29 replies to this topic

[mini-geek]

for followers and springs you may as well buy a cam kit from kent, that way you get the right springs for the cam and good quality followers (and believe me that's important)

[mattso118]

for the gearbox rebuild soes anyon know what the minispares close ratio gearkit would be like? Dont think that sccr will be necessary with the power im expecting.

thanks matt

[bmcecosse]

A cms is a simple thing to make - mine cost me nothing! But it was 40 years ago........ 1330 engines (+40 overbore) are much less liable to overheating/cracked block between bores/head gasket failure- and there is room for a further bore in the future. I really can't accept that the extra 50 cc (less than 4%) is going to make a noticeable difference to the engine - especially as the flow capabilities of the head are the limiting factor anyway.....

[MRA]

1380cc Mini engines do not crack any more frequently than any other bore size, that is simply old wives tales

There you go again.......... it's got nothing to do with limiting factors.

The 1380 will breath heavier which will increase the port velocity and hence increase the torque at the bottom and mid range..... I have not even mentioned the higher RPM were any restriction may cause a slight loss of BHP..

Restrictions are only an issue when higher revs are concerned as you need to cram in air faster, more fill ups per minute...

Try drinking cola with a 1" (25.4mm) straw.... how effective is it ?

Now try with a 1/4" (6.35mm) straw and see how better this is....

Well it is similar when trying to get air in to a slow revving engine ie at 2000rpm or so.

BMCECOSSE, can you talk with experience or are you just guessing, as reading your posts above it is blatently obvious that you have never driven or owned a 1380.

Edited by mra-minis.co.uk, 08 February 2011 - 11:02 PM.

[mattso118]

Leaving the 1330vs 1380 debate for those with more knowledge than myself, can anyone enlighten me as to the necessary requirements for a cms, If it has any possible advantage, then I may as well get one fitted, as they dont seem to be expensive and any increase in reliability will always be a bonus.
Also anyone run a 1380 on twin hs2? or do most go with a bigger carb?

thanks

[MRA]

It's not only wear you have to look out for it is also fatigue failure, due to cyclic stresses, these stresses increase exponentially along with the increase of RPM.

the forces acting on the pistons due to increased power/torque also reduce the reliability...

However I believe the OP will be more interested in the lower end torque characteristics, so an AE piston would give more than enough reliability. As long as the ignition and fuelling are sorted out.

[mattso118]

It's not only wear you have to look out for it is also fatigue failure, due to cyclic stresses, these stresses increase exponentially along with the increase of RPM.

the forces acting on the pistons due to increased power/torque also reduce the reliability...

However I believe the OP will be more interested in the lower end torque characteristics, so an AE piston would give more than enough reliability. As long as the ignition and fuelling are sorted out.

What sort of rpm would you expect from a build like this, I thought that lightweight flywheel and the cam would mean an engine that will be revvy and cammy ? Does anyone run Ae powermax on a high revving engine ?

[mattso118]

Can anyone vouch for any good engine builders that I might not have thought of ? If they are in the south even better, or info on any engine kits ?
Thanks Matt

[Cooperman]

The 21253 is a good piston, but not exceptional. I've used them in a couple of 1330 engines with 276 and 286 cams and revs of up to around 7000 rpm. Comp ratios of up to 10.8:1 have been fine, but it would not be a good idea to run them with too much advance or too lean a mixture for a long period. The advance curve is very important in this sort of application.
The best pistons I've ever used are Karl Schmidt, but the last set I found, at +0.040", cost me over £500 for the set.
It is good to fit a cms if you are going to rev over about 6500 on a regular basis and they are low-cost to do.
A close ratio gear kit with a 286 is good, but it makes 1st gear very long and a 3.44 fdr or lower is needed. Probably a 3.76:1 fd if traffic driving is involved.
The 1330/1380 issue is really about the continuing availability of 1275 A-series blocks. Although in theory you can bore again from 1380, it is by no means guaranteed and it is possible a 1380 block may be scrap when re-bore again time comes around. With a 1330, at re-bore time it can be sleeved back to 1275. Apart from that the only other minor issue is the head gaskets on a 1380, but that may not be an issue with the latest gaskets. It is important that the machine shop understand about offset-boring to get to 1380. Don't laugh, but I recently had an engine brought to me which had been bored to 1380 but not offset. The so-called 'expert engine builder' had also bored/honed it on average 0.004" oversize and it just threw its oil out. The block could not be bored again as it was not offset and was thus scrap. An expensive exercise all told.

[aston19uk]

stop the detbate, just buy something. lol if you look after any engine. it will last

[bmcecosse]

Yes MRA I had a 1380 and it cracked between 3 and 4. So for me - it's a risk not worth taking for a tiny extra advantage.
You seem determined to challenge most of my posts.....I thought it was an open forum where folks calmly discussed problems. There are bound to be differences of opinion - and varying experiences to be offered. I shall continue to offer my views where I think they are helpful and may assist others to avoid wasting money!

[starletman]

Can anyone vouch for any good engine builders that I might not have thought of ? If they are in the south even better, or info on any engine kits ?
Thanks Matt

Slark race engineering in Amesbury.

[MRA]

Yes MRA I had a 1380 and it cracked between 3 and 4. So for me - it's a risk not worth taking for a tiny extra advantage.
You seem determined to challenge most of my posts.....I thought it was an open forum where folks calmly discussed problems. There are bound to be differences of opinion - and varying experiences to be offered. I shall continue to offer my views where I think they are helpful and may assist others to avoid wasting money!

Roy I have sent you a PM with regard to the above statement

I only challenge those that are either dangerous or simply incorrect.

We are trying to get a forum that gives explanations and proof not simply heresay

one bad example of an engine and its all bad never again etc...
My first Mini broke down on me on the way from buying it, should I have swapped over to Fords etc.. ??

Read the beginning of this post, (the bit in pink)

For me personally as a Moderator and Trader, the Moderator hat is the main one whilst I am on this forum, you will see that I don't recomend the fitment of the CMS however we manufacture them, We stock Omega and AE pistons I always try to steer a customer down the reliability route..... power without reliability is nothing !

[mattso118]

Right everyone thanks for all of your help, have taken on board peoples advice and decided that a sacrifice of reliability for power for cost isn't worth it. Still undecided about the 1330 1380 debate so will see what's available. But glad I was on roughly the right lines with that spec. So again cheers for the helpful advice.

Thanks Matt

[hepple]

Where and how much did you get quoted for that spec may i ask ? (: