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Old 04-27-2001, 09:04 AM   #1
Gambit
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Question Does Honda use vtec in F1?

As the title...
Anyone know? If not why not?
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Old 04-27-2001, 09:10 AM   #2
Strepto
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I doubt it. The way those motors are built there's really no point in VVT. Another thing is that those motors don't use cams. The valves are controlled through a pneumatic (or is it hydrolic) system that is computer controlled. I guess when it comes down to it there could be a change in valve openning/closing if they wanted to program that into their computes. My understanding of the use of VVT is more of an emissions control device while still being able to have a higher output in the top end (but that's on road cars).
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Old 04-27-2001, 10:44 AM   #3
GarySheehan
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Strepto,

If I remember correctly, the F1 engines DO use camshafts. They don't use conventional metal valvesprings. They use high pressure air to control valve closing times, not valve opening.

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Old 04-27-2001, 10:54 AM   #4
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No, honda doesnt not use a variable vavle setup in ANY of their race engines. From their F1 engines, to their CART engines, to the AJGT engines. The only cars that are raced with honda badging that have VTEC are cars that are raced under Group-N rules. I.e. showroom stock, with minor mods for safty. And even some of those cars have the VTEC disabled, and run on the high slope cam only.
VTEC is a set up used to retard the timing, and use a softer cam for streetability of the engine. VTEC doesnt add HP, it just makes the engine drivable on road to the average driver that could not handle the low torque, and massive clutch slip thats needed to drive a car with a high cam slope.
The Problem with VTEC is that the system takes to long to engage. On average about .002 of a seconed. Thats not enough that a street driver would even notice. But in a race car, thats an eternity. Plus with VTEC the engine does not rev smoothly, as the timing changes mid rev range. Thats not a good thing when racing. The smoother the rev's the better. Easier to predict for downshifts etc.

In F1 the engines do run a cam. Camless engine technology is relativly new, and has yet to be incorperated into racing. With a camless engine your timing is limitless, and things like engine stals and redlines would become almost nonexsistant.
Anyway, they do have a cam, BUT that cam is spinning at 23,000+ RPM at full chat. At that speed a valve springs can not return the valve fast enough to keep it from venting out compresed fuel, or slapping the top of the cylinder. So they designed a compressed air valve return system. So as the cam pushes the valve down, the compressed air is constantly pulling against it to close it. Becuase the air will always have the same reaction time reguardless of engine RPM, and mechanical disagvantage, they can run the rediculasly high RPM ranges with no worry about haveing the engine detonate becuase of valve failer.

Make sence?
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Old 04-27-2001, 11:16 AM   #5
donjuan
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Are you sure an F1 engine's cams turn that quick?? (23K+) Seems a little quick for a camshaft



[This message has been edited by donjuan (edited April 27, 2001).]
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Old 04-27-2001, 11:56 AM   #6
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Haha, the cam has to turn at the same speed as the engine crank...or it wont work.

So if the engine turns at 23k+ RPM, you can only ASSUME that teh cam does as well.
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Old 04-27-2001, 02:06 PM   #7
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Gary is right. Think about it, if your cam turned at the same rate as your engine, you'd in a whole lotta trouble!!! Anyways, all F1 (and other major race leagues) are Otto engines (spark ignition) so 4 strokes needed per cycle OR two engine rotation. Thus, for every 2 revolution of crank, you need one revolution of cam.

BTW, completely electro-hyraulically controlled valves are being developed and tested. However, they suffer from slow response (due to many issues). From what I've seen, they max out at around 8000 rpm, which just doesn't cut it for race teams! Plus, they're currently very expensive (according to what I've read - but I personally think they can me made much cheaper though) which prevents consumer use.

FYI, VTECs are completely useless to race teams - that's what transmissions are designed for. They race w/ their engine in a tight rev band. The only time they deviate from that is when they wipe out or when they pit. BTW, BUCK-O, I don't think VTEC cam change does not take only 0.002 seconds - more like around 0.1 seconds (again, I don't know any hard specs about the VTEC but 0.002 just sounds WAY to quick). Heck, the superfast auto-manual trannys take around 0.2 seconds to shift (down anyways).

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Old 04-27-2001, 02:13 PM   #8
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Quote:
Gary is right. Think about it, if your cam turned at the same rate as your engine, you'd in a whole lotta trouble!!! Anyways, all F1 (and other major race leagues) are Otto engines (spark ignition) so 4 strokes needed per cycle OR two engine rotation. Thus, for every 2 revolution of crank, you need one revolution of cam.
DOH!! Thanks for pointing that out. Makes perfect sence.
I have seen cars running with the real time telemetry and they are turning 20k+ RPM. They where hitting close to 23.5k on the straight at Hokenheim(sp?) and at Indy.

Im preaty sure they will turn that many RPM. 18k doesnt seem like a whole heck of a lot (all things considered).

as for the .002 figure. I pulled that out of my ass. It probibly is more. But even at .002 thats still too slow to be praticle. And if you look at a dyno sheet from a VTEC engine, it dips preaty severly at the change over. Thats definatly not somthing you want in a racing engine. I thought the .2 time was the minimum they could shift in. And ferreri could change gears WAY faster and was use the excess time to control wheel spin through the clutch, or somthing along those lines.
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Old 04-27-2001, 08:47 PM   #9
jhuang76
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I checked around and found that at high RPM, it can upshift at around 0.15 seconds. See: http://www.fortunecity.com/silversto.../tech_gear.htm

Still, 0.1 seconds is a good speed (esp. for a shift). 0.002 seconds is way to fast. In fact, if the crank made one revolution at 0.002, then it would be going at 30000 RPM!
Anyways, even if VTEC could shift in 0.002 seconds (so fast that it would not be noticable) it would still not be used. There is just no need for VTEC in a race car (F1 anyways) since they use such a narrow rev band! This is especially true since implementing it will require huge modification to the heads - making them more complicated and adding more things that can go wrong. All for gains ONLY appreciated when coming out of a pit stop (and don't forget the speed limit there anyways)!!!
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Old 04-28-2001, 12:00 AM   #10
donjuan
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Camshafts turn at the same speed as the crankshaft?? Not quite. You might wanna check into that...



[This message has been edited by donjuan (edited April 27, 2001).]
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Old 04-28-2001, 12:03 AM   #11
Strepto
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ah, thanks for clearing that up. I heard something about camless technology a while back and thought it had been implemeted in the motors
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Old 04-28-2001, 12:13 AM   #12
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But the highest reving engine in F1 right now, from BMW afaik, is claimed to spin at only 18K. Honda and Renault(Benneton this year) are working on electronic valvetrains(camless afaik) which should reach 20K+, but none of them are using it yet.
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Old 04-28-2001, 12:54 AM   #13
GarySheehan
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Buck-0,

Cam is 1/2 crank speed.

Gary
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