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Engine Rebuild  Rating:  Rating
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 Posted: 03-29-2006 03:00 am
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Paul Koehler
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An inquire for those that have been there. If we condiser a stock JH with Z/S carbs and ~140HP  as a starting point and fast foward to the same JH at ~200+HP as an ending point, what is the order of progression  to get to the end point, if we were to make it into a  pay as you go project. Every year an improvement would be done with the caveat that, everything done year to year, would be useful in achieving the end point

For instance, if the cams were changed the 1st yr to 107/104, and the 2nd year, maybe new higher compression pistons added and so on. What would be the most efficient order of sequence of doing the improvements? What are they? How many years would/could it take?

The firm of West Coast Racing is frequently mentioned as THE PLACE to send your head for preparation. Has anybody used an alternative? Or is it the fact that WCR has done so many JH heads that they know all there is to know and do an excellent job?

Thanks,

Paul Koehler

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 Posted: 03-29-2006 04:45 am
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Greg Fletcher
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In my mind it would be time and money better spent to perhaps find a spare engine, prepare a plan of action and proceed with a project as funds allow rather try to piece meal an existing engine here and there. Slapping on a 107/104 cam combo to a low compression Federal engine with Strombergs would not really be buying you anything.

Any engine rebuild should start with the basics- meaning a bottom end with new pistons. 2.2 or 2 liter should be your first decision as you'll need one or the other. I rebuilt my first 907 engine (a spare from a junk yard) years ago by buying a few bits here and there and after 3 years, I had a nice, new 2 liter that's still running today.

Richard at West Coast does a great job and he does it once. He has done a bunch of 907 heads and knows his stuff (he owns a JH, can your local machine shop say that?)- just as important he cares about doing a good job. If you just need a stock going-over, almost any competent machine shop can do that, but you'll be better off finding someone that has a bit of experience with "exotic" type stuff.

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 Posted: 03-29-2006 07:30 am
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Harkes
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I couldn't agree more with Greg. Before my engine rebuild to 2.2L, my old 2.0L engine had the C cams with strombergs. I switched to 45mm dellortos and 2 x 107 cams, but there was little performance gain, simply because my bottom end wasn't what it should be. Start with the bottom end, 2.2L stroker crank and 10.5:1 (or higher)pistons, then good porting of the head, 107/104 combi cams, dellortos 45mm and good exhaust header/pipe. If you don't have the budget for it now, drive on for a while and save the money until you do (that is what i did). Or like Greg said, find a decent 907 spare engine and start taking it apart and build it up budget permitting.

good luck

erik

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 Posted: 03-29-2006 02:27 pm
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Jensen Healey
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Start with the 2.2 crank and HC pistons. Then do the flow work, cams and Dellortos or fuel injection. Or forget all that and graft in a supercharger from a Buick.

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 Posted: 03-30-2006 03:54 pm
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edward_davis
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Has anyone actually made a FI JH?  I could see the possibility, with aftermarket kits designed for Webers, but I didn't know anyone had actually done it.  Seems like it would offer improved performance without giving up as much fuel economy.  But it would also be a giant pain...

Edward

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 Posted: 03-30-2006 07:50 pm
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Judson Manning
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Yes it has been done.  Actually, the first Lotus prototype 907s used FI to achieve ~220hp, it's not a new idea.

Considering the cost for material, I could easily justify spending that cash on other items like a stroker kit or some quality head porting.  Then there is the time involved in charting the unknown, and how much your sanity is worth.

Anything is possible, but after 14 years, I'm to the point where I'm enjoying driving my JH more than experimenting on it!

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 Posted: 03-30-2006 08:07 pm
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Jim Sohl
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Check out http://www.topline.com/Photo%20Album/Jensini/index.html

it has been done, and I can imagine many times over.  As Judson correctly states, the parts are out there, the complete system is big bucks.  The difficulty of setting up the computer is entirely in the mind of the beholder, ie. it will seem like a school project to some and a s.o.b. nightmare to others.  See the Megasquirt web site for an intorduction into 'cheap' FI.  As is true of all things digital, you can easily spend 3 to 10 times more on essentially the same thing if you really feel the need.  As an example, Formula Atlantic (4 cylinder) racing FI equipment is available to anyone with the bucks.  It is also quite likely that such a set up would cost more than many of us paid for our entire JH.

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 Posted: 03-31-2006 12:55 am
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upstate mike
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Ok for my 2 cents I've been looking at FI with an engine rebuild. I found these guys

http://www.twminduction.com/Home/Home-FR.html

With bumping up the compression to 10:1 or possibly higher - I want to be able to on run pump gas.  They make a set up for to replace dellortos and looking at it it seems comparable in price to the dellorto set up in the club store. My main concern is will the block take it? Well food for thought,dreams and nightmares - think of the dyno time to get it right.

 

                    Mike Kolstee

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 Posted: 03-31-2006 01:51 am
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Paul Koehler
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Another option can be found at :http://sidedrafttbi.com. The man has figured it out for TR6's which also use ZS carbs. How much of a leap is it to go to a JH?

Paul Koehler

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 Posted: 03-31-2006 02:29 pm
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Judson Manning
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I can't say I'd suggest doing all that work and going the TBI route, but to each his own.

Unlike 2V american iron, 4V engines (including the dozen or so 9XXs I've built) routinely run +10:1 c/r on pump gas with no problem.  Later 912SE engines have Nikasil coated aluminum liners and came stock w/ 10.9:1 c/r. 

However, as you've pointed out:  "Can the (907) block take it?"

In stock form, the short answer is no.  Reliability beyond 160hp will eventually be a problem, but there are ways to improve the 907's bottom end.

Our crank is bigger than most V8s, but take a look at the difference between the much wider and beefier 910 bottom end vs. the 907 (exactly why it's difficult to shoe-horn one into a JH!):

http://jhppg.com/gallery/album08/P1010012

To beef-up the 907 bottom end is pretty simple: 

1.  Add dowels to keep the main bearing panel from shifting under load (the 910 uses a total of 3, the Esprit Dry-Sump Turbo used a total of 10).

2.  Cross-drill the crank.

3.  Line-bore the main saddles to use the larger OD 180^ bearings from the Chrysler 318.

 

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 Posted: 04-09-2006 06:19 am
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Dan Eiland
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I was wondering if anyone has put together some kind of list of all the sealants used on the 907 engine during a rebuild and where each one is used? Also would like to find something on all the most up-to-date rebuild tips. I know the Lotus company made many changes over the years to correct all the issues with the 907 engine. I would just like to know what all those changes were and what chemicals or sealants are now used? Judson mentioned something that was mentioned to me by another person who has a lot of experience with the 907 engine and both mentioned Adding dowels to keep the main bearing panel from shifting under load. I think the other person mentioned using 10 dowels. Plan to follow this advice but I'm not sure what to tell the rebuilder to make sure it is done right. I have just about everything I need to do the 2.2L conversion. I have my original engine which has less than 8000 miles on it since it was rebuilt in 1989 and a second block and head that have already been prepped for the 2.2 conversion. I have the 10.5:1cr JE pistons with a 2.2L crank and complete set of matching Vandervell bearings. I have a new intake manifold but need to purchase a set of Dellortos to go with it. I have a pair of DHLA 40's but think I need to go with the 45's. The head has already been rebuilt with new larger than stock ss exhaust valves, Delta's competition valve springs and 104 cams. The intake and exhaust ports look like they have been ported and lightly polished. I'm concerned that the cam towers were mounted using the new gaskets. I thought I had read the gaskets should be tossed and a sealant should be used that basically has a zero tolerance once assembled which means the valves would need adjusting again. Any assistance would be appreciated. I would like to purchase all the sealants and chemicals I might need for the assembly of the new engine which is why I am asking.

Thanks ahead,

Dan Eiland

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 Posted: 04-09-2006 03:24 pm
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Judson Manning
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I think it would be easier for me to make a DVD of rebuilding an engine lasting about 40hrs!

Seriously, a lot of the 'local knowledge' comes from years of trial and error.  It's very hard to communicate through several hands how to tell a machinist what to do.

Dan, if you'd like, I could quote you on building an engine for you here locally, testing it in one of my cars and shipping it to you complete.

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 Posted: 04-09-2006 03:56 pm
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Dan Eiland
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Judson, what do I do with all my parts and the two engines I have? I would welcome the quote. You can email me off this forum at deiland1@elp.rr.com so we can talk.

Thanks,

Dan Eiland

Last edited on 04-09-2006 03:57 pm by Dan Eiland

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 Posted: 04-09-2006 04:38 pm
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Greg Fletcher
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Regarding your question on list of sealants, this is all basic stuff. I can't stress how important it is to have a copy of the JH shop manual. It's not the greatest, but it does have all the essential specs needed to get stuff done. The manual clearly lists what sealants are needed during the rebuild process such as hi-temp RTV, Hylomar and Wellseal, and I would update that by using the rubber camshaft cover gaskets and by using Loctite 515 under the cam towers and on the pan gasket, as this no longer comes in the gasket kit.

While doweling the bottom end is a very useful method of dealing with high rpm block flex, I'm not altogether convinced that this is always necessary or even desirable. If you plan on doing some racing and will be flogging the engine quite a bit, them you should probably consider the mod, but for many owners that just want a fast street car, I think it's more trouble than it's worth.

On the cross drilled crankshafts- I know it sounds good, but keep in mind that Lotus raced plenty of non-cross drilled 200hp+ engines sucessfully. Also, with high quality ACL bearings available at just above $200 for a full set, I would not recommend to owners that they convert to Chrysler bearings, which would in fact, cost much more taking into account the machining needed.

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 Posted: 04-09-2006 05:00 pm
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Ron Earp
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Hi Dan,

I'v built a fair number of motors over the 37 years I've been plodding around.  I SCCA road race so it sort of neccesitates doing that since last year we blew the same one up twice.  We also build customer cars for people and completed three spec miatas from the ground up last year, although it took all my free time. Which leads to....

I am FINALLY (I'll do another thread on it) about to finish up our Jensen Healey road race car (SCCA Improved Touring S) and it'll go out for the first time in two weeks.  To make a long story short, I used my machinst here that I'd used a lot for V8 builds and then assembled the motor myself. However, it didn't work out that well, even though I have a decent idea of what must be done and so did my machinist. There are some little tricks with the 907, especially if you'd like it to have a long life as it should.

To make a long story short, the motor didn't work well and needed to be pulled again and rebuilt.  So, I sent the motor to Judson, let him rebuild it whilst working on other projects, and then picked it up from him. He'd run it in on his test mule car and I was able to drive it that way, then help him remove my motor and re-install his old motor. Motor runs great!!! And as far as conversion to 318s, it isn't expensive. I did that here the first go around and it will allow you to use $30 main bearing sets, with more selection available (grooved, 180, 360, plain)  instead of $200, $300, or $$$ with little selection.

If you need a rebuild I highly recommend using Judson. He is knowledable about the motor, has done a bunch of them, and he'll save you money in the long run - I know it helped me out and when it goes boom, which I hope will be a couple years at least, I'll send it to him again.  Highly recommended if you need a rebuild.

Ron

Last edited on 04-09-2006 05:06 pm by Ron Earp

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 Posted: 04-09-2006 07:20 pm
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Judson Manning
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Thanks for the plug Ron, my main interest is seeing your car on track smacking around RX7s and 240Zs.  That is true job satisfaction!

Greg is correct in that the x-drilled conversion can be much more expensive than the ACL bearings.  Not the best option for a street and or budget rebuild.  Regardless of main bearing options, ACLs on the rods are THE only way to go!

The 907 bottom main bearing with it's wide and shallow groove (plus a huge hole in the middle) is the dumbest thing I've ever seen.  Because it is so poorly designed, the 907 mains wear first which cause the rod bearings to starve -  then BOOM!

The ACL  groove design is far superior to the OEM 907 bearings, and makes an excellent choice.  Alternatively, x-drilling and going to 180^ main bearings is a 'worst-case-scenario' option better suited to a competition engine. 

To give you some idea of what we're talking about:  The 907s I've rebuilt using the stock bearings and 20W-50 oil produced 45-60psi when hot.  Ron's engine running 5W-20 oil produced 70-80psi. 

I'm willing to bet the ACL main bearings net a 5-15psi increase over the stock bearings - can anyone share some field measurements?

 

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 Posted: 04-09-2006 07:45 pm
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Esprit2
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Paul Koehler wrote: An inquire for those that have been there. If we condiser a stock JH with Z/S carbs and ~140HP  as a starting point and fast foward to the same JH at ~200+HP as an ending point, what is the order of progression  to get to the end point, if we were to make it into a  pay as you go project. Every year an improvement would be done with the caveat that, everything done year to year, would be useful in achieving the end point

For instance, if the cams were changed the 1st yr to 107/104, and the 2nd year, maybe new higher compression pistons added and so on. What would be the most efficient order of sequence of doing the improvements? What are they? How many years would/could it take?

The firm of West Coast Racing is frequently mentioned as THE PLACE to send your head for preparation. Has anybody used an alternative? Or is it the fact that WCR has done so many JH heads that they know all there is to know and do an excellent job?

Thanks,

Paul Koehler

Paul,

IMHO,  the best thing that can be done to a 907 is to install the 2.2 liter stroker crank.   Even if the engine isn't really hotrodded any further,  the increase in low-end torque transforms the engine.   W-a-a-y more than you would expect from a silly little 0.2 liter increase in displacement.   Go 2.2 and you'll never go back.

Regardless of which stroke you choose,  use the cross-drilled version of the crank along along with the plain lower bearing shells (no hole/ no groove).   The plain bearings are the "plus" feature,  the cross-drilled crank is what makes using them possible.   Without the plain bearings,  the cross-drilled crank is of marginal incremental value.   No harm...  but little gain.

Shuffle-pinning the crank (dowel pinning all ten studs) does significantly strengthen the block/MBP assembly.   Properly done,  it's very worthwhile.   However, doing the job properly also involves align-boring the main bearing bore "after" the dowel pins are installed.   Go the whole 9 yards,  or don't bother at all.   Dowel pinning without the align-bore has the potential to do more harm than good.

The semi-hemi combustion chamber is very tolerant of octane/ compression.   A 10.9:1 to 11.5:1 compression ratio can be used with the pump gas that's available in most areas of the USA and Canada.   10.9:1 is very comfortable if you don't mind the higher cost of Premium grade fuel.   If you live in an area where the available fuel has a low or inconsistant octane rating,  then it's probably wise not to increase the CR much above stock.   Well,  not Federal-stock...  8.4:1 is lame.   Something more like 9.5:1  or  10:1.

The stock cast aluminum pistons are a failure waiting to happen.   Go forged with the next set.   JE Pistons has a forged piston set for the 9XX engines in your choice of compression rations.

There's no need to "upgrade" from carbs to fuel injection just to accommodate higher compression.   If you are putting the work into the engine that would support ~11:1 or higher compression,  then it makes sense to upgrade to Dellorto DHLA 45 carbs;  but IMHO,  the cost of a custom fuel injection will not produce a justifiable performance increase.   That money could be put to better use paying for other more meaningful upgrades.

Besides,  carbs make that lovely noise.

The cylinder head has a lot of un-tapped breathing potential.   The easiest head upgrade is to simply install more aggressive cams.   The popular 107 cam upgrade is actually milder in terms of duration.   Their big advantage over stock is more low-end torque rather than more horsepower.   Then to avoid a power loss,  the valve lift was increased.   In the end,  the 107 is actually a pretty milquetoast cam.   It's a step up for a near stock street car,  but if you are thinking about really hotrodding the engine and doing the stuff discussed here,  then the 107 is really too mild to consider.

Stock 907 tappets are are cast iron and not reliable much beyond 7200 rpm.   And when they break, things get expensive in a hurry.   Current Lotus service replacement tappets (1995 onward) are steel and good for around 9500 rpm in a properly prepped engine.   Lotus still set the rev limit at 7500 rpm,  but then they were saddled with a warranty program as well.

The three "C's"...  compression, carbs, cams.   Always keep them in balance.   If a significant change is made to the the compression ratio,  the full return on the investment will not be realized if the carbs and cams are left stock.   Same with any of the other "C's".

Going to a set of DHLA 40's with 34mm or smaller chokes is pretty much a latteral move from the Strombergs.   They're easier to tune and feel more responsive,  but they don't really make more horsepower than the Strombergs.   However, if larger chokes are to be used,  especially in a set of DHLA 45's,  then the full reward won't be realized unless the compression ratio and cam timing are upgraded as well.

For a hot street engine in an area where emissions testing isn't a limiter,  I'd suggest  2.2 liters,  10.9:1 to 11.5:1 compression,  DHLA 45's.  36 or 37mm chokes  and at least 104 cams.   A 2.0 on 104's isn't much fun below 3500-4000 rpm,  but a 2.2 is perfectly tractable with 104's.   I'm using Dave Smith's DS-2 cams in my 2.2 907 (a step up from 104's) and the engine is comfortably driveable in traffic.

Carbs are only part of the breathing problem.   Putting huge carbs on the smallish stock ports doesn't gain much.   Next to the stroker crank,  the best thing you can do to a hotrod 907 is a generous port job.   The original 907 ports were pretty darned small.   My 907's head has an aggressive port job and you can roll golf balls down the ports.   Well, okay... maybe not.   But compared to the OEM ports,  it sure looks like it.   When I install a new intake manifold gasket,  I  have to enlarge the openings quite a bit.

In the USA,  Westcoast Cylinder Head knows as much about porting 907 heads as anyone and he has a good relationship with the JHPS.   But my personal favorite is Dave Smith in the UK.   Dave was formerly with Lotus and built all the factory team race engines for the 4-time champion Sunbeam-Talbot-Lotus World Rally cars as well as Chamberlain's LeMans Esprits.   He's sorta slow (slower if you push on him), expensive,  and it requires big shipping charges round-trip from the USA.   But if there's horsepower hiding in a 9XX cylinder head,  he knows how to let it out.

Big valves will give high rpm power at the expense of low-end torque.   For a hot-street engine,  the stock valves might be the better choice.   That's a personal call you have to make on your own.   For the serious boy-racer,  track days or club racing,  larger valves are a plus once you get the car launched.   The best starting point for the cylinder head would be the current service replacement head from Lotus (1995 onward)...  the Zeus head.

The Zeus ports are re-configured in the casting and specially contoured around the valve seat to work with the unique contour on the back side of the larger Esprit S4s intake valves.   A different port and runner shape plus more material around the runners allows you to go places with a die-grinder that you just can NOT go with an early 907 head.    But that's like the fuel injection...  big bucks for a questionable return on a street engine.

If you port the head,  then dowel-pin and match the intake manifold to the head and continue the port job all the way to the carb mounting flange.

The engine runs better and makes more power with an enclosed airbox.   The open, K&N-style air cleaners make glorious noise,  but they breathe hot air from within the engine bay.   In a properly tuned system,  the total length of the runners, plenum and the cold air trunking to the front of the car all influenced the "tuned length" induction system.   I'm Lotus guy and not all that familiar with the J-H's stock induction system (it looks a little huge and convoluted),  but I would think the airbox and trunking from a Lotus Elite/ Eclat would easily fit under the J-H's bonnet.

If, rather than pulling the engine and rebuilding it,  the plan is to simply bolt some external enhancements onto a 907,  then I would start by installing the cams first.

A stock 2.0 907 doesn't have enough torque to peel a grape.   Anything that will improve the low-end torque will make the car much more pleasant to drive on the street.   A pair of 107 cams will do that...  more torque, but not necessarily more horsepower.

The 107/104 cam combination won't specifically help the low-end torque,  but it will give a horsepower gain on the top end without hurting the bottom end.   Usually,  you have to rob Peter to pay Paul,  so this is almost like a freebie power gain.

If you're starting with a "Federal"  907,  then I'd bump modifying the distributor to the top of the to-do list.   The Federal ignition timing totally emasculates the 907.   Cuts 'em right off.   Simply cranking in more static timing (~14 BTDC) will make a big difference and that only takes minutes.   Re-curving the distributor to give about 16 degrees of mechanical advance all in by 2500 rpm would take a little more time and effort,  but would put some life back into the engine.   (Have a second, stock distributor on hand if annual emissions checks are an issue).

Next, convert to Dellortos.    DHLA 40's if you don't plan to stray too far from stock/street.   DHLA 45's if you really have any aspirations of reaching that 200 hp level you mentioned (only J-H 907's came with 40's,  all Lotus 907's came with 45's...  they do work).   I'd top them off with a Lotus Elite/Eclat airbox and a cold air duct to the nose.   There's a hole in the front bulkhead low and to the right of the radiator that would be about right for an air duct.   The Lotus duct is actually tappered (larger at the airbox, smaller at the inlet) and is supposed to make a difference in how well the engine runs compared to a typical straight duct.   I haven't dyno tested that myslef,  but that's Lotus' story.

As I mentioned earlier,  a pair of DHLA 40's with 34mm or smaller chokes won't make much more power on a dyno.   But throttle response will be much better so the engine will feel more lively.   Plus they are easier to tune and stay tuned longer than Strombergs.   If you are thinking "hotrod",  then go for DHLA 45's with 36mm chokes as a starting point.   38mm chokes are about the limit of the range for a hot 907 with the right compression and cams,  but you won't like them on the street.

The stock exhaust manifold actually flows rather well.   However,  if you have done the other upgrades,  then there's "maybe" 3-5 horsepower max to be gained with a good set of headers.   During the bolt-on phase,  I'd leave the headers for last.

Beyond those simple bolt on's,  you really need to pull the engine and go inside.   You "might" see 160 hp with bolt ons.   Some of those Shetland Pony kinda horsepower like Lotus' optimistic dyno used to report.   But if you really want to pursue more serious horsepower,  then you need "build" a proper hotrod motor from the inside out.

Good luck

Tim Engel

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 Posted: 04-09-2006 10:38 pm
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Ron Earp
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Greg Fletcher wrote:

On the cross drilled crankshafts- I know it sounds good, but keep in mind that Lotus raced plenty of non-cross drilled 200hp+ engines sucessfully.

 

You sure about that one? Doesn't matter what series a motor is raced in, you can be sure someone has gone through it and taken advantage of what they can.  Technically, it is illegal for me to cross-drill and use the 318 bearings, but we felt we needed to in the interest of reliability and future rebuilds. I'd be suprised if Lotus didn't drill those cranks.

Nice write up Tim.  I will be dynoing the JH and Judson's motor after next weekend I hope. And, I bet we'll find some of those JH ponies out of the corral and MIA! Still, we'll tune it for whatever we can get and hope for the best. Plots will be reported and posted here because to my knowledge nobody has done a rear wheel dyno on a Dynojet yet - all I've seen are engine dynos, which vary pretty widely, and guesses.

Ron

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 Posted: 04-10-2006 03:18 am
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Dan Eiland
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Greg and Judson mention the ACL bearings. What are these ACL bearings and how do they compare to the Vandervell bearings that came with my 2.2 Crank? What can I realistically expect so far as the reliability of my engine with the 2.2 upgrade, 104 cams, larger ss exhaust valves and the JE 10.5:1 pistons without all the other upgrades? I'm not looking to build an all out race engine. I just want an affordable and reliable street performance engine. I don't want to turn a bearing at 3000 miles or have a 190 to 200 hp engine that overheats in the middle of the summer when it is 115 degrees outside and I have the AC on inside the car. I am sure I have the non-cross drilled crank with the Vandevell bearings supplied by Delta to match the crank. I know the bottom end was not modified with additional dowels, but I was considering having this done. Now I'm reading that I should have done this first then had the engine align bored. Can I go back and have this done without causing a problem? This is why I originally asked if someone had put together something on doing a 2.2L conversion so people like myself can collect all the parts and have the work done slowly in order to afford doing this at all.

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 Posted: 04-10-2006 05:08 am
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Greg Fletcher
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ACL bearings are what we sell in the club store, you can read the description there. They are actually better quality than the original Vandervells, which are almost all gone and will not be coming back. Keep in mind, you wouldn't be able to find these easily either, ACL in Tasmania considers these obsolete and only does one small run per year on a world-wide basis which get snatched up by resllers (I've heard that some Lotus dealers are selling these as well for the early engines). A special run (for drilled and cross drilled cranks) is quite costly and it's not clear at the moment that there is enough interest to support that. We have a pretty good stash for the immediate future for the non-cross drilled cranks.

If the engine is put together properly and you don't abuse it, your engine will be fine. As mentioned before, a moderately higher output engine will normally live a shorter life, but not by a large margin, all things considered. The detuned, Federal engines have an annoying habit of loosing piston ring tension after years of sitting around.

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