if you're in it for the challenge, then do it on a 998, make all of your mistakes and when you're done, redo it with a 1275

kirby

i have a build guide available for the Twinky conversion

i also have extractors available

i also have turbo exhaust manifolds & dump pipes avalaiable

will will have wiring looms available to suit Adaptronic computers soon (atm we make them to order for the engines that we build & install)

any competent engine reco shop (&/or machine shop) can do any/all of the work needed to modify the mini block , inc boring & plugging holes, re-drilling etc

as for the pistons to suit low compression for forced induction,,, easy to just have the tops of them lopped off at the desired height (providing you choose your pistons wisely) & therfor no need for valve reliefs (cut-outs)

"ALL" mini con-rods are off-set---> However, off-setting the bores is easy & very common & there is plenty of room on the rod/pin/piston for clearance,,, if you stuff it up & go over-bored with the offset then a slight grind on the small end of the rod will correct it

Its much easier & cheaper than any Jap engine conversion, by a long shot & no body or frame mods needed either

good luck with your engine, which ever way you go

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

The crankpins don't line up with the bores anyway- unlike most other motors, all A series (and A+ too) rods are offset.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

some stuff we make for the Twinkys

http://i376.photobucket.com/albums/oo201/madmatttheminiman/Photo0005.jpg

& a couple of Twinky donks,,, one 8v & one 16v

http://i376.photobucket.com/albums/oo201/madmatttheminiman/Photo0320.jpg

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Hey kirby look at the for sale section Matt is selling a 60bhp 998 twinky donk for 3k, even with freight on top it should be a decent buy. I've been quoted 3k to rebuild a standard 998 that would only make half that power.

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Respect mine and I'll respect yours.

Now that I have the head in my hands I can understand much better whats going on.

I saw your twinky how to videos on you tube, mini-man, very helpful.

Ive been inquiring about 1275 blocks and the prices people are asking just doesn't seem worth it for what I want. So its down to 998 or 1098.
How much weaker is the crank in a 1098, the extra size does sound tempting, but the motor will be boosted so bottom end strength is a concern.
I doubt ill ever do any serious racing so it does not need to rev really high but it does need to stay together.
Will the standard rods be up to it?

Id like to see more than 60bhp from my engine. Atm I'm thinking of +.120 pistons, 1098 crank, sc12 with maybe 10-15psi boost (depending on final CR)

anymore concerns I'm overlooking?

1098 cranks are good for torque, and last OK IF you don't rev em hard. But I guess if fitting a Twinky head, you are hoping it will.
Not a great crank for a revvy twincam IMO, but OTOH if fitting a turbo they do make good HP. Benjamin got over 125 ATW, and I think pristic even beat that.

Personally, after 20 years of them I'm over twincams. My 1360 makes way more HP and torque than my modified 1438 twincam Fiat ever did. Pushrods- simple technology that works.

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DrMini- 1970 wasaMatic 1360, Mk1S crank, 86.6HP (ATW) =~125 @ crank, 45 Dellorto (38 chokes), RE282 sprint cam, 1.5 rockers, 11.0:1 C/R.

how much are you selling them for matt.

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Aussie Leyland, Aussie Factory, Aussie Mini S.

well Doc,,, what can i say??? maybe you should go visit Michael & go for a run in the moke

Drexel,,, sorry mate,,, i`m WAY booked out with the damn things,,, can`t even get time to get onto my own twinky

i`m out of conversion kits now,,, so i`ll look at getting back onto the CNC machine & make some more once we have the new Ayers 410 Speedway Sprint car up & running

yes,,, we`re going V8 sprint car racing now (we as in Brad Ayers,,, i`m just crew)

We have a brand spanking new Eagle chassis,,,& have just acquired the very best torque spread alloy 410 V8 donk avaliable,,,, this will be awsome,,, can`t wait,,, Sorry But Twinkys have NOTHING on these things


&&&&&& the new 20v, injected, alloy block , steel crank, 5-main, mini engines are coming soon (well ok not too soon but still they`re coming)

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

kirby

I've got one of matt's twinky kits and I was looking at another option for a 1275 engine, check out link

http://www.minispares.com/Product.aspx? ... AND%20RO...

that way you've got new block, pistons (that will require valve pockets machined in them), rings, crank, bearings,bores etc....

so although the intial cost of the new block rods and crankshaft is more, start adding up the cost of first getting a 1275 suitable for rebuilding, then all new parts and machining, and I think you'll come out ahead.

...and there is the possibilty of throwing in some cooper s rods and offset grinding the crank for bigger capacity or short stroking it for a high revving beast

more to think about

Kirby, quick question. What's the advantage of using the SC12 with a Twinky kit, rather than a turbo..? If you're talking SC12 and 5 port head, it makes a heap of sense - just grab the kit and go for it. But given a cross flow head, you're looking at making up new inlet manifolds, etc. Whereas Matt's got turbo Twinky manifolds ready to go. Sounds a lot simpler to me. And as the good Dr's pointed out, there are a few blokes on here who've had great success with turbo'd small bores. Twin cam turbo 998 +0.120" on the bore? Sounds like a pretty interesting engine to me! Nice stroke/bore ratio (76.2mm stroke, 67.63mm bore - if I'm correct!), nice capacity (1095cc), so it'd be reasonably revvy, inexpensive parts (compared to a 1275), and plenty of capacity to boost up. And off the shelf parts!

That said, those Mini Spares blocks... Not a bad idea. I don't imagine it'd be easy to find brand new, unmolested 1275 blocks any other place these days.

Not wanting to start a turbo vs supercharger thread here, but I prefer supercharged, no lag, no extra heat, no extra gizmos (turbo timer inter-cooler etc) and I already have an sc12.

Im not hearing much support for 1098 cranks and theres some horror stories I found doing a search, looks like ill be going 998.
are the standard con-rods up to the job? how different are they between 998 and 1098?

We are actually building a super-charged 16v 1360cc Twin-Cam for Stewy (don`t ask me why),,, he bought a BMW MINI Blower so that`s what he wants to use,,, just cause it`s different & he likes making more work for me just to shH1TT-Me_off

the small bore rods are not as strong as "S" rods,,, but seem up to the job (depending on the grunt & rev level you desire)

& yes i`d stick with 998 crank,,, they are a tad stronger than the 1100 & the engine will be all round smoother because of that

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Oh but if you choose your turbo well, then you shouldn`t have any lag at all,,, & the intercooler is a good thing no matter what type of pump you use

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No offence intended here but--> anyone writing a book about minis 30 years ago may not have experienced such worn or stuffed-with components as we are finding these days.

You should put your heart & soul into everything you do.

Already having the SC12 certainly explains a bit, and makes it more understandable that you'd want to go that way. Good luck with it.

I'm normally very much in favour of blown engines, I like low end torque (it's cheaper than revs in terms of fuel consumption). But any form of forced induction will increase heat in the charge and the engine bay. I'll admit it doesn't require you to keep the exhaust in the engine bay as long, which isn't a bad thing, but it's worth remembering that no forced induction is without a heat penalty. A turbo timer's not strictly legal or necessarily required, lag's dependent on boost and turbo size (i.e. smaller turbo, faster boost), even intercoolers are optional. Advisable if you want any real boost, but optional. Any high pressure supercharged setup should really have an intercooler too... An example is the Corvette ZR1's LS9 engine - blown, but it has an integrated charge cooling system.

Even though I'm normally in favour of a blower, with something like a Twinky conversion - where you're improving breathing - then a turbo makes more sense. Especially on a small bore. Why? Because the bigger valve sizes and cleaner ports can only be used to their full potential at higher revs in a small bore compared to a big bore. And superchargers, much as I like them, are more efficient at low revs than high revs, whereas turbos are the opposite.