Lotus Elan

CAMSHAFTS

PostPost by: rgh0 » Mon Dec 10, 2007 9:56 am

Dag
I fully agree that you need to get everything in balance. No good having a top motor if the handling is hopeless the brakes dont work, the driver useless, and it breaks down before you finish.

People tend to focus first on the engine as thats the macho bit you can talk about around the bar. How many people measure their brake temperatures ?

If searching for a quick lap time the cheapest place to find it is almost always just track time for the driver for us amateurs. I have developed my car substantially over the last few years but I am not much quicker because I just dont get the track time I did 10 years ago. I could believe that with a couple of days time on the track and help from a coach I could go 3 seconds quicker but I would loose it again in a couple of weeks unless i raced almost every weekend. I see that at every race meeting - my quickest times are invariably in the 3rd race on Sunday afternoon after a day of practice, qualifying and 2 previous races.

My order of developing a car for competiton would be:

0. reliability ( make sure what you have will finish)
1. tyres ( sticky ones that work)
2. suspension ( make the good tyres work properly)
3. brakes ( now you got it going make sure it stops)
4. driver ( now it goes and stops learn how to do it properly)
5. Engine ( now work on making it go quicker still while not forgetting to keep working on 0 to 4 also)

cheers
Rohan
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PostPost by: gordont » Tue Apr 19, 2011 8:42 am

Looking at getting some of these, I understand I need better springs - any thoughts on springs / valves?
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PostPost by: twincamman » Tue Apr 19, 2011 12:00 pm

SIMPLE SOLUTION ---DRIVE FASTER and smoother -- :wink: -ed
dont close your eyes --you will miss the crash
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PostPost by: rgh0 » Tue Apr 19, 2011 12:09 pm

Tony Ingram sells the best spring, retainer ( including titanium retainers) and valve combinations for engine development if planning to build a full race engine in my opinion.

You can buy similar from people like QED and Dave Bean and others but I prefer the flexiblity in application details and performance of Tonys components. His springs are still a little stiff for my taste but so are everyone elses - one day I will have time and money to do a run of springs that suit his retainers but with a lower spring rate to limit difference between seat and cam nose peak loads a little and make them less sensitive to installed height and cam lift changes so building a range of engine specs from a single spring pack is easier and possible

you can contact him at TONY INGRAM [[email protected]]

I have a word document describing what he sells but at 5 meg it is to large to attach - send me a pm and i will email it to you

cheers
Rohan
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PostPost by: gordont » Wed Apr 20, 2011 9:42 pm

Thanks Rohan, you have PM.

Are you off to Lotus 2011? Looking forward to some pictures....
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PostPost by: elangtv2000 » Wed Apr 20, 2011 11:15 pm

+1 on the recommendation for Tony Ingram's parts. Tony is a good friend of mine, so my opinion may be biased, but he was a supplier before he was a friend, and his parts and service are excellent. He also really knows how to build great race engines, and not just Twin Cams. His parts prices are also very reasonable. Tony will soon have his website up and running, so look for that soon.
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PostPost by: pauljones » Fri Apr 29, 2011 6:15 pm

Hi all,

I know this is in the racing section but I was wondering if i could get some advice on a standard twincam on webbers.As i will soon be upgrading to emerald fuel injection,the twink will have to be set up propery.So,keeping with a standard engine,is there a set of cams that are a straight swap in that will give a better torque curve.I was thinking a bit more lift with a short duration was the modern standard practice,but most cams available seem to build on a longer duration and not much more lift than standard.I have also been told that L1 cams are the way to go,but cant find much info on them.

Can anyone advice on a good fast road/torquey set up.Im also running the small valves,but not really sure that a big valve head flows much better,is it worth the swap to bigger valves on a non ported head?

Loads of question I know,

Paul
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PostPost by: rgh0 » Sat Apr 30, 2011 1:12 am

To get a nice fat torque curve and more power out of the twin cam you need a high lift and relatively short duration cam as you say.

John McCoy at Omnitech in the US sells a .450" lift above the base circle 280 degree seat to seat cam that works really well in my experience for both road and track use. The combination of high lift and short duration gives power out to 8000 plus rpm with race porting but good midrange torque for getting out of corners on the track.
It works well on the road in a road ported engine with standard bottom end as the good torque curve means excellent power below 6500 rpm also.

Potentially in a road ported engine you dont need the full .450 lift of the McCoy cam. The QED 420 cam is similar duration but with less lift at .420". I have never tried this cam pesonally but it also gets good reports and produces similar dyno curves from what i have seen in road engines.

The L1 cam ( originally a Cosworth design but now a generic term) is an older style race cam design and has around .410" gross lift and around 305 to 310 degrees duration seat to seat ( the numbers vary a little depending on who you buy it from these days) and produces less power due to its lower lift and with a poorer torque curve due to its longer duration. The tractability of the L1 in a road car on road compression ratio would be marginal on carbs - maybe better on fuel injection. A race compression ratio of 12.5:1 helps with its lower speed torque curve

You get the full benefits of these cams with bigger valves and porting. None of the cams are a straight swap as all need new valves and valve springs and usually also cam followers to fit the extra lift into the space available. You cannot get more than around .38 to .39 lift from the standard valve spring setup. if pulling the head and doing the valve and spring work you may as well do the porting to suit the cam and car use also.

Lots of cams are sold by the various cam companies as "performance cams" with longer durations than the original 266 degrees seat to seat going out to around 320 degrees seat to seat and lifts less than .39" as these can be easily swapped in with no other changes. Unfortunately the best outcome from these is a slightly better top end but a big hole in the torque curve reducing signficantly road tractability.

cheers
Rohan
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PostPost by: gordont » Sat Apr 30, 2011 2:49 am

Sounds like the QED420 are the go for me, will post in the wanted section but on the off chance someone has a pair gathering dust and looking to sell them send me a PM or email gordont66 hotmail com (dots in the usual spots)
Gordon
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PostPost by: SJ Lambert » Tue Jul 19, 2011 10:40 am

elangtv2000 wrote:+1 on the recommendation for Tony Ingram's .............will soon have his website up and running, so look for that soon.
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G'day Greg

Any update on Tony's website?

Cheers

James
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PostPost by: elangtv2000 » Tue Jul 19, 2011 1:12 pm

Hello James,
Yes indeed - it's been up for a couple of months:
http://lotus7.com/Home.html
Tony is currently in the UK, so may be hard to reach, but his email is [email protected].
Tell him Greg says it's time he checked in... :)
Cheers,
Greg
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PostPost by: SJ Lambert » Tue Jul 19, 2011 1:22 pm

Thanks Greg - I'll check it out!

James
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PostPost by: SJ Lambert » Fri May 18, 2012 10:48 am

How much torque do the best camshafts produce these days?

I'm planning on using a TILTON clutch with a 200 ft/lb capacity, I reckon that in an open wheeler, that it will be fine. I don't want to use a heavier clutch because besides being "heavier" I'd have to move the slave cylinder from a remote mounted one to a bobbin replacing one.
Last edited by SJ Lambert on Sat May 19, 2012 2:05 pm, edited 1 time in total.
Ford Escort Mk1 Lotus Twin Cam
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Elfin Type 300 (Holbay S65 - 120E) mechanic

[email protected]
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PostPost by: twincamman » Fri May 18, 2012 9:26 pm

:? :?
Last edited by twincamman on Thu Jan 17, 2013 11:51 pm, edited 1 time in total.
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PostPost by: SJ Lambert » Sat May 19, 2012 1:06 am

For sure!
It's a long story, am really just looking to match components in a second drivetrain as clutch and flywheel that are going onto a new Stage 4 McCoy Stromberg conversion topped motor were on hand and will, by coincidence, be ideally suited to the new motor unless someone thinks it's not up to the job as I don't think I'll need to use a 250 pound clutch.

James
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