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912 SE Engine  Rating:  Rating
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 Posted: 05-31-2005 05:32 pm
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Paul Noakes
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Hi Guys. Firstly, my appologies if this topic has been covered in past threads. A complete 912 SE Hi comp. engine from an Excel is looking for a new home.  Can anybody advise if this engine will fit into the Healey without to many problems. I know the 911 Sunbeam engine wont fit because of differances in the Sump/Crank carriage area, but will the 912? Any advise or comments would be appreciated.

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 Posted: 05-31-2005 11:57 pm
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Esprit2
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Paul,

I don't know exactly where the 911 interferes with the Jensen-Healey,  but I would think all the Lotus 2.2 liter engines would have the same issues.   The 907 engine wasn't as stiff as it should have been,  so Lotus widened the bottom/ main bearing panel on the 910/ 911/ 912.   The cylinder block itself is basically the same right down to the joint line with the MBP, but the MBP flares out wider as it goes down. It has a double outer wall... original wall, space, then a second, flared-out wall that's wider overall at the very bottom. Of course,  the sump also got wider to match.

I've seen 910 Turbo based engines fitted to Jensen-Healeys,  so whatever the problems are,  they must not be insurmountable.

Tim

Last edited on 04-10-2014 10:45 pm by Esprit2

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 Posted: 06-01-2005 02:43 pm
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Judson Manning
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As Tim points out, all later versions of the 907 (i.e 910/911/912/920) are wider below the split-line of the crank, and require modification of the front x-member.  In realative terms, it's not such a big deal (except for you right-hand drive JH owners) and the benefits far out weigh the consequences.

Where is the engine located?

http://shorpac.com/v-web/gallery/album08

 

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 Posted: 06-01-2005 06:42 pm
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Paul Noakes
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Thanks Tim, Judson.

I live in the UK and as such my JH5 is RHD. I have been given conflicting information on this matter. Some have said that the 912 will drop straight in and others say that i would have to basically rebuild my 907 using 912 internals. I assume from your wording Judson that being RHD also complicates matters further?

What kind of modifications would be required to enable me to use the 912 engine as it is? 

 

Many thanks for your help.

Paul

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 Posted: 06-01-2005 06:53 pm
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Judson Manning
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Paul,

RHD is a problem according to Garry Kemp who gave me the inspiration to do my swap.  He did it, but told me it took A LOT of cutting&welding but did make it happen.

One thought...build a hybrid using the 907 bottom end and everything else 912 (i.e x-drilled crank, pistons, liners, cam covers, etc).  Depending if it's an SE or non-SE of course...

Then by 10-doweling, line-boring, and machining the 907 bottom end to accept 912 bearings, you should have plenty of stiffness in the block for 200+hp.

And ship me the shell to install in a LHD car!  lol

Judson

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 Posted: 06-01-2005 08:03 pm
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Scott Robinson
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I can tell you that a high compression 2.2 is a wonderful addition to a JH from a driving/performance standpoint.

Probably a couple of years back Greg reproduced a letter from me in the magazine that discussed my experience putting a 912 in a JH in 1990. I only tried it because it was pre-internet and I didn't know it "couldn't be done". While it wasn't a drop in, it wasn't all that difficult. However, my car is LHD. You should contact Garry Kemp. He sent me photos of his conversion in a RHD JH, and I'm sure he would do the same for you. For most mortals I can see where the "can't be done" concept came from. As Judson said, RHD is a whole lot more involved, but Garry is the guru who can guide you and help you make an informed decision. The much stronger bottom end is sure nice to have if you drive your JH with vigor.

Scott

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 Posted: 06-01-2005 09:32 pm
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Paul Noakes
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OK. I think that we have established that this aint a five minute job.

I would like to contact Garry Kemp for further pain i think! Would someone be good enough to provide me with his email address / contact details.

Thanks to all of you for your input and support.

Paul

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 Posted: 04-10-2014 08:10 pm
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Schorse
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I know I am digging up very very old stuff but I somehow didn't find the answer to my question but tends to go into the same direction as stated here.

I have the possibility to get a 912 hybrid engine. It has iron liners and is believed to have a HC head. Is there any way to check by numbers if the information is correct?

More importantly will the block fit the Getrag box directly or is some adaption needed? What work will be neccessary on the x-member?

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 Posted: 04-10-2014 08:58 pm
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Schorse
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btw the guy said it would be a turbo block but as it has iron liners this seems improbable correct?

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 Posted: 04-11-2014 04:57 am
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Esprit2
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Schorse wrote:
(Snip)... I have the possibility to get a 912 hybrid engine. It has iron liners and is believed to have a HC head. Is there any way to check by numbers if the information is correct?Check the engine number stamped into the top side of the block's rear flange... near/ above the starter. The number will start with the engine's model code... 907, 910, 911, 912 or 920. That will quickly tell you if the hybrid is based upon a 912 or 910 block & main bearing panel assembly.

Engine Number format examples:
LC 910 8210 20520
DC 907 7606 12844
1st letter = basic engine build spec (early engines used a 1-leter prefix).
2nd letter (if used) = engine equipment variation.
907 = Model (also 910, 911, 912 & 920).
7606 = Year & Month of manufacture (1976, June).
12844 = Serial Number.

Note that Lotus part numbers, like the block/ MBP assemblies and cylinder head numbers given below, begin with the model number in which the part was first used. But a block assembly that starts with B912 doesn't mean it was exclusively a 912 block. Once introduced, it was used across the range. For instance, the bucket tappet used in the 9XX from the 907 through the early Turbo 910s is the same as that used in the vintage Lotus-Ford Twin Cam, and carries a Lotus Elan part number, A026E0024Z... ie, where it was first used.

If 'part' numbers appear on the parts, they will be 'stamped' into the parts. Numbers 'cast' into the parts are the raw, un-machined casting numbers... same with forged parts.

*~*~*~*
Block & Main Bearing Panel Assembly (match-machined sets):
The 912LC used the iron liner block ass'y, B912E0750J. Note that the 912LC and Pre-1986 910 Turbo shared the Iron Liner block. A Turbo 910 with a 912LC block has the correct block.

The 912HC used the Nikasil liner block ass'y, A910E9195J. Note that the 912HC and 1986-onward 910 Turbo shared the "Nikasil" Liner block. A 912HC with a "Turbo" block has the correct block.

The block/ MBP were re-tooled late in the game, and the Esprit S4s used block ass'y A910E2604J.

*~*~*~*
Cylinder Head Assy:
The 912LC used cylinder head ass'y, C907E0703J.
The 912HC used cylinder head ass'y, A912E9056J.
The Esprit S4s & Sport 300 Zeus head is P691.4005.800BJ.
(Zeus is the name of the foundry that produced the new head).

Other 907 heads (Federal Elite, Eclat, Esprit S1-S2):

A907E0703SH 1974 Federal WITHOUT air injection ports.
C907E0703S as above, but without heater water take-off port in right-rear corner.

B907E0703S WITH Federal air injection ports near exhaust ports.
D907E0703S as above, but without heater water take-off port in right-rear corner.

Federal 910LC heads (Iron liner engines):
A910E0703J Federal Carbureted 910 Turbo WITH air injection ports.

Federal 910HC heads (Nikasil liner engines):
A910E9057J Federal Fuel Inj'n 910, both Bosch & GM, thru Esprit S4, WITHOUT air injection ports.

P691.4005.800BJ big valve Zeus head, Federal GM fuel inj'n, 300Hp Esprit S4s & Sport 300.

Combustion Chamber Depth = 12.32-12.57mm (0.485-0.500 in)
Inlet valves ... = 35.47-35.65 mm (1.396-1.404 in) all thru Esprit S4.
Inlet valves ... = 36.37-36.63 mm (1.432-1.442 in) big valve (+1mm), S4s & S300 .
Exhaust valves = 30.70-30.91 mm (1.209-1.217 in).

All heads will fit all blocks without the need to fettle. Turbo 910 heads up through the 1993-94 Esprit S4 have the same size valves as the 907, and are a direct fit. However, the Turbo exhaust valves are an upgrade material to take the greater heat, and hence, a different part number. A 907 head will interchange onto one of those Turbo engines, but the exhaust valves won't be up to the task, long term. The late Zeus 910 head used on the Esprit S4s and Sport 300 had 1mm larger diameter intake valves, and will also bolt onto a 907.

Compression ratio is controlled by the pistons, not the cylinder head's combustion chamber. An "HC" head is a head from a HC engine, but there's no such thing as a "high compression head". And all 9XX cylinder heads will result in the same compression ratio when retro-fitted onto different vintage short-block assemblies.

Jensen-Healey & early Lotus 907 heads had 24mm intake ports.

Later 907 / 912LC heads had larger, 25.5mm intake ports.

912HC/ Esprit S4s & Sport 300 Zeus heads had even larger, re-contoured intake ports with special intake valves with the backside of their heads contoured to complement the port's tulip shape.

If you're porting the ultimate race or track day head, the Zeus head is the best starting point. Second best is the late 907/ 912LC head with 25.5mm ports.

The intake manifold to head gaskets all have the same size port openings, so laying one on different vintage heads quickly highlights differences in port sizes.

*~*~*~*
Cylinder head gaskets have changed over time, and new gaskets came with new torque specs for installing the head. Lotus hasn't sold the original steel-asbestos-steel gasket for decades, but if J-H sources still sell it, then you can use the torque spec in the manual. The current Lotus composite gasket uses a torque-angle spec in degrees, and the similar aftermarket composite gasket from JAE requires a torque wrench, but to a higher torque than original. When you buy a new head gasket, 'ASK' for the current torque spec to use with it.

Schorse wrote:
(Snip)... More importantly will the block fit the Getrag box directly or is some adaption needed?The short answer is that it will fit directly.

The bell housing mounting flange at the back of the block is the same pattern for all 9XX 4-cylinder engines. The J-H Getrag/ bellhousing that bolts to a 907 will also bolt to a Turbo 910S... I just don't advise the combination, unless you wish to see the Getrag grenade.

Early J-H 907s had a rear main rope seal, and later engines were configured for a rear lip seal. From that change point onward, there's very little difference in Lotus 9XX four cylinder blocks, in terms of fundamental dimensions. As some accessories were added, like A/C, complex brackets were used at first to adapt the new bits. Whenever the block was re-tooled, the opportunity would be taken to add new bosses or flanges as required to eliminate or simplify the bracketry, but the block's "engine function" dimensions remained fundamentally unchanged.

All the width difference between the 907 and the 910, 911, 912 & 920 is in the Main Bearing Panel (MBP). The joint with the block has the same footprint, then the MBP flares outward as it goes down, like a skirt. It's double walled. The original narrow wall is still there, then a gap, then the outward-flared wall. Of course, the sump is also wider to mate with the wider MBP.

Two exceptions. 1) Aluminum is not as strong as cast iron, so the necked down spigot diameter at the bottom of the cylinder liner (the part that pilots into the cylinder block) had to have a thicker wall in aluminum... which meant a larger OD. That, in turn, required a larger spigot bore diameter in the later "Nikasil" blocks. Externally, all major block dimensions were the same. An iron liner block can be re-bored to take the larger OEM Nikasil liners (ie, they're metal safe), but you can't cut a Nikasil block smaller to take iron liners. Aftermarket suppliers provide custom iron liners in aluminum dimensions as an inexpensive alternative for replacing Nikasil liners.

2) The 920 2.0 liter Turbo used the same basic cylinder block casting, but the deck height was slightly reduced (same casting, different machining). That change forced a ripple effect cascade of small parts changes that makes the 920 block a poor choice for a 907 owner looking for a replacement block. The 920 engine saw limited use in the Esprit GT3 which was originally developed for the Italian market (big tax on engines over 2.0 liters), and was later sold in the UK and Euro markets. The 920 and GT3 were never sold in North America, never sold in high volume, and are the rarest of 9XX street engine parts. If you don't own an Esprit GT3, then IMHO, the 920 parts hunt just isn't worth it.

Schorse wrote:
btw the guy said it would be a turbo block but as it has iron liners this seems improbable correct? Scroll back up to the Engine Number format, above, and notice that it provides the engine's build date. Lotus used iron liners on all it's engines, 907, 910, 911 & 912, up through 1985. The Nikasil coated aluminum liners were introduced across the board in the 1986 model year. So it's very possible that a turbo block assembly could have iron liners, depending upon it's vintage.

In each case, the cylinder block has spigot bores (liner sockets) machined to ID's appropriate for the liners being used. Other functional dimensions in the block are unchanged.

Last edited on 04-13-2014 02:54 pm by Esprit2

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 Posted: 04-11-2014 07:00 am
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Schorse
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Thanks Tim, that is of great help and very valuable info

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 Posted: 04-12-2014 02:54 pm
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pbahr
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Tim,
Thanks for the epistle on Lotus engines.  I've copied it and inserted in my Shop Manual.
YELODOG

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 Posted: 04-12-2014 07:03 pm
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Esprit2
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Pete,
I'm glad you found it helpful. However, I just edited it, adding some info about intake port sizes in the various heads. Sorry to make more copy-paste work for you.

Last edited on 04-12-2014 07:07 pm by Esprit2

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