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>>>stan, if u use lighter weight pistons then yes, u can spin them higher than u otherwise could...dont know if using something that exotic would be cost beneficial here though.... <<<

Two different points. And the stock pistons are not exactly boat anchors...they are about 300 something grams apiece someone claims. Cutting that weight does not change the piston speed issue I've brought up. Usually high revving race type engines use a big bore short stroke layout...not the reverse...
 

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Stan said:
>>>stan, if u use lighter weight pistons then yes, u can spin them higher than u otherwise could...dont know if using something that exotic would be cost beneficial here though.... <<<

Two different points. And the stock pistons are not exactly boat anchors...they are about 300 something grams apiece someone claims. Cutting that weight does not change the piston speed issue I've brought up. Usually high revving race type engines use a big bore short stroke layout...not the reverse...
Both points are valid...and there are others. The increased piston speed will result in increased stress on the bearings and bearing bosses unless lighter components are used. The force goes up with the square of the speed.

Also, stroking will increase the rod angle, thereby increasing the side loading on the pistons and rings, causing more wear. That will likely cause more additional wear than just the mere increasing of piston speed.

Although, with the amount this engine can be stroked, it is not likely to cause any appreciable difference in any case. The factor most limiting the redline in this engine is the valve train. Some improved valve train components would safely allow 9000 RPM, though the slipper cam followers do not have good wear characteristics and there isn't any replacement alternative that I am aware of.
 

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hmmm....so basically were up the the creek as far as making any power n/a??
hmmm...looks like if u wanna do something special we will have to do a rebuild and hope there is a supercharger kit available..?
60 more hp and that car will rock even more than it does now....
 

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Forced induction increases torque not RPM (Higher temperatures and pressures within the engine).

Therefore the reduction of masses which are moving up and down is not required. ( lighter but not stronger titanium conrods, lighter pistons )

But the crankshaft and its bearings may be a bottleneck within the engine.
Also the pistons may become hotter than they are designed for.( Spray oil from beneath for cooling them?)

Another point where higher temperatures may be critical are the valve shafts.( Better heat conductivity have shafts filled with sodium ) Valve guides made out of special bronze may be helpful, too.

Cylinder head gasket and the studs keeping head and bloc together could be critical, too.

Find somebody who really knows where are the bottlenecks of that engine, but money invested in upgraded cooling systems will always be paid back in engine lifetime.


Rüdiger


PS
My guesstimate was 7000 $. Will this be enough ? :(
 

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that 220 hp claim....yeah, maybe at the crank...

in that 5k estimate for motor, the lsd really shouldnt be included there...
great job digging that stuff up though...
basically rebuilding the motor ur looking at around 3800 bucks, and for me, thats not including a new block...i want to save the original motor as is.

i saw a price for the blitz supercharger kit for 6k?? wow, thats expensive....

im still thinking were looking at a rebuild and s/c kit...
 

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I was just at a Honda-Tech forum event in Danbury....had some 2ZZ guys look over the Elise. Overall there is definitely room for a turbo - there is actually *more* room than the Celica has available on the exhaust side. Some bits from a celica kit appear to be useable as is, intake plumbing would be different of course but that is not hard to do. Various intercooler options came to mind. I'm not interested in doing this but thought you guys might find this of interest.
 

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thats some nice work on that celica....

thanks for the info stan......
i think if i was gonna do this now, i would supercharger rather than turbo.....i have both....the supercharger is much more linear,
as for the guys who say s/c dont make power up top where this motor likes to rev, ur wrong because they do.....but the s/c will also provide more low end than a turbo and as stated earlier, a much smoother power delivery...
plus i think it would be so cool to go driving past and people hear that faint supercharger whine...:)
 

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For selecting the new forged pistons I found the following little diagram :



That diagram tells me e.g. : If the super- or turbocharger makes up to 10 psi then the you have to find pistons which allow a geometric compression of less than 8:1!


Druck = Pressure
1bar=14,5037psi= 100000Pa=0,9869 atm ( Pound per Square Inch )

or : 0,7 bar = ca. 10 psi

Verdichtung= compression, ( max. = 11, 5 :1, with the original pistons IIRC )

Cheers
 

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Do not forget that all that thrilling flywheel torque has to be transferred to the wheels.

Somebody knows for how many Nm that gearbox etc are made for ?
 

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Ruediger said:
Do not forget that all that thrilling flywheel torque has to be transferred to the wheels.

Somebody knows for how many Nm that gearbox etc are made for ?
Good Point.... My 300hp Miata likes to enjoy one tranny a year for breakfast. That is why I would only want a modest 50hp or so and not 100+.
 

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I converted a Porsche 914 to Chevy V8 power years ago. Stock P. gearbox with an adapter. They warned me that the box would live just fine if it was not launched hard, speed shifted and basically accelerated hard only when in-gear. The box survived, but I went through some CV joints until they were beefed up.
 

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1fastmx5....are you replacing stock trannies every year?? if so, check with sheppard racing and see if they will do a rebuild on that trans...if they do, it will be about bullet proof....

what kind of suspension is in the rear??
irs? straight axle??
i keep forgetting to check when i see the car....
 

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The Elise appears to have different, closer, gears than the US Celica. Maybe it has the Euro gearbox hence the model number variation?
 

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Interesting discussion here:

http://www.british-cars.co.uk/cgi-b...ject=2050&source=T&thread=2004092710495614387


Thumb rules to avoid piston / cylinder problems ( gouging, seizing etc )

But in other cases where you have very slim con rods it may be a better idea to provide shorter rods when increasing the pressure in the combustion chambers by getting more air / fuel into them ( Remember: Forced induction is only one but the most effective method to do this)

Therefore best would be to get the whole engine design checked by the Yamaha- engineers who really know its critical points and where upgrades are required for forced induction.

The other method is learning by the mistakes others who tried it before have committed .
Somebody can read Japanese ? I am sure that in Japan some Celica- tuners and their customers have collected very valuable experiences concerning that engine, too.

Cheers Rüdiger
 

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Stan said:
The Elise appears to have different, closer, gears than the US Celica. Maybe it has the Euro gearbox hence the model number variation?
Correct. It is from the Euro Celica T-Sport.
 

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i snapped a few pics of the lotus' engine bay....even smaller than i remembered it....anything will be a very tight fit.

im thinking....how do the celica guys tune their ecu's? reflash or standalones?? im thinking if they reflash we can too...i know lotus tuned it, but it should still basically be the same celica box. if were able to reflash, the tune will probably be better overall for cold starts and idle etc...
 
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