Educate me on Astrons.

[Spac2]

I've read a lot, but not much of it makes sense, because it assumes I know the differences between Astron 1 and Astron 2 and the olther, later stuff.

Make it simple for a noob!

What are the important differences?
Is it worth chasing a late model motor for a fairly serious NA build? Why?

[Superscan811]

In a nutshell...

Astron I:
a. Head has a small "CAST" combustion chamber, less sharp edges.
b. Head has smaller valves.
c. Head has smaller ports.
d. Pistons are dished to lower compression.
e. Blocks are typically "stronger" than the Astron II because the castings are thicker.
f. Mechanical tappets.

Astron II
a. Head has larger "machined" chamber, with more sharp edges.
b. Larger valves.
c. Larger ports.
d. Better shaped ports (M6, M7, M8 M9 heads).
e. Flat top pistons.
f. Hydraulic tappets with standard or roller followers.

ALL Front Wheel Drive Astron II engines are Narrow Block.
ALL Automatic Transmission Astron engines (I or II) are Narrow Block.
ALL 2.0L Astron engines are Narrow Block.



The only other noticeable difference is the oil pumps.
On the later (TS Magna 2.6L) Astron II engines, the oil pumps have an approx 30% larger flow.
There is a FORKLIFT variant of these engines with a completely different style of oil pump and larger main bearings (66m instead of the standard 60mm), apart from that, all the other parts are pretty much interchangeable.





Cheers.

[Spac2]

Excellent, thank you.

This leads to a few more questions:

Which of the later heads offers the best flow?
For a NA motor making around 100kW ATW, is there any reason to use an Astron1 block?
Can the later hydraulic rockers be converted to solid?

[Sigmaproject]

Regarding the cam and lifters, you can put the early solid lifters on an Astron 2 head. You just need to use the early cam and rockershafts. So basicly swap the whole rocker assembly from an Astron onto an Astron 2 head.

The biggest issue with just swapping heads over is that the 2.6 Astron motor had dished pistons, and Astron 2's had flat tops.

[cheaterparts]

Excellent, thank you.

This leads to a few more questions:

Which of the later heads offers the best flow?
For a NA motor making around 100kW ATW, is there any reason to use an Astron1 block?
Can the later hydraulic rockers be converted to solid?

the M6-7 have the highest flow however the M8-9 are a little easier to up the comp

most 2.6s can handle quite large cams
the biggest problems to getting real good performace is induction -- twin 45 mm webers are ok but realy not big enough for higher breathing engines
and the other thing is the high weight of every thing that moves -- the smart move is to use the narrow block ( auto block ) and use a lightened 2 lt flywheel

one thing that is is your favor is that 100 Kw NA atw is quite easy to get even 110 Kw is fairly easy with some thought
from there it dose take a bit of work

for a 100 Kw atw

I would look at a cam of around 44 / 78 and run around 10.5 : 1 comp
use an M6 head thats a little cleaned up and maybe some 1 mm over sized valves
use the narrow block with a lightened 2 lt flywheel
ether twin 45 mm DCOE webers or a magna EFI with a 65 mm TB and after market ECU
removed Balance shafts and a full balance job done on the engine
4 into 1 header with a 2.5 inch system ( and no muffler before the diff )