83mm pistons for 4AG

[jezza323]

this thread has some info on the car, including some from Dave himself (power figure)

http://www.austarletclub.com/forums/...opic=4340&st=0

[takai]

Ah, i had missed the latest updates to that thread, and the article doesnt give the new engine setup. Hence we are really just guessing.
It does make sense that it is an offset crank though.

Ooooh, power figures. I missed that one. 212hp certainly isnt bad.

[30psi 4agte]

I wouldnt recommend it where positive pressure is being used as the blockes are prone to cracking in high hp applications.

But i dont think we are talking turbo / sc applications here.

Like bill said are you game enough to try it or wuse out ( Joke)
It would be tuff to spend all the money on pistons and machining only to find out that the motor runs too hot or that the bore ends up cracking.

[Billzilla]

Yeah, but a lot of the NSW guys run to the closest 100cc to add some intentional vagueness as to their engine setup. Its concievable that an 1850cc engine would be listed as 1900cc.

Interesting about the offset crank though, cheers

There's specially made long-stroke cranks that can be had (for a lot of money) and they make the stroke up around 90mm odd I think, and so between 1.9 to 2.0 litres.

[takai]

88mm i think it would be Bill.... still massive stroke.

[Hiro]

I was very seriously looking at going to 83mm for the new engine, but I got nervous as to how thin the bore walls were going to end up so I wussed out and went for 82mm.
That's the 7A block though, it may well be a little different.

The 7A would have the same bore centres as the 4AGE though, so apart from oil/water galleries the bore wall thickness would be the same for a 7A and 4AGE

[allencr]

Headgasket!

[Billzilla]

The 7A would have the same bore centres as the 4AGE though, so apart from oil/water galleries the bore wall thickness would be the same for a 7A and 4AGE

A fair bit of talking to various people leads me to believe there's small differences between the different blocks, however, I have nothing firm to back that up with sorry.
The 7A's were supposed to be the best for over-boring, though talk to someone else and they get very nervous with anything more than 82mm bore.
So what do you do?
Bore a heap of blocks to get some real info once and for all. But who is going to destroy all those blocks ... ?

[takai]

Once i get sick of breaking rods i might see what it would do with BP pistons.

[oldcorollas]

Bore a heap of blocks to get some real info once and for all. But who is going to destroy all those blocks ... ?

1 of each type of block, and section the buggers with a big bandsaw

or... get the bore thickness checked with a thickness checking thing (NDT tool) for each type of block...

[30psi 4agte]

im keen for results on that one!


TAKAI : what rods you breaking ?

[takai]

7A ones, this is for the engine which will go into the Celica.

[Hiro]

That'll probably be my situation in about a year's time, the KE55 will probably end up getting a hot 7A when I turn it into a hill-climber

[30psi 4agte]

just off to the side abit here but what sort of RPM do these 7a combos pull with an over square stroke

[takai]

Certainly not as high as the 4A. Ive heard figures of around 7500rpm with the stock rods. Although in the video of Lofty and Hislop im pretty sure he is revving a bit harder.