SA1100 build recommendations

[goff]

What are small bore head studs?

What are small bore head studs , almondgreen I found out that after fitting the 1300 studs that came with the engine ,when i fitted the head the studs they were to long !!!! , if you think about it the block has had aprox 6mm machine from the top ( decked ) , so the head would sit 6mm lower than the studs , the studs ran out of thread and started to bottom out , i have a couple of 1100 engines , so i removed the studs and found they shorter , i learned the hard way by fitting the studs , gasket ,rockers , head and then tried to tighten everything up !!! , you learn something everyday , if you have a die you could run it down a bit , BUT they are high tensile or maybe a machine shop could do it for you '

photo attached showing studs difference ,

hope this helps

Goff

[LuisM]

Hey Luis, Mazda and Honda Jazz Pistons are available in those sizes, I can look a little later at the Pin to Crown Heights but I'm sure they are all lower than A Series.

Hey Chris,
did some searching and came up with some Mitsubishi 4G36 engine pistons , 73mm bore and 39.5mm compression height..1.5mm than the mini ones.

http://www.totopiston.co.jp/cat/piston/toto11ma-1.pdf

if i get one of these cranks, i'll check further these pistons.

Cheers
Luis

[Spider]

Hey Luis, Mazda and Honda Jazz Pistons are available in those sizes, I can look a little later at the Pin to Crown Heights but I'm sure they are all lower than A Series.

Hey Chris,
did some searching and came up with some Mitsubishi 4G36 engine pistons , 73mm bore and 39.5mm compression height..1.5mm than the mini ones.

http://www.totopiston.co.jp/cat/piston/toto11ma-1.pdf

if i get one of these cranks, i'll check further these pistons.

Cheers
Luis

Cheers Luis,

The SA 1100 - as best I can find out - has a nominal stroke of 2.75" and the 1275 engines a stroke of 3.00".

In order to use a fairly unmolested 1275 block for a SA 1100 build, the Pin to Crown heights would actually need to be 1/8" (3.175 mm) or there abouts higher. Therefore, according to my rough numbers here, the Pin to Crown height ideally needs to be in the region of 41.15 mm. None the less, at a height of 39.5, that's very much worth considering.

[timmy201]

I think you should have 3.2" stroke for a 1275?

So the amount off the top is 0.225" or 5.7mm

[Spider]

I think you should have 3.2" stroke for a 1275?

So the amount off the top is 0.225" or 5.7mm

Ha !

Yes !!

Or 1/4" added to the Pin to Crown heights

[mk1]

Without putting too fine a point on it. Using tall pistons is just daft. The whole idea of these engines is to me a free revving unit. Sticking daft great heavy pistons in it is a seriously retrograde step.

[251 ENG]

Mark is correct about pistons compression heights

BUT

If anyone wants to build one of these engines ,s we have some +20 omega forgings with increased crown height that could be available at a very reasonable price

[Spider]

Without putting too fine a point on it. Using tall pistons is just daft. The whole idea of these engines is to me a free revving unit. Sticking daft great heavy pistons in it is a seriously retrograde step.

Absolutely !

That's why the 'trend' with most modern engine design has been to lower this height and why there's nothing in the Japanese Engine Range that fits this bill.

[gr4h4m]

I run a SA crank, bored plus 40, using calver pistons and a set of longer H beam rods with the correct size for the crank journal, to save chopping the block. I used Williams rods, the bloke peddling them is not far down the road in north wales. He was very good to deal with. I met a mini 7 racer that runs them to 9600. My cars rev limiter is current set at 8300, it gets there very quickly and makes great power.
The engine tuned out better that I thought it would, it’s fantastic and I love it.

[timmy201]

I run a SA crank, bored plus 40, using calver pistons and a set of longer H beam rods with the correct size for the crank journal, to save chopping the block. I used Williams rods, the bloke peddling them is not far down the road in north wales. He was very good to deal with. I met a mini 7 racer that runs them to 9600. My cars rev limiter is current set at 8300, it gets there very quickly and makes great power.
The engine tuned out better that I thought it would, it’s fantastic and I love it.

Thanks Graham, what cam are you using out of interest? Good to hear you like this style of engine

Edit: I’ve remembered I’d already read about your engine build on turbo minis and you had a supercharger. I’ll have a read up to see how you went

[gr4h4m]

I run a SA crank, bored plus 40, using calver pistons and a set of longer H beam rods with the correct size for the crank journal, to save chopping the block. I used Williams rods, the bloke peddling them is not far down the road in north wales. He was very good to deal with. I met a mini 7 racer that runs them to 9600. My cars rev limiter is current set at 8300, it gets there very quickly and makes great power.
The engine tuned out better that I thought it would, it’s fantastic and I love it.

Thanks Graham, what cam are you using out of interest? Good to hear you like this style of engine

Edit: I’ve remembered I’d already read about your engine build on turbo minis and you had a supercharger. I’ll have a read up to see how you went

Yes I cheat a bit and run an sc12 kit from Ben92 (Aus mini).
I use the re13t cam on 112lca but that is more about the fact I’m using the supercharger.

I was worried about sinking the cash into the engine and box and putting it all together myself, that was the main reason I didn’t want to chop the block. As crazy as it sounds it was a budget build, not that my account felt like it at the time. I tried to keep it simple not that it ends up like that. I was concerned it wouldn’t feel much different that my 1060. My uncle had a 1071 in a van when I was a kid and to me it had a cult status. So I was worried the real thing was going to be a let down, it made about 18 bhp more but man what a difference the car is now, it lived up to my expectations!

[timmy201]

Thanks Graham. I have the same thought about going from a long stroke 1100 to a short stroke 1100, but I'm hoping it'll be completely different to drive a a lot of fun

The crank was finished today at the machine shop. It measured up at 70.0mm stroke, I've found an old post from Rich saying this was one of the factory sizes they made.

[timmy201]

Thought I'd add in some photos here as there isn't much happening at the moment. It came up as 10/10, which was great news.


I like the comparison between the SA1100 crank and the normal 1098 crank. The 1098 has no overlap between the main and big ends, the SA crank is much beefier!

6CCCE7C3-8414-492B-BC7E-644F8EFD1BA2.jpg

I picked up some really nice A+ rods, they still even had the standard size factory pistons and big end bearings

[LuisM]

What is the par number of these SA1100 cranks, are they stamped/have markings ?

Thanks
Luis

[timmy201]

It's 12G2827

[LuisM]

12G2827

Thanks Tim!

[Sean1380]

Nice seeing a detailed thread on the SA 1100 cranks.

I remember when I could pick them up for R50 each.

[timmy201]

Nice seeing a detailed thread on the SA 1100 cranks.

I remember when I could pick them up for R50 each.

I was lucky enough to get this one - shipping took 3 months from SA to Australia!

Here's an interesting comparison photo from the SA mini forum showing the big top pistons fitted to the 1100
http://samini.co.za/showthread.php?tid=73

IMG_2232.JPG

[Vegard]

Blimey, the 1100 pistons are hideous

[almondgreen]

Do you use the standard length cylinder head studs?