Lotus Elan

Lotus 2litre into a +2, does it go?

PostPost by: robcall » Mon Apr 28, 2008 3:10 pm

mikealdren wrote:Russ,


As to the origins of the 907, it was originally based on the Vauxhall engine. Rob, I think you're unfair describing it as a Van engine. Although it was used in the CF van, it was primarily used in the cars (Victor, Magnum, Viva, Victor Firenza etc). Commercial factors led to Lotus eventually casting their own blocks and taking it all in house. Vauxhall then brought out its own twin cam head and had great success in rallying (Firenza and Chevette HS) although, if I remember correctly, they also got caught using Lotus heads at one point!

Mike

Only to the extent that Lotus did their head testing in Bedford vans.
Do you have a reference to the 907 being based on the Vauxhall engine?
All mine show the block only being used to test the Lotus head!
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PostPost by: mikealdren » Mon Apr 28, 2008 4:12 pm

Nigel (sorry, I've just seen your name!)
It's an interesting question. I worked for Vauxhall for most of the '70s and received opinion was that Lotus had intended to use the Vauxhall bottom end but couldn't come to a commercially satisfactory arrangement so they went their own way. Given the twink precedent, this always seemed reasonable.

The similarities are more than just bore spacing, they are both slant engines with the similar bottom end geometry. The Vauxhall short engine was a good choice at the time, it was modern and strong and the slant layout allows low bonnet lines.

Mike
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PostPost by: desprit dan » Mon Apr 28, 2008 5:17 pm

Many thanks for the replies, I would like to have a closer look at the feasability regarding the fitment of the 907; I don't have any experience of the zetec, (and so no predjudice's) either.

The Price of twincams is a bit alarming, but if major problems re the 907 are encountered that will probably be the route I'll choose, as for the Triumph engine, I'd rather cut holes in the floor, or fit the pedal box from a Triang!

With regard to the twincam, is anyone familiar with the modification, to provide extra oil feed to the oil pump/ distributor drive, that involves drilling a small hole through the side of the block, (where the oil pump mounts); back in the '70's I watched a friend of mine do this, with a mixture of admiration, and horror!
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PostPost by: steveww » Mon Apr 28, 2008 7:34 pm

elan_fan wrote: A custom crank and rods, a tall block and work on the combustion chambers will give a Twink of nearly 2 litres but will require quite a bit of specialist machining, but it would fit.


http://www.wilcoxengines.demon.co.uk/ do an off the shelf 2.2 litre twinc. I would just love one of those :twisted: if my pockets were deep enough.
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PostPost by: davidj » Tue Apr 29, 2008 11:54 am

Hi,

I did see some pictures a while ago of a +2 fitted with a Triumph 6 engine and an (original) elite front end grafted on. It did not work as well as you would think.

Personally, I think you would have to be very brave and have deep pockets to fit anything other than a zetec, because they are so (relatively) cheap. For the cost of a good 907 you could buy a spyder chassis to go with the zetec as well.

An interesting, although totally unrelated link!

http://www.time.com/time/specials/2007/ ... 83,00.html

David
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PostPost by: mikealdren » Tue Apr 29, 2008 11:59 am

Does anyone know whether a 907 will fit? It's a wider engine than the twink.

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PostPost by: tower of strength » Tue Apr 29, 2008 8:31 pm

As mentioned earlier, the factory did some styling exercises (drawings only I believe) of the plus 2 with the 900 series engine.According to GAs writings the marketing team(I guess that was himself!) wanted an 1800 cc version of the new engine in a plus 2 based car to sort engine issues prior to the Elite launch. Chapman insisted on a 2 litre and nothing else, hence the 2.2 being a stroker engine, theres insufficient room for enlarging the bores within the block.

As to there being enough room in the chassis for a 900? No idea this end, however I may be able to get some 900 measurements by the weekend. we'd then need some one with an empty engine bay to see if it will fit without major surgery. I rekon the inner wings/engine bay sides would need re profiling and that there may not be enough room between the suspension turrets.
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PostPost by: garyeanderson » Tue Apr 29, 2008 8:55 pm

I think you will find the length of the 907 to be a bit longer than the twin cam. There isn't a lot of extra room in that respect in the stock chassis. Spyder has cut a chunk out of the vacuum tank/crossmember to make the Zetec fit. If I remember corectly the 907 had a bore of 3.75 inch verse the twin cams 3.25 inch and the belt drive would adda bit too compaired to a single roller chain. I measured the twin cam from bellhousing face to the front of the pulley bolt at 19 1/4 inches or 490 mm
Good luck in your search for a suitable power unit.

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PostPost by: rgh0 » Thu May 01, 2008 11:38 pm

I have complete Lotus 912 and twin cam engines sitting in my workshop - I will do some measuring to see what the challenges are to fit the 912 in a plus 2.

The 912 engine is about 150 mm longer than a twin cam and I suspect the biggest issue will be fitting it between the firewall and the front chassis cross member. Width may also be a problem and clearance between the front inner wheel wells as it is a fairly wide package compared to a twin cam

The Lotus 5 speed gear box could be used with it and would fit the chassis

regards
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PostPost by: john.p.clegg » Fri May 02, 2008 5:23 am

Rohan

It'll have to be the 5 speed out of the elan/plus2 as the change casting will not fit from the eclat etc...
John :wink:
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PostPost by: robcall » Fri May 02, 2008 6:25 am

As an aside..
Found this on the net for the 907 engine.
I'd be nice to have a twink version>

http://www.jhps.com/Merchant2/merchant. ... ry_Code=CC
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PostPost by: rgh0 » Fri May 02, 2008 6:42 am

Here are some comparision measurements.

Lotus 912 engine

Width - 400mm at bell housing, LH side at top comes out 350mm from centreline of crank due to lean

Height - 550 mm overall - 390 mm above crank centreline at front

Length - 640 mm bellhousing flange to front of water pump pulley

Twin Cam

Width - 300mm at bell housing, at top 370mm carb flanges to thermostat

Height - 560 mm total, 380 mm above crank centreline at front

Length - 500mm bellhousing flange to front of waterpump pully



Looking at the plus 2 engine bay your going to have problems in a range of areas that would require substantial work if at all possible. Possibly the only way to do it would be to cut and extend the chassis and body by around 150mm in the engine bay area

1. Engine will not fit between firewall and chassis front cross member, would need to at least modify front cross member to lower it down in the middle so engine can sit above
2. Longer engine will foul bonnet, need bulge in bonnet to clear cam pulleys
3. Even if the engine lean to left fits in above the plus 2 front wheel well inner surface very little room to fit exhaust, would need some creative body work in this area
4. Bellhousing flange to wide to fit in chassis Vee, need cutouts in chassis and body in this area to fit engine back against firewall, may be better with a spider chasiss that has more space in some places this area due to spaceframe design.
5. The sump is at the rear of engine maybe enough space behind rollbar and chassis brace but some mods probably reuired with their location.


All round not an easy swap. I think I would buy an Excel if I really want this engine in a 4 seat sports car

cheers
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PostPost by: robcall » Fri May 02, 2008 11:02 am

This is the article I referred to earlier-
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elan  2litre.jpg and
+2 2litre
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PostPost by: robcall » Fri May 02, 2008 11:13 am

I agree with the other posters regarding the difficulty and amount of modifications required-but this would make a very interesting +2 project with at last some historical connection!
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PostPost by: desprit dan » Fri May 02, 2008 12:12 pm

Thanks again to all; I have to admit it doesn't look promising, you can't argue with the dimensions, 6" longer is a lot of room to find.

To be fair this was why I asked the question in the first place, reinventing the wheel, is as pointless as it sounds, I always work on the premise that someone has tried it before, and their advice should be sought; all the same if I find a cheap engine and box , I might have a look for myself, but have put on hold, plans for a production line!!
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