1.2 /1.3 blocks

[will699]

What is the differents between the 1.2 and the 1.3 if the 1.2 was bored out too 1.3 would it go just as well or do they have a different stroke ect?

[craig green]

1.2 is the bigger bore, 1.3 has smaller bore with a longer throw crank.

Search out topics on 1400 big bore conversions.

[Novasport]

As above. 12ST block is also shorter than 13SB.

[_Jake]

14nv block, 12st pistons, 13sb crank and rods if you want a fun motor.

[Novasport]

What compression were you at on yours & what head were you running? I think an NV block is also shorter than an SB.

[_Jake]

What compression were you at on yours & what head were you running? I think an NV block is also shorter than an SB.
Iirc 12.5:1 with a c16se head. got bored and never finished it, building a 1600 8v turbo ******* child instead now.

[Novasport]

I have a 13SB block & pistons, 12ST Mahle pistons & C16SE head. Just need to get around to building it. The 13SB block is taller than the 14NV so compression should be slightly lower. Would be interesting to see the comparison in height between 12ST and 14NV.

[_Jake]

I have a 13SB block & pistons, 12ST Mahle pistons & C16SE head. Just need to get around to building it. The 13SB block is taller than the 14NV so compression should be slightly lower. Would be interesting to see the comparison in height between 12ST and 14NV.

id imagine the st to be shorter

[Southie]

id imagine the st to be shorter
So will this be a higher revving engine then? Surely a decent setup with a lightened flywheel and cr gearbox will also help.

What would the gain of a mixed engine be then?

[_Jake]

So will this be a higher revving engine then? Surely a decent setup with a lightened flywheel and cr gearbox will also help.

What would the gain of a mixed engine be then?
The 12st would in theory rev quicker being as its a short stroke engine. cant pass comment on it though as the 12st is the only 8v iver ever driven. gains of 12st pistons in a 13 or 14 block is higher compression and slightly bigger bore. Ill finish mine off one day lol

[Southie]

The 12st would in theory rev quicker being as its a short stroke engine. cant pass comment on it though as the 12st is the only 8v iver ever driven. gains of 12st pistons in a 13 or 14 block is higher compression and slightly bigger bore. Ill finish mine off one day lol
Thing is I don't get what the gain would be, faster revving but lower top end then? So ideal for rallying???

[mowgli]

the 1200 revs lots.... the 1300 has 20 more hp... the home made 1400 has more like 30-35hp extra over the 1200..

it was a serious tuning option before the mk1.5 upgrades, when the factory 1400 was introduced.. the home made 1400 could be done with really high compression, or, like mine, it could have the piston crowns machined to give 10.5:1.. it never had the head done or some decent carbs, it was just standard gm stuff, including the 1200 carb, but it had tons of torque & would usually embarrass lots of bigger engined stuff

[_Jake]

personally with the right headwork / cam and some tb's i think you could see 120hp out of the hybrid.