Aerodynamic

Hi, a few years ago I bought a K24a4 and now some years later I have started to build on it and planning to have it in an Opel Speedster. While building and Learning about the Engine I noticed the cam gear I got with the Engine is a different kind compared to the "performance" K Engines, it have spokes. The K2Xa2 (performance) Engines have a solid cam gear.
I bought this new solid cam gear because i thought it was needed using a2 cams because the cam gear is stronger.

A4 exhaust to the left and a2 to the right.


And sure, itīs a lot stronger then the a4 gear.
a2


a4


But looking at the cam gear is making me confused, sure itīs stronger but it isnīt motivated since the cam it self would brake in the screw Point first or something like this.

Looking at the cam gears weight is also interesting and gave me an idea about a flywheel shock absorber taking up pulses from the more agressive exhaust cam.

a2


a4


After a guy here in sweden got some Engine codes for stretched cam chain using aftermarket performance cams after about 2 seasons, it seems to me to be even more clear itīs a shockabsorbing flywheel.

Am I right or someway totally off? Anyone know the answer of this?

Thank you.
BR, Per

Joe McCarthy

Congratulations for using your brainpower on this! You're correct, the heavy cam sprockets act like flywheels to help dampen out the violent nature of the cams being driven.
Its unfortunate that Morse doesn't make HyVo chain in this size, its both stronger and will handle even higher RPM. So expect to change your cam chain on a season by season basis if you want to retain accurate valve timing.
Even worse than the spoke design low performance cam sprockets are the adjustable ones made by the aftermarket. They use Aluminum! Really stupid!

Aerodynamic

Ok , nice to hear my theory is true.
I agree with you that those alu aftermarket camgear sounds really stupid, only negativ is higher mass and higher mass higher up, thinking about road hold.

Thank you, Per

Joe McCarthy

Concentrate on mounting the engine so the crank centerline is as low as humanly possible and you'll notice a big difference in transient response and stability.
I've been making massive improvements in Lotus Elise handling this way since 1997, using Honda engines naturally. Lotus really screwed up on engine positioning with both the Rover and Toyota engines so in both cases I was able to lower the crank centerline by a minimum of 50mm with B-series and K-series engines. 50mm makes a HUGE difference, but even 10mm is worth the work of making new engine mounts.
Mounting the driver in the car as low as possible is really important too. Get in the car and the CG moves up 5-6", its horrible.
So concentrate on the heavy items, not so much on the light ones.

Rocket

Good stuff, Per.

You should weigh the VTC intake gear for comparison.

Runnerdown

I observed this a few years ago when doing a side by side comparison of the toda and skunk2 adjustable sprockets. The toda has weight similar or the same as oem and the skunks was mostly aluminum and is very light.

Aerodynamic

Anyone have a VTC camgear loose and could check the weight of it?
Would be interesting to know the weight of this also, good Point there Rocket.

BR, Per

Joe McCarthy

I weighed all of them about 10 years ago, but I can't recall the numbers so I'll do it again. I have over a dozen VTC's so no problem there.

Joe McCarthy

I hope nobody's been holding their breath for this tid bit of data.
A stock Honda 50 degree VTC mechanism weighs 959.5 grams, or for the scientifically challenged 2.11 Lbs.
I don't have any of the new 5-bolt VTC's, and they're a bit thinner so I assume they're also a bit lighter, but they've never been used on any of Honda's high rpm K-series engines and they don't fit on 'normal' K-series intake cams so they really don't count.

Aerodynamic

So unusual when itīs about cars it seems like Heavy is the way to go.

Br, Per