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Faster 60foot time?
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JSF55
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1955 Ford Popular 103e

PostPosted: Mon Jul 05, 2010 1:51 pm    Post subject: Faster 60foot time? Reply with quote

Right the 60foot time on the pop is crap at 2.524 Sad so what technique do i need to get 1300kg of steel off the line quicker, it runs a 4 speed hp22 box gearing works ot at about 20mph/1000rpm in 3rd which tops out at about 88 over the quarter. Is the convertor stalling out too low? i think i can just about hold it on the brakes at about 1600rpm. after that the front tyres give up Laughing
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kiwicar
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PostPosted: Mon Jul 05, 2010 2:56 pm    Post subject: Reply with quote

As far as I see it there are three factors here you can change to effect your 60
1 Grip
2 Torque band
3 reaction time in getting the brakes fully off

If you are spinning wheels off the line then you need more grip, this can be helped with anti squat suspension geomitry (if it is a 4 or 5 link set up). Anti tramp bars and slapper bars and moving shock mountings about if you have cart springs locating everything.
If you have enough grip and you aren't spinning wheels then you need more torque or be better placed in the torque band. Where is peak torque on your engine? how many revs do you have between the engine peak torque and peak power? A looser torque converter will give you more torque off the line, but if you are bearly able to hold it on the brakes on the line you may want to upgrade a bit before you fit a looser torque converter, also if you do you will probably want to gear it up a bit so you don't run out of revs at the top of the track and to make use of that part of the power curve off the line.
For the last one, light weiight footware and more caffine.
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mgbv8
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1975 MG MGB GT V8

PostPosted: Mon Jul 05, 2010 3:25 pm    Post subject: Reply with quote

What is the stall speed of the convertor? If its a road use one I suspect it might be around 1700rpm. I use a 3000rpm stall convertor.

If you have a low stall convertor and your engine responds well when going to full throttle instantly from idle, you could try launching from idle rpm. This will give the engine a bit of a run up before it hits the stall speed and may get you away a bit quicker. The downside may be less fuel economy on the road.

Is it the front tyres losing grip or are the brakes slipping a bit?

I use slicks on the rear and launch with nitrous so I can hit 60 foots around the 1.5-1.6 area.

As Mike says, you need to know where the engine is making its best torque so you can utilise this for better gear shifts.
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http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

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Coops
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1986 Ford Capri

PostPosted: Mon Jul 05, 2010 3:40 pm    Post subject: Reply with quote

i was running 2.3ish 60fts
changed to a pair of BFG drag radials and went straight to 1.8 60fts
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kev_the_mole
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PostPosted: Mon Jul 05, 2010 4:00 pm    Post subject: Reply with quote

I was thinking of improving my times by launching from an Acme Bungee Catapult. I've seen Wile E. Coyote do it and I know there's no cliffs near Podington Very Happy
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DaveEFI
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PostPosted: Mon Jul 05, 2010 4:03 pm    Post subject: Re: Faster 60foot time? Reply with quote

JSF55 wrote:
Right the 60foot time on the pop is crap at 2.524 Sad so what technique do i need to get 1300kg of steel off the line quicker, it runs a 4 speed hp22 box gearing works ot at about 20mph/1000rpm in 3rd which tops out at about 88 over the quarter. Is the convertor stalling out too low? i think i can just about hold it on the brakes at about 1600rpm. after that the front tyres give up Laughing


Torque converter stall speeds are usually over 2000 rpm.
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JSF55
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1955 Ford Popular 103e

PostPosted: Mon Jul 05, 2010 4:15 pm    Post subject: Reply with quote

I didn't expect so many replies so soon ! there's no tyre slip, my mate confirmed this, the car squats down and goes ! it's a full jag irs in there ... heavy Sad tyres currently at 20psi bf goodrich something or others Confused
The fronts are quite skinny 145x15 firestone 560's, they loose grip before the brakes will ! torque should be low down the rev band, hurricane cam rhodes bleed down lifters, standard SD1 exhaust, well to the Y piece anyway Laughing upgrade planned over the winter is too slot in a 3.9, so i might just have to curb my enthausism ....... mmmm ....nitrous Twisted Evil
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gelmonkey
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PostPosted: Mon Jul 05, 2010 7:08 pm    Post subject: Reply with quote

kev_the_mole wrote:
I was thinking of improving my times by launching from an Acme Bungee Catapult. I've seen Wile E. Coyote do it and I know there's no cliffs near Podington Very Happy


Mr Mole
You do make I larff.
Not really much help to JSF I'm sure but worth a thought though.


JSF nitrous it is then Very Happy

cheers
Paul
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JSF55
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1955 Ford Popular 103e

PostPosted: Mon Jul 05, 2010 7:56 pm    Post subject: Reply with quote

mgbv8 wrote:


If you have a low stall convertor and your engine responds well when going to full throttle instantly from idle, you could try launching from idle rpm. This will give the engine a bit of a run up before it hits the stall speed and may get you away a bit quicker. The downside may be less fuel economy on the road.

Thats interesting, as i've always held it on the brake and given it about 1500 rpm launches, i got an old video fromm shakey HRD 07
http://www.youtube.com/watch?v=2VguzAB0BfQ
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mgbv8
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PostPosted: Mon Jul 05, 2010 9:02 pm    Post subject: Reply with quote

This was just over a year ago. Before I started running more nitrous. I used to bring the revs to about 1000 and then smack the pedal down as soon as I saw the 3 ambers. This picked the revs up quick and seemed to hit the stall speed of the converter to give me a good shove off the line. Now I have plenty of gas on tap to launch at high rpm without bogging.

http://www.youtube.com/watch?v=hvC4pPC3Zws&playnext_from=TL&videos=-IyP7k_EKfA
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MGB GT + Rover V8
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Now looking for 8 seconds with a SBC engine
http://www.youtube.com/watch?v=nVscbPHgue0&list=UUqIlXfSAoiZ--GyG4tfRrjw

https://www.youtube.com/watch?v=eg3avnsNKrc&index=2&list=FLqIlXfSAoiZ--GyG4tfRrjw
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ian.stewart
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PostPosted: Tue Jul 06, 2010 5:14 am    Post subject: Reply with quote

5k launches, Toyo 888Rs, and 1.5 60 fts ------------------ but it is a manual car
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kev_the_mole
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PostPosted: Tue Jul 06, 2010 9:00 am    Post subject: Reply with quote

Ian,

what's your technique from first to second. Speaking with an old-skool racer last night he reckoned that get it moving in first and then slam into second. No point in maxxing it in first otherwise you just get more wheelspin.

Cheers,

Ian

PS This year I've got 888R SG's
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kiwicar
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PostPosted: Tue Jul 06, 2010 10:39 am    Post subject: Reply with quote

Hi
If it is holding against the brakes at 1600 rpm, doesn't that make the stall speed of the converter about 1600 rpm or did I miss somthing?? If the rear tyres are not slipping then from a purly mechanical view point it would seem a good idea to put in a higher stall converter, say 2600 stall, then he should be within 1400 revs of peak torque and be off the line much quicker, once some way has been found to get the front tyres to hold it (big bag of cement behing the radiaror?). If the back end is squatting prior to launch it might be worth raising the front end mounting points of the lower trailing arms locating the rear suspension.
Best regards
Mike
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DaveEFI
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PostPosted: Tue Jul 06, 2010 11:06 am    Post subject: Reply with quote

kiwicar wrote:
Hi
If it is holding against the brakes at 1600 rpm, doesn't that make the stall speed of the converter about 1600 rpm or did I miss somthing?? If the rear tyres are not slipping then from a purly mechanical view point it would seem a good idea to put in a higher stall converter, say 2600 stall, then he should be within 1400 revs of peak torque and be off the line much quicker, once some way has been found to get the front tyres to hold it (big bag of cement behing the radiaror?). If the back end is squatting prior to launch it might be worth raising the front end mounting points of the lower trailing arms locating the rear suspension.
Best regards
Mike


I got the impression the brakes wouldn't hold it above 1600rpm. So keep well away from the end of the strip. Wink
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JSF55
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1955 Ford Popular 103e

PostPosted: Tue Jul 06, 2010 11:13 am    Post subject: Reply with quote

kiwicar wrote:
Hi
If it is holding against the brakes at 1600 rpm, doesn't that make the stall speed of the converter about 1600 rpm or did I miss somthing?? If the rear tyres are not slipping then from a purly mechanical view point it would seem a good idea to put in a higher stall converter, say 2600 stall, then he should be within 1400 revs of peak torque and be off the line much quicker, once some way has been found to get the front tyres to hold it (big bag of cement behing the radiaror?). If the back end is squatting prior to launch it might be worth raising the front end mounting points of the lower trailing arms locating the rear suspension.
Best regards
Mike

Ideally a higher stall speed would help, just not sure whats available for the zf4hp22, i heard they come in small medium and large Shocked the front tyres are the reason it slipped over the lights in the video, not the brakes Laughing
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