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

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

Mike

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.

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.

Gary

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
Rohan

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:

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

jhps.com/Merchant2/merchant. … ry_Code=CC

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
Rohan

This is the article I referred to earlier-

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!

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!!

Have a look at this from Hugh Haskell’s book Colin Chapman Lotus Engineering

Sean


Here’s the 907 engine in a lotus7.
vrd.snagroup.com/Lotus7_1.htm

Great reference Sean!
I’d still describe the all-alloy Lotus built 907 as a Lotus engine :smiley:

As an example I had a small oil leak from the distributor in the Excel.
The seal is a Lotus only part! It was cheaper to have the distibutor modified to accept a reguar sized seal than place a Lotus one!

Yes, of course it’s a Lotus engine, just as the Ford 1500 was transformed into the Twincam.

The magical ingredient is that Chapman’s genius has been added ! :smiley:

Sean

Ehh-no!-to be specific thats the Lotus-Ford Twincam!

You won’t Vauxhall or Ford or Isuzu or Toyota or anything else stamped on the 907 castings!

Heres an article that answers both sides

belchamber.org/techhistory.html

Yes, very informative article on the Lotus 907 engine and its origins. :smiley:

Sean