Drag/Acceleration Mods to improve ¼ mile times and unofficial track thread

[Terry@BMS]

Using IAT spoofing will increase boost more effectively than increasing the boost target?

During very cold weather it can be useful to get a little more boost presuming the octane will support it.

 

[Tonkabob]

During very cold weather it can be useful to get a little more boost presuming the octane will support it.

This morning IAT spoof certainly worked better than boost spoofing. (Jb4 stacked with ECU tune). Best spoofing was 11.63, timing looking a little off.
Switched to IAT spoof only and ran 11.54, 11.51 with smooth timing, added 1PSI at 6K and up in addition to the IAT and back to 11.67 and wonky timing.
Still need that 11.49! 2 - 11.51s now.
So mixing the IAT with less boost spoof might help you Xot1?

 

[Terry@BMS]

I thought it would. Log?

Maybe another +10F on the spoof will get you there?

 

[Kato_the_kia_stinger]

Man, that DA is to die for!

 

[Tonkabob]

I thought it would. Log?

Maybe another +10F on the spoof will get you there?

Just below 85 iat had the 11.51, next run just over 85 iat and hit the 5k rpm torque limit in 5th gear, so still riding right on the edge.

 

[Terry@BMS]

Ah got it, that darn torque limiter in your flash. Hopefully it's fixed soon!

 

[Tonkabob]

Man, that DA is to die for!

Should be one of the best days of the year around here. Tomorrow is about the same maybe better.

 

[xot1]

This morning IAT spoof certainly worked better than boost spoofing. (Jb4 stacked with ECU tune). Best spoofing was 11.63, timing looking a little off.
Switched to IAT spoof only and ran 11.54, 11.51 with smooth timing, added 1PSI at 6K and up in addition to the IAT and back to 11.67 and wonky timing.
Still need that 11.49! 2 - 11.51s now.
So mixing the IAT with less boost spoof might help you Xot1?

View attachment 34720

I just gave my IAT wires to a friend that needed it for a new JB4 install yesterday. Need to order them again.

 

[Terry@BMS]

It's just a wire with a 1k resistor soldered in to it, easy to make yourself in a pinch.

 

[Tonkabob]

Sorry i didnt get that Thanksgiving 11.49 i was shooting for but did run another 11.51 the day before thanksgiving. Temps got a little too cold 22-23 degrees and the trans was also having issues either from the cold or my big burnouts or both. Trans is fine now.
25 seems the limits for the 4s to get traction.
11.49 before the new year if i get some dry days.

 

[Terry@BMS]

The trans is definitely the weak point with the platform. Curious to see how that 600hp lap3 turbo kit cars are holding up doing 1/4 mile runs, etc, on the factory trans. Or if they've developed a trans flash that helps.

 

[xot1]

No TCU mapping yet, they just remove the RPM limit AFAIK. Most big turbo with 600+WHP (7~8 cars so far) don't do drag racing so its hard to know how the transmission holds. Next year we will have more info.

 

[xot1]

I have a question for those doing drag racing with RWD cars.
What wheels/tires would you recommend?
Currently I have 19" wheels that weigh 19lbs in the rear. Width is 8.5J (same as stock) and I have 245s PZ4 (narrower than stock).
I want to get myself a pair of wheels/tires that I would use only for drag racing and I wonder what would be the better option.
Go 18"? or stay 19"? what tire width? Going too light on the wheel/tire may only increase spin. Going super light and using JB4 boost by gear is also one option..
Have any of you found the sweet spot for 480~500whp RWD cars?

 

[Terry@BMS]

18" with drag radials, or 17" if you don't mind modifying the sway bar end links!

 

[xot1]

18" with drag radials, or 17" if you don't mind modifying the sway bar end links!

What tire dimensions would you recommend?
Is it for the sole purpose of reducing rotational mass?

 

[Tonkabob]

In the rwd, the tire hook up will be more important than the rotational weight so go wide. 285s or bigger. 18s have a bigger side wall for more flex and more road contact.
I have some 275 30 19, 245 35 19s arriving for my awd today.

 

[xot1]

What about rolling resistance? 285 is quite wide..

 

[Tonkabob]

1/4 mile the launch still more important but you may lose a mph or two top speed, as in 178 instead of180 mph not in the 1/4.

 

[Terry@BMS]

What tire dimensions would you recommend?
Is it for the sole purpose of reducing rotational mass?

It's tricky to get 17" rims that fit. But if you can go 17" you get a larger selection of tires, lower rim weight, more tire sidewall to absorb the launch, etc, etc.

 

[Rakker]

I have a question for those doing drag racing with RWD cars.
What wheels/tires would you recommend?
Currently I have 19" wheels that weigh 19lbs in the rear. Width is 8.5J (same as stock) and I have 245s PZ4 (narrower than stock).
I want to get myself a pair of wheels/tires that I would use only for drag racing and I wonder what would be the better option.
Go 18"? or stay 19"? what tire width? Going too light on the wheel/tire may only increase spin. Going super light and using JB4 boost by gear is also one option..
Have any of you found the sweet spot for 480~500whp RWD cars?

I have a RWD and traction even at the drag strip is an issue with the stock tires and having mods. I just went to 18" wheels and will be using some 285 drag radials this coming spring. Unfortunately it's too cold here now for the drag strip so I'll have to wait until the spring to see how much the new wheels and tires work.

Here's a link to my setup
Aftermarket Wheels