i think if you get a good launch down in the 1.6 range and dont bog then you will have a higher MPH than say if you rip off a 2.2 60'... is this correct?

i see no other way to explain the 110 mph+ trap speeds on bolt on cars other than their extremely low 60's. also why Frank95Z can run a 11.42 at 116 mph with a small cam...his 60' is like 1.49!!

 

I am also curious on this. I saw a post on LS1tech a while back of a stock ZO6 going 119MPH and then he put ET streets on and could barely muster a 118mph?

 

This is MY experience, but the better 60ft my car cuts the lower the mph is.

I guess the only way I could halfway explain it is. If you are spinning your tires, you are not going to move that far on the track but you will build speed so that when you finally get traction you have built up mph with out going that far, instead of dead hooking and going. I do not know if this is the right way to look at it.

 

well that is how i used to think of it but the #s just dont add up when you look at some of the guys running really low ET..they all have really high MPHs and all this seems to corrispond with low 60's.

it just seems if you can launch out of the hole at 5k and keep the RPMs up then you should have a great run and high MPH b/c you dont bog.

 

On my low 11 sec runs with a 150 shot of gas it works the same for me. If I get a little worse 60ft time my mph goes up. I leave the line around 4000rpms on na and nitrous runs and don't bog either way. When I had et streets instead of slicks my mph was even higher, I wasn't getting good traction with et streets.

 

That is weird. The lower 60' we get in our Z, the higher the trap speed.

This is something I have really been pondering about.

Case in point. let's take the following in consideration....

On the 96Z, my brother has a huge problem with traction. His experience tells me the following he spins part of first, and second, and by the time he hits 3rd, the car bogs. He then tells me something is wrong with his ignition.

I counter by saying (and proven it) that if he is spinning first, the car is 1.) not building speed. 2.) He is climbing through the rev's......., he then shifts to second, the car is 1.) speed is lower than 1st gear is capable of, 2.) revs are not in proper range, but gear is low enough to pull hard anyways......as he goes through second gear he still spins even more, revs climb, and then comes shift to 3rd.................car bogs/does not pull as strong as rpm's are not properly matched as actual speed of car puts 3rd gear out of optimal rpm's range.

I run the car myself, go through first with a hint of wheel spin, shift into 2nd, baby it a little as i climb the rev range, little spin....shift into 3rd in with speed adequate to be in 3rd gear's optimal rev range.......get better times, and trap higher than he does.

So in fact, if we effectively climb the rev range through all gears without spin you will.....1.) max out top speed at every given gear. 2.) build actual car speed through the whole rpm band 3.) avoid time-robbing hesitation, wheel spin, 4.) Trap higher!!!


Ofcourse this will only hold true to certain point as raw power is the final deciding factor.


If you spin tires, you are not building speed!!! how could you if you will only stop spinning if you lay off the throttle at the same speed you started spinning. The actual speed of the car remains the same regardless what you car thinks it is going because the tires are spinning faster than what the car speeds would otherwise indicate!!

Speed is not how fast your tires turn, it is how fast your car is moving!!

 

So you are telling me that you have never been in a car that was moving forward while spinning tires? If you have been in a car that is moving forward while spinning tires, since you are moving you are gaining speed, unlike leaving from a dead stop.

I can spin well into 3rd gear but I know, without having to ever take my foot of the gas, that the car will stop spinning when I get near the end of 3rd gear. I am talking about cars that you can spin in first for like the first 5 feet and even though you never let of the gas you stop spinning. Not 500hp cars that would net 3 sec 60ft times from spinning so bad.

I was not talking about spinning through 3rd gear. I was talking about 2.0 60fts compared to 1.6 60fts I get. If you have that much spin you will not see low 2 second 60 ft times.

I know if I use the 150 shot on street tires my mph would decrease because I would not be able to go WOT till past the 1/8 mile which would kill my 60ft times. But my highest mph's have come on my higher 60ft times.

I know what speed is. But you are moving forward and even though you might not be able to understand this your car is gaining speed even though you are hitting the rev limiter while spinning the tires.

 

Sax,

That is not totally true.

You quote:

"I know what speed is. But you are moving forward and even though you might not be able to understand this your car is gaining speed even though you are hitting the rev limiter while spinning the tires"

The speed you talk about is not speed being build by the tires but just pure momentum the car built while it did have traction.

On a even playing board, two similar hp/weight/gearing cars will perform diffrently by the following fact.

If car 1 is climbing its rpm band without spinning tires it is faster than car 2 if car 2 is climbing the rpm band while spinning tires.

Car 1 simply is building speed more rapidly because it is using its full gearing/hp potential most effectively because of good traction.

You are saying because the spinning tires are rotating faster than those of the non spinning car, the non-spinning car will be faster. Then how is it, that the spinning car is going faster, if the tires are spinning as if they were in thin air. How is the car building speed faster if the tires are spinning faster than the car speed indicates?

Law of dynamics man!!

 

heres my $0.02 cdn worth

before i got slicks, on kumhos i was trapping around 113 @ 2.1 60'
on BFG DRs i trapped 114.5 @ 1.97 60' (ran once)
on ET streets i trapped 114.7 @ 2.0 60', and 115.7 @ 1.84 60' ..

(edit: my bad, i just rememberd that i got a dyno tune before i ran 115.7 and gained about 30 hp, though on the same day, the lower my 60', the higher my mph was )

now, the higher mph could be related to lighter wheels and tires in the back (15" welds and ETs are a LOT lighter than 16" salads and DRs) .... thats one way of looking at it .. or u can just say that my lower 60' times made my mph higher

but lets think about a hypothetical situation where the track is made out of raspberry flavored jell-o till the 1/8 mark... u launch and get upto 6th gear red line doing 220 mph spinning on jell-o .. u hit the 1/8 mark and ur tires are spinning at 220mph, and ur car is going 100 mph, whats gonna happen !? (say u got enough hp and wont bog, and wont break nothing etc) BAM, cars gonna shoot out and get up to 220 by the 1/4 mark

now all these numbers are exagerated .. but u get the idea !!!

though this is AGAINST my personal experience at the track.. but i agree with SAX on his explanation ...

maybe i'll put on some light street tires and just roast the sh*t out of them for the hell of it and see what will happen...

or maybe i'll just hold the line lock and get it upto the top of 3rd and then go.. i bet i'll be getting halfway into 5th by the time i get to the end of the track ..

 

I can dump the clutch in my car in first gear, trust me their is no traction(not even for a millisecond), and the car still moves forward. I am not saying a car spinning the tires is gaining insane amounts of speed or is going to accelerate anywhere near what a car is going to accelerate at.

Here is some factual proof of how my car responds to different amounts of spinning. No change in anything, just some runs on et streets and the others on et drags(both tires have the same exact dimensions).

ET Drag Run

r/t-.753
60'-1.652
330'-4.956
1/8-7.725
MPH-87.92
1000'-10.134
1/4-12.144
MPH-110.10

ET Street Run(less traction and some spin)

r/t-.589
60'-1.805
330'-5.122
1/8-7.835
MPH-90.27
1000-10.289
1/4-12.336
MPH-112.64

Like I said this is just MY experience. Different cars act different ways.

 

MPH is a result of HP. Good traction will decrease the ET but shouldn't change the MPH or only very little.

When I still used a 383 SBC I was getting 1.7x 60' times and running 117 mph. The 3.27 gears were a dog off the line but the top end HP gave my a huge mph since the car crossed the finish line way before it was close to the engine's red line.

Gearing and traction get you through the first 1/8 mile. The last 1/8 mile is a brute HP pull to the end of the 1/4. If a car doesn't have any top end HP then the 1/4 MPH will be low. Most cars only gain an extra 22-27 mph in the last 1/8 mile.

Even top fuel dragsters only gain about 60-70 mph in the last 1/8 mile.

 

My exprience has been that if you improve your 60' time your final et is better but your mph is lower. That said, your average mph over the run did increase though...thats how you get there in a shorter time with a lower final mph.

There is alot of other variables that can result in better 60' and higher ending mph as well as higher ave mph....so I dont think there is a "right" answer other than to lower your et you have to increase your ave speed.

 

a car will generally run between 78-80% of the 1/4mi trap speed in the 1/8th. You also have to remember that tq will help accelerate a car out of the hole and if your car doesn't have enough of it down low, the MPH will probably hurt some.

 

To me it makes sense to have a faster mph if you have a good 60' time. If you get to 60' sooner rather than later it would imply that you either a) reacted faster and/or b) Got there faster (hooked good and accelerated quickly). This gives you more time to build up speed by the end of the 1/4 right? I'm assuming this is based on hooking and doing "X" time compared to not hooking and doing a slightly slower "X" time. If you were to do the same 1/4 mile time tho and have a slower reaction you would need to "catch up" and do a faster mph to make the same time had you reacted faster.... oww my head hurts -=/

 

Your reaction time has nothing to do with et.....the clock for the et doesnt start till you break the RT beam. Thats howcome you see a car with a slower et beat one with a faster et in a headsup race on occasion.