Going up to 1380
Turbo Mini Forums

I just took on a nice panel van thats going to be turboed soon so plans have changed. Instead of dropping the engine in as is in my rusted up authi, I figured I would freshen it up a bit and was thinking of bumping it up to a 1380 and adding a Stage 3 alloy head instead of my Avonbar stage 3 head.

Any goods or bads of bumping the cc's and any piston recommendations? I also dont hear much of anyone running alloy heads. Whats the general thought on going to an alloy head over standard? I'll probably be staying with the Kent 500 cam and going to 1.5 roller rockers and whatever else is on the motor right now because its all pretty solid.

-james

Omega pistons are excellent but possible harder to get nowadays. Mini Spares Mega range is another option but have not personally used them. You need to be careful about CR, it is tricky with 1380 and turbo.

Check out the decompression plates thread.

I am going BINI supercharger route. Boost is limited by blower efficiency and so big capacities/lots of torque/low revs are the go.

With a standard MG head, 11 CC pistons and 4ccs of head gasket you still need to have 15cc from somewhere (IIRC). I have come to the conclusion that decompression plates are a great idea. The theory adds up perfectly. Basically laser cut guage steel. 2 head gaskets.

HAVING SAID:- I HAVEN'T FIRED IT UP YET!!!!

Bugger off, I'm getting there.

Hi Jukka,

I am using the Mega pistons for about 12000km now without any problems; but they are only available in +040.

Bimmer Twinky headed and turboed A-Series:
http://www.minifreunde.at/harry/projects.htm

I'm 99% sure you can buy 75.5mm JE forged pistons with 18cc dish... not cheap (comparable to Omega) but available...

75,5 mm, that'll make the wall beetween cyl 2 and 3 mighty thin (texas accent)

73,5mm Dave, 73,5mm!

fat (americanised) fingers...

Wow, your americanized already Dave? So you already put yourself into debt and drive a car you cant afford?

Thanks for the help guys.

Here's the plan so far. The alloy head is a Moss Motors 12 stud head. Its supposed flow as much as a Stage 3 out of the box. Its got 1.3" Intake valves and 1.15" exhaust and a 24cc chamber. There will be some port work done also but nothing crazy as its not required.

My other thoughts are to go with the JE forged 1380 pistons so I can machine the piston to get the comp ratio I desire. I remember a mention of a 21cc piston being ideal but i'm not sure thats with a 24cc chamber. Also planning on Carillo rods and a forged Paul Ivey crank with 4 bolt center steel main cap. Definitely not going to be cheap but should be bulletproof.

Still havent decided on a gearbox yet but i'm going to fabricate my own alloy sheet metal intake and SS exhaust. Should all go together nicely.

I work at a chassis/fabrication shop here in the states and we really dont play with anything with a turbo smaller than 95mm so i'm taking advice from these guys just not sure if what works in a Ford engine will work in a A series. I appreciate everything you all have to offer so all advice is welcome!

-james

"Wow, your americanized already Dave? So you already put yourself into debt and drive a car you cant afford? "

thats the way life is............

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

I had a look into machining pistons and it isn't a good thing. The crowns are often quite minimal in thickness allready, you go scooping some more out and see what happens.

Just as an onlooker, these guys using relatively normal engine components are running some silly horsepowers. Using an alloy head and forced induction immediately says expansion difference, which is going to be marked compared to an N/A engine. With minimum gasket space, you are allready pushing it hard. I'd personally stay the hell away from alloy heads. You could minimise the shear by using 2 head gaskets and a decompression plate which would 1/2 the force each gasket experiences.

Anyway.........I know jack shit anyway.

Bugger off, I'm getting there.

My problem is that I know nothing about engines either. Im basically going off what I hear from others but not others that play with mini's!

I'm still thinking that the alloy head will be a plus in any case. Your basically unlimited in the amount you can modify an alloy head over cast. If I screw it up I can just weld it and machine it back to where it was. As for machining the pistons, the JE pistons i'm looking at are specifically made to be machined but I was told by one of our engine builders that I can order exactly what I want direct from JE. I'll have to call JE to confirm that.

My thoughts here are to build a totally bombproof longblock. I'm not worried about the expense but just that it'll hold together when pushed. These guys are definitely pushing out some good power with fairly stock stuff but unfortunatley I dont have the semi local recources you all have with A-series engines so I need a good base to start.

-james

What are you trying to achieve?

Bugger off, I'm getting there.

Basically a very powerful and reliable engine that can be driven without the worries of dropping something out the bottom. Not really planning on racing it other than the occasional trip to the dragstrip or maybe an autocross.

-james

Isn't this a contradiction:"very powerful and reliable" ?? :)

Get yourself a Subaru.

I think that Carrillo rods are a definite overkill, with the revs turbo engines use there is basically no need for fancy stuff. Most of the turbo engines give max power at 6000-6500 rpm so there is no need to go much higher. Balanced A+ rods with ARP bolts will last forever unless you do something silly. Steel crank is not really required, A+ cranks are excellent stuff. Most of the people on this forum run factory cranks and I doubt that anyone has broken one, despite double digit boost.

When you order the pistons, make sure that the have big dish, crown to top ring distance of about 5/16 to 3/8" and make sure that they are flush with the deck at TDC. Stu?s idea about decomp plates is practical but most likely will be more prone to detonation.

Alloy heads are beneficial since they usually tolerate more CR for a given head spec, due to better heat dissipation. Also easier to weld if something breaks.

As for Dave?s fat (?) fingers: remember where the hamburgers originate ???

Jukka, surely if you make the decompression plate bores slightly smaller, you get to keep your squish? I've convinced myself that this is right, are you with me or am I talking rubbish?

Bugger off, I'm getting there.

I think usually the decomp plates are shaped with the head gasket as a template. However, you could use the combustion chamber as a template and cut the plate kidney-shaped. You need to compensate with a little thicker plate but this way you retain the squish band and gain some cc?s. It might work ... or then not. I guess there?s only one way to find out.

Had the Subaru. Still regret selling it!

I dont think powerful and reliable is contradictory. It can be done or at least tried. Might not be too succesful in holding gearboxes together though. I'm not looking for big boost but big cfm. I do agree now that I have heard from just about everyone that the stock parts will hang. My worries are that if a rod lets go its going to take everything else with it which, in my mind, justifies spending the money on better parts.

As soon as I start to get some numbers down I paper i will be getting a set of made to order JE pistons with the desired cc to get a CR of 9 or 9.5 to 1. The higher compressions going to let me run a bigger hybrid turbo and give me more cfm at a lower psi. The idea of a decompression plate is good if your ona budget but in the long run just gives you another part capable of failing! I do appreciate the tip on the piston crown height also!

I completely agree with your thoughts on the alloy head and i'm happy to finally hear that from someone other than me!

-james

IMO after talking to a Abingdon bloke about this, big overbores and forced induction cause big problems between 2 and 3. Alloy heads being a particular pain. That's what I was told anyway, try it and see! From the bloke who's 850 mini with cabin blower put out 100hp at the wheels!

Bugger off, I'm getting there.

After speaking to some knowledgable folks i've decided to keep the bore a bit smaller than 73.5mm and maybe keep it in the 1310cc area. Gives me alittle more room to fix it if something fails.

-james

Stu,

haven?t blown a single head gasket with 1380 turbo, and currently run 16 psi. Maybe it?s only luck, I?ve only done 34000 odd miles ?

NYAuthi, things are a bit simpler with smaller overbores, especially with getting the CR where you want it.

34000 miles, Jukka are you deaf yet??? I love my mini, but I don't think I could spend that much time in it

Team Racing

jukka,

If you wouldnt mind too much could you give me a basic rundown of what combination of parts your running in your motor and gearbox and what size turbo. You can e-mail me direct at james.gocke@delta.com if you dont want to make anything public. 16psi was more than I was planning on running and would love to know whats keepin on after 34k miles! No biggy if you dont want to share your knowledge, just tryin to get set in the right direction. Still kind of wondering around on what to do!

-james

-james

Deaf ?? sorry mate can?t hear you... Well, long journeys are not that bad but the comparison against wife?s 1995 Passat is not fair. I mean, passat may not be quiet but after sitting in a Mini it is QUIET. On the other hand, my V8 Minor is so loud after 70 mph that I can?t hear the engine. Why ? Because there are no door seals fitted.. Why not, because the damn doors will not shut with the seals fitted. British coach building quality.

James, there are no secrets, most of the facts can be found in my pages, have a look at www.geocities.com/jharkola . Anyway, I used a Austin Allegro block (one of the milestones in british automotive industry i.e. CRAP !!!!) But they have a great block. Bored to 73,5 mm with Omega cast pistons, 11 cc dish. A+ crank from MED, A+ rods with ARP hardware, centre main strap, ARp head studs, std turbo metro head gasket, head is with about 35 cc chambers, cut by me, 36 mm intakes, 31 mm ex valves offset in the head. Nothing exotic actually. Std helical drop gears, standard Cooper S Mk3 helical gears, 2,95 diff with Minispares cross pin diff. Turbo is a Metro T3 unit that I bought second hand in 1995 with unknown mileage. Fitted with 10 psi actuator and solenoid controlled bleed valve to give 16 psi. Forgot the bloody thing open 2 years ago and it felt so good that it has stayed on ever since.

I have the head off so if you want some pics of the head or chambers

The only thing that is causing problems are exhaust valve seats. Despite running Redline additive with generous doses valve seat recession takes care of the seats. I had 35 % leak down in 2 cylinders when I put it in the garage last October. The rest of the two were marginally better. I have bought a late model unleaded head which I intend to use but with std sized ex valves.

Thanks Jukka,

Great website and thanks for the info! Would you mind if I dropped you an e-mail? I want to pick your brain about an idea I have.

I think I saw the pics of the head with the recessed valves. I would love to see more pics if you have them.

-james