A+ and the Metro Turbo
Turbo Mini Forums

Hello all,

Just this second registered to this forum. Have been meaning to do so for a while now as its got loads of very good details. Well done for a good site. Anyway...

I have a couple of queries I hope you can help me with.

I'm considering building a turbo engine from scratch for maximum power and I read a post that the 1275 MG has exactly the same block as the metro turbo. I was obviously delighted when I read this because I already have an MG metro installed and that would save me any bother of sourcing a turbo block. However I have read in Vizards book:

'For high boost applications, because of the fact that it has less rigidity, avoid using the 1275 block which has a hole over the centre main bearing...if starting from scratch, use a turbo metro block'.

I am also a novice at this type of thing, and I am wondering what the maximum bore sizes are for 73.5mm taking into account strokes etc.

Any comments would be very much appreicated!

Regards,

Chris.

73.5mm bore with

81.28mm stoke = 1379
79mm stroke = 1341
84mm stoke = 1426
86mm stoke - 1460

go for 73.5 and no further, makes 1380cc
if you want more cc go for stroked cranks

Thanks for the posts.

In the Vizard book it states that:

'if turbocharging is your intention and the engine is to do any amount of mileage, then a 0.060" overbore should be considered the maximum permissible'.

I am only using this car for a fun car and will do limited mileage each year. I would very much like to do 73.5mm, however I am unsure whether to stretch this far because I am also considering nitrous.

In his table it doesnt give possible cc capacities when using different stroke lengths for +0.060". Im interested in knowing what cc can be achieved for a +0.060". Anyone know this?

Also does anyone have any advice as to whether a 73.5mm & 84mm stroke equaling 1425cc would be tolerable or would it be a bad idea when running perhaps 10psi and 50hp nitrous?

Any advice would be greatly appreciated!

Chris.

Edited by Turbo Tel on 6th Apr, 2008.

website:- http://www.terryhunt.co.uk

Not sure he doesnt specify - simply states '1275 block' on p.354 in bold writing if you have the book.

The only block with the hole, is the A blocks up tp 71 or so it seems.

Well, I just looked and neither the A+ nor the Turbo blocks have a hole, I would say that he is reffering to the A series blocks.

I dont think there is anything different about the Turbo block when compared to an A+ Metro block..

Edited by Turbo Tel on 6th Apr, 2008.

website:- http://www.terryhunt.co.uk

Thats good news! thanks for the effort Turbo Tel.

Do you know anywhere where I can find information oncapacities for 0.20, 0.40 and 0.60 overbore sizes when used with different stroke lengths?

I am trying to determinethe capacity of 0.60 overbore of 1275 with a stroke of 84mm for instance.

Regards,

Chris.

you can use this.

http://www.motorgeek.com/index.php?page=6

on std stroke 81.33mm

+20 =1293
+40 =1310
+60 =1330

you can jiggle the bore to sute in the calculator then change the stroke.

Exactly what I need mini13 nice on:)

AlexF2003 has a site, AFracing.co.uk which used to have a great Xcel file for all the CR/bore/stroke stuff but its gone.

maybe he can put it up again or maybe post it, I found that a really simple and useful calculator

Terry

Edited by Turbo Tel on 6th Apr, 2008.

website:- http://www.terryhunt.co.uk