc.), weight changes, tire pressure changes, etc.

(1) Use NO 2 Step, i.e. leave off of the wood with no 2 step (Example: our Converter goes to 4300 Motor with no 2 step);
(2) Build in a 7531 Box Launch Retard Timing Retard & Ramp it for whatever works (Example: motor is @ 33* with 1st stage @ 18*, 2nd stage @ 12* but we set the LR @ 10* total on stage 1 & 2* total on 2 stages & Ramp for 1.0 seconds);
(3) Build in a 7531 Box soft rev limiter "dots" to maintain ERPM & DRPM on the Launch (will depend on car's actual ERPM & DRPM);
(4) Tighten the Converter by sending it off, or at least add thicker John Deere Hy-Guard fluid to lower the stall speed by about 200-300 rpms;
(5) Make sure there is NO Delay in the Retard "on" setting in the 7531 Box (we actually have .20 set as "on" & .05 set as "off", but we needed this because our ERPM & DRPM were actually lazy up to .40 seconds);
(6) Set a Gear Retard to calm the car down once it launches & is down track (I have not used this option yet);
(7) Use a smaller / weaker n20 tune (n20 jetting);
(8) Use a progressive controller to ramp in the power over time or rpms;

I think there is a fine line between getting down the track with power to the ground, and running a tune-up with less power. Trial & error. But as an example, and not that this is impressive at all, but on a loose track, leaving as low as 2* total timing for 1.0 ramp, we still went BEST 144 to the 1/8 on 29.5 x 13.5 tire with old school ladder bar car @ 3350#. Our 60' at 1.26 was worse on 2 stages than our 1.23 best on 1 stage.

Good luck, and I'm sure I did not cover everything.
 

·
Registered
Joined
·
1,197 Posts
Good question, as we are always needing to kill power on the Launch due to less than tight track conditions.

Here are the options as I see it (to reduce power @ Launch)...

I will leave out the obvious items such taller & wider tires, higher rear gear, higher 1st gear, better suspension or suspension adjustments (shocks, ladder bar or 4 link adjustments, tieing the front end down more or less, etc.), weight changes, tire pressure changes, etc.

(1) Use NO 2 Step, i.e. leave off of the wood with no 2 step (Example: our Converter goes to 4300 Motor with no 2 step);
(2) Build in a 7531 Box Launch Retard Timing Retard & Ramp it for whatever works (Example: motor is @ 33* with 1st stage @ 18*, 2nd stage @ 12* but we set the LR @ 10* total on stage 1 & 2* total on 2 stages & Ramp for 1.0 seconds);
(3) Build in a 7531 Box soft rev limiter "dots" to maintain ERPM & DRPM on the Launch (will depend on car's actual ERPM & DRPM);
(4) Tighten the Converter by sending it off, or at least add thicker John Deere Hy-Guard fluid to lower the stall speed by about 200-300 rpms;
(5) Make sure there is NO Delay in the Retard "on" setting in the 7531 Box (we actually have .20 set as "on" & .05 set as "off", but we needed this because our ERPM & DRPM were actually lazy up to .40 seconds);
(6) Set a Gear Retard to calm the car down once it launches & is down track (I have not used this option yet);
(7) Use a smaller / weaker n20 tune (n20 jetting);
(8) Use a progressive controller to ramp in the power over time or rpms;

I think there is a fine line between getting down the track with power to the ground, and running a tune-up with less power. Trial & error. But as an example, and not that this is impressive at all, but on a loose track, leaving as low as 2* total timing for 1.0 ramp, we still went BEST 144 to the 1/8 on 29.5 x 13.5 tire with old school ladder bar car @ 3350#. Our 60' at 1.26 was worse on 2 stages than our 1.23 best on 1 stage.

Good luck, and I'm sure I did not cover everything.
I just went to a 7531 box and have a lot to learn about it. :rolleyes: I've always used a progressive to ramp nitrous in and had great success that way. I was always comfortable that since it pulsed both fuel and nitrous the same that my tune-up was coming in clean.

Now that I am considering using timing as you've mentioned it has me wondering what it does to a clean tune-up. We work hard to read plugs and get good information in order to make our motors live and a key component is getting the timing correct relative to the amount of fuel and nitrous. Seems to me that if you pull a ton of timing out as a traction control measure, then the tune is going to be off.

Seems to me that it is going to be rich for that 1.0 +/- seconds and possibly damage pistons? Or because it is for such a short timeframe, its not an issue?

This has probably been answered a thousand times...
 

·
Registered
Joined
·
6,825 Posts
Wheelsup, I'm no expert, but still learning at the track. I think you are right. In the early stages of a pass, when the timing is taken out for say a second or less, the motor will not be its happiest, but it cleans up as the pass continues, even on just an 1/8 mile run. By the time we cross, the 1/8 or 1/4, the A/F is right where we want it, and the plugs look good. The ET & MPH does not indicate that the timing retard has hurt performance. The headers might take a bit of a beating, with excess heat in them from the fuel being burned late due to the retarded timing. Good luck.
 

·
Registered
Joined
·
180 Posts
68maro are you saying if you raise the 2step higher this will kill some power an make the car less violent of the line?
 

·
Registered
Joined
·
6,825 Posts
Ghost, question was not directed to me, but that is what I've always been told. Lower the 2 step allows the Converter stall to chase up prior to Launch, and hits the tires harder, vs. "on the wood" with no 2 step. On our small tire car '71, we leave on the wood to minimize the initial hit on release of the TB.
 

·
Registered
Joined
·
6,825 Posts
Maybe so. Makes sense.
 

·
Registered
Joined
·
2,233 Posts
Yes raising it will help the car leave. The converter plays a part but also nitrous. What does nitrous make most? TQ down low. On a 150shot you may see 300ft lb of tq increase down low. So if you lower the 2step your increasing the tq multiplication plus the convertor flash and other things. Raising 2 step seems to help the convertor hit and takes away the tq spike. Thats the short of it. I can go into a long winded explanation but that sums it up lol. Tq moves the car so picture where your cars tq curve is plus the nitrous tq and work from the forget hp numbers.
 

·
Registered
Joined
·
180 Posts
Kroid yes its back together!! I plan on making some shake downs in Hattisburg Ms in march we found out a lot of things that were wrong with the car, the chasis shop in Michigan had set the rear suspension up total wrong!!!! When they lower the car it tru the IC completely out of wack an the angle of the upper ARM were screwed up as well and with all of the going on the rear was binded up!!! He also had preload in the right side upper arms with pulled that side of the car down, when we took it a loose that hole side snaped up!!!!! The new shop said John force couldn't drive it like that...Loi I was lucky
 

·
Registered
Joined
·
2,331 Posts
Good Info on using the 2 step as a launch "softening" tool. I was always going the other way thinking the lower launch rpm would be easier on the tires....

Thanks guys.

The lower I set my 2 step the harder mine hits the tires because it flashes the converter higher when the nitrous comes. If I raise my 2 step it doesnt hit the converter so hard and it doesnt flash as high making it easier on the tires.
 

·
Registered
Joined
·
4,453 Posts
Kroid yes its back together!! I plan on making some shake downs in Hattisburg Ms in march we found out a lot of things that were wrong with the car, the chasis shop in Michigan had set the rear suspension up total wrong!!!! When they lower the car it tru the IC completely out of wack an the angle of the upper ARM were screwed up as well and with all of the going on the rear was binded up!!! He also had preload in the right side upper arms with pulled that side of the car down, when we took it a loose that hole side snaped up!!!!! The new shop said John force couldn't drive it like that...Loi I was lucky
good news
 

·
Registered
Joined
·
527 Posts
How low can you set the rpm on the launch limiter and still be safe when the nitrous comes on?
 

·
Registered
Joined
·
6,825 Posts
I assume you are referring to the 2 step (launch limiter). Don't know what might be 'too low', but I don't think I'd set it much lower than 3500. Just my 2 cents.
 
1 - 20 of 21 Posts
Top