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Postby David Gentleman » Sun Aug 06, 2006 4:02 pm

You have to remember, gearbox wise, the main people that have had problems are the GT40, kitcar brigade, with naturally aspirated high torque engines, and even bigger rear ratio due to them running things like 265-60-15 tyres - very over tired...

End of the the day, bhp ratings means nothing, its all torque related. 350lb ft is a ideal maximum safe limit - the Venturi 400 and Lotus V8 can run over '400bhp' with no problems, but the torque needed to make 400bhp at higher rpms is still only in the 350lb region..where as Peters car only makes say 260bhp, but has the same torque. It could do as much damage as the 400bhp Venturi to the gearbox if treated without respect..

It all comes down to where your torque is, how hard you launch, and mechanical sympathy..

What could be changed to Peters map, is to run a little less advance down low, to reduce the peak torque back down to around 300, then run slightly more boost to bring both the torque and peak power up again.
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Postby peterg » Sun Aug 06, 2006 6:44 pm

I'm glad youre all concerned about my lovely gearbox!! :lol:

What could be changed to Peters map, is to run a little less advance down low, to reduce the peak torque back down to around 300, then run slightly more boost to bring both the torque and peak power up again.


Sounds like a good idea.....once the car is up and running...maybe over the winter. Last event of the year in October at Kames is all about low down grunt.....will keep it til after that! Ive got a championship to win :D
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Re: Transmission worries!

Postby Stunned Monkey » Mon Aug 07, 2006 12:22 am


Torque don't mean diddly on the drag strip...


okaaaaaaaaaay...

Accelleration is about torque, top speed is about power. (the words of someone infinitely more wise than me). This is -why- the PRV powered cars always look so slow on paper then whip everything else on the road, it'a a torquey little lump :-)
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Postby Stunned Monkey » Mon Aug 07, 2006 12:27 am

David Gentleman wrote:
End of the the day, bhp ratings means nothing, its all torque related. 350lb ft is a ideal maximum safe limit - the Venturi 400 and Lotus V8 can run over '400bhp' with no problems, but the torque needed to make 400bhp at higher rpms is still only in the 350lb region..


Hell no - the V8 Esprits will bust their gearbox and twist their own driveshafts off at stock 350hp. The Esprit uses the 3.89:1 final drive too. I dunno that there are enough 400GT's out there to know if they have reliability issues :-)
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Re: Transmission worries!

Postby David Gentleman » Mon Aug 07, 2006 10:04 am

Stunned Monkey wrote:on paper then whip everything else on the road, it'a a torquey little lump :-)


...we said drag strip....

If Petes peak torque is at 3000rpm, but he launches at 5k, and then when he changes up in each gear his revs drop to 4500 each time, then when is he going to make best use of his peak torque?

:wink:
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Postby David Gentleman » Mon Aug 07, 2006 10:10 am

Stunned Monkey wrote:
Hell no - the V8 Esprits will bust their gearbox and twist their own driveshafts off at stock 350hp. The Esprit uses the 3.89:1 final drive too. I dunno that there are enough 400GT's out there to know if they have reliability issues :-)


Can't be that easy Martin, I have two friends with Lotus V8's and are both are old now, 1996 models, and never had a problem, its not like its a 'common' fault otherwise there wouldnt be any V8's on the road. People have broken UN1s on 150bhp Renault 25's, Like I said, it is all down to how you treat it...

The Lotus's run a triple plate clutch, so any abuse will go through the box instead of inducing slip..
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Postby gt5 » Mon Aug 07, 2006 11:37 am

It would be nice to see a 12 second GTA going down the 1/4 mile :) give it a try peter when you get time off the championship, and the car sorted of course :)
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Re: Transmission worries!

Postby gt5 » Mon Aug 07, 2006 11:45 am

David Gentleman wrote:
Stunned Monkey wrote:on paper then whip everything else on the road, it'a a torquey little lump :-)


...we said drag strip....

If Petes peak torque is at 3000rpm, but he launches at 5k, and then when he changes up in each gear his revs drop to 4500 each time, then when is he going to make best use of his peak torque?

:wink:


What torque was peter getting at 4500? still must be pretty decent at those revs, is a power plot going to be posted? or is it wait n see for the new turbo, would be nice to see one before the turbo upgrade ect :?
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Postby David Gentleman » Mon Aug 07, 2006 11:59 am

Im waiting for the plot to be emailed over..
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Postby clee » Mon Aug 07, 2006 12:02 pm

Where's that John Lane thread again ........................ :lol: :lol:
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Postby David Gentleman » Mon Aug 07, 2006 12:12 pm

clee wrote:Where's that John Lane thread again ........................ :lol: :lol:


lol, ive lost it. Felt like 360ft/lb though.... :lol:
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Postby Stunned Monkey » Mon Aug 07, 2006 7:39 pm

David Gentleman wrote:
Can't be that easy Martin, I have two friends with Lotus V8's and are both are old now, 1996 models, and never had a problem, its not like its a 'common' fault otherwise there wouldnt be any V8's on the road.



All I'll say to that is - they're not trying hard enough :-) Ring Kevin at GTO and let him tell you all about the V8 boxes he's done or sold gearsets for. It's over 100.

Let Dan tell you about the twisted driveshafts on his old 2.2 4-pot.

Hey - I truly hope I'm wrong!!!

Tony's car is fun :-D

Martin
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Postby David Gentleman » Mon Aug 07, 2006 7:47 pm


All I'll say to that is - they're not trying hard enough



Yes, and that is a good thing...hence my point about mechanical sympathy.. :)


Let Dan tell you about the twisted driveshafts on his old 2.2 4-pot.



Ive heard about Lotus driveshafts..luckily we dont run them.. :lol:
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Postby David Gentleman » Mon Aug 07, 2006 10:09 pm

Here it is..

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Slightly more torque than 360 at the flywheel. Worked out at just over 300lb/ft and 210bhp at the wheels...

Peak power is only at around 4500, so its starting to hit the breathing limits of the engine, so better turbo and more boost is the only way forward.
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Postby peterg » Tue Aug 08, 2006 8:02 am

The 258bhp was only a projection......due to the set up he has he isnt able to calculate transmission loss so he added 20% which is a very conservative estimate considering the 255 width rear tyres and the UN1 box.
If anyone else is interested in getting the ECU fitted, Jonathon reckons he can easily do it in a week...drop it off on the weekend, get the train home and collect it next weekend :D Mine cost £740 for fitting mapping and the sensors and throttle pot mount he made......he will beable to do it for less now he has the hang of things.
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