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Discussion Starter #1
Just got my Elise back from my 600+ mile tune-up, so I'm green for 6,000+ RPM shifts... you guys, you haven't experienced half of your Elise until you've reached this point! Can anyone else back me up?!

I swear to god, it's like another engine kicks in and throws you back until 8.5K RPMs... completely amazing... :) :p :D
 

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m100 Sean said:

I swear to god, it's like another engine kicks in and throws you back until 8.5K RPMs... completely amazing... :) :p :D
I remember that review of the 111R at Seloc. He said when the other cam comes on it feels like you were rear-ended. Someday
maybe I'll get to find out. Glad your ejoying

Steve
 

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well sean, when ihad my test drive a couple of weeks ago we went as far as 7500 rpm and it's not my idea to tell you the truth. it's the salesman who told me to punch it that's why i can't tell you which dealership i got my car ordered. the elise 5000 rpm and below is not that far compared to my civic which it has some minor mods but when it hits 6000 and up just get ready for the ride of your life. awesome car. that's why i'm still waiting for it for the last 3 1/2 years after i got my deposit down.
 

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m100 Sean said:
Just got my Elise back from my 600+ mile tune-up . . . .
Did you mean 1,000 mile? . . . . because the owners manual is incorrect.
 

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When I did my test drive I hit the on-cam RPM and I nearly sh*t myself. I've never driven a car anwhere close to the Elise. It made my BMW M Roadster feel like a truck afterwards.

Why can't I have one now... :(
 

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I admit to partaking in the V V on a daily basis. It's just too damn much fun!

And I can't wait until the next autocross-bigger track, where the V V will actually come into play. Those guys ain't seen nothing yet!
 

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I could only imagine. Well actually, I'm sure it was quite similar to the the first time I took my S2K to the second cam. It is quite shocking the way things speed up.
 

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Discussion Starter #10
I had the service done at 817 miles yesterday. Sorry if I was a little bit early. I've been reading it's 600+, so I actually thought I was late!

Can anyone explain what's going on in the engine above 6K RPMs?
 

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m100 Sean said:
I had the service done at 817 miles yesterday. Sorry if I was a little bit early. I've been reading it's 600+, so I actually thought I was late!

Can anyone explain what's going on in the engine above 6K RPMs?
You're switching to a different cam profile. So you get a longer duration and higher lift on the valves. In other words more air and fuel = more power.
 

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iwilson,

That's what I've always read, but I've always been curious exactly how the cam profile gets changed?

Also, is there a way to reprogram the computer so that the cams change over at a lower RPM? Would doing that improve lower-end acceleration?
 

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Below is an image from one of the Toyota engines using the dual cam lobe concept:



Basically the engine runs on the low-rev-suited lobe at low revs and the high-rev-suited lobe at high revs.

If you had the high rev cam engage at say 4000 instead of ~6000 then the output would actually go down a bit. The idea is that cams are suited for different conditions. If you dynoed the engine with it being fixed on the low-rev cams all the way to redline and followed that by the high rev cam being used from low to high revs you'd have two curves. Where the curves touch is a good crossover point and in this case it's at about 6000 Rs.

To keep the same top end rush without using the VVT thing, the low and midrange would have suffered. To keep the same bottom end without using VVT the top end would suffer. So to answer your question about switching to the high cam earlier, it wouldn't help much if at all and would likely hurt.

I don't think Toyota is using it here (I'm sure someone knows for sure) but you can also vary the cam's relationship to the position of the crankshaft on the fly in some motors. BMW does this. This is like adjusting a cam gear as you drive. Same lobe is used.

You can also do this only on the intake side, or on both intake and exhaust. Most of the benefit comes from the intake side.
 

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Nice description below. Our motor has two cam lobes for both the intake and exhaust sides. As well as variable intake cam phasing (the cam gear thing I mentioned before). This is similar to Honda's i-VTEC. And a neat engine block using iron plated pistons!


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7TH GENERATION CELICA ENGINE INFORMATION & SPECS
Two versions of the ZZ-series 1.8-liter inline four-cylinder engine with dual overhead camshafts and four valves per cylinder have replaced the 3S-series 2.0-L (Japanese) and 2.2-L (U.S.) engines in the previous-generation Celica. The type 1ZZ was first launched in the current U.S. built Corolla, and then adopted in the larger Japanese-market Vista. Below it is fitted with the VVT-i continuously variable intake-valve-timing system and given the FE suffix. The 1ZZ-FE produces 107 kW (145 hp) at 6400 rpm and 170 N•m (125 lb•ft) torque at 4200 rpm on a 10.0:1 compression ratio with regular-grade unleaded gasoline. Above, the 2ZZ-GE is a new-generation engine equipped with a two-stage variable valve lift/timing system called VVT-L on both the intake and exhaust sides, combined with the VVT-i continuously variable intake-valve timing. The 2ZZ-GE puts out 140 kW (190 bhp) at 7600 rpm and 180 N•m (133 lb•ft) at 6800 rpm on a raised 11.5:1 CR with premium unleaded fuel.

The two engines share the common bore pitch of 87.5 mm (3.44 in), but have different block constructions and cylinder dimensions. The 1ZZ-FE's aluminum block has cast-in gray iron liners, which are 2.0 mm (0.08 in) thick, leaving 8.5 mm (0.33 in) of metal between cylinders. The engine has a long stroke of 91.5 mm (3.60 in) relative to the 79-mm (3.11-in) bore, obtaining a total displacement of 1794 cm3. Measuring 639 mm (25.2 in) long, 586 mm (23.1 in) wide, and 632 mm (24.9) tall, the 1ZZ-FE is about 25 mm (1 in) shorter than Toyota's own 4A 1.6-L unit. It has a mass of 102 kg (225 lb).

The 2ZZ-GE features a shorter stroke of 85 mm (3.35 in) to a large 82-mm (3.23-in) bore to attain a higher redline of 7800 rpm versus the 1ZZ-FE's 6800 rpm. The block is made of fine-ceramic-fiber- and grain-reinforced aluminum-silicon alloy. The piston's rubbing surface is iron-plated, and the pistons are internally cooled by oil jets. The 2ZZ-GE's cylinders are tightly packed, with only 5.5 mm (0.22 in) of metal between the adjoining bores. The cylinder block is split at the crankshaft centerline, and the cast aluminum lower block carries five main bearing caps.

Dual overhead camshafts are driven by a single-stage silent chain of 8.0-mm (0.3-in) pitch in both engines. The 1ZZ-FE's camshafts act on four valves per cylinder via shimless bucket-type tappets. The new upright intake port design allows a narrow valve included angle of 33.1°. Valve diameters are 32.0 mm (1.26 in) for intake and 27.5 mm (1.08 in) for exhaust, and their lifts are 9.3 and 8.4 mm (0.37 and 0.33 in), respectively. The 1ZZ-FE adopts Toyota's VVT-i vane-type continuously variable intake valve timing system.

The high-performance 2ZZ-GE's cylinder head is unique to this engine. Valves are inclined at a wider angle of 43° for freer breathing through the upright intake ports. Valves are larger in diameter, at 34.0 mm (1.34 in) for intake and 29.0 mm (1.14 in) exhaust. The 2ZZ-GE combines the VVT-i continuously variable intake-valve-timing device with the new VVT-L, a Honda VTEC-like variable-lift and -timing system, employing two sets of cam profiles for both intake and exhaust. Below 6000 rpm, the VVT-L employs the low- and mid-speed cam profiles, and above 6000 rpm, the high-speed profiles. The high-revving 2ZZ-GE's camshafts are sprayed with lubricant oil. Timing and lift characteristics of the 1ZZ-FE and 2ZZ-GE engine are shown in the table.

Toyota betters Japan's transitional low emission vehicle standards, achieving NOx emission of 0.06 g/km, HC emission of 0.06 g/km, and CO emission of 0.67 g/km on the country's urban 10/15-model cycle. (The forthcoming 2000 national standards stipulate 0.08 g/km, 0.08 g/km, and 0.67 g/km, respectively.)

Celica Engine Timing and Lift Characteristics

Variable system VVT-i VVT-i and VVT-L

1ZZ-FE 2ZZ-GE
Intake valve opening 5-48° BTDC 10° ATDC to 33° BTDC
High-speed intake valve opening
15-58° BTDC
Intake valve closing 55-12° ABDC 58-15° ABDC
High-speed intake valve closing
97-54° ABDC
Exhaust valve opening 42° BBDC 34° BBDC
High-speed exhaust valve opening
60° BBDC
Exhaust valve closing 2° ATDC 14° ATDC
High-speed exhaust valve closing
36° ATDC
Intake cam lift 9.3 mm (0.37 in) 7.25 mm (0.29 in)
High-speed cam lift
11.2 mm (0.44 in)
Exhaust cam lift 8.4 mm (0.33 in) 7.25 mm (0.29 in)
High-speed cam lift
10.0 mm (0.39 in)



The following information on Toyota's Variable Valve Timing and Lift (with intelligence) system is derived in large from the October issues of Sport Compact Car and Car and Driver. As always, I encourage you to obtain a copy for yourself.

The VVT-i portion of the system continuously varies intake valve timing throughout the rev range by hydraulically rotating the camshaft relative to its drive gear. Note that VVT (without the "i") did not do this continuously. The VVL portion of the system is similar to Honda's VTEC system, incorporating two distinct cam profiles. However, the actual mechanism is quite different. Both cam lobes operate a single wide rocker arm that acts on both intake or both exhaust valves. A needle-bearing roller on the arm follows the low-rpm, short-duration, low-lift lobe, forcing both valves to open and close on that profile. The roller design and roller bearings on the rocker arm pivot help to minimize valvetrain friction. The high-rpm, higher-duration, longer-lift lobe rubs on a hardened steel slipper follower mounted to the rocker arm with a spring. Even though the high-rpm lobe is pushing down further than the low-rpm lobe, the spring absorbs the extra movement. At 6000rpm, the ECU sends a signal to an oil control valve at the end of the camshaft that puts oil pressure behind a lock pin in the rocker arm, sliding the pin under the spring-loaded slipper follower, locking it to the rocker arm and forcing the arm to follow the high-rpm cam profile.
 
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