Variable cam timing
Thread Starter
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Variable cam timing
It seems that all manufacturers are going to, or exploring, "variable cam timing."
Wouldn't it be nice if someone cam up with an aftermarket kit that would allow me to retrofit my '92 LT1 with variable cam timing.
The big problem with this is you would need "crank triggering" instead of the Opti-Spark or any other cam triggering.
Anyone out there working on this?
Tom Piper
Wouldn't it be nice if someone cam up with an aftermarket kit that would allow me to retrofit my '92 LT1 with variable cam timing.
The big problem with this is you would need "crank triggering" instead of the Opti-Spark or any other cam triggering.
Anyone out there working on this?
Tom Piper
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
I have seen some engineering white papers on variable cam timing, more accurately, variable lift, on push rod engines.
someone is working on such a thing, that moves the pushrod in or out, in relationship to the rocker... it's a little abstract.
If these were OHC engines, I see real advantage... I see it as an RPM limiter on a SBC.
someone is working on such a thing, that moves the pushrod in or out, in relationship to the rocker... it's a little abstract.
If these were OHC engines, I see real advantage... I see it as an RPM limiter on a SBC.
Drifting
Joined: Jan 2005
Posts: 1,344
Likes: 320
From: San Antonio Tx
Variable cam timing is not new, several companies made kits back in the 60's. It just never was very popular back then so they quit. No one cared about gas mileage or low rpm torque. And , of course there was the problem of timing change with the mechanical distrubuter. We just wanted that bad cam sound and WOT power! 
It used weights and springs to advance with rpm's. Shouldn't be too hard to set up the timing curve now using a computer controlled distributer. Might still be a warehouse full of them somewhere! 
It used weights and springs to advance with rpm's. Shouldn't be too hard to set up the timing curve now using a computer controlled distributer. Might still be a warehouse full of them somewhere!
Thread Starter
Safety Car
Joined: Feb 1999
Posts: 3,504
Likes: 4
From: Mexico Beach FL
Originally Posted by Nathan Plemons
IMHO you're talking about a lot of overhead for minimal gain. It's one thing to design something originally but to try and retrofit you'd see more headaches than it would be ever be worth.
But, there are many new engines with it today.
It allows a small cubic inch engine to have both low-rpm torque and high-rpm horsepower while still getting better gas mileage.
I think this trend will only escalate.
Tom Piper
Race Director
Joined: May 2001
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Back in highschool I wrote a paper about electronic valve technology. At the time they had actually run this on a 4-cyl ford ranger. Rather than have any kind of camshaft, the valve were actuated by electromagnets. Because they were electronic, they were completely computer controlled, meaning you can completely control valve timing to do anything you want. For a gasoline engine cycle, that is the ultimate in efficiency. You could create the optimal camshaft profile at ANY RPM. You truly could have something that would idle perfectly smooth yet make big RPM power like an all out race cam and the transition would be perfectly smooth.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
There is progress being made... Renault is working on such a concept, but using pneumatics, for the F1 engine.
It is expected to raise redline about 5000 RPM. That was on a V10, they expect the new 2.4 litre V8s to be spinning in the low 20000 RPM range... mind boggling.
I have always loved the Honda H22 VTEC engine... 190~220hp, depending on version, out of an NA 2.2 litre I4... impressive.
It is expected to raise redline about 5000 RPM. That was on a V10, they expect the new 2.4 litre V8s to be spinning in the low 20000 RPM range... mind boggling.
I have always loved the Honda H22 VTEC engine... 190~220hp, depending on version, out of an NA 2.2 litre I4... impressive.
Race Director
Joined: Jun 1999
Posts: 14,924
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From: Merritt Ils Fl
Originally Posted by Nathan Plemons
IMHO you're talking about a lot of overhead for minimal gain. It's one thing to design something originally but to try and retrofit you'd see more headaches than it would be ever be worth.
I think it would be eaiser to move to a DOCH engine if you really needed the small across the board gains you would get.
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Team Owner
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From: altered state
St. Jude Donor '05
GM had plans use a 3 valve head with electronic valve actuators. Don't know if the idea was shelved or if they are still working on it. Looks like the 3v head itself will become a production reality fairly soon. The speed that technology progresses at nowadays is astounding.
Racer
Joined: Jul 2005
Posts: 301
Likes: 0
From: Dallas/Spring Texas
Originally Posted by Nathan Plemons
Back in highschool I wrote a paper about electronic valve technology. At the time they had actually run this on a 4-cyl ford ranger. Rather than have any kind of camshaft, the valve were actuated by electromagnets. Because they were electronic, they were completely computer controlled, meaning you can completely control valve timing to do anything you want. For a gasoline engine cycle, that is the ultimate in efficiency. You could create the optimal camshaft profile at ANY RPM. You truly could have something that would idle perfectly smooth yet make big RPM power like an all out race cam and the transition would be perfectly smooth.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
I know the project you're talking about. I was actually theorizing the use of electronicly actuated valves when I came across an article about it in one of my automotive engines textbooks. Ford had the ranger and GM had tried a similar system on a Cadillac, but the processors used at that time were not powerful enough to control the valve actions at all speeds and, like you said, it was so noisy they didn't think consumers would approve. I always thought it was a superb idea that just needed better technology and some polishing to be right. I just don't know that, for a street vehicle, if the advantages warrant the expenditures.
Instructor
Joined: Dec 2004
Posts: 176
Likes: 0
From: Oakland CA
I thought some version of the LS1 or LS2 has variable timing. Beyond that look up BMW Valvetronic. Variable lift and timing such that they don't use throttle plates. The engine is throttled with the cams. Used on the V-8 BMWs.
Racer
Joined: Apr 2003
Posts: 342
Likes: 0
From: Kalamazoo MI
Originally Posted by sickspeedvette
I know the project you're talking about. I was actually theorizing the use of electronicly actuated valves when I came across an article about it in one of my automotive engines textbooks. Ford had the ranger and GM had tried a similar system on a Cadillac, but the processors used at that time were not powerful enough to control the valve actions at all speeds and, like you said, it was so noisy they didn't think consumers would approve. I always thought it was a superb idea that just needed better technology and some polishing to be right. I just don't know that, for a street vehicle, if the advantages warrant the expenditures.
In addition to the processor workload, the biggest problem was the solenoids generated too much heat to effectively dissipate quickly and they failed in a relatively short time. Additionally there is a theoretical limit to just how quickly electronic solenoids can actuate the valves. The problem is somewhat analagous to how much faster and cooler transisters are compared to vacuum tubes.
As for actual variable valve systems, Ferrari's is by far the coolest. The cam lobes have 3dimensional profiles and the camshaft slides one way or the other to alter timing. Pretty slick.
Check out this crazy a$$ valvetrain
http://www.coatesengine.com/
Race Director
Joined: Sep 2005
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From: Sharpsburg Georgia
GA Events Coordinator
a little off topic, but if you like engines, here is one that has alway got my attention.
http://en.wikipedia.org/wiki/Bristol_Centaurus
http://en.wikipedia.org/wiki/Bristol_Centaurus
Safety Car
Joined: Dec 2004
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From: Poop land
The only thing that amazes me even more is how a 1.3L Suzuki Hayabusa DOHC 4 cylinder motor can push over 200 hp, N/A with mild cylinder port work. I also wonder about the 85 ft-lbs of torque, but I bet if they put this in a small 1000 lb car, it would haul some *** and run with the Vettes! If my TPI had that efficiency, looks like 1100 hp would be feasable on a 5.7L.
Race Director
Joined: Dec 2002
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From: SCMR Rat Pack'r Charter Member..Great Bend KS
Originally Posted by Nathan Plemons
Back in highschool I wrote a paper about electronic valve technology. At the time they had actually run this on a 4-cyl ford ranger. Rather than have any kind of camshaft, the valve were actuated by electromagnets. Because they were electronic, they were completely computer controlled, meaning you can completely control valve timing to do anything you want. For a gasoline engine cycle, that is the ultimate in efficiency. You could create the optimal camshaft profile at ANY RPM. You truly could have something that would idle perfectly smooth yet make big RPM power like an all out race cam and the transition would be perfectly smooth.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
At the time I wrote that the biggest concern was high RPM and noise. Because the valves kinda just slammed open and closed it was pretty loud and they had trouble actuating them quickly enough at higher RPM. I kinda figured they would have made more progress on it by now, but apparently somebody figured out there was too much gas to be saved by the project so somebody probably shot the people doing the research.
Formula 1 engines have used this method at VERY high rpms with success.
Larry
code5coupe
Safety Car
Joined: Dec 2004
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From: Poop land
Originally Posted by cuisinartvette
It probably has to spin well past 10k to make anywhere near that hp#. 85 lbs of torque wouldn't budge that car IMO
Remember for the street, its all about torque.
Remember for the street, its all about torque.
Given a 9.11 rear axle, the same gear ratios as a ZF6, 11000 rpm shift points and a 900-1000 lb race weight, it looks like a winning combo. Gearing seems to help out to an extent since they are a way of multiplying engine torque.
Say you have a corrected 350 ft-lbs to the wheels between 3000 and 4000 rpms /w the peak power made at 5000 rpms, 2.68 1st gear and a 3.45 rear end. That is roughly 2900 ft-lbs of torque at the motor's peak torque rpm. I'll assume the race weight of the vehicle is 3000 lbs.
Now, lets say you have another vehicle with a corrected 85 ft-lbs to the wheels from 6000-8000 rpms /w the peak power made at 10000 rpms, a 2.68 1st gear, BUT a 9.11 rear end, as funny as it may seem. Let's say the race weight of the vehicle, er go-kart is 1000 lbs. That is a little over 2000 ft-lbs to the wheels at the motor's peak torque rpm.
Yeah, you'd still have to wind the **** out of that motor though to get it going on the street. Still looks good IMO, but that is more of a high rpm race track setup for a light car.
