Low MPH in the 1/4

[coopz06]

I have been reading the posts about trap speeds in the 1/4 and my speeds are much lower than most posts. My fastest trap is 111.89 MPH with ET streets and I run at Houston Raceway Park. The car (03 Z06) is stock except for wheels and tires. I launch the car at 3500 RPM, speed shift through the gears (shifting at 6000 - 6200 RPM) and run consistant 12.5x with 1.8x 60 ft times. I have about 70 passes on the car and can't trap higher than 111 MPH. Is it my car or driving style that is hurting my trap times. Please post your opinions.

Thanks.

[Paul]

Coop,

With ET Streets you could/should be a little more aggressive on your launch. With BFG DRs I launch between 4500 and 4700 and, on the occasions when the track is prepped very well, around 5000 rpm. I run 15 lbs of air my my BFGs and my 60' times are now consistently in high 1.60s. You should also try shifting around 6500 rpm rather than 6000 to 6200.

Before I modded my car I was trapping between 111 and 113 mph in summer months. After putting in a Vararam and Borla and in much cooler weather I'm trapping 115-16 mph. So, I don't think you're that far off the mark considering your location/weather.


Paul

[RandyN]

Try staying in third as long as possible. I raised my rev limiter to 6800. The key to high traps is winding out third. My best mph when stock(Misc bolts ons) was 117.3 in 100 degree weather with ET streets.

Good luck
Randy

[McRat]

Our car ran 110 at it's fastest when we got it. I autotapped some passes and found that WOT timing was about 14-15 degrees!!!

Why?

Your Intake Air Temp sensor (IAT) is built in to your metal-bodied MAF. It gets heat soaked sitting in staging lanes. My IAT was reading 150 DEG at launch. There is a table in the PCM that pulls timing based on IAT, up to 9 deg.

I used LS1Edit to zero out the IAT Retard table, and MPH immediately jumped to 114. This is what got me into the 11's for the first time. Yes, I was running 11.9x at 113-114 mph on a 1.75 60'.

Like above:

Launch harder - 4500 is a good start point for a typical track.

Shift higher. I recommend shifting at 6600 rpm or higher, but that means you need to remove your rev limiter. If you don't want to, shift at:

1-2 = 5800-6000 (tach lag will often hit the limiter at 6000 observed).
2-3 = 6300 (lag means about actual 6400)
3-4 = 6500 (Actual limit is at 6600).

[coopz06]

Thanks for the replies, it sounds like my trap speeds are in line with my driving style and conditions.