1400 high compression engine

[daverobson]

would like as much info on this engine/how to build, as possible, the one built from 1200block 1300 internals and head?
thanks alot
rep given.

[comptoncj]

1300 block, 1200 pistons 11:1 CR IIRC not sure how people come up with 1200 block, 1300 crank and rods to make a 1400 thought it would put a piston through the top due to the 1200 block being shorter lol.

[daverobson]

urm, sure i herd that its 1200 block, maybe rods and pistons too. just 1300 crank?

[greg1.4]

buy mine..

check out parts for sale, my nova is breaking..

£300 for a short stroke 1400cc 8v competition engine!

[daverobson]

would like too but dont have any money, just trying to work out what to put in mine next

[garyc]

why not over bore a 1400 they are the same stroke as the 1300 and easier to get hold of.

[comptoncj]

Not sure, my uncles made their ones out of 1300 engines using 1200 pistons, just if you put 1300 crank and rods in a 1200 surely the longer stroke would put a piston through the head? But i definatly know the 1300 with 1200 pistons works. with good power :)

[Royston]

1200 engines have larger pistons/short shroke than 1300

1300 engines have smaller pistons that 1200 but longer stroke

1200 pistons, 1300 conrods/crank = @1400

Hope this explains.

Don't know what CR you get.

This also assumes the little end centre line to piston crown are the same

[rwaggers]

so would you get more power out of doing that or more power by using a normal complete 1400 bottom end?

cheers ross

[Balley]

My dad used to tell me to do something like this to a Nova when i was about 12, he said use the 1200 head as well i think ???

[jimbob-mcgrew]

slap a 1.2 head on a 1.4 block and hey presto, no hasless of pulling cranks and pistons out, dropping them on the floor and going "oh sh1t, which one is it" and putting the wrong one back in and blowing the engine up, cocaine all spew out the crankcase after it blows a rod,., ppfttt, 1.3 head would make a better daily, 1.2 would be good fun tho, see if u get 200 miles out of it before it goes bang lol

[daverobson]

hmmm, i see

[Sloth]

pm mowgli.

[mowgli]

pm mowgli.

thats the best bit of advice on this thread so far.

the 1200 block & the 1300 block are the same size. the bores are different, as are the strokes. the 1200 piston & the 1300 piston have the same height from the gudgeon pin to the top face.

PMC of tamworth invented the conversion about 20 odd years ago, they would modifiy 1300s & 1200s(at an extra cost)

the 1300 is a better base for it because the crank & block have been running fine for years & won't need line boring of the mains to make sure all is straight.

the 1200 will have massive wear grooves at bdc which will be a problem when the longer stroke crank (and shorter rods) are used, so you will still need a rebore & new pistons, so the 1300 is still the better option.

i can give the dimensions for machining the crowns that I used on mine, but each conversion is different & a bit of measuring combustion chamber cc, gasket thickness etc is needed, along with a bit of maths to get the cr that you are happy with. for competition, a cr of 11:1 is ok with additives, but for road use, 10:1 is nearer what is needed. that is what i did mine to.

[SR-Rally]

I'm running 1400 bottom end with 1300 group a head at the moment, I have a set pmc pistons out of a 1300 competition engine plus 1300 lightened crank, would I be better off fitting these pistons into another 1300 with crank then running standard 1400? The engine is for competition use.

[mowgli]

/\ pics of pistons please..

[SR-Rally]

Will get some later, got invoice to but not sure where.

[mowgli]

the 1300 comp pistons will be pretty much flat topped with valve cutouts at a guess, i'll keep a watch for your pics though

[daverobson]

hmmm i see, because i have heard people say 'just get a 1200 and put 1300 crank and head on and bam! about 100BHP'.
looking at building a fast small block engine for daily road use. any ideas on best thing to go for? cheers

[lmc123]

I cannot understand how anyone can fit a 1300 crank(which I would call a long stroke) into a short stroke block. Its nothing to do with conrods either as the short stroke block has also has shorter conrods as well

[JordyzNova]

why not just use a standerd 1.4 sr engine ??

[lmc123]

why not just use a standerd 1.4 sr engine ?? Same stroke,same bore = same power

[mowgli]

why not just use a standerd 1.4 sr engine ??

the whole concept is that by fitting 1200 pistons to a 1300, you get a high compression 1400 version of the 1300 engine, and the 1300 tuning stuff, ie. irmscher sport manifolds & cams fit straight on, the ignition system & all other ancillaries fit easily etc, and you get a ton more horsepower than a std 1.4


Same stroke,same bore = same power

14nv 77.6mm dia, 73.4 stroke 9.4:1cr 80 odd hp

home made 1400 77.8mm dia, 73.4mm stroke 10:1 cr minimum 90 odd hp minimum,

[lmc123]

the whole concept is that by fitting 1200 pistons to a 1300, you get a high compression 1400 version of the 1300 engine, and the 1300 tuning stuff, ie. irmscher sport manifolds & cams fit straight on, the ignition system & all other ancillaries fit easily etc, and you get a ton more horsepower than a std 1.4



14nv 77.6mm dia, 73.4 stroke 9.4:1cr 80 odd hp

home made 1400 77.8mm dia, 73.4mm stroke 10:1 cr minimum 90 odd hp minimum, Surely for all this tuning stuff all you need to do is change the head where most of the compression is gained from. As for .2mm larger bore I don't think it will = 10 bhp

[mowgli]

Surely for all this tuning stuff all you need to do is change the head where most of the compression is gained from. As for .2mm larger bore I don't think it will = 10 bhp

if you skim a head, you might possibly gain a few fractions of cr, ie from 9.2:1 to 9.4:1... skimming the heads make the valves closer to the pistons, so not good there, and if you make the head too close to the block, then the cam timing will be out too...

the 1200 pistons can get more than 11:1cr with a std 1300 head, which is where the big horsepower is.

[matt_vaughan]

lmc123 skim too much off the head to get similar comp ratios etc you're looking at valve clearance problems etc.

Mowgli has given me much info on this before, he knows what he's talking about, and many on here will vouch for that point.

What he's trying to explain is using either the 1200 or 1300 block you're going to need to rebore etc etc.

So....the ideal mixture, and the one I gather he used is...

1300 Block rebored to take 1200 pistons = high compression version of the 1300....with the stroke lengthened this means a CC capacity of ~1400.

On the Corsa-A website there is a table with listings of the bore sizes of the different engines, showing what needs to be taken out of the 1300. I'm sure this information is also available in the Haynes manual.

EDIT: my post took so long to wright i missed the fact mowgli had posted lol ill leave it on anyways.

[lmc123]

Thanks for the return answers, but what I had originally asked was how a 1300 crank and rods could fit into a short stroke 1200 ?

[matt_vaughan]

Should do, but as mowgli is trying to explain, it's not worth the effort doing it that way round.

Easier and in the long run cheaper to keep hold of your 12st and get hold of a 1300 block, and just slam the pistons from the 12st into that, after having the blocked bored out ~3mm iirc (i will take a look at the bore sizes in a min) to accomodate the larger pistons.

Edit bore sizes on Opel Corsa A site

Clicky (http://www.opel-corsa-a.com/index_e.php?seite=Motoren/Motoren_e.htm)

Check out the difference between the 1300 engine and the 12st.

12ST = 77.8 mm bore

1300 = 75 mm bore

so....have the 1300 bored out 2.8 mm.

I'm no expert, but that's what I gather is required.

[mowgli]

Thanks for the return answers, but what I had originally asked was how a 1300 crank and rods could fit into a short stroke 1200 ?

because the crank is longer stroke, and the rods are shorter, and the 1200 pistons are the same height as the 1300 pistons, and the blocks are actually the same height. so it sort of just fits. i ran one for about 90000miles then sold it on

[Novasport]

Anyone know what a 1300 block will safely rebore to? Say I wanted to use a set of 0.5mm or 1mm oversize 12ST pistons. A 3.3-3.8mm overbore.

[SR-Rally]

here are some pics off one of the pistons. not sure what make they are? could be standard :S will need to find the invioce that came with the car, i still have the block in the shed although it has a hole in the side :( so can take measurements although its def a 1300. when i got the car i had it rolling road set up with this engine. it made 102bhp at the wheel and john yeomans the owner of the garage said the compression was unreal.
http://i573.photobucket.com/albums/ss177/sr-rally/P1010139.jpg
http://i573.photobucket.com/albums/ss177/sr-rally/P1010137.jpghttp://i573.photobucket.com/albums/ss177/sr-rally/P1010128.jpg

[SR-Rally]

btw its not me holding the piston :) there my girlfriends nails :P

[jimbob-mcgrew]

liar, you like to dress up on the weekends dont you lol

[SR-Rally]

:S busted

[Sloth]

they look like ae hepolite slugs, uber expensive

[Novasport]

they look like ae hepolite slugs, uber expensive

Not really, just standard replacement stuff. Mahle pistons are what you want.

[Sloth]

ae pistons are used by some of the top drag racers and stock car v8 builders, they are very very good pistons and if made as a one off set, very expensive.

[Novasport]

They just look like standard replacement 12ST pistons to me.

[mowgli]

They just look like standard replacement 12ST pistons to me.

that is what i reckon they are too. i hope you weren't fleeced for them

AE21294 is the number for a 12st piston.

i had KS pistons in mine, and machined the dish down 5mm so the bottom of the dish was flat, with a radius in the corner. this got them down to 10:1, which is what i wanted for long term road use.

get some new rings in them, bore the block to 77.8 & you'll have a strong bottom end.

[SR-Rally]

Came in the engine with the car which I got very cheap for condition :) so i'm not fussed, plus the engine made more then he said it would on rollers :) Will try find invoice. Would it be worth me fitting these into a 1300 bottom end, will there be much power increase? I compete in 1400 under class and want as much power as possible from 8v :) but can't use twin 40's and none standard throttle bodys.

[mowgli]

they will be a good upgrade on a 1300. then a weber replacement on a 1300 manifold... unless the regs allow a car that came with twin 40's as std....ie: a sport.

[SR-Rally]

They use to but standard production has gone now :( so sports can't run the forties :( I might start a thread in next few weeks as want to get most power out of 1300 or 1400 as possible with in regulations.

[mowgli]

They use to but standard production has gone now :( so sports can't run the forties :( I might start a thread in next few weeks as want to get most power out of 1300 or 1400 as possible with in regulations.

get the full regs posted up asap