2.8? astron in l300

[barana]

Gday guys, well ive a little time between jobs, and i have my donor (trmagna with m6 head) engine on the stand, I have to see the engine bloke tomorrow, i have been lurking
here a little while and i see a fella thats ofset grinding the crank and using mits os pistons - i think to get a 2.8 l astron.I like this ide as i will be occasionally towing a trailer sailer, and honestly
my 209k klm 1.8 sirrus while ok suxx badly on anything resembling adequacy (try towing a box trailer laden with not much camping gear and being ground down to 1st on a few of the hills from wandai to maroochydore) so, as you can see i need some decent power behind my foot, and a bit of tourque for the trailer sailer towing (planing on bringing it with me on the harvest trail from the sunshine coast to lake argyle, in the kimberlies)
Have many people done the 2.8 mod?

Im wanting to build this machine and have it reliable - or at least gunna laast 250k klm .
I have a steel crank out of a pajero.

I wonder how the stroking will affect my comp ratio and how i can calculate this - waana be able to run it on 91 octane around town - if i can

also, the thread on this forum used shorter v8 rods, im not gunna thrash my machione in a big van body, im im guessing i can use std rods??
- albeit shorter, is there any mitz product that fits the bill? -
(depending on comp ratio id like to keep a std deck to piston clearance.)

or another solution maybe? - id like to keep the std journal size if i can.

The other qtn I have is to do with the injection intake manifold - Ive been told that a tp intake will fit but is dimensionally smaller to clear my small engine compartment, but looking at tp engine bays, the manifold seems the samesize - i dunno
Ive been also told that its to do with the thermo housing being on the tp intake- again I dunno,
Could someone please tell me why i need it? i suspect its to do with rwd applications - i just have a smaller engine bay than most....
thx fellas, - Barana

[Superscan811]

A 2.8L Astron is possible but for the time, effort and money, a nicely built 2.6 will give you a great result.

Personally I have towed over 2 ton from Melbourne to Sydney with my Sigma wagon, with the engine I built (pics and info here, if you haven't seen it already).

It has a 3.308 ratio diff which is not conducive to towing, especially taking off up hill from a set of lights, but it managed it without stalling once..

If you are keen on a 2.8L Astron, you would need 92.5mm pistons and to offset grind the crank around 6mm, making a 104mm stroke, that will give you a 2795cc engine.
You can use the standard rods, which are quite strong, but instead of using Astron pistons, use the 6G72 pistons.
Same sizes as the Astron but they have a 3mm lower compression height, which will work perfectly with the offset ground crank.

The compression ratio, with zero decked pistons and the standard magna head would be close to 9.5:1, which is fine for 91 or E10 fuel.


Hope this helps.

Cheers.

[barana]

6g72 pistons are 91.1mm according to wiki
I would have to get oversize pisons, what sizes for oversize pistons aree produced?
.020 .040 .060 ?

[Superscan811]

6g72 pistons are 91.1mm according to wiki

Std 2.6L Astron pistons are 91.1 as well..

You will need the +.060 (max oversize) if you are attempting the 2.8L.

The only other problem will be the big end bearings. No idea on where you are going to find some 3mm under-sized bearing shells.

Cheers.

[A112H]

Out of interest. If you fitted 6G72 pistons to a stock 4G54 you would reduce the compression ratio enough to turbo it and not have to worry about copper head gaskets and stuff?

[Superscan811]

If you fitted 6G72 pistons to a stock 4G54 you would reduce the compression ratio enough to turbo it and not have to worry about copper head gaskets and stuff?

It would drop the CR down to approx 7.4:1, which would be fine for a standard turbo setup.


Cheers.

[astronturbo77]

you wont get 2.8 with 60 thou over size.. the crank journals will end up too small

[Scorpma82]

6G74 (Magna 3.5L) are 93mm.......could a 4G54 block be honed out that far (reliably)???????

Those Ralliart Magna's are tuned to 185kw from factory....

Are the 4G54 Magna cranks any different to the Sigma Astron II cranks?????

[cheaterparts]

6G74 (Magna 3.5L) are 93mm.......could a 4G54 block be honed out that far (reliably)???????

Those Ralliart Magna's are tuned to 185kw from factory....

Are the 4G54 Magna cranks any different to the Sigma Astron II cranks?????

std 2.6 is 91.1 mm if you bore them .060" that makes the 92.6 mm and thats fairly normal so another .4 mm should not be a problem

and 2.6 magna - sigma - triton - fork lifts and pajeros and canter trucks all use 98 mm stroke and all have the same 53 mm big end
there are a couple of different main bearing dia most engines run 60 mm dia main but there is a 66 mm main I think it was used on the canter truck and fork lifts ( not sure )

cheater

[Scorpma82]

Just out of co-incedence Cheaterparts......do you still race that blue/yellow GE thats in your display pic???

If so...where does it race and in what class??????

[cheaterparts]

Just out of co-incedence Cheaterparts......do you still race that blue/yellow GE thats in your display pic???

If so...where does it race and in what class??????

I still have it but it hasn't run for a while - its built to Improved Prodution regs ( CAMS class ) I burnt a hole in a piston last outing and that was at a Sandown state race round
Since then the money has been on the short side - I shut down my engineering shop and ended up on the dole
I have had the parts to do a rebuild for some time and the cost to rebuild the engine and fairly cheap but
If I fixed it Iwould wont to play with it so I left it broken

It was built to do hillclimb in 1999 and has run at many spints / hillclimb and a few state race rounds since

[Scorpma82]

Shame really.....woulda been great to see a Sigma on the track....i was planning on going into the IPRA with a GJ Sigma.....i love watching that class of racing for its diversity of cars.....theres a black Cordia that I like to pay attention on as he is basically the only Mitsubishi out there in the field.......Unfortunately....the costs of entering the car for every meeting (that i wanna do), plus (to start racing) the costs of preparing the car....getting all the safety gear.....costs of CAMS equipment etc etc etc....was just too much to spend for a weekend of non-competitive racing (as in i'll be in a car that's not competitive).......i also noticed that the 2.6L Sigma would be in the same class as a 500hp 6L Commodore......not worth it if u wanna be up the front. If i had the money......i'd be in the field in a flash.......unfortunately..it's not the case..and i'll have to slowly piece a street machine together slowly (as in..years slowly)

[cheaterparts]

Shame really.....woulda been great to see a Sigma on the track....i was planning on going into the IPRA with a GJ Sigma.....i love watching that class of racing for its diversity of cars.....theres a black Cordia that I like to pay attention on as he is basically the only Mitsubishi out there in the field.......Unfortunately....the costs of entering the car for every meeting (that i wanna do), plus (to start racing) the costs of preparing the car....getting all the safety gear.....costs of CAMS equipment etc etc etc....was just too much to spend for a weekend of non-competitive racing (as in i'll be in a car that's not competitive).......i also noticed that the 2.6L Sigma would be in the same class as a 500hp 6L Commodore......not worth it if u wanna be up the front. If i had the money......i'd be in the field in a flash.......unfortunately..it's not the case..and i'll have to slowly piece a street machine together slowly (as in..years slowly)

to do state race rounds does cost a bit apart from the car build that is costly enough a race suit/ helmet
and to get your licence
each round will put a hole in your back pocket about $ 1500 or a bit more

a more cost effective way to get out and play is to start with hillclimb and sprints
by the way a 2.6 sigma can make a very good hillclimb car in fact theres no reason it cant be a class winner
I had a very good run doing hillclimb in fact I won the 2001 -3000 improved production class aust hillclimb champ in 2004
in a time faster than the over 3000 class ( 35.87 sec )- that was at morwell hillclimb
second place was a turbo suzuki swift and third a RX7
if you know anyone that ran on morwell you will find that braking into a 35 sec run was quite quick
that with a NA 2.6

as for sprints that gets you out on the same circuits that the state race rounds use and more

for outright pace the 2.6 does struggle against the big horse power cars on racing circuits but in its class its not as far behind the 8 ball

[Scorpma82]

Arent the classes in IPRA (vic) < 2000cc and 2001cc - 6000cc????

thats the impression i was under

[cheaterparts]

Arent the classes in IPRA (vic) < 2000cc and 2001cc - 6000cc????

thats the impression i was under

http://www.camsmanual.com.au/pdf/02_rac ... Q411-1.pdf

above is the current rule book - check out rule 16 classes

0 -1600
1601 - 2000
2001 -3000
3001 - 6000

[Scorpma82]

ah ok.......the sigma would be a good contender in that class......especially if you can get very close to 3000cc N/A in a GE Sigma.


You planning on doing anything with your car in terms of getting it back on the track at all?????
I would love to see it racing and knocking off bigger cars on the track


I'm very keen as to what's being used in terms of brakes/suspension/motor (with power figure)/transmission and diff.......i personally would think that your car would be a good benchmark for me (not a turbo man)