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I saw this on Puresportcar.com posted by Cuturo.
Has anyone else heard about this?

I had the privelege to attend a Lotus Engineering presentation, in which they modified the current Yamaha (Toyota) engine to achieve 250HP @ 8000 rpm and 175 Lb.ft @ 7200 rpm.

Although the purpose of the experiment was for fuel efficiency, it's clear that this engine offers great potential.

It was accomplished with an Eaton M62 Roots blower with integral bypass, no modification of compression ratio, the production intercooler from the Opel Speedster Turbo, and a fifth injector at the plenum entry, together with a modified Lotus T4 engine management.

Impressive results in a small package. 32% increase in power, 27% increase in torque and 9% gain in fuel economy.

No indications that these mods will be fitted in production Elise according to Lotus Engineering....but I'm quite sure customers will love it!
http://www.puresportscar.com/forums/showthread.php?s=&postid=733#post7353
 

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Better fuel economy? How do they work this one out. A supercharger costs a lot of energy to turn. FI engines are normally tuned to run richer to avoid detonation.

These kinds of engines i.e. high reving, high compression, big valve overlaps are not suited to FI.
 

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Well I wasn't talking about what hurts. I was only pointing out that the charateristics of a high rpm engine are not optimal for a FI engine. But since you mention high compression as being the only disadvantage. I should explain why the other two are also negatives.

Excessive valve overlap: On a supercharged engine this results in boost flowing straight out the exhaust. On a turbo engine this can result in exhaust gases flowing back into the cylinder, not a desirable effect.

High revving - not really a big issue but to get a turbo to work on a high revving engine you need a big turbo so that it doesn't become a restriction at high rpm. The side effect of this is lag. Not really an issue for a SC but a centrifugal design works best for high rpm engines - these designs provide very little boost at low - mid rpm.

As I said before the Toyota engine does not have the characteristics that make it a good candidate for FI. Nothing stopping you from doing it, but it will never make the power of an engine designed for FI from the ground up e.g the Audi 1.8 which can make 350hp/350ft lb of torque without any internal mods.
 

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im fairly familiar with how turbos work...im getting 450hp to the wheels in my evo....its a big turbo yes, but the new garrets turbos are pushing a lot more air at lower rpms than they used to..i hit full boost, which on my setup is 25psi at 4k....the stock turbo hits full boost, 20psi, at 3600 rpm....
i rev to 8k.

is valve overlap the same as blowby? sounds like it. pardon my rudimentary term....dont know much about that, havent run into that problem.....dont see why it would be a problem though in the toyota engine and not all the other engines with turbos. what is it about the design that is so different??

ur other points, like restrictions at higher boost, has more to do with efficiancy than do-ability.
a small turbo like a 16g would be perfect in the elise. full boost at 3600rpm's or so?? psi good to 19-20psi??

honestly, i like linear power curve of superchargers than the harshness of turbos....and the on/off with boost is much more abrupt in turbos than superchargers....

anyway.....
 

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I think a primer on Turbos and Superchargers is probably in order here. CLICKY

When I refer to overlap I'm talking about the engine inlet and exhaust valves. A blow off valve (if this is what you're referring to) is something completely different. It's a device for controlling boost by either venting or re-circulating excess boost.

On an engine operating at high rpm the cam profile will be such that at times both the inlet and exhaust valve will be open at the same time in order to maximize the amount of fresh charge flowing into the engine. In a turbo charged engine because you have a big restriction in the exhaust i.e. the turbo you will have positive pressure between the turbo and valve allowing exhaust gas to flow back into the cylinder if there is to much overlap between the intake and exhaust valve. This is desirable for an NA engine since as rpm increases there is less time for the exhaust gases to exit so a long overlap allows the intake charge to sweep out the old charge.

This is the beauty of VTEC, by running two cam profiles you can use a profile that is optimal for low rpm - less overlap and duration and have another profile for high rpm with more overlap and duration.

Most engines are not designed for operation at 8,000rpm+ therefore they don't have the amount of overlap that the Toyota has to have in order to make power at this rpm. This is why such engines are not good candidates for FI. It just so happens that these engines are performance engines so young boys buy them and slap turbo's and supercharger's on them. Boy's with enough money replace lots of moving parts in order to get decent performance from using FI on an engine not designed for it.

Your Evo has an engine designed from the ground up for FI, with cam profiles optimized for turbo charging. You will never get this kind of power from the Toyota - unless you are prepared to replace nearly every moving part. Yes turbo's have become more efficient with new turbine designs. But the killer for turbo's is lag. A big turbo has lag because it's big and weights a lot so it takes longer for it to spin up (than a small turbo that weights little). The cheapest way for a manufacturer to reduce lag is to make a smaller turbine (which will restrict high rpm performance). Otherwise you need to either accept the lag or use expensive materials to reduce the weight of the turbine.

I btw have driven an Audi turbo powered Elise 250hp/250ft lb, absolutely brutal in a straight-line. I didn't cane it through the corners (not my car and was on the road not track). But I can imagine it would be an absolute nightmare. A light car and a big turbo do not go together - attempting to balance the car on the throttle (as you do with an Elise producing 200hp+) would in many cases fire you off the road as the fine throttle adjustments would result in massive changes in torque going to the wheels as the boost fluctuated. In a heavy car this is ok, but in a lightweight car hopeless. The developer of the conversion knows this and is working to try and develop an electronic solution whereby the ECU attempts to control the boost characteristics to prevent the above scenario from occurring. Info on the Audi conversion - sorry S1 owners need only apply here.

Leaving the car NA or supercharging is imho preferable to turbo charging with regard to the Elise. Although the Audi turbo conversion in the UK is producing big numbers it remains to be seen how this will translate on the track
 

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iwilson, no i wasent talking about a blowoff valve, but thats ok...

i agree with just about everything u said anyway....
i think a turbo is the wrong route on this car also.
i prefer superchargers....at least for street apps.
 

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evomind said:
iwilson, no i wasent talking about a blowoff valve, but thats ok...

i agree with just about everything u said anyway....
i think a turbo is the wrong route on this car also.
i prefer superchargers....at least for street apps.
And yet you drive an EVOLUTION? I would have though a Mustang Cobra, or perhaps a Mercedes would have been more up your ally? I like the little kick the turbo gives you. It was always fun to drive, but I can see your point, especially if youare running 20+ pounds of boost and it hits hard ar 4500 rpm. A good turbo system would be aiming for more torque, and the 3000-6000 area which is gutless.
 

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so what will be a realistic way to get a little more juice out of the elise? talking out my butt here but what would it take to get a 250-300hp drivable elise - something that ran to 60 in the mid 3s and such?

is it even possible? lets put money aside - just is it doable and in a way to maintain the cars control? when I had my 450hp S4 I had multiple ECU's - i also had before that an APR chip that had different "maps" to use - so you could run stock or chipped or race gas programs - giving you a 250 stock mode, 310, and 340 (whatever the numbers were)

would that be possible on this car? to have a sort of track mode with medium power and a more acceleration mode for more straight line kind of uses?


humor me :)
 

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>>>Most engines are not designed for operation at 8,000rpm+ therefore they don't have the amount of overlap that the Toyota has to have in order to make power at this rpm. <<<

I think the engine would turbo just fine within CR related limits. The duration and overlap is not a big deal since the Rs are up at the time. If you used the high cam down low it would be more of a problem FI than NA but we wouldn't do that.
 

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I think the engine will take 6 PSI or less of boost just fine with the appropriate ECU and fuel system tweeks.


Here are numbers from some existing Celica GT-S kits ...

The Blitz and Trial supercharger kits for the 2ZZ run at a maximum of 7 PSI of boost (6.3 PSI as measured at the throttle body) and have been reliable.

The C2 Power turbo kit runs at 5.8 PSI of boost. Being as this kit is new, there are no reliability reports yet.

The XS Engineering turbo kit runs at 7.5 PSI of boost. There have been a few reports of blown engines, low octane gas was suspected to be the root cause.


One other thing ... The choice of supercharger type and intercooler location would cause me to think that this was just a Lotus proof of concept. I would hope that they pick a Lysholm supercharger design for an actual production unit. Also, the location of the intercooler would reduce airflow to the A/C and radiator.
 

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iwilson said:

I btw have driven an Audi turbo powered Elise 250hp/250ft lb, absolutely brutal in a straight-line. I didn't cane it through the corners (not my car and was on the road not track). But I can imagine it would be an absolute nightmare. A light car and a big turbo do not go together - attempting to balance the car on the throttle (as you do with an Elise producing 200hp+) would in many cases fire you off the road as the fine throttle adjustments would result in massive changes in torque going to the wheels as the boost fluctuated. In a heavy car this is ok, but in a lightweight car hopeless. The developer of the conversion knows this and is working to try and develop an electronic solution whereby the ECU attempts to control the boost characteristics to prevent the above scenario from occurring. Info on the Audi conversion - sorry S1 owners need only apply here.

Leaving the car NA or supercharging is imho preferable to turbo charging with regard to the Elise. Although the Audi turbo conversion in the UK is producing big numbers it remains to be seen how this will translate on the track
You make a lot of very good points (which I have thoughtfully snipped from the above quote :D), but on this last point, I disagree. A properly-sized turbo wouldn't have the sudden surge in torque that you describe. As an example, I hold up the Mazdaspeed Miata. Power comes on early and controllably, and continues to redline. As long as you don't enter a corner at 1200 rpm, you don't have to wait for the turbo to spool up.

Jim
 

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iwilson said:
I think a primer on Turbos and Superchargers is probably in order here. CLICKY


Most engines are not designed for operation at 8,000rpm+ therefore they don't have the amount of overlap that the Toyota has to have in order to make power at this rpm. This is why such engines are not good candidates for FI. It just so happens that these engines are performance engines so young boys buy them and slap turbo's and supercharger's on them. Boy's with enough money replace lots of moving parts in order to get decent performance from using FI on an engine not designed for it.

here.

Let us not forget real racing, instead of simply using the old bench racing philosophy. Remember F1, they use turbochargers. Also, there are many other racing engines that do to. The theoretical application of facts that can't be applied directly is inaccurate, but perfectly appropriate for a message baord. Remember that a turbo's efficiency and backpressure are the real issues that you are highlighting.

Also, there will be turbo'ed Elises running around soon. I plan to get mine done in a few weeks. I am aiming for more torque, and am not concerned with the peak numbers. I want 200+ lb-ft and above 240 hp. Forcefed is developing a kit with similiar attributes. Talk to them directly if you want to buy a real power application instead of the magical exhausts made from honed snake oil, and forged unicorn horn...

I said before, many months ago, and I will say it again, that the aftermarket will develop the best performance parts for this car. I was chastized from some people on this board for thinking something like this, but it seems to have played out. Lotus can't even make enough cars to fill their wait lists, they aren't going to spend a lot of money trying to get more power out of an engine that they didn't even develop. Lotus has no reason to sancion these aftermarket endevors, especially if the Exige is coming here and will cost a lot more than the standard Elise.

That is why I am going to go with a company who has had experience with this engine, and small turbo applications such as the MR2. I think that with the 2zz's natural desire to rev, and a bump in torque, the car would be even more of a giant slayer, and a little more fun in the perverbial straight line :rolleyes:

On a side note, I feel as though I would run the car less hard by dipping into more toque in a given gear than having to drop 2 gears and wring out the engine untill 8500 RPMs. :rolleyes:
 

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mean tt....
ha, i DO have a supercharged mustang cobra....when it "only" had 470hp it felt like it came from the factory that way, thats how spot on the tuning was and how linear the power curve was....since then, i have added an intercooler, full griggs suspension, t56 6 speed, stage 3 headwork, forged bottom end, and dropped 2 pulley sizes....im expecting around 600hp on 93 octane...
i do like turbos but i should probably clarify....when the power comes on, 4k rpms full boost, not 4500 by the way, :), it feels like a big nitrous shot....a smaller turbo feels much more linear and smooth...if i were to turbo the elise, obviously a small turbo would go a long way...given a choice i would rather go supercharger..

agent orange....250-300hp out of the elise would need a new engine with lowered compression and go from there...u realize your talking about double the hp of the stock motor....and say you get it...u will be ripping up half shafts like crazy...if u can get traction....probably start breaking a lot of thing with that hp and traction.
can it be done?? theoretically yes. given someone makes a supercharger system that fits in the engine bay.. then just drop a pulley size or 2, and tune. the turbo is a little more limited as far as a turbo designed to put out a given psi can only put out that psi, so u have to wait for a 300hp kit, if theyll make one...
anyway, without going into a lot of detail, there it is
 

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from the little research i've done it seemed to me 250-ish was doable without any major engine mods besides turbo, fuel system/injectors and such, and a few other components - with the high compression of hte elise 5-7psi would be possible. I haven't done enough research to talk about this intellegently but that's that
 

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your right...u can probably do 5psi reliably...7 is a bit close...
guess what? u will still be a far cry from 250 hp...at the wheels anyway...i probably wouldnt go 7 psi on this CR. so lets say 5psi...lets say u gain 40hp to the wheels...ur right around 205-210 at the wheels....i mean, thats good, but ur a ways off still from 250 at the wheels
 
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