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Discussion Starter · #1 ·
Hi,

I'm planning to go to the drag this week to do the quarter mile.


I did some research over the internet and the Lotus Exige S 220HP should make it in 12.8 and 13.2 at around 105MPH according to different magazines and website.


I worry about two things because I never did the quarter mile with any of my cars before.


1. What should be my RPM in Neutral before to start and drop the clutch ?

I was thinking about 4500RPM ...


2. What pressure ( PSI ) should I have in my tires Front and Rear for the drag.

Right now I'm having 26PSI Front and 29PSI for the rear but do I have to remove some pressure to get a better start or not ?


3. I saw the other day some people that used Ice cubes to cool their engine,radiator or intercooler. Is it worth it to do that ?
 

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Don't do it.

1. You'll damage your IC (hood arm will hit IC as the motor moves a lot during hard shifts) - suggest you remove the hood arm before doing any hard shifts.
2. Drivetrain and half shafts aren't designed to for hard launches.
3. You'll void warranty (if you still have one).

Having said that, I did a 1/4 mi drag day once (got about 3 runs) - running best of 12.2 but in the process pretty much destroyed my stock clutch. I was running about 255 wHP at the time (Engine #1). Tranny has never sounded the same since.

Bags of ICE will help, but ONLY if you start the car just before your ready to hit the staging lane, otherwise engine heat from idle will remove any benefits of cooling the intake/IC.

Launch RPM will vary based on track conditions and power/torque curve of your motor -- in my case I'm making close to max Torque around 4000 rpm so in theory that's my target RPM to keep during clutch release. I've done a few years of drag racing, but I'm certainly no expert, I'm a road racer not a 1/4 mi guy.

I can show you a pic of the damaged IC thanks to that hood arm/shock.

As for drag times, stock was anywhere from 12.5 to 13.5.

Rob
 

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There is no one correct rpm to drop the clutch. It depends on your grip and that depends on the surface, your tires, temps, etc.

In general, more grip allows a higher rpm launch and you want as high an rpm as you can go and not get too much wheel spin or hop. You want just a little wheel spin. If the car hops, you can break things. Too low can induce a hop also.

You have to experiment and be ready to quickly adjust at the lights.

I would start about 4000rpm. Colder? Drop to 3000. Rain? Drop to 1500.

Dont worry about pressures. That also will vary depending on the tire and the temperatures/grip.

Cooling is good.

And yeah, it is not easy on the car. I did over 100 launches on the Elise at SCCA ProSolos.
 

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Discussion Starter · #4 ·
Don't do it.

1. You'll damage your IC (hood arm will hit IC as the motor moves a lot during hard shifts) - suggest you remove the hood arm before doing any hard shifts.
2. Drivetrain and half shafts aren't designed to for hard launches.
3. You'll void warranty (if you still have one).

Having said that, I did a 1/4 mi drag day once (got about 3 runs) - running best of 12.2 but in the process pretty much destroyed my stock clutch. I was running about 255 wHP at the time (Engine #1). Tranny has never sounded the same since.

I can show you a pic of the damaged IC thanks to that hood arm/shock.

As for drag times, stock was anywhere from 12.5 to 13.5.

Rob

You are right for the hood arm, it already hit one time my intercooler on a start but it was because I forgot to remove the TCS and the motor cut off suddently and that was enough to make the car shaking and hit the top corner of my IC. I will remove it if I do the drag. Thanks to make me remember of this weakness.


How come can I destroy a clutch by doing 3-4 fast start on a 3500 miles brand new car and clutch. Our car arent designed to do that ? Racing ? Hard start is part of the game no ? Lotus are proud to claim that their cars do the 0-60 in less than 5 seconds but hey you cant do it cause youll void your warranty and the car is too fragile.

What about If I drop the clutch not to hard and not revving over 4500RPM in neutral can I still do a good time and not put to much stress on the clutch and tranny ? When you did 12.5 sec you were probably doing a very very agressive start.


what about the tire pressure now ?
 

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Lots of cars have a clutch that will not stand up to hard launches. Others will have to speak to the strength of the Elise clutch under drag race conditions.

Start off slow and have fun.
 

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If you haven't dragged yet I would definately recommend skipping the clutch drop to start with. Learn the tree and focus on your shifting. Once you get that part down move on to focusing on your revs. I've always been able to rip off respectable times without clutch drops in other cars. Plus don't talk too much sh[t beforehand and you won't have that pressure. If you do, just be sure to bone out
 

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I also think the clutch is a weak point when used in this manner. Mine was. I replaced it.

And I agree with Mnnis that it is not that huge of a factor. Eventually we stopped doing higher rpm launches so as to not break mounts and stuff. In my Noble, I also will not do a high rpm launch.

But it was fun leaving Corvettes off the line in the Elise.
 

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Discussion Starter · #8 · (Edited)
<embed src="http://videos.streetfire.net/vidiac.swf?video=dceb54ef-cee8-4ad6-8436-9b3400d8d603" width="428" height="352" allowFullScreen="true" type="application/x-shockwave-flash" pluginspage="http://www.macromedia.com/go/getflashplayer"></embed><br/><a href="http://videos.streetfire.net/video/Lotus-Exige-S-2007-great_191313.htm">Lotus+Exige+S+2007+great+sound+!</a>

I did some start last year on this video for the first time but I dont know if that kind of start are good enough to get a good time on the quarter mile.

What do you think ?

My expectation is to do mids 13 secs or better. Is it that hard to make it possible. My fear woulb be to do 14+ secs which would be very slow for a 65K car.
 

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If you miss shift then worry about a 14. You should get a low 13, no revs, even in a high altitude with an S. Like I said earlier focus on a smooth run without getting fancy and your car will perform. 12-13's are not that fast- you just need to shift correctly so you don't get an embarrassing time. If you get it right it will be fun for a couple runs but then you will want more.
 

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Discussion Starter · #11 ·

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I did a 12.2 not a 12.5, but that was when I had 255 wHP and a so/so start with a less that gripy stock clutch. I've seen 12.5 to 13.5 on relatively stock 07 Exige S.

How well you do in the 1/4 mi all depends on how well you do at the 60 ft mark -- drag racing is all about the start, after that it's just going thru the motions/gears. Power shifting thru the gears gets you maybe a 1/10th, hitting a perfect launch/start gets you 1 full second or more. Also, don't be surprised if your better starts (times) actually produce lower trap speeds.

Since this is your first time out, don't be too disappointed if you get 14's. I've seen Vipers, Vettes, etc. etc. run 14's - but those drivers slowly started to improve each run and got the car close to "review" times.

My 12.2 was done with moderate rpms and quick clutch release while adding a little throttle -- it was not done with a clutch dump/drop. If you slip the clutch too much you'll smoke the clutch which can bring a early death to it, if you drop/dump the clutch with too low RPM you'll just bog the car, if you drop/dump the clutch with too high RPM you'll just spin the tires.

And finally, do you have LSD with your 07 Exige S? That will make a difference on available straight line traction and adjust your launch RPM.

Rob
 

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I'm no drag expert, but putting ice on very hot parts of your car after runs can't be a good idea. Once saw a AMG 63 run a bunch of runs and over heat. Then I saw him buy about 4 ice bags and drop them on his engine. Won't he start cracking manifolds or stress fracturing any hot metal parts?
 

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Not with ICE, maybe liquid nitrogen, but not ICE.

I'd be surprised to see a street car overheat from drag racing 9-15 seconds of accel, even with a bunch of runs back to back.
 

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It was a while ago (over a year), but I think my rev limiter was set to 8500 (maybe 8600) and I was close to toping out 4th - pretty sure it was like 111 or 112 mph. Don't recall my 60ft -- think I have the time slip somewhere.

Rob
 

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Discussion Starter · #17 · (Edited)
Hi again everybody,

I just come back from the drag tonight with my Lotus and I want to let you know the results.

I did my start with my RPM around 3000-3500 only. So it was not a hard start to break something but it started pretty well anyhow. The tires are amazing I do not got wheelspin. It goes straight right out of the box.


I did 4 run and all 4 were 13.5 seconds at 103.7 MPH.

I were hoping to get a low 13 but it never happen. If I had dropped the clutch like a monster probably I could have done better.


Now next time that I will go to the drag it will be with the Gotham ECU reflash and I hope to do 13 seconds flat.


Thanks a lot for your advice everyone!

Enjoy your car like I did tonight!
 
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