73.5mm pistons 11cc dish
Turbo Mini Forums

i have found some 73.5mm pistons with 11cc dish, they are fast road turbo 1380 pistons.
what kind of compression ratio would these give? what kind of boost would be safe to run on these?
thanks

an engine with the following spec:

73.5 mm bore
24cc head
std gasket
and a 11cc dish

Will have a CR of 9.6:1

Bit high fo turboing and also 1380s don't have as stiff a bore.

Alex

AlexF

so i take it its not a good idea to go for them then?
there are also 1293cc 10cc dish omega turbo pistons.
would i be better goin for these? what comp would these give?

std pistons are 12cc...

you would be better off with as near a std bore as you can get! Better for gasket reliability, bore flex and a few other things.

those 10cc piston would give you about 9:1 on a std head, remember thou you can fairly easily modify the head to drop the cr right down, but its easier and better to get the biggest cc piston.

Alex

Alex

AlexF

We actually like the 1380 turbo conversions as long as you do not run say more than 10psi of boost and the block is properly offset bored, the o/e turbo head gasket sits on the block prefectly. Our old Metro turbo with switchable boost ran 8 then 16psi we had 165 bhp @5500 rpm at the wheels on hi boost that was on auto techniques rolling road in 1986 we kept that car for 3 years and never had any problems with either the engine, turbo or running gear just the gearbox!!!! thing is not many machine shops know how to offset bore !!!!!

http://www.avonbar.com

assuming 24cc in the head 3.8 cc for the head gasket, 11 for the pistons 0.7 for the ring land to piston top and say pistons @ -0.25 down bore at TDC my calculation is just over 9/1 which is fine if the head has been modifisd correctly see our web site for chamber pic

http://www.avonbar.com

9:1 is still fairly high though, plus running the pistons down the bore isnt ideal. what head gasket is that for? seems a lot as well..

Guess different people want different things but with a choice of 1380 of 1283 id stick with the 1293 every time

10cc`s missing somewhere iain!!!!

Everyone knows that instructions only have to be read if the thing doesn't work....

Special pistons! lol! when i have them turned down and only bored 10" over!

arh the secerts of a citroen driver.

Everyone knows that instructions only have to be read if the thing doesn't work....

thats it mate! cant just use the same bits as everyone else, that would be too easy!

Citroen?

xsara rich mans xantia

Everyone knows that instructions only have to be read if the thing doesn't work....

Cheap as chips they are! Get a lot of car for not much money. Anybody want to buy it?!

Want to get something a bit quicker for the daily drive to work.

But its french???

your right Arno... who wants French!

alex

AlexF

Hi

I've been thinking about doing one for a while at the mo its 1380 73.5 bore 11cc dish,I know that I won't be able to take enough out the head to get low comp,but i work for a coatings company doing parts for jet engines f1 cars etc.
question is if I apply a thickness 2-3mm of tungstone carbide to the head face(excluding the combustion chambers)would this work ? If lapped flat to a couple of light bands and possibly the top of block too,I might not even need a head gasket as they should wring together like slip gauges do.We do this for gate valves for oil rigs.
Or can't a slice be taken of the top of an old block and used as a spacer
Another interesting one a few years back we thermal barrier coated an exhaust system for ferrari f1 to keep the heat in and stop the electrics overheating,normally used in the centre of a gas turbine engine to allow parts to operate above there melting temprature.

any feedback thanks Brian

Metro turbo weekend driver,Mini turbo in the making again!

Just wondering who you work for? As i work for a gas turbine manufacturer

it is tempted to barrier coat the exhaust rather than wrap to keep under bonnet temps down. might have a look into it for the exhaust manifold.

Praxair surface technologies(world leaders) used to be union carbide when I started.
Also tried thermal barrier coating inside the exhaust ports

Edited by Dangerous on 29th Nov, 2004.

Metro turbo weekend driver,Mini turbo in the making again!

never heard of them! lol! we use sermatech if that means anything?

thought id ask anyway

there is no reason 1380 cant be reliable im doing one at the mo, my mate has just done his t3tone and it goes bloody well running 12 psi and got 165 at the flywheel.
get the head out to 30 cc and you are away, should be able to run 12 psi reliably along with a intercooler.

always looking for them bigger bunches of bannanas

Interesting about using a spacer gasket. I have seen lazer cut steel ones for other cars. I could use one to save me having to swap the pistons on my test engine. I think you need 2 head gaskets to get it to seal properly. I haven't heard of anyone using them so it must be a bad idea.

For the 1380 idea, you could look at how deep the dish is and then scoop a load more out. Keeping your squish area at the top and just taking a big spoonful out on the lathe.

Again, probably not the best idea.

I'm in the same boat and even on the cheap, it's very pricey.

Bugger off, I'm getting there.

1380 IS reliable, as long as its built properly etc (same as any other engine). I was origanally going to go the 1293 route but insisted on some advise from a m8 (not mentioning any names MW) and decided to keep with what i allready had. I am so pleased with the results of this engine that if i was to do another i would bore my spare block out to 1380.

-MINI CLUBMAN 1380 TURBO-

This could be the other idea in order to lower the CR is to have customise heard gasket. In my engine, i use a metal head gasket and it is about 2mm thick.

I?ve said it before but say it anyway, 1380 turbo engine is reliable when done properly. If you just put the parts together without thinking what you are doing it does not make any difference whether you have 850 or 1380.

As for boost, I run 7,8:1 at 16 psi, the pistons are 73,5/11cc low comp height Omegas flush at the deck.

Barrier coatings are a BIG issue in US speed shops. The piston tops are coated to keep the heat in the chamber, not the piston. There was a good article about the coatings in Hotrod magazine, the actually used a torch to melt the piston top. A huge difference between coated vs. non coated piston.

Anyway, back to the issue here. 1380 has a lot more low down torque to begin with and when turbocharged, makes a very nice street engine. If racing, go for 1293.