ET vs trap speed

[03E39LemansBlue]

I was watching Mr. Blonde's video (I think) of him at the drags. (streetradials.avi , its a pewter Mcoupe). When he raced the muscle car in the second pass, a question came up. The muscle car ran an 11.0 at 122, whereas the Mcoupe ran an 11.9 at 132. Where does this disparity come from/ how can it be explained. I have a few ideas, but wanted a more thorough explanation.

[James]

The explanation lies in the 60' time and the reaction time. Mr. Blonde has considerably more horsepower than that muscle car, hence his higher trap speed. What he likely doesn't have are the reaction and/or 60' times of the muscle car, which is why he lost by close to 1 second.

[Glucas21]

Reaction time doesn't factor into the final time and speed at all. You can sit on the line all day and still turn an 11 second pass. The muscle car gets of the line quicker because of the torque and drag slicks, but its trap speed is not as high because of its lack of horsepower and poor aero dynamics. It also doesn't have as many gears, so it can't pull as hard at higher speed, mostly because it was never ment too.

[03E39LemansBlue]

My original thoughts were mathematical:

Car A goes from 0-100 in 6 seconds, then takes 4 seconds to get from 100-120. He spent considerable more time at high speed than car B.
Car B goes from 0-100 in 8 seconds, but because of turbo is able to get from 100-140 in the last 4 seconds. He will not be able to cover as much ground, though he will be going faster at the end. I know there is more math behind this than the simple example I am giving, but I am fairly confident that this is more likely the way it works.

It is also my understanding that reaction time is not factored in.

Drag slicks would definately help off the line, although I'm not sure of their importance except at shifts (beyond say second gear). There is probably some more to this aspect.

Does anyone else have any ideas? I am/was under the impression that it is possible to get drastically different ET with similar trap speeds, and visa-versa. Please, teach me something (and if Mr. Blonde reads this, could you chime in too?).

Thanks

[1q2w3e4r]

Could be also that Mr Blonde accelerates as quick as the muscle car except Kenny's got a shit tin more wheel spin!

The M Coupe spins through 1st, 2nd, 3rd gears. It still spins first and second I believe with the slicks. When it grips thats when it starts moving.

It's since run a 10.7 first run out on slicks.

Kenny you around to explain this?

[MrBlonde]

Trap speed is a close indicator of horsepower; the more horsepower your engine is making the higher your trap speed. My M Coupe makes a lot more horsepower than the Mopar (owned by my friend Jayson) which is a 392 small block or the 302 powered Ford Capri with wheel tubs.

ET is determined by a lot of factors, including your car's suspension and rubber as well as your launch abilities.

In the case of the two runs against the Ford Capri racecar (pass 42 and pass 45) he was running huge slicks and a three quarter chassis, along with no exhaust and C16 fuel. I had my drive every day street radials, a full street exhaust and pump gas.

With race suspension and huge slicks you're going to get off the line fast! And with street radials I'm trying hard not to wheelspin for the entire quarter mile.

Pass 42: Ford 60': 1.606 M Coupe 60': 2.285 (launch RPMs 3250)
Pass 45: Ford 60': 1.578 M Coupe 60': 2.176 (launch RPMs 3000)

So even though I've got a big horsepower advantage over the small block Ford, he has a huge advantage in traction because of his slicks and race suspension. The Ford would also be a shitload lighter than my street car (maybe 400 lbs). You can see this from the pass 45 movie where my car is reeling the Ford in after half track at a rate of knots (horsepower advantage). This guy was talking to me in the pits afterwards and told me how he could see me a-comin' in his rear vision mirrors! But he got me well and truly that night.

Take a look at the movies 'patience' and 'getthatbig' which were taken two weeks later when I had my Mickey Thompson ET Drag slicks on. This was pass 45 against my friend Jayson with his Mopar. A different story:

Pass 48: Mopar -- M Coupe
60': 1.617 -- 1.600 (launch RPMs 6000)
Half track: 7.121 @ 98.02 MPH -- 7.092 @ 104.92 MPH
ET: 11.140 @ 121.49 MPH -- 10.775 @ 134.35 MPH

When your car overpowers it's tyres as badly as mine does, then slicks make a huge difference. I can also launch at 6000 RPM and get bite (as you can see from the 'getthatbig' movie).

Unfortunately the 10.7 was the last pass I was permitted to do until my car gets a full six point roll cage and other stuff to meet the ANDRA racing regulations. These come into effect once your car runs 10.999 or quicker.

I'm taking to opportunity to do some other modifications and will be back quicker and faster at the start of next season (April 2005 in Australia).