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Discussion Starter #1
I was just wondering why the Elise engine reaches the higher cam profile at such a high rpm (6200rpm). Why didn't they change the cam profile at say at 5000rpm. Would there be any drawbacks to lowering when the higher cam profile is initiated, besides gas mileage??
I wondered the same thing with the Honda S2000 which changed at 6000. Is there any way to change when the cams switch? I guess it would be a software issue.
Cheers Doug
 

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There may be several reasons; at some point bringing the secondary cams in at lower RPM would result in a HP loss versus the primary cams, and there may be an emissions related reasons.
 

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If you bring the second cam in too soon it will create a big hole in the torque curve. Theoretically you could use a different cam profile and then change the switchover point, but it would take a lot of development ($$$) work.
 

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Courtesy of monkeywrenchracing.com (a great source for performance parts). No I'm not affiliated with them.
 

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Well in a perfect world, you want to switch cams when they are both producing the same torque/hp. If you switch anywhere else, then you are loosing HP over some range of rpm simply because you aren't using the cam w/ the greatest HP.

That said, due to engineering limitations, it is probably neccessary to have some sort of histeresis to keep the cams from hunting near the changeover point. Thats why the changeover is at 6200 on the way up, and 5800 on the way down. If you lower the changeover point, you can probably pick up some speed on your first shift, but then when coming out of corners etc, you might be loosing time if you don't get back on the 1st cam.

In practice, it seems that once you get on the second cam, you can pretty much stay there, so I guess it doesn't matter much.
 

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It's not the switch over that is the real issue it's the large difference between the two cams. Our small cam has 7.25/7.25 mm lift with 228 degrees duration. The high cam has 11.4 / 10.0 mm lift and 292 degrees duration. I think Toyota did this to help it's heavier cars get off the line. For the Elise a more aggressive small cam would work well....maybe 20 degrees more duration and something like 1-2 mm more lift on the intake side would help out the 4000-6000 range without hurting the low end too much.
 

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>>The real issue is the large difference between the two cams. Our small cam has 7.25/7.25 mm lift with 228 degrees duration. The high cam has 11.4 / 10.0 mm lift and 292 degrees duration. I think Toyota did this to help its heavier cars get off the line. For the Elise a more aggressive small cam would work well.... <<

Lotus apparently could not get a slightly different engine from Toyota for their Elise. But I guess that the USA you also have some special suppliers for camshafts. In UK they have Piper in Germany we have Dr. Schrick and others.

It’s not black magic to design better camshafts for the Toyota engine used in the Elise, if enough owners really want have them.

IMHO also the Honda 20KA engine could be improved a little bit when being used in an Elise.
I guess that’s less critical than boosting this engine.

Ruediger
 

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I read a long time ago that it wasn't exactly easy for Lotus to get approval to use the Toyota motor in the first place.
 

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Discussion Starter #9
Anyone heard of "Skunk2 Racing"

I saw a brochure from Skunk2 at a performance shop where I was getting an alarm removed from a car and in it there were two Honda engines, one from the Integra type R and the Rsx type s, and they were tuned to deliver 250hp and 300hp respectively. Would these engines fit into the Elise? If so they would make it one heck of a rocket don't you think? And those hp numbers are without turbo or supercharger, which is better because no lag.
Cheers
 

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Many motors will fit the Elise, but who will be the first to do the custom work? The turbo kits you can expect to see for the 2zz will hardly have any lag. They'll be using small turbines. The rev happy 2zz will keep the turbine equally happy. Of course I always love to see high output NA motors. Gives that factory reliability.




If they'd visit the realm of Toyota motors that'd be great.
 

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Re: Anyone heard of "Skunk2 Racing"

Maverick1 said:
I saw a brochure from Skunk2 at a performance shop where I was getting an alarm removed from a car and in it there were two Honda engines, one from the Integra type R and the Rsx type s, and they were tuned to deliver 250hp and 300hp respectively. Would these engines fit into the Elise? If so they would make it one heck of a rocket don't you think? And those hp numbers are without turbo or supercharger, which is better because no lag.
Cheers
yes they will and there are already conversion kits for them. prototype racing (they have a website) is one example, but let's not get into the prototype discussion - do a search on most Elise related boards & you'll find plenty of info on Prototype & other K20 conversions.
 
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