Engine capacity bordering class designations

[poeee]

I'm contemplating building a car for what you guys all love. Just gathering information and understanding the rules before I make a decision about which way to go.

Class will be 'PRO'. Looking at running a 998cc engine. Now of course that falls in to 'I'. However, with engines that are all at least 30 years old, it's tough finding one that doesn't need a rebore, and then it's even harder finding pistons to suit the application that are std size (flat top to raise compression).

I believe +020 pistons are common. This gives you a bore size of 2.5620". With the stroke at 3", it gives you 61.86277226912832 cubic inch or 1013.7491102911296 cc. From my understanding 'I' is 46 - 61 cid or 0.76 - 1.00 L, and 'H' is 62 - 92 cid or 1.01 - 1.50 L.

So it's bigger than 61 cubic inch, but smaller than 62 cubic inch.

Of course I don't want it to be in 'H' as it will effectively be two thirds the size of what can run in that class.

Please help me understand the rules in this instance.

[Lynchy]

Sorry - can't help myself....

What if you start with a 997cc motor??

I'd say based on the strictest interpretation of the rules you would be in H, but I haven't heard of any motors in Aus being torn down for a measure.

[poeee]

997 engines are very hard to find. Different stroke based on an 850 engine. I have 1/2 a dozen 998 engines sitting at home!

Another option is find a 970 crank, which uses the same block as a 1275. The 970 was specifically designed for under 1L competition. Again, those cranks are extremely rare and really the only way to get one is buy a billet crank. Adds to the costs, and although I do have a few 1275 engines sitting here, it's not making the best of what i've got laying around.

I think I have some more thinking to think about.

[ben james]

everybody hide , the mini geeks have found us again

[momec]

Welcome aboard

62 is H so therefore 61.99999999 can only be I.

Go for it.

Chris

[fredeuce]

Should be able to use a Morris Minor block which came with same stroke as a 998 but slightly smaller bore from memory. They came in at 948cc.

Looking at the manual the 948cc block has a bore dia. of 2.478 whereas the 998 is 2.543 . You might be able to stretch one of those older blocks to standard 998 bore and know that you will still be under 1 litre.

[poeee]

More researching (on my website haha). Using an 850 block and crank, you can bore it out and fit 998 pistons and 998 rods. The block will need to be decked a bit to suit the piston height. Now for a 'Mini geek', using an 850 block and crank is a very romantic idea. Although my head says use a 998 crank as they are stronger. Waiting to hear about the availability of good flat top 850 pistons.

Also turns out that top quality flat top 998 pistons can be easily purchased new. So that just means finding a 998 block with top condition std bores (not likely!). It was also common back in the day to fit 998 or 1100 cranks and pistons in a bored out 850 block, so using that idea could get get nice fresh bores in std 998 size.

[Cookey]

Have you talked with JP Pistons at Windsor Gardens SA?

[poeee]

I have heard of people getting 850 pistons from there. Might enquire about pricing.

[the randy dero]

Leigh Russell drove a Suzuki hatch from Brisbane to The Lake with a race engine in the passenger seat. Raced it and drove it home. Smaller than a mini but went heaps better. What a story that joker is. The only reason to use mini parts is to set the Salt Lake Breakdown Record. BMC parts are sooooooooo passe.

[nitro-nige]

I don't have an SCTA rule book but I think they use 46.000-61.999 for I and 62.000 to 92.999 for H.
So I imagine similar would apply to DLRA.
Ask the chief steward.

[Rob]

I'm with Chris,

Anything less than 62CID and greater than 46CID is "I".

You have 4 and a bit months, get to it.

Rob

[Last Minute Racing]

What BMC should have done

http://www.youtube.com/watch?v=H70vEq_FMvs

See you all at the Lake all going well

Thanx
Dave