20V Blacktop/Silvertop hybrid

[3sgte]

How is the profile different?

Mine (blacktop) had a rounded profile, it looked close enough to a "normal" 4AG one that I didn't notice anything different.

Clearly nothing like a 4AFE one, but I think that is understood...

[Sam_Q]

this might make you guys squirm but I was thinking of shaving the block to raise the compression. It looks like I will have to CC the heads to work it out mathematicly, something I really wanted to avoid, oh well.

the head gasket is the same right?

[Dimitri]

gasket is the same.

tooth profile is definately differant. look at 2 side by side.

[AE86slut]

i have only heard of anyone ever choosing ST rods over BT rods once. was mentioned in TAKA's spec's.. he was running toda forged pistons though. possibly the extra weight warranted the choice.

It's actually pretty common, especially in high comp or turbo motors, because while the blacktop rods are thinner and lighter, they silvertop ones are quite a bit stronger. Of course, going to a set of Eagle H-Beams or something would kill both birds with one stone!

[Sam_Q]

whats the weight of some eagle rods compared to silvertop ones? also where do I buy some and what might they cost?

[AE86slut]

whats the weight of some eagle rods compared to silvertop ones? also where do I buy some and what might they cost?

Sam, I'm not sure on exact weight, but you'd be looking at around the $700 mark for a set I would think.

Cheers,

Jeremy.

[psychofox]

Sorry but Eagle don't make rods for 4AGE. So cheap (ie less than $1K) forged rods are not a reality for this motor. Crower, Pauter, Cunningham, etc. do however. Cheapest set I have seen are Crower rods for $1100 from Wei at Vision R (on super duper special).

I also find it very hard to believe that the tooth profile on the cam gears (not the belt) is different between the blacktop/silvertop - but I spose I'm wrong. Why would they change the bottom pulley??? Easiest way to rectify that would be to run either all silvertop gears/tensioners or all blacktop. It's probably going to be cheaper to go all silvertop and easier to get parts as well.

[Sam_Q]

ah shit, oh well thanks I will look into it.

I also dont understand why they would change the pulleys, I see no reason why a silvertop set wouldnt be interchangeable. Maybe though because the cam profile is slightly different the pin is in a 5 degree different starting position than the silver, anyone know? I would like to use silvertop gear if I can.

[Ben Wilson]

You should have a look at the sponsors area:

http://toymods.net/forums/showthread.php?t=7912

[Sam_Q]

I just did and I just made a post, they are considerably heavier than what I have...

[Sam_Q]

did some research:

crower: 470g
argo 488g
stock 438g

seems everyone has boost in mind

[AE86slut]

Sorry but Eagle don't make rods for 4AGE

Oops. Sorry for that Sam. I was sure I got a quote from somewhere for 4AGE Eagle rods, but I guess not.

[3sgte]

tooth profile is definately differant. look at 2 side by side.

Not disputing, I was just hoping for a belt or pulley picture. I don't have the belts to look at unfortunately.


I tried to satisfy my curiousity for pictures and I found this belt information site:
http://www.sdp-si.com/D260/D260cat.htm#S5
The world of timing belts...


Engines that I know of that have different tooth profiles are:

1992 4A-FE --> 1993 4A-FE
1993 3VZ-FE --> 1994 1MZ-FE
19XX 4A-GE --> any year 4A-FE

[Sam_Q]

hey guys does this mean I have to change the cam belt drive on my crankshaft?