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This discussion is about the possiblity of putting an engine in an Elise in the more traditional configuration where the engine & transmission is lined up the same direction as the car. Like a typical rear wheel drive car. An Elise/Exige is normally setup with a transverse drivetrain so that the transmission is beside the engine and lined up between the wheels, like a front wheel drive car, only in the back.

Transverse has some advantages, especially when setting up a mid engine car because you can use a front wheel drive setup which opens the choices on transmissions. But limits you on the length of the engine since you are limited by the width between the wheels.

A longitudinal setup lets you use a bigger engine and transmission, but there are only a handfull of transmission choices.

When I first heard of the Hennessey Venom I admired that they chose the Elise/Exige (Elige) chassis as the basis, but I knew that there had to be a underlying reason they chose the chassis. If you look at the Venom you can see that the back end is stretched quite a bit. Normally stretching a chassis is quite a bit of work, especially if you want to get the suspension points working again.

Replacing the engine in my car allowed to me to really get a good look at the way the Elige chassis was constructed. I was very surprised to see that this car is setup about as easy as they could make it to stretch the car. I believe that the Elige could easily be adapted to using a longitudinal engine.

The engine bay "frame" is split in half with it consisting of the front 75% of the car and the rear 25% of the car (approximations of course). There are 4 points that tie the 2 halves together. You have the strut bar that goes diagnoly and you have the main chassis flange.



You then also have an attachment point for the suspension.



The main thing to notice here is the chassis is flanged right down the middle. So that the two halves butt up and are bolted together.



There is a bolt at the top



And one at the bottom



Whats awsome is that with the flange being forward of the wheels the suspension geometry gets preserved.



You can see here at this bare chassis the flange from the front part. You can see the 4 bolt holes.



Its hard to find pictures of the Venom chassis, but you can see that the flange is exactly where they extended the back end at.



Now it looks like the Venom uses a bespoke suspension setup, and thats fine for a million dollar car. If anything it may have been to use a much wider rear wheel while still maintaining the overall width of the car. They would have had to move the suspension inboard.

Now for us DIY'ers. We could use the stock suspension points and use a wider wheel/tire, maybe something like a 290 or 300mm, but it would just require the rear clam being widened. But don't worry your already going to be doing some major work on the clam anyways since the car will be stretched quite a bit. Probably along the lines of 2 feet.

I measured the width of the engine bay and at mid height the narrowest area, where the exhuast passes through the rear frame is about 32". So width wise you got plenty of room. From the firewall to the flange position is only about 17" and thats not nearly enough for any real engine.

To stretch the frame you could make a spacer that has flat end pieces for the flanges and then something like metal tubing in the middle.

Engine choices.

Really the choices are numerous. You can go exotic like a Ferrari or Lambo setup, but most of us would look at the value conscious choices. You will also have to consider the tranmission choices as well. Also, Federal law states that any engine swap must be at least as young as the car it is going into. So since the Esprit stopped production in 2003, thats means no Esprit V8, plus the UN1 transmission I think adds too much practicality issues.

These are the 2 main engines I would consider for cost/power/availability

The LSx motors from the Corvette. You know, logically there is nothing wrong with this engine. In fact its win on almost every single focus point.

> Lightweight
> Compact/Narrow
> Very Reliable
> Cheap / Available
> Excellent power
> Incredible redline for an OHV motor (peak power at ~6500 RPM)
> Adapters for rear transmission already available

What GM has done with this thing is magic, no doubt. Its just so 20th century that its not something I would choose with out rolling my eyes a little.

The Coyote engine from the current Mustang GT. This is an exciting engine. Its the first American production line engine I can really get enthusiastic about.

> DOHC
> 4 valves per cylinder
> variable valve timing.
> Dyno'es at ~390HP on a completely stock motor.
> Ford sells the engine as a complete crate motor >> Link <<
> Also sells a full wire harness including an OBD-2 port >> Link <<
> Engines measures in around 28"L x 26"H x 28"W

This new motor shares the same bellhousing as the previous Ford Modular V8's which did actually have a rear transmission made for it. The Ford GT had a Ricardo unit that can handle tons of power, plus had an LSD and all that. They are very limited though. But if you could fine one, it would bolt right on.

Transmissions

This is going to be the hard part. There just aren't that many that would be interesting. There is the UN1 of course that Lotus used for ever in the Esprit. But they are limited to 300HP-400HP, which isn't much now-a-days. Plus they aren't easily available in North America.

There is the the very popular Porsche transmission. These things are very popular in the Ultima kitcars and other similar designs. The G20, G44, G50, G97, G96 are popular choices and are available in 6 speeds. You have to look at them specifically for power ratings. But they seem to be good for 500-600HP.

There is also a company call Griffin Gearboxes that makes mid engine transmissions that supposedly are ready to mount to American V8's.

Anyways hope that gives you some inspiration. I might revisit this topic after I pay off the current round of upgrades and get bored with the TVS :)

I will not comment on how stretching the Elige effects handling. Obviously it will, but I don't know the end result. I don't track my car, so not as important to me. Having much wider tires outback will also have an effect as well. You would probably look at adding an additional 300-500 pounds as well to the car. It would still be significantly lighter then anything on the market and you'd be looking at at least 400HP, with the possibility of 600HP not really being that hard to get on the modern engines. It would be fast no doubt.
 

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The center of gravity of the GM LSx motors is much lower than the Ford Coyote. The Coyote is also much wider due to the OHC set up. If you look at the information about putting these engines in a Cobra replica, like a Superformance, you will see how much more compact the LS is. A N/A LS3 is about 530HP+ with headers and cam; S/C 640HP+. Both pump gas.

If you are a Lotus owner that reads "Hot Rod" magazine, I am, you can find recycling yard LS engines from trucks that can be completed for well under $3K. They were throwing Chinese turbos on them and getting 800HP or more, for a while anyway.

My pet "The Car Lotus Should Build" is a N/A LS3 211 track car for about $80K. Dry-sumped, 500HP+ and 2100 lbs. Make it look like a 1970 Can-Am car.
 

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I would love to do the build your own from scratch LS9 at the factory. That option is so cool I just wish other companies would offer it. AMG doing this would make me a happy mam.
 

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Awesome information! I cant believe how simple it would be to extend the chassis, I wonder how much reinforcing you would need to do per 1" of extension?
 

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you would have to go with a bespoke suspension, because the driveshaft output (wheelbase) will move out, a good bit. putting the chassis pick up point far away.

you would want a "short" block length. so probably a v-6, turbo.. would be the way to go

and center drive. i think the "sorting" would be the most time consuming thing... track time and data to tune the suspension.

fabricating the rear sub frame is totally doable by any good race car fabricator. i know a guy here in san diego that could do that.

body work would be a lot of time.... a lot of money. its gonna be ~6k to paint, and lots and lots and lots of labor.

totally not worth it IMO - just a get a noble (tranverse i know), or caymen or whatever it is your are trying to "match"
 

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you would have to go with a bespoke suspension, because the driveshaft output (wheelbase) will move out, a good bit. putting the chassis pick up point far away.

you would want a "short" block length. so probably a v-6, turbo.. would be the way to go

and center drive. i think the "sorting" would be the most time consuming thing... track time and data to tune the suspension.

fabricating the rear sub frame is totally doable by any good race car fabricator. i know a guy here in san diego that could do that.

body work would be a lot of time.... a lot of money. its gonna be ~6k to paint, and lots and lots and lots of labor.

totally not worth it IMO - just a get a noble (tranverse i know), or caymen or whatever it is your are trying to "match"
+1
 

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You guys seem to be forgetting the most important issue here, power density. All of the engines you've mentioned are long on pork and short on power. Lengthening the wheelbase of an Elise (to a degree) can actually make it easier to drive fast, and what you've suggested has already been done by Lotus themselves a long time ago using a weenie 400 HP 3 liter V6 coupled to a Hewland 6 speed sequential transaxle. They called it the Sport Exige and it was raced by Proton for a few seasons then sold off to someone.
As an alternative to the mega-labor intensive longitudinal approach, how about just using an engine with excellent power density that already fits transversely. It may not have the same WOW factor rating as that POS Hennessey sells, but it'll be plenty fast enough for most people's taste and a LOT easier on the wallet.
Since 2001 I've been using Honda K-series engines in the Elise/Exige, and while gaining substantially in the HP Dept. the car loses 70 lbs. of excess fat. I can build one of these to make 390 HP on pump gas naturally aspirated, and if you prefer supercharged power then 600 HP on pump gas isn't out of the question. All without making the car any heavier than it was to begin with.
My current street driven Elise setup makes 454 HP at 9,100 rpm on Arco pump gas and weighs 1,820 lbs. Just let your imagination work on that scenario for a while.
 

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You guys seem to be forgetting the most important issue here, power density. All of the engines you've mentioned are long on pork and short on power.
Joe, you may be looking at this through Honda colored glasses. A quick check on the web, so guesstimate +/-10% variances, says

The most flattering numbers i found, and I am not an expert, is a K20Z1
210 HP, 142FT/LBS, 400Lb weight, not sure if that includes flywheel.

LS1, GMS least athletic LSx aluminum motor (why you would go through the hassle of modifying your Lotus to an LSx motor and use an LS1 is beyond me, but i am using their conservative numbers), is
345HP, 350FT/LBS, 497LB weight, that does include flywheel/clutch.

So each K20 HP has to move 1.9 pounds of motor
So each LS1 HP has to move 1.4 pounds of motor.

Then, the part that makes me question my small bore love a fair ism if you use the old saying that "HP is how fast you can go and Torque is how quickly you get there", give me an LSx motor.

Now these are stock Google figures, and I see you are not running a stock motor. Your setup sounds fun, and I would love those numbers in my car. Your fun/hassle to build ratio looks great!

But..... If we get to look at HP/LB of modified motors, I see Power to weight potential of something like this (but the fun/hassle to build ratio is not as attractive)....
 

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Doug,
A fully dressed K20A weighs 257 lbs, and that includes a 9 lb. flywheel and a clutch (lighter stuff is available, this is just what I've weighed personally). The transaxle weighs 92 lbs with LSD unless you opt for the TSX case which is Magnesium, then subtract 5.5 lbs. Including the trans in the calculation for power density is a valid consideration because its a necessary part of the system and can't really be ignored. There are quite a few big torque handling transaxles around that weigh more than my engine!
The lowest HP K20A I've ever used in an Elise made 240 HP, and that's measured at the drive flanges not the flywheel. You can't use Google here.
I have absolutely no brand loyalty to any manufacturer. Honda is an outfit that's only made a few really good engines in their entire history, and this just happens to be one of them. I've witnessed a 2,188cc K-series engine make 1,125 HP Turbocharged, although I wouldn't advise driving it on the street. The custom built trans on that engine weighs 112 lbs. and lives.
That's 514 HP/L, and to get there with an LS9 you'd need to be making 3,598 HP. Probably not, huh?
What I think would really be a lot of fun is to build a V8 based on the K20A, although I'd increase the bore centerline a bit in the process. I've got quotes from pattern makers for all of the castings and it looks like I could do it for about $400,000. Problem is there's no real market for it so it'll most likely just remain a sweet dream. But just imagine a naturally aspirated 640 HP 4 liter V8 that'd be happy at 10,000 RPM. Cool or what? It'd sure make Ferrari look pitiful, and that's always fun.
 

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Back when Formula-1 allowed unrestricted designs of naturally aspirated 3-l engines or 1.5-l supercharged engines, the 1.5-l engines outperformed the 3.0-l engines. You had I-4s beating V-12s. Now let’s take a look at the advantages and disadvantages of longitudinally mounted engines; lower center of gravity and narrower. For a single-seat racecar, narrower is very important for aerodynamics…the diffusers run along both sides of the engine. Weight distribution is also better…your engine mass is not right over your rear wheels – this is where the polar moment of inertia comes into play and changing directions of the car is faster…you are not swinging a barbell.

Should it be done to a Lotus? The bottom of the car is flat, so aero is out…no advantage there. You will have to design and build a complete rear sub-frame…this is a big job that requires specialized tools and skills. A lower center of gravity will only be realize if the engine is dry-sumpped…this was not mentioned yet – only a crate engine was mentioned – no dry-sumps on those.
 

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Gee Doug, I didn't even know we were keeping score!
Off that topic and on to the next.
F1 will be using smaller Turbocharged engines again soon, although I doubt they'll let it go as far as it did the first time around.
Where did you get the idea that a longitudinal engine/trans would result in a lower CG?
Anyone contemplating the conversion to a longitudinal engine/trans layout had better be well versed in the engineering and fabrication skills required, and as such would already have the tools. I toyed with the idea of doing this a LONG time ago and decided against it primarily from the excess weight standpoint, but also from envisioning the huge amount of work it'd be relative to the benefits.
Fabricating a new sub-frame is a piece of cake compared to the work involved in creating a new rear clamshell. I've already designed a tubular 4130 sub-frame to replace that galvanized sheet steel monstrosity Lotus sells us, and it weighs 60% less and is much stronger. The sub-frame on an S1 Elise weighs 30.5 lbs. On the US Elise it weighs 58 lbs. and there's STILL no structure directly in line with the suspension loading. Mine takes care of that massive oversight as well.
LS9 engines are equipped with a dry sump.
 

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Where did you get the idea that a longitudinal engine/trans would result in a lower CG?
It’s not an idea, it’s geometry…just take a look at it from the side…oil pan and all.
Anyone contemplating the conversion to a longitudinal engine/trans layout had better be well versed in the engineering and fabrication skills required, and as such would already have the tools…also…the huge amount of work...
That’s exactly what I was trying to say.
…decided against it primarily from the excess weight standpoint,…and it weighs 60% less and is much stronger.
Excess implies useless, therefore in one place you say more, then in another, less… I agree if you mean that the specific strength of your subframe will be higher…I’m sure I could accomplish that too.
…LS9 engines are equipped with a dry sump.
I did not know that…just goes to show how interested I am in Detroit Irons… :D
Fabricating a new sub-frame is a piece of cake compared to the work involved in creating a new rear clamshell.
Not really…it’s all in the tools that you have and what you are used to building. But, they are both monumental tasks.
 

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I don't think it's a bad idea to engineer a longitudinal engine.. but that's probably because I haven't tried it. dry sump systems are available for any ls engine. Longer wheelbase should make it more stable in the turns by providing a closer to 50/50 weight distribution. Most importantly - 1000hp out of a 4 cylinder would be undrivable, or close to it. 1000hp out of a LS would be much less undrivable. Honestly, I would love to design and build it, but I don't have the time to do it.
 

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I doubt the science of triangles and circles (Geometry) has very much to do the CG differences between one engine design and another, especially if viewed from just one side as you suggest.
An inline 4 cyl. engine is problematic from a vibrational standpoint, but its got a LOT lower CG than a V8. If you'd like I'll explain it to you.
I won't even jump down your throat for taking what I wrote out of context to change the meaning!
 
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