can i turbo my 1275 mini?
Turbo Mini Forums

i dont want to replase it with a metro so can i still turbo it

Parts
prise
how hard

What is the spec on your current engine??

Team Racing

standard 1275
a+ i think
stage 1
k&n
thats it

enyone ?

yup... anything is possiible

but you'd be better off using a metro turbo engine :)

alex

AlexF

Alex is technically right - a turbo engine would be a better base, but a well maintained, low mileage sprite engine/box may well be a better bet here than a 100k+ mile turbo engine that has been abused all its life...
I'd say turbo what you've got - but accept that you need to stick to low boost pressures. If you decide you want more in the future, put together a more sutable engine and transmission as and when...

As said Dave, your sprite engine make a good base for an upgrade, and if you don't want to deal with a very low boost system( difficult to imagine how can be an engine with less boost than a metro turbo!! warf ),
it will need an effort from you in term of rebuilding your engine and higher specs parts , so money
the crank is the same as a turbo, just check it, and reuse it ( I found the 4 cv engines to be in very good condition in the past even after a high milage ( ie, crank needing just new bearings bore ok etc etc ), this said a nitriting and balancing are a plus
the bloc is the same and is less stressed
the oil pump need to be upgraded with a new turbo oil pump
the gearbox is the same ( just check the main bearing , and the secound syncro)
the pistons need turbo dished ones, if you find a set of 1275 ones use them, you'll do not need a rebore, if not buy a good set of omega's ms mega or other good make (minispeed stock also genuines +40 with large dish); at this time I would highly recommend to look at the 1380 side as, it 'll make a noticable increase in perf for nothing,it will not allow very high boost but will stand with 10/12 and certainly higher psi's...a very good roady engine (imagine a + 100 in cc equal at 2 free psi's with no back pressure ,no heat, letting the valves flowing a little more
the cyl head need new exhaust valves( stainless steell and bronze guides, I like the rimflow ones as they are helping in not letting the exhaust pressure to go back in tyhe combustion chamber .
.......that's all!
or perhaps a turbo st 3 , high lifts and a cam , as you want.
fab

I dont agree about the 1380...

when you have a turbo you don't need cc's and going up 100cc is pointless when an extra 1psi of boost will give you roughly the same torque and power increase.

There are other issues with 1380s... the main one is that extra swept area of the bore needs to be fitted into the same combustion chamber, so effectivly you raise the CR. This is not a good thing when we are at 9.4:1 already!!

What else? Bore flex... already an issue on turbo'd a-series and miles worse on a 1380, and thisgoes hand in hand with potensial gasket problems as the inter-bore region is so small on a 1380.

IMO you'll get more power and be more reliable with a 1275-1310cc engine :)

alex

AlexF

1380 Bore Flex? Just because Vizard made a refgerence to this in his bible it doesn't mean it is gospel... Cast iron is not renowned for being able to 'flex' by any significant amount either!

A properly offset bored 73.5mm block has almost the same distance between the middle bores as a std block on a +040"bore, of course the chamber volume is slightly harder to sort out, but Jukka has proven this can be done - i'm halfway through a head here and have 32cc, and it's still only 'roughed out, it'll probably be nearer 33cc when it's done.

As Regards Oil pumps, the standard pump has more than enough reserve at 70psi with a turbo - i'd rather use a Rover one than the Minispares item aswell!

Darrell Cripps has a standard 1275 HLE short engine in his mini turbo (with large chamber head). He runs 15+psi of boost, and has been running 50hp of Nitrous aswell this year. The standard rods and pistons have coped just fine, so i'd be inclined to leave these if you want to do it on a budget!

Cast iron certian does flex!

I'm not going by the bible... its mostly out of date anyways. Bore flex is an issue on all engines... particularly where BMEP is very high, such as diesels or highly turbocharged petrols. All the power your engine makes is directly artibutale to the bore seal you make between your combution chamber the head, the piston and the bore.

There are other distortions as well, the bore also distorts when you bolt the head down for example!!!

alex

AlexF

"by any significant amount" Youi forgot that bit


I'm not saying that you should or shouldn't do a 1380, simply that i've not seen enough evidence from properly offset bored 73.5 blocks to state that it will be a problem. Certainly Jukka has had no issues and has many miles on his 1380 with high boost.
Two Years ago i would have said exactly the same thing - stick to standard bores - but i've never seen any evidence to support this - only facts that discount it...

interesting, so a 1380 high boost turbo is possablilty? i was told that anything above 1293 and u get massive blowby?

I've seen the future and tbh its Pie

http://www.geocities.com/MotorCity/Factory.../1380turbo.html

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