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Hi all,

I’m after some recommendations for building an 1100 engine using an South African crank and 1275 block. So far I’ve got a standard bore block, standard grind crank and a standard 12G940 head. I have some of the conrods with the heavy caps, but I’m not sure if I’ll use these.

The aim is a fun street engine that’ll rev nicely. I’m yet to decide on:
Camshaft
Piston type and compression ratio
Final drive (I have a 3.44 and 3.76)
Head - valve sizes etc

Any tips or tricks would be appreciated as I can’t find anyone so far who has done this over here (Australia)

Not sure this will help but we’ve built this:
Bored +40’
Minisport stage 3 or 4 head (I can’t remember exactly what it is but it’s their highest spec)
SW5 cam
SC injection kit

Output on first rolling road set up 85hp 84lbft

We haven’t driven it anywhere yet but my initial thoughts are it could have done with an SW8 type cam.

It’s in my son’s GTM that we hope to have out at Blyton.

Andy

I’ve found the dyno print
We didn’t take it over 6000 as it was new.
Possibly a bit more power to come at 6500

Any tips or tricks would be appreciated as I can’t find anyone so far who has done this over here.

Jeebus! Rich & I must have built at least 10 of these over the years. I reckon I have imported somewhere around 100 cranks too.

The sensible spec for what you are after is as follows:

SA crank, balanced (Lightened if the budget stretches that far)
1275 block, doesn't matter too much about bore, my preference was always plus 40, but that's just my prejudice.
Chuck the heavy rods & either get some decent Innocenti ones or buy a set of the cheap H beam rods from China.
6cc Dished pistons, Minispares / swiftune cast are fine, or 21253 hepolite type
285 / 544 type cam (although an SW10 would probably be a good bet too, I have not used one)
Decent modified head with 29mm exhaust, no need to go stupid & start cracking valve seats. Ports need to be smoothed but left more or less standard shape.
Twin H4's
LCB
RC40

This will make around 75 bhp at the wheels & will be an absolute hoot to drive. Reliable, smooth & plenty fast enough for a Mini on the road.

My preference was a 3.7 diff, but it will pull a 3.44 perfectly well.

interesting topic

what is exactly the stroke of these SA 1100 cranks ? 76mm ?
I guess it will be safe to skim the block deck by 2.5 to 3 mm ( assuming 76mm stroke ) in order to use normal height 1275 pistons ?

Cheers
Luis

The actual stroke of an SA crank has in my experience been a little variable. But is nominally stated as being 70.2mm

I forgot to mention that the block needed skimming, but that sort of goes without saying.

If you want to be flash you can avoid the block skim by using fancy long rods, but this is really just excess expense that doesn't need incurring.

Lakeland997 wrote:Not sure this will help but we’ve built this:
Bored +40’
Minisport stage 3 or 4 head (I can’t remember exactly what it is but it’s their highest spec)
SW5 cam
SC injection kit

Output on first rolling road set up 85hp 84lbft

We haven’t driven it anywhere yet but my initial thoughts are it could have done with an SW8 type cam.

It’s in my son’s GTM that we hope to have out at Blyton.

Andy

Thanks Andy, that's a good result from the spec you have there. I guess you might want a cam which makes power a bit higher up the rev range, I'd be interested to see how it goes in the GTM

mk1 wrote:Any tips or tricks would be appreciated as I can’t find anyone so far who has done this over here.

Jeebus! Rich & I must have built at least 10 of these over the years. I reckon I have imported somewhere around 100 cranks too.

The sensible spec for what you are after is as follows:

SA crank, balanced (Lightened if the budget stretches that far)
1275 block, doesn't matter too much about bore, my preference was always plus 40, but that's just my prejudice.
Chuck the heavy rods & either get some decent Innocenti ones or buy a set of the cheap H beam rods from China.
6cc Dished pistons, Minispares / swiftune cast are fine, or 21253 hepolite type
285 / 544 type cam (although an SW10 would probably be a good bet too, I have not used one)
Decent modified head with 29mm exhaust, no need to go stupid & start cracking valve seats. Ports need to be smoothed but left more or less standard shape.
Twin H4's
LCB
RC40

This will make around 75 bhp at the wheels & will be an absolute hoot to drive. Reliable, smooth & plenty fast enough for a Mini on the road.

My preference was a 3.7 diff, but it will pull a 3.44 perfectly well.

Sorry Mark, I've updated the first post - haven't heard of anyone in Australia who has done one of these engines. mk1-forum is the only reason I even knew about them

Just to check the Innocenti rods are the 12G1298/9 part numbers? I've seen the cheap H beam ones on ebay, they seem a bit too good for the price, especially seeing as they apparently have genuine ARP bolts? They do seem a lot easier to buy than the Innocenti ones here

mk1 wrote:The actual stroke of an SA crank has in my experience been a little variable. But is nominally stated as being 70.2mm

I forgot to mention that the block needed skimming, but that sort of goes without saying.

If you want to be flash you can avoid the block skim by using fancy long rods, but this is really just excess expense that doesn't need incurring.

So you skim the block by the whole 1/4" to make up the difference in stroke?

Sorry, I don't know the part number of the Inno con rods. They used to be 10 a penny at one time & proved to be a good strong rod. Probably a bit rare now.

I have used the Chinese rods in a few engines now & they seem fine. I do wonder about the "genuine APR bolts though" They haven't bust yet.

Yes, skim the whole 1/4" off, it never seems to cause a problem, even the stud holes are deep enough to take it. I have only ever used Pre A+ blocks, but I know folks who have used A+ ones without any issues.

I built one of these with an SW5 cam & the results were very disappointing when compared to a 544.

Interesting topic, my SA crank is just at my engine builder.

Does anyone know more about the ARP bolts coming with the chinese rods?
I will use H-beam rods to get the clearance for the 8 port cam I will use....
(I have 2 sets of Innocenti rods for sale)

I will use H-beam rods to get the clearance for the 8 port cam I will use....

Ha, ha, ha, Andreas is using an 8 port cam with a 5 port head, that'll never work . . . . . . . Oh wait a minute. . . . . . Oh No. . . . . . . .

Maybe he is planning on blowing up an 8 port head next

Ha, ha, ha, Andreas is using an 8 port cam with a 5 port head, that'll never work

have you ever tried a 8 port cam in a 5 port head ? it must work, 8 is more than 5....

That makes it a whole 3 better

https://www.youtube.com/watch?v=KOO5S4vxi0o

I did a SA 1100 years ago, with lots of help of rich and southam mini centre. It was 73.5mm bore, cheap h-beams, head done by SMMC i forget the specs, BP300 cam and 1.3 rockers, on split 40's. It made 90bhp if i remember correct (cant remember if that was wheels or fly) and drove like a dream, had such a wide power band and you could take it to easily over 8000

I wouldnt do a BP300 again on a road car, not because its hard to drive, but the motor breathed really heavily and most pro's i spoke to suspected the cam was the reason. But my point is you really can put any cam in that motor and barely notice it, it picks up so smoothly.

Does anyone know more about the ARP bolts coming with the chinese rods?

i have a set of those 200£ H beam rods ( bought 4 years ago ) and i am pretty sure they had genuine ARP bolts, that said a mate has bought similar ones from Ebay 2 years ago and the bolts although stamped ARP look really low in quality/finish with a dark grey color instead of usual black ARP.
He replaced the bolts and fitted the rods, they did already a few track sessions on a 7500+ revving engine with no issues.

almondgreen wrote:Interesting topic, my SA crank is just at my engine builder.

Does anyone know more about the ARP bolts coming with the chinese rods?
I will use H-beam rods to get the clearance for the 8 port cam I will use....
(I have 2 sets of Innocenti rods for sale)

I'd be very interested to see if these clear the lobes ok on the 8 port.
I've got a nice 1380 block with a damaged head face so keep thinking of using one of these SA cranks under one of the 8 port heads.

Tim, I'm not sure what your time line is here, but I'll quite soon have a 1275 block that's had too much skimmed from the deck for it to be useful as a 1275. Given that it's a one way trip for these blocks, if yours is fairly unmolested, I'm wondering of you might be interested in a swap? I can skim this block down further for you to suit your build at no cost if that helps.

Lindsay Sieber has had the Chinese Rods let go, the rod itself failed, not the fasteners.

Ooh guys sorry, just remembered our engine is 73.5 not plus 40.
Rods are the SC ones as the crank was bought as a kit from them.
They are cheap but quite heavy compared with Swiftune/MED et al.
It also has 1.5 rockers

Sorry for the memory lapse I put it down to being in the Southern Hemisphere at the moment

I have just built one of these engines , Rich@minispares.co.uk recomended the following for a road going car , 1300 pre+ block ,+A rods,minispares dished pistons, MK3 cooper S / 1300GT standard head , minispares Evolution camshaft , twin 11/4 SUs , I decided not to balance ect , just a steady smooth road car ,Let the engine rebore/regrinder dry build the engine to determin the amount that needs skimming from the block, mine is skimmed to pistons TDC , best give Rich an email and tell him what it is going to be used for , then he will tell you which way to go , My engine is really smooth and a pleasure to drive from tickover.
Rich is known as Mr SA1100 , he's ya man on these engines .

Is it the maxspeeding Chinese rods people are using ?

mk1 wrote:I have used the Chinese rods in a few engines now & they seem fine. I do wonder about the "genuine APR bolts though" They haven't bust yet.

Yes, skim the whole 1/4" off, it never seems to cause a problem, even the stud holes are deep enough to take it. I have only ever used Pre A+ blocks, but I know folks who have used A+ ones without any issues.

I built one of these with an SW5 cam & the results were very disappointing when compared to a 544.

Thanks Mark. Good to hear of your experience with the rods. If they came with APR bolts I'd definitely be a bit worried

jetblick wrote:I did a SA 1100 years ago, with lots of help of rich and southam mini centre. It was 73.5mm bore, cheap h-beams, head done by SMMC i forget the specs, BP300 cam and 1.3 rockers, on split 40's. It made 90bhp if i remember correct (cant remember if that was wheels or fly) and drove like a dream, had such a wide power band and you could take it to easily over 8000

I wouldnt do a BP300 again on a road car, not because its hard to drive, but the motor breathed really heavily and most pro's i spoke to suspected the cam was the reason. But my point is you really can put any cam in that motor and barely notice it, it picks up so smoothly.

Thanks for the advice, I probably won't go as extreme as you, but it does show the potential of the 1100 engine!

Spider wrote:Tim, I'm not sure what your time line is here, but I'll quite soon have a 1275 block that's had too much skimmed from the deck for it to be useful as a 1275. Given that it's a one way trip for these blocks, if yours is fairly unmolested, I'm wondering of you might be interested in a swap? I can skim this block down further for you to suit your build at no cost if that helps.

Lindsay Sieber has had the Chinese Rods let go, the rod itself failed, not the fasteners.

Thanks for the offer Chris, that sounds like a really good option! I will send you a message

goff wrote:I have just built one of these engines , Rich@minispares.co.uk recomended the following for a road going car , 1300 pre+ block ,+A rods,minispares dished pistons, MK3 cooper S / 1300GT standard head , minispares Evolution camshaft , twin 11/4 SUs , I decided not to balance ect , just a steady smooth road car ,Let the engine rebore/regrinder dry build the engine to determin the amount that needs skimming from the block, mine is skimmed to pistons TDC , best give Rich an email and tell him what it is going to be used for , then he will tell you which way to go , My engine is really smooth and a pleasure to drive from tickover.
Rich is known as Mr SA1100 , he's ya man on these engines .

Thanks Goff, that sounds like a pretty mild spec and close to what I'm aiming for. Good to hear it's a great engine to drive on the road and is nice and smooth

251 ENG wrote:Is it the maxspeeding Chinese rods people are using ?

I think so, although it's actually maxpeeding (without the "s") for some reason! A bit crazy that over here the Chinese rods are around $400 including bolts on eBay and the ARP kits for BMC rods are $200-$300

Thanks to all for the ideas and combinations you've used, it definitely gives me lots of things to think through