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Interesting JH Engine Alternative  Rating:  Rating
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 Posted: 10-08-2007 08:28 pm
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discogodfather
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Massaging 200hp out of the 907 is a good value IMO, basically higher compression, good cam, and some webers/dells.  But going to 250hp is a big task, and 300hp seems only for the most unruley racing monsters.  As much as I love the Lotus 9xx family, I have to admit the JH with 300+hp would be astonishing.  Cost is always a factor- not from and labor/fabrication (that's just me) but the cost of components.

When I first got my JH I entertained the idea of going with another engine, something that weighed around 300lbs, wouldn't need much modification, low price, good 5 or 6 speed tranny option, and put out a good 300hp.  Naturally the first inclination was the Buick/Olds/Rover 215.  That engine I have always liked, low weight, all aluminum, capable of well over 300hp actually quite easily.  But putting a pushrod engine in the JH that taps out where the 907 just begins to rev up has always seemed counter to the design of the car in some way. 

We all have seen the various V8's put in the JH.   Keeping the weight distribution of the JH the way it is has always been the highest priority for me.  I found a blustering american V8 that weighed only 347lbs, but it was a $15,000 aluminum block engine for World products.  600hp drag racing engine.  Do you think the stock rear end will take that power (-joke-)?

So then I started to look at other engines including BMW and Mercedes V8's from 90's cars with some decent power (such as the BMW M60).  Heavy weight again- around 450-500lbs.  Also, the oil pan sump is placed in the front of the engine- a bad idea if you need to graft it into the JH chassis cradle.  There are some interesting V6's out of the Benz and BMW's, but they are expensive and not that impressive power wise (and hard to get a manual tranny). 

The latest engine that has come into contention is a Nissan VQ35DE.  Its a V6 out of a late 350Z.  This engine has over 300hp, a decent 270lbs tq, and weighs only around 350lbs.  It also has a great 6speed tranny.  You can pick these up for $2000 with the transmition from time to time. 

Looks like it has a forward sump but I am willing to do the welding/fab required to make it fit.  I would recam and make it a weber fed setup, junking most of the fuel injection.  Have a set of weber three-bank carbs from an old 911 porsche.  Well aware that the hood will have to be chopped to get the height worked out.  Haven't even begun to think about tranny size (chopping and modding the tranny well, etc) or exhaust problems.  The engine looks very compact though, and seems like it would fit well (height will be an issue).

Anyone have any other interesting JH alternative engines?  I know the huge ammount of work that needs to go into any engine graft, but I am willing to put in the time as long as the result is a 300hp JH. 

-thanks


Attachment: VQ35DE.jpg (Downloaded 61 times)

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 Posted: 10-08-2007 09:03 pm
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Jensen Healey
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Why not just build a tube frame and hang the JH body panels from it? Then you can use any doner car you want, think Factory Five Cobra.

If you use the JH frame you will be replacing the driveline, suspension and brakes anyway so you might as well start with a rigid frame. Come to think of it, the Cobra looks better anyway. ;-) Just joking.

The Rover is my favorite for weight and period correctness.

Kurt

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 Posted: 10-09-2007 07:28 am
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Sylva
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I run my 910 block in a space frame chassi, (not with JH body panels), the engine I looked at as a replacement was the Nissan Sr2 turbo up to 270 bhp 2 litre no weight, and you can buy them in Japan for 800 US$.

Problem is when you open the bonnet (hood) it has Nissan written on it, so rebuilt my 910 (again)

Kelvin

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 Posted: 10-10-2007 01:20 pm
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edward_davis
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It seems like going to 300 hp with the 9XX engine should be possible through supercharging or turbocharging.  Since the hp is proportional to the intake air pressure, you could take a mostly stock JH 907 and get it to make ~280 hp by blowing in 1 bar of additional pressure.  It would require a lot of work on the rest of the engine to make sure it was reliable with that much boost, but you could get there without having to go to the stroker crank or high compression piston set. 

I see turbo and supercharged cars every month in Hot Rod, and it makes a lot of sense with the equipment you can buy today.  Might be cheaper and faster to find a place under the hood for a turbo and an intercooler than to do all of the reworking necessary to get a different engine in there.  And it would be relatively easy to keep the weight distribution 50-50.  If you were worried, you could remote-mount the turbo in the rear and pipe the pressurized intake air up to the front.  I don't think that would be necessary, though, since the JH has a slight rearward weight bias in stock trim.

Just my bit o' bench racing.

-Edward Davis

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 Posted: 10-10-2007 03:33 pm
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Harkes
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I talked to Garry Kemp long time ago about the possibility of building a 2.5L engine and Garry replied he had built a few 2.5L Lotus engines already and that it is feasible to go even larger (2.9L)!

A 2.5L Lotus engine, using the Lotus 910 Zeus block can produce between 280-300 HP and between 220-240 lbs/ft of torque. Garry wouldn't recommend using the 907 for this.

In a JH this amount of torque makes the rears unstick but it can of course be done. Garry has all the tools and bits lying around in his garage but for his own JH he has built a 2.2L and not a 2.5L. The latter he uses for his Lotus Sunbeam racecar

the 2.5L crank alone is already around 1100 GBP!

good luck

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 Posted: 10-10-2007 03:43 pm
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Greg Fletcher
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Garry Kemp in the UK has had some very interesting Lotus engine projects over the years, converting older Lotus engines to modern 90's specs with such things as a Zeus head that has a custom water cooled exhaust valve set up. He also has built a custom 2.6 liter Lotus stroker engine. Garry has billet steel cranks with 88mm stroke and lightweight rods that can get close or at 300hp and still be good for 8500 rpm. If I heard this claim from anyone else I would not believe it, but Garry is the real deal and has the experience and dyno results to back up his claims. Expensive? Yes. But personally, if I was going to drop some cash into a super engine conversion, I'd rather be investing in more modern Lotus go fast bits that Japanese engines. It always makes me sad to see another aborted JH conversion project on ebay because the owner lost interest and money to complete it.

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