A series block
Turbo Mini Forums

I have an A series block sitting in my garage at the moment it has been bored out to a 1293, will it be okay to bore it out to a 1380?
Have many of you used a normal A series block to turbo or do you just go for an A+ ?
Would an A series block be reliable enough with the pressure?

It will be fine.

a-series blocks are good blocks. personally i prefer them. Only thing to look out for is a whole in the casting below the centre main. Apprently this is suppose to weaken the block. Although ive had no issues on one of my engines that reaches 8000rpm on a regular basis.

I would think it is better to rebore to next oversize. That way the block is not scrap so fast :)

www.shag.no

If the kid wants to throw a couple of hundred pounds out of the window, let him

So it would be best to bore it out to a 1310

Yes then you have a couple of overbores left.

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

the a series block is slightly weaker than tha a+ which had ribbing cast in to help stop block flex. I to would only go next bore size up for same reason also im not a big fan of 1380's as sometimes it scraps a block as some blocks break into an oil way (you can ckeck first) but also the block flexes more and you get blow by/ bad sealing on rings. you can get a smaller bore engine work just as well.

My small bore turbo project http://www.turbominis.co.uk/forums/index.php?p=vt&tid=473901

I think its a Myth to be honest, I've know more people to blow out bottom of the engine block on A+ engines than I have A series

WWW.TURBO-MINI.COM

This always happens to me. The bottom of the block just blows out like that tractor pulling vid on YouTube.

Now I strengthening plates on the crank an make sure I use the stronger turbo block.

In the 13's at last!.. Just

Lol Gary ^^^^

Audi s4 b5 - 470bhp & 486ft lbs

On 30th Apr, 2012 Brett said:
yeah stick the bit in and give it a wobble

I find the turbo ones too stiff so they fracture,

I use the A series ones with the big hole above the centre main..... the flex like a bamboo bridge and last forever!

Lol

In the 13's at last!.. Just

Don't joke Carl. Joe has done this on his! Lol

In the 13's at last!.. Just

Back on topic, it could well be that the A and Aplus are equally strong.

Adding ribs to the casting was often a designer's attempt to maintain strength but with much reduced weight (ie, cheaper).

Unless anyone has weighed the two, or preferably done some FEA on the two, who can say for sure ???

The only issue with the A is that most have the casting void above the centre main - but Vizard (and others) say this is only a problem at high RPM (which a turbo won't need).

Schrödinger's cat - so which one am I ???

If I had a choise between the heavier or lighter block i'd use the lighter one.

Personally unless turning over 8k with an a plus I wouldn't even bother with a centre main strap.

Unless delivering some serious cylinder pressure i.e over 170hp I'd not worry about bore flex either on 73.5mm bore. It seems that a lot of the issues being discussed here have been thumped about for years without anyone proving or disproving anything and without faliures.

My friend has just build his new 1380 engine round an a plus block as the old a series one had warped, and kept killing centre main bearings.

Edited by minimole23 on 31st Mar, 2012.

Has anyone bored at their block to a 1302, and turboed it?

+30 thou? can you still get pistons for that overbore?

Yes i moved to the darkside

Instagram @jdm_brett

I believe they are hillman pistons i need to check my vizard book again as it was a few weeks ago since i last read that section

Nope i got it wrong it isnt even mentioned in the vizard book my bad.
Is there anyway of boring it to a 1302?

I think 1302 is just a +0.030 overbore.