Competition Products "Variable Valve Timing Kit"

[MadBill]

Is anyone familiar with this? http://www.competitionproducts.com/Cam- ... j8ThbenGUk

On the one hand, it could be a very useful tuning tool. On the other, it appears that the tensioning feature is on the tight, rather than the slack chain side; not the best engineering practice...

[af2]

I am thinking that's how they are moving the cam.

[lefty o]

think they had something very similar in one of the older engine masters magazines.

[SupStk]

Don't see how it could work. The cam would supply enough resistance to keep the adjuster under spring tension anytime the engine is running. If there is any HP to be gained, all I could imagine it would be by elimination of chain cordial action.

Agree the tensioner appears to be on the wrong side of the chain.

[Keith Morganstein]

It looks as the spring load will take up the slack and keep the cam in it's most advanced position, as rpm's increase and load to drive the cam increases, the spring tension is over come and the cam becomes more retarded. How much and how consistent it is IDK.

[MadBill]

I first thought it was externally adjustable but yes, it appears to be functionally similar to the old Varicam device. http://wildaboutcarsonline.com/members/ ... bile_1.pdf
Guess the distributor would need a matching re-curve and the advance rate would be affected by oil pressure/pump drag..

[ptuomov]

I don’t think you can change timing with a slack side tensioner. To change timing, you must change the tension side geometry. No way around it.

[CamKing]

I came up with a somewhat similar system, but it was hydraulic and adjusted both sides of the chain.
I never produced it, because it wouldn't be legal in most forms of racing, and it would be such an advantage in the classes that it was allowed, that it would be quickly made illegal.

[ptuomov]

I came up with a somewhat similar system, but it was hydraulic and adjusted both sides of the chain.
I never produced it, because it wouldn't be legal in most forms of racing, and it would be such an advantage in the classes that it was allowed, that it would be quickly made illegal.

Porsche 968 has that sort of a system that moves both the slack and tension sides based on computer logic. It only operates on the intake cam, so it’s worth more than just advancing or retarding the both exhaust and intake. It’s very good solution for passing emissions and producing a smooth idle. People racing the cars remove the system because it doesn’t meaningfully improve the power band average hp at racing rpm range.

[pamotorman]

I came up with a somewhat similar system, but it was hydraulic and adjusted both sides of the chain.
I never produced it, because it wouldn't be legal in most forms of racing, and it would be such an advantage in the classes that it was allowed, that it would be quickly made illegal.

i believe some one in the engine master contest used a similar device.

[edsantiago]

Not worth the trouble. Save your money and add the cost of that POS to purchasing a quality timing chain kit or something.

[Keith Morganstein]

i believe some one in the engine master contest used a similar device.

IIRC, it was a Varicam

image.jpg

[PackardV8]

The Mechadyne Duo-cam has been used in the Dodge Viper V10 for several years now. Two concentric camshafts, a solid inner camshaft and an outer tube, the outer cam has fixed lobes keyed to a tube. The solid inner camshaft lobes move through slots in the outer tube. I keep expecting an aftermarket SBC any day now, but it hasn't happened.

http://www.mechadyne-int.com/products/duocam/

[Tuner]

i believe some one in the engine master contest used a similar device.

IIRC, it was a Varicam

LOL .. We sold a few of those deals when I worked at a speed shop in the late '60s. We had a hard time getting enough new springs to keep one working. The bummer was the broken variable spring invariably fell into the chain and sprockets and you can guess what came of that.

If you were blessed with a magical engine that had absolutely no torsional harmonics at all, it probably wouldn't work for more than a few minutes anyway. Every one we sold broke the spring in a few hours (or less) of operation.

One guy had it all, the Varicam and Rhodes lifters, plus several other latest, greatest, trick of the week incredible power producing products. The concentration of fail in a single engine was epic. Fun times.

[user-23911]

That's what I hate most about aftermarket parts.......they're all (most) low quality and don't last.

Anyway how many degrees of adjustability is on this new product?
Not much by looking at the length of the chain.
When you look ant OEM type VVT there's quite a lot of degrees of possible variation of timing.