For those seeking more power...

[mason]

For all of you thinking the Elise is quick but when I get mine I'm going to strap on a blower and eat Vipers for breakfast.

One little problem... the compression ratio for the Elise motor is 11.5:1.

What that means is forced induction is all but out of the question. When you start to force-feed an engine with that kind of compression it will start to make a lot of power and start to detonate. As it detonates it blows it self apart.

Blower kits are avalible for the Celica motor but few engines have survived.

On the plus side Celica owners have been able to make good power from intakes / headders / exhaust and if you really need more power NOS.

For bonus points try to find a production car avalible in the USA with a compression ratio higher than 11.5:1

[specialED]

If the owner is willing to keep the boost at very moderate levels (under 5 psi maybe) and run a good IC and water injection, followed up by careful attention to A/F ratio via dyno tuning, it seems possible. Any additional stress on a engine will probably reduce lifespan/reliability though.

A J&S Safeguard system to augment the capabilities of the stock knock sensing system wouldn't hurt either.

If you really want to knock down the C/R, the easiest route to follow without having to replace pistons would be to use a thicker head gasket.

Maybe not Viper-killing power, but I think a 50-70 rwhp gain is possible without constant fear of detonation/engine death.

Also, those of us at higher elevations can get away with a little more boost than those closer to sea level.

[bob]

Good point on the gasket. Anyone know the formula to calculate compression ratio based on volume?

I'm reaching, but IIRC a cylinder's volume is pi*r^2 * height, so would a straight ratio of 11.5/Vo = x/Vn work to figure it? (where Vo is original volume, and Vn is new volume w/gasket)

(I wonder if they make gaskets that are > 5mm :D )

[bob]

RE: Intake - I noticed a substantial increase in power with the addition of an AEM CAI on my 01 Celi GTS... by my seat-o-the-pants dyno, maybe 10-15hp on the second cam...

I'd probably have to get another one just to hear the engine when it kicks up!

[specialED]

Why bother doing math when you can just use someone elses?

http://www.knology.net/~jediklc/D.htm

That site is Honda-based (it has standard specs for certain pistons, heads, etc) but if you know the true bore, head combustion chamber volume, piston-to-deck height, etc. you can get very close to what the C/R will be with a hypothetical HG thickness.

I ordered a 2mm Greddy HG for a Honda application and in that scenario it dropped the C/R almost two full points. Apexi makes a 1.5mm too for the same D16 engine block - maybe something similar is available for the Celica motor.

BTW the measurements and calculations we made on the actual engine came within 4% of what the website predicted.

[mason]

Originally posted by specialED
If the owner is willing to keep the boost at very moderate levels (under 5 psi maybe) and run a good IC and water injection, followed up by careful attention to A/F ratio via dyno tuning, it seems possible. Any additional stress on a engine will probably reduce lifespan/reliability though.

I like your thinking... but I still don'tthink this would be a workable solution. At 11.5:1 compression ratio I think even around 5 psi would be very dangerous and not be worth the potential for catastrophic damage. Intercooling and water injection will help but still I think you're putting far too much stress on the motor.

Originally posted by specialED
If you really want to knock down the C/R, the easiest route to follow without having to replace pistons would be to use a thicker head gasket.

I'll agree with you here but also say that reducing the C/R also decreases the performance of the engine. Any thicker head gasket would only minimally reduce the C/R and adversly effect the baseline performance of the engine. I'm not sure the cost would make up for the performance improovement. Of course if money wasn't an object...

Originally posted by specialED
Maybe not Viper-killing power, but I think a 50-70 rwhp gain is possible without constant fear of detonation/engine death.

Dunno, if you added 70 rwhp to the Elise I think you'd be very close to Viper killing power in every respect but top speed.

[specialED]

Originally posted by mason



I'll agree with you here (about utilizing a thick HG) but also say that reducing the C/R also decreases the performance of the engine. Any thicker head gasket would only minimally reduce the C/R and adversly effect the baseline performance of the engine. I'm not sure the cost would make up for the performance improovement. Of course if money wasn't an object...

Like I said, a 2mm thick HG on the Honda took the C/R down almost 2 full points - as in from 13.0:1 to about 11.1:1. That's significant. It's also a really thick headgasket . . .

Your loss of HP from less compression will be more than made up for by forced induction. It's similar to the parasitic drag of a supercharger that eats up 15 HP but gains 85 HP from positive manifold pressure.

Would I personally do any of this on my own brand-new, still-under-warranty Elise? No - but you brought up more power . . .

[GRM]

Maybe not necessary, check these videos out! They are from a French site and take a bit to load but trust me their worth the wait ;)

http://www.1-111.org

Click on the video link

[mason]

Welcome to Pure Sports Car GRM.

I'm interrested to see the video but the link doesn't seem to work, maybe the host server is over its limit?

But I've got a link myself...


Lotus vs. Porsche GT3R and F40

[GRM]

I believe this is one of them. They have 2 videos so be sure to check out the other one.

[Eyelise]

There are FI kits out there now for the 2ZZ-GE running 8 psi and producing 250whp. No changes were made to the stock C/R. I'm sure engine longevity will be affected but I'm not concered. I'll be driving the car weekends and at the track exclusively. I can't help it. I'm a huge fan of forced induction. I'm pushing 1.8 bar in my A4 right now. 265ft-lbs at 2800 rpm (1.8T) just can't be beat. The Elise needs low end torque in a bad way.

[WEi]

I kindda wish Lotus went with the Honda B18C5 engine. It's got lower compression and is easier for FI. However, it's not impossible, there's S/C kits out there for the S2K F20C1, which is running at a lower 11.1.

Looks to me like there isn't much room in there for plumbing or charger of any kind. I'd say the only way to do this is to cut through the tub into the "trunk".

I guess I'm gonna have to wait till we see the car in person!

[Hugh]

For Bob ... "Anyone know the formula to calculate compression ratio based on volume?" ...

Here is a site with Auto Math Calculations ...

http://www.smokemup.com/auto_math/index.php

[Onikaze]

I don't believe that I would invest the money in buying the car, only to invest more money in making sure I won't be able to enjoy it as long.

yeah, the numbers are tempting, 1975 lbs, boy, if i could just break the 300 hp mark...whoo...

but i find that i get lots of enjoyment just from pushing the stock little fourbanger in my girlfriends moms saturn, and that it provides good enough performance to surprise people in tuners and force them to punch it off the line...and its only pushing 160 hp tops (probably more like 135-150)

having a 1 ton car with 190+horsepower will keep me smiling til my grave, im sure.

and the whole point of this car seems to be corners to me...

yeah, that viper might get out ahead of me at launch...but when that nasty 4 turn 3rd gear chicane comes up, lets see who's laughing.

[fitfan]

if you want to spend the money to make your Elise have BIG power and GO FASTER than this is how you do it...

...get your deposit back and go buy a Noble !!