Lotus Elan

Racing Spring Rates etc

PostPost by: davidholroyd » Mon Nov 01, 2010 9:51 am

Hi,

What would now be recommended spring rates and ride height for a full race Elan running on Dunlop Historic tyres M section to Appendix K rules ..

My car still has a standard ride height and relatively soft springs ... 2.03.2 Oulton this year with 163bhp with a great torque curve .. as it was used by me as a historic stage rally car for many years. What power does a front running car have on points / wet sump and what do they rev to ... my tops out at 7900rpm

At Donington this weekend the car was terrible through the craner curves ... it did not sit down and I had to lift off way too much ... racing a 911 and a 968 a few years ago I could take the craner curves as near as damit flat... is this shockers or ride height ? ( tyre pressure 24 all round )

All so I would recommend any 'racer' in the UK to the CSCC ...either their Appendix K race series or their Swinging Sxties, great fun and for a 30 min practice and a 40 min race fantastic value for money. If you want you can enter both in the same day.
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PostPost by: rgh0 » Mon Nov 01, 2010 11:11 am

Spring rates are a combination of personal taste and the tyres / track width you run. Maximums go up to around 300# fronts and 200# rears with 25mm front roll bar in a wide track Elan with slicks. With an historic Elan on dunlop historic tyres rates will be closer to that used by 26R's originally i.e. approx 150# fronts and 110# rears and a 23mm roll bar. You can go harder but it a personal choice of the driver on what he likes in the end and what suits the tracks you run on.

Ride height is as low as you can go while still having clearance given supension movement. I run my car around 110mm which gives me 70mm under the exhaust.

Maximum revs is up to 9000rpm and more but engine life is short at these revs if you use them regularly. I limit myself to 8300 rpm which gives me a good long engine life ( 20 plus race weekends).

Power possible is up to around 180 to185hp for a 1600cc European historic compliant engine in an Elan with the exhaust you can legally fit in without body work mods. You can get this power between 7000 and 8000 rpm. A little more is possible at higher revs but the trade off in torque at lower revs makes it generally slower around a track in an Elan. Engines with bigger ports than possible in the original castings and big 1.7 inch inlet valves can get more useful power but this is technically not compliant with what I understand are the European historic rules for Elans

cheers
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PostPost by: cabc26b » Mon Nov 01, 2010 1:18 pm

+1 on the personal tastes comment - FWIW - I have 225/150's and a 7/8" bar on the S1 . The S2 ran with a bit more spring front and rear and a 1" front bar , the S2 ran rod-ends everywhere, with 6" rims and 7x22x13 avons - I would think you would be better off closer to the S1 , maybe dag can weigh in.

Horsepower and revs -

I have not seen the horsepower that Rohan mentions out of a 1600cc fia motor between 7000-8000 rpm. 170-175 seems to be the norm. I have heard from some that the commonly used 421 exhaust tops out at 175hp -

My fia "illegal" motor made 179 horsepower - bigvalves drysump 1604cc , 4 into 1 exhaust with 2.5" collector.

As an aside to get 180 hp out of 1600 at 7500 rpm pegs the Volumetric Efficiency in a range i can't see a twincam achieving.
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PostPost by: rgh0 » Tue Nov 02, 2010 12:04 am

[quote="cabc26bI have not seen the horsepower that Rohan mentions out of a 1600cc fia motor between 7000-8000 rpm. 170-175 seems to be the norm. I have heard from some that the commonly used 421 exhaust tops out at 175hp -

My fia "illegal" motor made 179 horsepower - bigvalves drysump 1604cc , 4 into 1 exhaust with 2.5" collector.

As an aside to get 180 hp out of 1600 at 7500 rpm pegs the Volumetric Efficiency in a range i can't see a twincam achieving.[/quote]

Yes I was forgetting the small maximum inlet valve size allowed in a FIA legal motor ( we dont have that restriction in Australia) and that would probably limit you to to the 170 to 175 hp range up around 8000 rpm

cheers
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PostPost by: Dag-Henning » Tue Nov 02, 2010 7:11 am

Guess this is up to personal taste...... My taste is around 250/170 springs, 7/8" bar in the dry, 5.25 M Dunlops. Have a bit of understeer in the wet with that set-up, and struggle quite a bit to be fast when it is slippery. I do not realy believe the "wide" Elan is very driveable in the wet. Even the Cooper S's can push you around some times...
Car weights in at FIA weight 580 kgs. As far as I have seen, all "legal " FIA engines are in the range of 170 bhp, depending on the bench I guess...Mine is 167 at 7100, and I try to keep below 7500, but fail all the time. :D That old style EN 19 crank & rods pops up on the inside of my forehead each time I catch myself around 8000...... :?

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PostPost by: toomspj » Tue Nov 16, 2010 1:26 am

I run in HSCC with Yokohamas - my weight is at 640 (roadsports weight) and so my spring rates are a bit higher than the others. I run 300-320 # front and 200 at the rear. I have run as much as 250 # at the rear but he car tended to oversteer through fast corners which made it extremely quick but rather prone to swap ends.

Springs aren't that expensive and reasonably fast to change so i think it's worth experimenting a bit on a track or test day to find out what you like. I don't know about the other guys but mine is very sensitive to Shock absorber settings at the rear end.

I use DCOE 40's (regs) which limits my power and revs - around 170 bhp (155 at the wheels if I believe the rolling road) and it runs out of revs at around 8300 rpm (I regularly shift at just over 8000).

I'd like to try the CSCC - how is the driving standards on the track (gentlemanly or otherwise?) I raced in the Heritage GT series a couple of times and was astounded at the williness of people with $1million Astons to mix it to the point of serious damage.

Paul
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PostPost by: davidholroyd » Wed Nov 17, 2010 3:11 pm

So far the CSCC club driving standards have been great ... good clean fun. Most of the guys build and repair their own cars so bad driving is not a problem. I think the more money people have the worse the driving as they can afford to bend it and be out next week in another car. I raced with the Porsche club for a year and the driving standards at the front were very bad ... lots of bad accidents.
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