Technical Pick 'N' Mix engine

[craigb244]

Me and dad have been having a think (oh dear)
if i got a old Fiat 750 FIRE engine. (or maybe even 900)
and fitted it into a 1242 "shortened" block
I should end up with a very under-square engine which fitted with a high flowing head/mpi/throttle bodies should leave me with a very interesting little engine

but the question is... is it do-able
Ive seen a fiat 900 ohc engine and it is the same as the 1.1/1.2 but will the crank fit?

 

[Most Easterly Pandas]

Ive seen a fiat 900 ohc engine and it is the same as the 1.1/1.2 but will the crank fit?

That'll be 999cc, not the ohc.

FIRE engines came in 769, 999, 1108, 1242 cc and are basically all the same engine.

 

[Luke P]

Hi all,

Jon, the 999 is an overhead cam engine isn't it?! Speedreading again?

Luke.

 

[Most Easterly Pandas]

Hi all,

Jon, the 999 is an overhead cam engine isn't it?! Speedreading again?

Luke.

Probably, I'm not with all the lingo

Whats the 900 engine then

 

[lewey]

OHV perhaps?

 

[craigb244]

lol. i say 900 as i in around 900cc
I know there is a 750cc fire engine. and as its a fire engine then im guessing that crank "should" fit (assuming the crank/big end bearings match) into a 1242 block.

the plan would be to fit the 750 crank into a 1242 block with the 1242 pistons (not sure what rods to use... need to measure them)
then obviously the pistons will not come anywhere near the original deck height, and as such the block will need cutting down.

the other option would be to simply buy a 750 and bore out the cylinders then sleeve it to fit the 1242 pistons... problem with this option is it will cost ££££ while i can mill the top of the block down for nothing

the head would consist of a mpi head with the largest valves i can wedge into it (16valve would be better but they are hydraulic and would not cope at all with the kind of rpms this beast would make power at)

I have very good knowledge of megasquirt efi so fueling and timing wont be any trouble.

if the crank fits then ill simply fit it, cut block, drop it into a cento and see if it works (run it to silly rpms) IF it lives then start doing the valves and head work which is the part that will cost me money.


so now... need to find me a knackard old 750 to pull apart.... anyone?

 

[lewey]

If you've got the engineering precision, tools patience and confidence to do it, then go for it. You will certainly win the prize for the weirdest and most original engine!

I think the whole idea is completely nuts!

 

[craigb244]

750 crank with 1242 pistons:
Results:
Bore: 70.80mm
Stroke: 58.00mm
Cylinders: 4

Engine capacity: 913.36cc

999 crank with 1242 pistons:
Bore: 70.80mm
Stroke: 64.90mm
Cylinders: 4

Engine capacity: 1022.02cc

maybe a 999 crank would be better... not quite as hard core... keep piston speeds down a little to. lol

 

[craigb244]

If you've got the engineering precision, tools patience and confidence to do it, then go for it. You will certainly win the prize for the weirdest and most original engine!

I think the whole idea is completely nuts!

Thanks... I think....

basically i want to try it just to mess about.
the bore and stroke im looking at is in the sports bike engine realm

example:
Yamaha R1 1998-2003

Bore: 74.00mm
Stroke: 58.00mm
Cylinders: 4

Engine capacity: 997.79cc


obviosly i dont think a fiat crank/rods/pistons/oil pump/gearbox will last long at 12k but would love to hear it at 10k :devil:

 

[craigb244]

...So...Come on... one of you panda folk must have an old 650/999 bottom end laying around rusting away after a 1.1/1.2 upgrade

 

[Most Easterly Pandas]

...So...Come on... one of you panda folk must have an old 650/999 bottom end laying around rusting away after a 1.1/1.2 upgrade

Plenty of 999cc engines about I expect, but don't go killing any rare 769cc engines lol

 

[craigb244]

yeh seen a few panda 1000s been broken on ebay. know they will want lots for a crank tho so might just wait.

no 750s... must be very rare.

think a 1000 will be best tho. 750 stroke might be a bit on the small side

 

[craigb244]

Might be in luck... my mate has a old panda rusting away in the garden. said its 900 or something cc.
Expecting it to be a over head valve engine I asked what the engine looked like, he said it looks like mine

fingers crossed...should be the same as ohv and ohc look nothing like each other

 

[cartledge_uk]

I think its certainly possible. Using a 1242 16v block will allow the use of the crank ladder.

Cut the skirts of the pistons right down and lighten everything. And ARP the lot.

Should hold out to 9k, 10k+ I dont know, but i'd like to see.

 

[CLXCraig]

A few Members were selling old 999cc engines complete for serious low amounts.

PM AlexBPL. he had one for sale for a tenner a while back. not sure if it sold though.

Exhaust ideas?

 

[maddogmorg]

https://www.fiatforum.com/leisure-l...ka-yeah-thread-aaka-karbineftw-does-know.html

considered this myself a while back. An oversquare engine allows more valve area and also slower piston speed per RPM. Which are key ingredients for high revving engines.

Would be very interested to see the results.

 

[craigb244]

yep and lower friction loss

the 1.4 is a hugely long stroke. tractor engine, altho a 1.4 with the 1.1 crank would be a very nice setup.

boring out the smaller block would be the best idea but would cost ££££ because it will need sleeves fitting.
the other block would need cutting down and its quite a lot
999 stroke is almost 65mm
1242 is almost 79mm

so we are looking to remove at least 7mm of metal! most likely more cause id deck the block so the pistons are as high as it can get

if i get a 1.2 block i might just take the grinder with the disc to the water and oil feeds just cut 7mm deep slots and see if they stay in the same position/no holes appear

 

[maddogmorg]

the only thing is in terms of power a 1.4 may beat it purely due to displacement. but in a panda a high revving engine might be much more fun. in terms of fuel system personal preference would be for carbs, motorbike carbs might be best? seeing as they're for high revving engines anyway.

would probably need a stand alone ECU unless a distributor based system would work?

 

[maddogmorg]

Any progress on this idea?

 

[craigb244]

Any progress on this idea?

sorta, We are looking into using a 1.1 crank in a 1.2 block to make a slightly over square engine, high flowing head, spicy cam, itbs. be for a motorsport car

keep you up to date with any progress (might be a while tho, not at the top of the list)