Difference between Silver and Black top

[AE86Sideways]

i am going to swap a 20v 4age into my 86 and i was wondering whats the difference between a silver top and black top.

[punter]

Originally Posted by Redmist

I don't want to start a debate in regards to the benefits of the changes from silvertop to blacktop (it's been done a million times before and will be done a million times in the future) however I wanted to list everything that was physically changed between the two engines. I've stripped down both but have more than likely missed several of the changes.

Blacktop changes over facelift silvertop.

Intake...
-Airbox, larger capacity and bigger entrance.
-Trumpets are now made of rubber (silvertop are plastic), and are bigger in diameter (approximately the same length)
-TB now have a 45mm butterfly as opposed to the 43mm of the silvertop.
-TB's have a taper to the floor of the TB which mates into a taper in the manifold. IE TB to manifold face the TB looks like a D with the bottom of the TB filled in. Silvertop TB's have no taper in the floor, floor taper only occurs in the manifold.
- Manifold has slightly different shape to port entrance. A smoothing of the teardrop shape as introduced on the facelift silvertop. Ports are also bigger.
- Vacuum balancel now cast into the face of the manifold. Silvertop runs with an external collector based under the TB's.
- Blacktops are MAP sensored whereas Silvertops run AFM.

HEAD...
- Bigger intake port.
- Small port dividers. Silvertop has none.
- Open combustion chamber, silvertop has squish bands on both inlet and exhaust. (closed combustion chamber)
- Exhaust port is approximately 20% bigger in volume than the Silvertop.
- Cam Bucket fences are remoulded to hold more oil, but appear to allow for more cam lift.
- Additional support ribbing from sparkplug holes to cambearing platforms.
- Inlet cam has slightly more lift.
- Anyone cc'ed the combustion chambers?

INTERNALS.
- Same Crank. Based upon P/N. Also viewing cranks.
- Rods, noticeably lighter, smoother radiuses on all projections/ joins.
- Pistons have smaller valve relief’s in surface. Silvertop has 5 pronounced valve releases, Blacktop only 3 intake are visible. 2 Exhaust do not exist.

BLOCK....
- Blacktop uses a hydrolic cam belt tensioner whereas the Silvertop uses a spring arrangement.


GENERAL...
Exhaust manifold is much larger to mate to the larger exhuast ports.
Compression ratio raised to 11:1 from 10.5:1 on the silvertop.

That just about covers it.

[REN69]

What punter said.. and the fact that one is Silver and one is black.

[punter]

Originally Posted by REN69

one is Silver and one is black.

I knew I forgot something

[freakinbox]

I glanced over it, silvertop shares the connecting rods with the 4agze which is why it's more common to have FI due to them already being out of a FI engine

[micro214_kp61]

Exhaust manifold is much larger to mate to the larger exhuast ports.

this is news to me. i thought all 4AGEs have the same size of exhaust ports. can anyone confirm this? thanks!

[project trueno]

^2mm larger than ST

[punter]

Originally Posted by micro214_kp61

this is news to me. i thought all 4AGEs have the same size of exhaust ports. can anyone confirm this? thanks!

Yea the blacktop has far better exhaust ports, flows much more than a silvertop.

That said, there is only 5hp between them in standard form.

[micro214_kp61]

i thought for sure the only difference was on the intake ports and none on the exhaust. that's good to know.. thanks guys!

[AE86Sideways]

whats the differences in them spec wise? horespower, redline, torque, etc.

[REN69]

Searching usually works wonders.. lots of sites with information, here's a couple of links.

http://my.tele2.ee/levintrueno/engine/engine.htm

http://www.club4ag.com/technical_mai...tions and Data

[freakinbox]

well with the 20v's it's hard to find the hp rating since most are the toyota one on those sites and well people say toyota exagerated the power ratings in those engines

[punter]

Actual engine dyno readings done in Australia show 144hp for blacktop and 138hp for the silvertop. That’s freshly rebuild motors, completely standard.

So yes toyota lie about power figures, but before rubbishing 20v's keep in mind the fact that the 16v 4age's would have been measured in the same way.

[rice]

^thats true, although i've heard they use higher rating gasoline in japan, thats why when we dyno the 20vs' over here we get a much less hp rating

[punter]

In Aus an NA we can get 98 octane so not that different to japans 100