17 replies to this topic

[Mei]

Hiya,
i have a 998 mini, and have bought and fitted the following bolt on performance upgrades:

Stage 1 and 12G295 Unleaded Double valve springed cylinder Head.

A freind told me i have to inform my insurance comapny?
is this true? (ive been driving arond with out for a week)
anyway i did ring them and they have got naasty!
Saying they need an Estimated increase in BHP, or a rough figure of waht the BHP will be..

and well as u can guess i dont know, so ive asked here hoping someone will be able to give me a ball park figure

Any pointers would be greatly appreciated.

Mei

[Jammy]

12G295 isn't just a bolt on mod.

Yes, you have to tell them. And, possibly 15bhp.

[Mei]

12G295 isn't just a bolt on mod.

Yes, you have to tell them. And, possibly 15bhp.

Cheers Jammy..
Why isny 12G295 not a bolt on?? i just replaced it with my current cylinder head...have i done something wrong?

[Jammy]

You need to check the size of the combustion chamber. The 12G295 head is meant to be used with domed pistons (which standard small bores don't have), so if you just bolt one on you'll find the compression ratio is very low, and the engine won't produce any power.

[cradley-heathen]

12G295 isn't just a bolt on mod.

Yes, you have to tell them. And, possibly 15bhp.

Cheers Jammy..
Why isny 12G295 not a bolt on?? i just replaced it with my current cylinder head...have i done something wrong?

a 12g940 isnt a bolt on as its a 1275 head, but the 12g295 im sure is just a bolt on conversion as i had one on my last 998 mini a few years back?

it made 65bhp on the rollers and it drove very very well, and reved so freely, i shouldnt have sold that engine! my head had been given some work though to be fair.

anyway, as for telling the insurance, errr no, if the worst happened and you stacked the car, the insurance compant arnt going to take the rocker cover off and start checking casting numbers and such like. you dont have to take my advice and im sure someone else will tell you to ignore me and that being straight with insurance is the best thing but i have had some really silly engines in several of my cars (vauxhall c20xe/red top) and i never told the insurance company, and this is the point where you really should tell them when its a totally different engine from a different manufacturer etc, but swaping the head and putting on a stage 1 kit isnt going to make any difference if you dont tell them.

the ball is in your court, but personally i wouldnt give it another thought, its a standard 998 mr insurrance man, whilst i think of it my car insurance compant asked to see my car years ago when it was first insured, and they looked and said "looks standard enough to me" and that was footman james who deal with classic car policies.

[Mei]

oh dear!
Havnt noticed any decrease, i think the Head had been Skimmed or something the previous owner said itr would be fine bolting onto a normal 998.
cheers Jammy

[cradley-heathen]

You need to check the size of the combustion chamber. The 12G295 head is meant to be used with domed pistons (which standard small bores don't have), so if you just bolt one on you'll find the compression ratio is very low, and the engine won't produce any power.

i took my head off an engine with dished pistons in it, and i fitted it to my flat top pistoned engine, i can only assume it must have been skimmed then? and when putting it on mine the CR went up from what it had been on the old engine it was off

[Mei]

12G295 isn't just a bolt on mod.

Yes, you have to tell them. And, possibly 15bhp.

Cheers Jammy..
Why isny 12G295 not a bolt on?? i just replaced it with my current cylinder head...have i done something wrong?

a 12g940 isnt a bolt on as its a 1275 head, but the 12g295 im sure is just a bolt on conversion as i had one on my last 998 mini a few years back?

it made 65bhp on the rollers and it drove very very well, and reved so freely, i shouldnt have sold that engine! my head had been given some work though to be fair.

anyway, as for telling the insurance, errr no, if the worst happened and you stacked the car, the insurance compant arnt going to take the rocker cover off and start checking casting numbers and such like. you dont have to take my advice and im sure someone else will tell you to ignore me and that being straight with insurance is the best thing but i have had some really silly engines in several of my cars (vauxhall c20xe/red top) and i never told the insurance company, and this is the point where you really should tell them when its a totally different engine from a different manufacturer etc, but swaping the head and putting on a stage 1 kit isnt going to make any difference if you dont tell them.

the ball is in your court, but personally i wouldnt give it another thought, its a standard 998 mr insurrance man, whilst i think of it my car insurance compant asked to see my car years ago when it was first insured, and they looked and said "looks standard enough to me" and that was footman james who deal with classic car policies.

ooh damn,
well now ive told them something i dont know if im going to be able to get it away with taking it back!!! grrr.
But im now confused, i was told the 12g295 should just go straight on, but jammy said it wont!!
also is the 15 extra HP about right,

Mei

[Ru55boy]

ooh damn,
well now ive told them something i dont know if im going to be able to get it away with taking it back!!! grrr.
But im now confused, i was told the 12g295 should just go straight on, but jammy said it wont!!
also is the 15 extra HP about right,

Mei

The 12g295 is a head from a 1960's Cooper. I'm sure someone will coreect me if I'm wrong but the head is likely to be 40 years old and had several different owners, so the chances of it having already been skimmed to fit a later 998 is extremely high.

Its worth checking to see if its been converted to unleaded too.

[Mei]

Cheers
Yah,
Its an unleaded conversion, hardened Valve guides etc etc.
but im worried about this compression thing!
Would a compression Test show if im at the right Compression?
if so whats the minimum compression iot should be running??
Mei

[liirge]

Im interested in this one as im thinking of whacking a 12g295 onto my 998 rebuild, it will have flat pistons though.
Interesting to know what kinda of performance increaeses these heads manage

[Nickh_16]

i have a 12G295 head on my 998 and we did a straight bolt on, got it skimmed before to get a clean surface, it'd already been skimmed in the past though and it works fiine, more power than before, i also have a stage 1

[Jammy]

12G295 isn't just a bolt on mod.

Yes, you have to tell them. And, possibly 15bhp.

Cheers Jammy..
Why isny 12G295 not a bolt on?? i just replaced it with my current cylinder head...have i done something wrong?

a 12g940 isnt a bolt on as its a 1275 head, but the 12g295 im sure is just a bolt on conversion as i had one on my last 998 mini a few years back?

it made 65bhp on the rollers and it drove very very well, and reved so freely, i shouldnt have sold that engine! my head had been given some work though to be fair.

anyway, as for telling the insurance, errr no, if the worst happened and you stacked the car, the insurance compant arnt going to take the rocker cover off and start checking casting numbers and such like. you dont have to take my advice and im sure someone else will tell you to ignore me and that being straight with insurance is the best thing but i have had some really silly engines in several of my cars (vauxhall c20xe/red top) and i never told the insurance company, and this is the point where you really should tell them when its a totally different engine from a different manufacturer etc, but swaping the head and putting on a stage 1 kit isnt going to make any difference if you dont tell them.

the ball is in your court, but personally i wouldnt give it another thought, its a standard 998 mr insurrance man, whilst i think of it my car insurance compant asked to see my car years ago when it was first insured, and they looked and said "looks standard enough to me" and that was footman james who deal with classic car policies.

Sorry but thats possibly the worst advice given in a single post I think I've read on TMF so far. Forgive me if that offends...

But, at the very least you should check the comnbustion chamber. The 12G295 was fitted to either the 998 Cooper engines, or the MG Midget (I think, might have been Sprite, or both) 1100 engines, both with domed pistons. Ok, so it'll run if you don't bother doing anything with the CR (and we're talking about start CR here, not compression tested with one of the £15 guages from Halfords), but to make the most of the modification you might as well do it properly and make sure the CR is going to be suitable.

And as for insurance fraud, I should hope most people on here are sensible enough to know what the right thing to do it. If not, there are a number of examples on TMF of insurance companies using every excuse they can not to pay out on claims.

[Sleepy Stu]

Sorry just to clarify Jammy as i may need to do this in the furture you can or cannot find out the compression ratio using a cheapo £15 meter from Hellfrauds?

[Jammy]

The £15 guages from Halfords measure the compression (not the compression ratio) in each cylinder in order to tell you whether they are high/low, balanced across all cylinders etc. Very much a diagnostic tool.

Calculating the compression ratio by knowing things like the size of the combustion chamber, the dish in the pistons, the head gasket volume, etc, allows you you to alter certain things (usually either the piston or the combustion chamber) in order to make the CR suitable for the application of the engine, or the fuel that will be used, or both. A low CR is needed for forced induction/rubbish fuel, high CR gives you more power on an N/A engine, but you need to use the best fuels.