How much do 60 fts affect trap speed?

LarsD

LarsD

Founding Member
Jul 2, 2002
2,680
119
123
Texas
#1
I did a search and couldn't find anything, sorry if this is a repost.

Last weekend my car ran a little faster

14.16 @ 100 mph

2.15 60ft

As the night wore on, my 60fts were getting worse and worse, my et's and traps dropped accordingly. I'm wondering how much do 60fts affect trap speed? I'm running on Firestone firehawks right now at 26 psi (pony wheels). The car is very hard to hook up, I have lower control arms, new KYB shocks (gas-a-just) in the rear, and stock uppers. I wanted to get a couple of extra ponys to put some Nitto's or BF's on just for the track. I know my car should be trapping at least 105. So I'm wondering if my suspension/tires are working against me, or if my power is off. One of my buddies suggested that my motor may be having some trouble (like low comp) but I only have 5K miles on this motor, it gets great gas milage, runs smooth, doesn't exhibit any bad habits at all. Other than it's slow. Thoughts?

Thanks,
L.D.
 
#3
60ft's with the same car, same tune, if your 60ft's go down, you mph will also drop. A slipping car MPH will go up.

Faster 60'=slower MPH

I dont know that there is a rule of thumb about how much mph for each 10th, but it happens.

As far as your car goes, you need to get it to hook first, then tune the motor. Check the air/fuel ratio then work on the timing. Set your fuel for a safe ratio with an adjustable reg, then set your timing bumping up 2 degrees till the car slows down. You wont be able to tune without getting the car to hook. It will give false readings.
 
#4
It's stupid slow for the mods I have done. I've been fighting the tune all year, I finally got the gas milage up and cleaned up the drivability problems I've been having, but it still won't run worth beans. A 306 shouldn't be this hard to tune...
 
#5
BlooDReigN said:
I would get that thing on the Dyno and get it tuned ASAP...Seems like your times are pretty low for the mods you have done.
Click to expand...

Yeah, I agree. You have a good H/C/I combo, gears, new engine and I think it should run a lot stronger than that.

14.1 at 100mph, actually, your mph is better than the et. Not always but most cars loose mph when they get better et's and 60ft's because they have less time to accelerate. 2.1 60ft isn't bad on stock tires and suspension, with DR's you could be in the 13's but I doubt the ET's would improve much at all. MPH can increase with more traction if your not able to put down the full throttle at the starting line. Traction improved my car's mph more than it did the ET because before I had to feather the gas through first and softly shift into second or it would spin out, with traction, I was able to put full throttle down once I got the clutch pedal all the way out. I am still only launching around 1700rpm but that's just enought to get the weight transfered for the engine to put it all down.

If your only going to run the tires at the track, either get some slicks or ET Streets, DR's you will like more on the street.
 
#6
90mustangGT said:
MPH can increase with more traction if your not able to put down the full throttle at the starting line. Traction improved my car's mph more than it did the ET because before I had to feather the gas through first and softly shift into second or it would spin out, with traction, I was able to put full throttle down once I got the clutch pedal all the way out. I am still only launching around 1700rpm but that's just enought to get the weight transfered for the engine to put it all down.
Click to expand...

Well, that's kinda what is happening. Almost all of 1st is wheelspin, I feather the clutch and gas, and I get slower, if I just spin out of the hole, my 60fts get better, but they don't stop spinning until 4000-4500rpm. I'm planning another trip to the dyno anyway, but I was thinking that my tires couldn't keep up with the 4.10's.
 
#7
LarsD said:
Well, that's kinda what is happening. Almost all of 1st is wheelspin, I feather the clutch and gas, and I get slower, if I just spin out of the hole, my 60fts get better, but they don't stop spinning until 4000-4500rpm. I'm planning another trip to the dyno anyway, but I was thinking that my tires couldn't keep up with the 4.10's.
Click to expand...

Well if your tires stop spinning at 4000-4500rpms...it seems like your losing power at those rpms (and possibly above)...your a/f ratio could be off (which is in the tuning)...that is just a suggestion (as I don't know your car)...on what could be wrong...

I know on my stock h/c/i (in a 1st gear dump)...mine would quit spinning around 5500rpm...which is usually where a stock h/c/i car will "stop" breathing which is where the power tapers off and helps regain the lost traction...
 
#8
i've got the same problem as you and almost the same combo. However my car's an aod. It runs 14.2's @ 101 all day with 2.3-2.4 60 foots. I got it to run a 2.2 60 foot on one pass and got a 13.8 @ 102. So i'd say that mph goes up with traction if your having bad traction issues. Mine will spin all of 1st and all of 2nd on the street. At the track it does all of 1st and half of 2nd on street tires.
 
#9
from what ive seen and experienced, your trap speed will go up the better the 60ft, up to a point, say like up to 1.8ish, then the trap speeds begin to come down some. Really depends on the car. Spinnin 3rd gear is a much bigger problem on dropping MPH in the 1/4 since your not really accelerating much but you have decent speed to where your losing more ground to actually accelerate when you do finally catch. kinda hard to explain if you dont already get it. get it?
 
#10
and your 60's arent that bad, you might have 1mph left in it, MAYBE 2 tho i doubt it, with that tune, unless your really spinnin 3rd. There have been times where ive gotten about 2.1's low 2.2's 60's but spun 3rd REALLY bad and end up losin like 4MPH in the trap. So what was the baro, temp, dew point and all that other good stuff? That could be some of the cause for the lost power, if there is any.
 
#12
LarsD said:
Guess I gotta get a WB back on it. I have a TwEECer R/T that I've been using. I thought I had my tune nailed down, but it's still way to slow (obviously).
Click to expand...

Just an idea here...but how are you at driving...a slow shift can do bad "wonders" on mph...and where are you shifting at?
 
#13
id say get good tires, my car can't be floored in first or second when racing, it just breaks loose, even when i do it gradually, you need to find the limit of your tires, then go to it, and don't powershift or dump the clutch in first. try launching in second, you may have too much gear for your tires, and if it works better, get better tires(wider+softer).
 
#14
Your 60' is normal for stock suspension.

You time is waaay slow though for what you have. I have most the same kind of stuff (no heads/intake) in a heavy (3600 lbs!!!) convertible and run high 13.70's at 99 mph all day long without pulling anything out of the car or doing cool down, shortbelt, etc...

Something is not right.
 
#16
TrickStang37 said:
well dont look at the times, just worry about the MPH's right now.
Click to expand...

Yep...the mph shows the power...the time is usually power and traction...

Look at the mph and once that is addressed then start working on getting the E.T.'s lower...
 
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