Engine
Turbo Mini Forums

What are the advantages or disadvantaged of a 1380 turbo against 1293 turbo.

http://i28.photobucket.com/albums/c248/spe...er1/mini007.jpg

If it a'nt broke don't fix it !!!!!!!!!!!!!!!!!!!!!

Achieving the correct size combustion chamber, can be difficult or expensive, which ever way you look at it

bore flex? hee hee

"Turbo's make torque, and torque makes fun"

"did you know you can toast potato waffles?"

Yep, it's gotta be Bore flex. Apparantly if you go to 1380 you'll blow head gaskets before even putting fuel into the tank and the pistons will fall apart.

Same with unleaded seat inserts with a turbo - the heat will make the inserts 'fall out'. Nothing more, nothign less - they'll just 'fall out'.

Oh - and the beak in the iron combustion chamber with water flowing just a 1/2" over the top of it will glow, whilst the un-cooled alloy pistons with their lower melting point will be fine (assuming you don't go 1380 of course).

Hope that helps.

lol

AlexF

Bore flex?

Piffle!!!!

Bassicly to sum up Gavin, many people will tell you it can't be done, although I've never heard of it beeing done and failing.

If I was going to make another, I'd go 1380!!

Team Racing

In the 13's at last!.. Just

There must be an advantage of going from 1293 to 1380, but unless you have the extra air flow in the head and the turbo is properly matched, you wont see it.

The advantage is equivalent to about 1psi boost.

Saul Bellow - "A great deal of intelligence can be invested in ignorance when the need for illusion is deep."
Stephen Hawking - "The greatest enemy of knowledge is not ignorance, it is the illusion of knowledge."

The little extra capacity should help spool the turbo and also help a little off boost (if not going for a silly low compression it should be noticable).

Both of mine where 1293 but if doing it again I'd go 1380 ..... in fact I am!!

Every day is a school day ...........

How fast and how expensive ...... the same question...

The only reason stopping me from doing this when I build/ have built my engine is that once the blocks at 1380 thats it no more rebores. (ok for those who have had the last 20 odd years to build up a stash)

Also you would need a better gasket than a BK450 as the fire ring pokes into the cylinder by 0.5mm (approx).
Regards
Dave

Edited by Sprocket on 4th Oct, 2007.

Yep, It's of that order. Hard to determine exactly as the gasket has some variance the bore spacing so I can't just measure both diameters and get an exact result.
Plus the two stud holes that are supposed to locate the gasket have some discrepancy so worst case could give approaching 1.0mm overhang into the bore.
In fairness I have to admit that it's an FAI BK450 equivalent rather than a Payen.
Having said all that I would never build an engine with the fire ring sticking into the bore.
Regards
Dave

a compressed BK450 fire ring is slightly oval, its in the order of 73 x 73.5mm, therefore if the block has been bored correctly, there should only be an over hang of 0.25mm at the areas adjacent to each cylinder.

The AF460 has a fire ring dimention of 73.5x74mm so on the 74mm bore the same situation is aparrent, tho now hwere near as bad as if i were to use the BK450

AF460, all the way, like I said, it also has a little more cc helping the CR along the way

see www.wdrake.co.uk if you want it boring correctly dave - theyre not far from you, it's where I will be taking mine when funds allow my engine plans to proceed, but have not decided between 1310 and 1380 - i am just thinking that i get another overbore should i want it with the 1310

My block is already 1380. I am trying to find what is supposedly correct. Is it equal spacing or not? Someone must know.
Regards
Dave

Edited by danboy on 5th Oct, 2007.

sorry dave - would be nice to know what the correct boring measurements are though

my best arnswer is ask t3tone lol.

any way 1380 gives your block some extra life after the 1293 and 1310 turbo application.

i have done that and got the t shirt and i will still go back to buy another t shirt when the time comes lol.

always looking for them bigger bunches of bannanas

Off set bore the block. Move cylinders 1/2 and 3/4 in pairs, each pair by 10 thou out from the center of the block, thereby increasing bore centers of 1/4, 2/3 by 20 thou, but centers 1/2 and 3/4 remain the same.

This increases the bore wall thinkness in the middle of the block. On my 74mm bores the center is something like 2.5mm and the others are about 2.75mm.

If you measure a BK450 gasket or the AF460 gasket you will find that the fire ring at the center measures less than the other two as well. It is not symetrical.

If you are getting that much overhang on a 73.5mm bore, there is something amiss, only use top quality gaskets and the payen stuff is hard to beat, however i will never use a bk450 ever again!!

Edited by Sprocket on 5th Oct, 2007.

sprocks, why do you noy like bk450's? I've nerver had problems with them

Team Racing

Ive had three fail but never the AF460.

I built an engine for Jackman. He broke down in germany with suspected head gasket failure. I was rather concerned, considering the engine was three weeks old and 1500 miles on it. Stranded in germany for another two days with a chain smoking german recovery truck driver who didnt speak a word of english. LOL, anyway, it was the gasket. The engine spat its coolant out in about 500 yards. Oh and it leaked as well before the fire ring gave in.

They are just TOO thin.

I run a AF460 on the 1400 with high compression and the 'bad' overhang into the bore and no problems, the wifes standard bore 1275 mini ran the AF460 after having the BK450 replaced twice cos it leaked, last year I ran a bk450 on the 1400 until it leaked. And before anyone says anything about flat surfaces Jackmans and my engines were freshley faced surfaces.

Just my experience, the bk450 is crap!

Not that you have to worry much about the bk450 Jimster,it wont leak on yours, lol.

Edited by Sprocket on 5th Oct, 2007.