Lotus Elan

BDA Elan

PostPost by: Ianashdown57 » Wed Oct 31, 2012 4:09 pm

Hi,

I've just beed offered a rather interesting BDA engine making about 190 BHP and have and early S2 Ex-Autocross car the already does not have its original engine. I'm have thought of building a BDA powered Elan as an interesting road car. It occurs to me that the standard semi-close ratio transmission and maybe the CWP may not like 190 HP for very long!

I'm interested to hear any thoughts as to the best powertrain upgrades to cope with the power of this engine. The chassis is a strengthened original Lotus and I'd prefer to make as few mods as possible to fit the gearbox, but the Type 9 or the MT75 both seem like good options. I'm not so concerned about the shift location as I suspect the seating position may need to be revised.

I have a good solution for the driveshafts, and figure there will probably be some sustension upgrades etc, but all in all it seems like an achievable and really fun project. I even have an original Hard Top which might just finish things off very nicely, not that it's really needed in Southern California!

All input gratefully recieved!

Ian
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PostPost by: holywood3645 » Wed Oct 31, 2012 4:54 pm

Ian, you should also look at the ZF S5-18/3. There are 2 versions that would work, one is a close ratio version dogleg first and 5th being is 1:1 they were used in the MK1 and MK2 rally escorts. (and were 240BHP with the 2 lrt BDG/A)
Ratios in the CR ZF box are.
2.83 (or 2.3 in the ford long first gear kit)
1.8
1.36
1,14
1

A cheaper option is the one used in the lotus sunbeam and masareti biturbo ZF S5-18/3 they also are a 5 speed box but top gear is lower than 1:1, I cannot remember ratio 'Edit' are included below, but a www search should get you the info. This may be better option fro road use,

Type S5-18/3 with the ratios
2.99
1.76
1.30
1
0.874

Magnesium and alumium bell housing are availiable with starter locations on either LHS or RHS. Plus they are like the 2000E boxes in that they have gear selector short or long options. The gear leaver would sit higher than the standard lotus elan, but close to the orginal lociation.

I have one of these boxes as I orginally was going to build a BDG elan with this box, but changed plans and went to a standard specification. I have the motor and box for my Mk1 Gp4 project now underway. I don't have a bellhousing yet and need to order from the UK.

You are welcome to try (test fit) the box in your chassis, Still in O/side

There was a guy who raced a 2ltr BDG with the ZF in the UK years back elan. It was a blue radical wide body car with huge whale tail on it. I think his first name was Barry (Correction Phil Jones, see pic and link).

http://www.pjed.co.uk/engine_development_gallery.htm


James
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Phil Jones.jpg and
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PostPost by: Elanintheforest » Wed Oct 31, 2012 9:13 pm

Ian, you don't need any mods at all to the transmission or brakes if you just want to use the car as a fun road car. My Plus 2 has run a BDA for 40 years, and was used for 10 of those to commute in and around London, as well as take a couple of European touring holidays a year. The guy who built it ran a tuning shop (Dave Smith in Ilford, Essex) and the car was used as a showcase for his work.

Initially he built the engine for maximum power, with some fairly wild cams and a pair of 45s, but found that setup too much like hard work for the road, and finally settled on 'mid range' BD3 camshafts and went back to the 40s. This put the petrol consumption back into double figures, and the engine is totally un-temperamental.

In all, the car has travelled 80,000 miles with the BDA using standard gearbox and differential, but it has the later output shafts (not the strengthened TTR ones) and solid shafts...the only modification. It feels like a fast Elan, developing 170 bhp on the dyno, and there are no signs of wear in the gearbox or differential. It also uses the standard full width radiator (early Plus 2 and S3 Elan) which has been fine for UK use, and occasional hot climate use in Spain....but I would guess that you may need to review that in California.

So my recommendation would be to fit it and try it in your otherwise standard car to see how you get on. My bet is that you will want to de-tune it just a little to make it more useable, and unless you really want to perform wheel spinning starts all the time, the rest of the drive train will be fine. If you want to push it a bit harder, then go for the upgraded output shafts and solid driveshafts.

Remember that the original skinny tyres act as another clutch and soften the effect of the power on the rest of the car....and give the fun at lower speeds! If you want to use wider wheels and sticky tyres and still want to do GP starts at the lights then obviously you may have to re-think the whole drivetrain.

First things first though....check out the BDA to make sure that the cam carrier and head don't have any cracks....quite common in old competition units. You may just see small cracks between the exhaust valve seats, which is not a problem.

Mark
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PostPost by: Spyder fan » Wed Oct 31, 2012 9:59 pm

Hi Ian,
Fit stuff that is low cost and readily available. In the UK MT75 boxes are a cheap robust item and the differential from a Ford Granada Scorpio is often pressed into service, couple this all up to some good CV driveshafts, add brakes from a +2 with uprated calipers and you have a hard wearing and relatively low maintenance solution. The MT 75 moves the gearlever back about 3 inches, the type 9 moves it back a whole lot further.

The original Elan gearbox is quite robust, as are all the other components, but their service life and service intervals are shortened when you put that 190bhp through them, and they are not as cheap to replace as the items I mention above. Sell them to a purist and buy some new bits.

Both my cars run similar power and a bit more torque than your BDA, they both run MT75's and Scorpio diffs.

Keep us all posted on the car if you decide to go ahead.
Kindest regards

Alan Thomas
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PostPost by: rgh0 » Thu Nov 01, 2012 10:51 am

For road use the standard box and diff will be fine. As others have said you probably will want to replace the diff output shafts if the orginal early version still and put in CV drive shafts if you dont have them already.

cheers
Rohan
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PostPost by: Ianashdown57 » Thu Nov 01, 2012 7:54 pm

Hi,

Interesting stuff!

I'm thinking a 5-speed would be nice for all the damm freeways here in California, leaving 4 useable gears for the fun raods! A LSD might be nice to have with this much power.

This car hasn't moved under it's own power since 1974 so, yes the output shafts are all original, so is just about everything else except the engine! It was an autocross car so treated as such, not respected as it would be today. I have designed and am having made a Tripod driveshaft system so I'll fit this when the time comes.

I'm picturing an ultra light weight, high power, part old fashioned, part modern sort of Juxta position sort of car! Just thinking at the moment. It doesn't get expensive until I start buying stuff!!

Ian
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