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4AGE 20V Adjustable cam timing with VVT

Posted: Mon Sep 26, 2016 4:00 am
by matt dunn
So you can get aftermarket adjustable cam wheels for the 4AGE 20V,
I know TODA and a few other make them, I had a set in the previous engine build,
but they all do away with VVT, which is a big downside.

I have been thinking about trying to make the factory VVT cam wheel adjustable.

It only goes onto the cam in one spot as there is only one hole for the locator dowel.

What if you re-drilled a few more holes around inside the wheel, so it can fit on in multiple locations?

If you were accurate enough you could have a couple of different holes for a few degrees either way.

It would mean taking the wheel off to re position it each time, but I think it should be possible.

Has anyone seen this done before,
and can anyone think of a possible downside.

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Mon Sep 26, 2016 7:57 am
by oldeskewltoy
matt dunn wrote:So you can get aftermarket adjustable cam wheels for the 4AGE 20V,
I know TODA and a few other make them, I had a set in the previous engine build,
but they all do away with VVT, which is a big downside.

I have been thinking about trying to make the factory VVT cam wheel adjustable.

It only goes onto the cam in one spot as there is only one hole for the locator dowel.

What if you re-drilled a few more holes around inside the wheel, so it can fit on in multiple locations?

If you were accurate enough you could have a couple of different holes for a few degrees either way.

It would mean taking the wheel off to re position it each time, but I think it should be possible.

Has anyone seen this done before,
and can anyone think of a possible downside.



not sure it can be done on a VVT pulley, but drilled timing pulleys are nothing new... original TRD 16V pulleys are not vernier(slid-able), they had multi holes drilled to adjust cam timing

middle set -

Image

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Tue Sep 27, 2016 3:04 pm
by jdm86gtz
Does the pulley oil return hole have to line up with the notch in the cam thrust face?
I would assume it does but don't have the parts to hand to check.

http://i.ebayimg.com/images/i/371411731 ... -l1000.jpg

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Fri Sep 30, 2016 12:26 am
by matt dunn
Good point,?

I dont think there is a feed and return oil hole,
just one feed that either has pressure applied or is vented and has no pressure.

From memory lookimg into the cam wheel there was one hole for the locator dowell,
but dont remember seeing where/how the oil gets into the mechanism.

I will have to investigate.

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Fri Sep 30, 2016 2:49 pm
by jondee86
The intake cam appears to have an oil pressure hole on the end face on the opposite side
to the knock pin. and this pic shows the pulley face that matches to the end of the cam...

Image

Obviously the knock pin goes in the round hole, so it seems that the oil flows from the cam
to the pulley via the semi-circular cutout. TODA have an offset knock pin that compensates
for something I can't remember just now. So it looks like there is room for a small amount
of +/- adjustment on the pulley.

Also, according to this...
Timing cams is going to be relatively easy for me. I have access to both an AE101 and AE111
intake gear. There's a 5 degree difference in timing between the two. I can also install a Toda
offset pin, which provides a further 5 degrees. So I get a choice of four discrete positions for
my intake timing, and of course their respective "VVT on" positions. I will likely not screw with
the Toda pin unless it would be necessary to get closer to the Tomei centerline.

... taken from here viewtopic.php?t=26 there is another potential adjustment option.

Cheers... jondee86

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Mon Oct 03, 2016 4:17 am
by matt dunn
From what I remember when I looked into when playing around with bits,
the 5 degree difference in the ST and BT cam timing is in the cam.
Swapping from a BT VVT camwheel to a ST VVT camwheel did not change the actual cam timing at all.

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Mon Oct 03, 2016 1:11 pm
by jondee86
This is what TODA says...
In the case that the STD cam pulley is to be used (Intake with VVT function) the following
information is required: TODA's 4AG20V IN camshaft is based on the AE101 engine, so no
extra modifications are required. The AE111 engine (Black head cover) can also use this
IN camshaft but may require the following modifications. This is due to the cam dowel pin
location on the STD camshaft.

The position of the STD cam center angle when used with the STD pulley of the AE111
engine is 120deg. TODA's camshaft center angle become 125deg when used with the STD
pulley, this may require the camshaft to be advanced by 5deg. Those wanting to re-time
the cam to the manufactures STD central cam timing position, we recommend that you
use the two stepped dowel pin

This new position of the camshaft advances the timing by the required 5deg (from 125deg
up to 120deg as AE111 standard central angle).

If I undertand this correctly, the pin location is different between the AE101 and AE111. But
does it follow that the pulleys are also different ? Or are the pulleys the same and the AE101
runs 5deg more timing on the IM cam than the AE111 ?

Cheers... jondee86

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Tue Oct 04, 2016 12:22 pm
by BattleGarage_RS
I have made my VVT pulley adjustable by slotting the hole in the VVT gear and flattening the dowel pin on one side. This gave me about 7 cam degrees to play with. The other issue is VVT adjustment is too much when using larger cams, would be neat to have a solution that limited total travel to about 15 degrees when using 270 duration cams or above.

Grant

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Tue Oct 11, 2016 1:33 am
by jondee86
Just came across this on another site....
So anywho, i now have a TODA stepped dowel pin, a silvertop VVT pulley, and a blacktop VVT pulley. I did all the measurements of it today, and i basically have these options:

119 degree centreline - BT 20V pulley, stock position
114 degree centreline - BT 20V pulley, advanced 5 degrees (TODA pin)
109 degree centreline - ST 20V pulley, advanced 5 degrees (TODA pin)
104 degree centreline - BT 20V pulley, retarded 5 degrees (TODA pin) + advance cam gear by one tooth


Put it here out of general interest :)

Cheers... jondee86

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Wed Oct 19, 2016 1:47 am
by matt dunn
Was back at the dyno last week with the new build.

When we originally built the engine years ago, we ran with the cam timing retarded.
When you use the 7A block you lift the head up 17mm
and so the cambelt pulls the camwheels about 1/2 tooth retarded.
We ran it this way for few years and it made good power and went alright.

Next build we tried to correct this so we fitted aftermarket cams and TODA adjustable camwheels,
using the camwheel adjustment to correct the timing, but of course we lost VVT function.
It made about 7-10 more hp in the very top end,
but lost a lot in the midrange.

This build we have gone back to standard cams and camwheels and have VVT again.
We corrected the cam timing by cutting a new keyway in the cambelt drive pulley
so the cam timing is as per a standard 20V blacktop.

We made pretty much the same torque,
but with the VVT it now makes max torque at 4800rpm instead of 6350 rpm.
We tired moving the VVT point and still had the adjustable wheel on the exhaust,
but that is about where it ended up.
In total we lost about 70hp @7700rpm,
and gained about 50hp @ 4800.

It was a complete new build with a new head and different rods/pistons etc,
and although we still run the same standard valve springs
we suspect the ones in this head are not as good as the ones in the previous head.

Otherwsie did we really loose 70hp in a few degree's of cam timing?

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Wed Oct 19, 2016 2:32 am
by jondee86
Sounds like you just moved the torque peak down to a lower rpm. That's where
your extra 50hp came from. Now the torque is dropping off earlier. And since
power = torque x rpm you have lost 70hp off your power at 7700rpm.

Cheers... jondee86

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Wed Oct 19, 2016 2:52 am
by matt dunn
yeah understand that,
but didn't think that a few degrees of cam movement would make that difference,

The VVT can show the gain in the low range,
as the timing could be up to 25 deg difference between VVT and no VVT,
but VVT turns off again at high RPM, 6200 or something,
so the difference between VVT off and having no VVT is only a few degrees.

Re: 4AGE 20V Adjustable cam timing with VVT

Posted: Wed Oct 19, 2016 1:05 pm
by jondee86
Yuss... but you are comparing stock cams with VVT to aftermarket cams without VVT.
Unless I am mistaken, those aftermarket non-VVT cams would have had a fair bit of
duration and probably a bit more lift than stock cams. If so, it is likely that they would
shift the torque peak higher to give more hp at high rpm. Typically the gain at high
rpm is at the expense of a reduction in hp at lower rpm.

As I understand it, VVT is not there on a 20V to give more peak power, but to produce
a bit more "grunt" in the low to midrange where a 1600 needs all the help it can get.
Your experience seems to bear this out. The change in cam design made a lot more
difference than a couple of degrees VVT timing on stock cams. Just my 2c.

Cheers... jondee86

PS: If you aren't comparing stock cams with VVT to aftermarket cams without VVT,
then chuck this post in the bin and move on :?