Productive Easter...

[Mettler]

I put some work into my 3d VH valvetrain simulation project over easter and made some good progress:

Modeled the finger rocker as accurately as I could measure with my flatmate's verniers:





Some minor adjustments to be finalized on the HLA pivot point recess (due to vernier measuring limitations), but it should be within 0.5mm of its actual location, allowing more work to continue on the assembly for now:



It is only necessary to design the cam timing profile on the front two valves on cylinder 1 as seen here... saves processing power. The other lobes can simply be patterned off this one using derived sketches, and have already been positioned according to cylinder timing:









Testing rocker movement between seated to max lift position... check out how the tangent point of contact on the finger's nice machined curved surface changes along the top face of the valve stem:



Also take note of the nice little oil cavity inside the finger rocker's pivot point, providing even oil distribution around the bearing surface at all times during operation:



Interference detected at 12.7mm lift... note the tiny red dot on the right by the pivot point, representing the volume of the interfering bodies. It's absolutely miniscule however, and at this stage I will not worry about it until I've finalised the exact dimensions for that difficult to measure part of the finger rocker. If however it still interferes, then it's just a short job with an air tool to grind a tiny bit off each finger before installing cams with this much lift:



Lastly, I'm designing the profile using a spline with 72 points, each one on a line divided by 5 degree increments.

At present the assembly is connected up and when I spin the cam, the profile of the lobe will cause the valve to go up and down. What you're looking at however is a set up drawing area ready to go, but all 72 points of the spline are currently coincident with the base circle.

I will be using a gear mate between the crank and the VTC sprocket to make the cam spin at 1:2 ratio with the crank. Have been having an issue with this function, so need to figure out another way to make it work:



And that's where I'm at. Got a busy week ahead so don't hang out for further updates! Will post more stuff as I make it!

[tmorgan4]

Awesome!!!

[PanzerAce]

Man, looks like some nice stuff.

Is there any special reason you are working it to .50", or is that just the maximum possible lift? And what kind of duration are we talking about with this cam?

Finally, how long are we going to have to wait before we can buy these?

[Mettler]

No real reason other than that's what the stockcar guys use and seems to be a fairly common "high" valvelift value. It's also around 133% of stock lift, so provides a good increase in curtain area, which in my opinion, is where a lot of gains are to be found.

Whether even going this high is necessary is debateable, but meh.

The duration isn't known yet because I am designing the cam to achieve 8.2:1 dynamic compression ratio, and with the intake valve opening at the earliest opportunity, the duration is going to be a byproduct of those two factors.

If anything, I expect the duration to be very close to the standard figure... just a big increase in lift and steeper ramps to provide a longer dwell around max lift.

So my particular profile may not be suited to max HP gains, but by setting the DCR to 8.2:1 I'm raising the power across the whole rev range, as opposed to increasing duration & overlap which results in higher HP at higher RPM, but losses at the low end.

That's my design intent anyhow, so I'll have to see how it all pans out first

Oh... as for buying them, I'm not planning to produce these. The economy is just too wasted and machining is just too expensive to look at that as an option. I'm going to simply make the 3d assembly available to everyone once I've reached a point where I feel it's satisfactory for others to play with... then it'll be up to you to get your own cams machined.

Hopefully somebody on here can find a mint deal for having them made, then perhaps we can all get them through that source?

[PanzerAce]

No real reason other than that's what the stockcar guys use and seems to be a fairly common "high" valvelift value. It's also around 133% of stock lift, so provides a good increase in curtain area, which in my opinion, is where a lot of gains are to be found.

Whether even going this high is necessary is debateable, but meh.

Ah, cool. I guess it also looks like without custom or at least modified rockers it basically is the max that you can push anyways.

Quote »The duration isn't known yet because I am designing the cam to achieve 8.2:1 dynamic compression ratio, and with the intake valve opening at the earliest opportunity, the duration is going to be a byproduct of those two factors.

If anything, I expect the duration to be very close to the standard figure... just a big increase in lift and steeper ramps to provide a longer dwell around max lift.

So my particular profile may not be suited to max HP gains, but by setting the DCR to 8.2:1 I'm raising the power across the whole rev range, as opposed to increasing duration & overlap which results in higher HP at higher RPM, but losses at the low end.

That's my design intent anyhow, so I'll have to see how it all pans out first [/quote]Ok, so if I get what you're saying, this cam is built for better HP but still retaining driveability, correct? So if a builder wasn't as worried about driveability, the easiest thing would just be to increase duration? And if you are aiming for a 8.2:1 DCR, what is the current DCR on the cams? And how do DCR and SCR interact?

Quote »Oh... as for buying them, I'm not planning to produce these. The economy is just too wasted and machining is just too expensive to look at that as an option. I'm going to simply make the 3d assembly available to everyone once I've reached a point where I feel it's satisfactory for others to play with... then it'll be up to you to get your own cams machined.

Hopefully somebody on here can find a mint deal for having them made, then perhaps we can all get them through that source? [/quote]Gotcha. The only shop off the top of my head that I can think of approaching would be Rebello Racing out here in CA.

I don't suppose these also fit VKs...

[Orphan]

VK's don't use rockers so I doubt they would work greatly with a VK. What I can't wait for is the VK50VE :O the SR20VE's are insane little engines, cams + spings + exhaust + tune usually = around 220whp, imagine 100hp/L+ out of a 5L haha.

The model look great met, when you are done you are so doing a fully rendered opperating engine model and putting it on youtube haha :P even from what you have done it s***s over many I have seen besides the crazy ones produced by engineering firms.

I assume your going to include VTC acuation in this model?

I totally dislike dynamic compression ratio's they are confusing haha. The book I have doesn't really cover them in any real detail either.

Great to see your still active haha I'm hoping to get into my project once I get a bit more info. Can't wait to see what cam results people get once the ball gets rolling. Is your 41 with 45 internals still puttering around?

Why couldn't the VH just use buckets lol, be soo much easier and also be a VE haha.

[hannibal]

I'm guessing this is a VH41 by the double cam gears. Is the VH45 the same?

Are the cylinders sitting parallel to the valves called HLA's? What is their function?

[PanzerAce]

HLAs make sure that the lash is set properly automatically, so that valves don't get stuck open or start clicking all the time (with corresponding lack of opening).

[Mettler]

HLA = Hydraulic Lash Adjuster... they pump up with oil pressure and push the finger rockers hard up against the cam lobes.

The VH41 and VH45 have slightly different VTC mechanism setups, but the valvetrain has the same geometry and I'm using the VH45 bore and stroke for this simulation, so the results will be directly applicable.

[hannibal]

Thanks guys...

[Guishnu]

Good Effort Mettler I'll catch you on MSN sometime soon and we can talk more. Loads of updates, lots to do.