83 replies to this topic

[minispecial]

hi I drive a 1980 mini special which currently has a 1098 engine. However I have recently been driving a 1.6 golf and after going to the mini i feel it needs some more umph.

i have a budget of around £200-300

what do you recommend for more power and quicker top end?

cheers

Edited by minispecial, 19 September 2009 - 11:20 AM.

[minimanclive]

Start with a decent stage 1 kit. I'd recommend Mini Spares or Maniflow. Check how it'll affect your insurance first though.

[minispecial]

Start with a decent stage 1 kit. I'd recommend Mini Spares or Maniflow. Check how it'll affect your insurance first though.

I already have a Sportex straight through exhaust with cooper maniford what else would I need for the equivilant power increase of a Stage 1 kit?
and do you recommend getting twin carbs?

Edited by minispecial, 19 September 2009 - 11:33 AM.

[james962]

To get the equilivant to a stage one kit, you would also require a K&N air filter, a better flowing inlet manifold, different carb needle.

After that, i think you would be better off starting to look at a different camshaft or cylinder head rather than twin carbs.

[Cooper-202S]

There are two main issues with the 1098 engine that affect its performance,
1) It has the longest stoke of all the std small bore engine therefore it has to work the hardest to draw in the combustion mixture and expel the exhaust gases.
2) they were always bult as low compression ratio (8.3-1) to run on two star leaded petrol rather than the more common 9.5-1 + of the later engines.

They therefore benifit most from breathing enhancements; ie:
A well ported cylinder head and inlet manfold.
As previously mentioned a performance air filter.
Correctly tuned exhaust system (the section in Vissards book on exhaust tuning is definity worth reading twice)

Twin carbs will only give you more if you sort out the above first, singles need far less tuning as well.

The other major gain is to raise the compression ratio, but as you are not planning a full rebuild then you would have to do this by getting the head skimmed to reduce the chamber volumes . A word of caution, to get to 9.5-1 ( ideal for ordinary unlead fuel) you would have to skim quiet alot off the head which can give you an issue with the lenght of the valve push rods.
The better way to raise the compression is to fit pistons with a 3cc dish or flat tops instead of the 8cc dish fitted as stanard and the take less of the head.
If your planning on keeping the mini or doing more work to the engine later then i would get a 12G295 head converted to unleaded and skimmed enough to give 9.5-1 with new pistons which you can do later. but the budget is a little tight for that.

One other piece of advise is to make sure the crank damper is in good condition because the 1098 crank is the easist to break through vibration stress if you going to drive it hard>

[minispecial]

There are two main issues with the 1098 engine that affect its performance,
1) It has the longest stoke of all the std small bore engine therefore it has to work the hardest to draw in the combustion mixture and expel the exhaust gases.
2) they were always bult as low compression ratio (8.3-1) to run on two star leaded petrol rather than the more common 9.5-1 + of the later engines.

They therefore benifit most from breathing enhancements; ie:
A well ported cylinder head and inlet manfold.
As previously mentioned a performance air filter.
Correctly tuned exhaust system (the section in Vissards book on exhaust tuning is definity worth reading twice)

Twin carbs will only give you more if you sort out the above first, singles need far less tuning as well.

The other major gain is to raise the compression ratio, but as you are not planning a full rebuild then you would have to do this by getting the head skimmed to reduce the chamber volumes . A word of caution, to get to 9.5-1 ( ideal for ordinary unlead fuel) you would have to skim quiet alot off the head which can give you an issue with the lenght of the valve push rods.
The better way to raise the compression is to fit pistons with a 3cc dish or flat tops instead of the 8cc dish fitted as stanard and the take less of the head.
If your planning on keeping the mini or doing more work to the engine later then i would get a 12G295 head converted to unleaded and skimmed enough to give 9.5-1 with new pistons which you can do later. but the budget is a little tight for that.

One other piece of advise is to make sure the crank damper is in good condition because the 1098 crank is the easist to break through vibration stress if you going to drive it hard>

thanks for the advice mate ill let u know how it goes

[bmcecosse]

Stick a 12G940 (ie ex 1275) standard small valve cylinder head on it - gives a huge power increase for very little money. You should sink the exhaust valves into the head by 40 thou - although not ALL heads need this doing, and if you feel competent you could measure and check if it's required or not - but I have to advise you to DO it! With a 'Vizardised' HIF38 on an alloy manifold - it will make 60 maybe 65 bhp.

[george91]

You may well already be aware of this, but on the home page under latest tech they have an artical on tuning the a-series engines, on this they have the stage one kit explaining everything included, and then they go on to the next upgrade which is rockers and cam upgrade, it is deffinatly worth checking out if you haven't yet. I am in a similar situation with my 1275, i've just got an lcb maifold and link pipe, and i already have an uprated exhaust back to the cat, i'm thinking of removing the cat though, and an uprated air filter and next is the rockers for me.

[bmcecosse]

High lift rockers definitely NOT worth the hassles! Or the expense.

[liirge]

Stick a 12G940 (ie ex 1275) standard small valve cylinder head on it - gives a huge power increase for very little money. You should sink the exhaust valves into the head by 40 thou - although not ALL heads need this doing, and if you feel competent you could measure and check if it's required or not - but I have to advise you to DO it! With a 'Vizardised' HIF38 on an alloy manifold - it will make 60 maybe 65 bhp.

Sorry, a 12g295 will suit a 1098 much better than a 940, due to low reving nature of the engine. Gains from the 940 in comparison to a 295 will only be seen at the very top of the range on a small bore engine, and to get to this the engine need to rev. There is another thread i have written in tday about the 1098 engine mods. i'l link to it:
here

Edited by liirge, 22 September 2009 - 12:43 AM.

[mini7boy]

You may well already be aware of this, but on the home page under latest tech they have an artical on tuning the a-series engines, on this they have the stage one kit explaining everything included, and then they go on to the next upgrade which is rockers and cam upgrade, it is deffinatly worth checking out if you haven't yet. I am in a similar situation with my 1275, i've just got an lcb maifold and link pipe, and i already have an uprated exhaust back to the cat, i'm thinking of removing the cat though, and an uprated air filter and next is the rockers for me.

which homepage are you speaking of, George?
do you have the link?
Thanks.

[scoticus]

Stick a 12G940 (ie ex 1275) standard small valve cylinder head on it - gives a huge power increase for very little money. You should sink the exhaust valves into the head by 40 thou - although not ALL heads need this doing, and if you feel competent you could measure and check if it's required or not - but I have to advise you to DO it! With a 'Vizardised' HIF38 on an alloy manifold - it will make 60 maybe 65 bhp.

when you say sink the exhaust valvue.. what do you mean.. im abit thick lol.. and why does this need doing?

[liirge]

Stick a 12G940 (ie ex 1275) standard small valve cylinder head on it - gives a huge power increase for very little money. You should sink the exhaust valves into the head by 40 thou - although not ALL heads need this doing, and if you feel competent you could measure and check if it's required or not - but I have to advise you to DO it! With a 'Vizardised' HIF38 on an alloy manifold - it will make 60 maybe 65 bhp.

when you say sink the exhaust valvue.. what do you mean.. im abit thick lol.. and why does this need doing?

The Valve that opens when the bang has happened in the cylinder and allows the Exhaust gas to leave. But like i said what you should do is put a 295 head on which requires no bodging valves!!

[liirge]

You may well already be aware of this, but on the home page under latest tech they have an artical on tuning the a-series engines, on this they have the stage one kit explaining everything included, and then they go on to the next upgrade which is rockers and cam upgrade, it is deffinatly worth checking out if you haven't yet. I am in a similar situation with my 1275, i've just got an lcb maifold and link pipe, and i already have an uprated exhaust back to the cat, i'm thinking of removing the cat though, and an uprated air filter and next is the rockers for me.

which homepage are you speaking of, George?
do you have the link?
Thanks.

Take a wild guess here, but Homepage kind of gave it away.....www.theminiforum.co.uk....

[mini7boy]

You may well already be aware of this, but on the home page under latest tech they have an artical on tuning the a-series engines, on this they have the stage one kit explaining everything included, and then they go on to the next upgrade which is rockers and cam upgrade, it is deffinatly worth checking out if you haven't yet. I am in a similar situation with my 1275, i've just got an lcb maifold and link pipe, and i already have an uprated exhaust back to the cat, i'm thinking of removing the cat though, and an uprated air filter and next is the rockers for me.

which homepage are you speaking of, George?
do you have the link?
Thanks.

Take a wild guess here, but Homepage kind of gave it away.....www.theminiforum.co.uk....

First place I looked. I saw nothing that sounded like the "latest tech".