13 replies to this topic

[JimF]

Currently got a 998 mini and I'm tempted to build up a 1275 for it as I've decided that tuning the 998 to approx 90bhp isnt cost effective.

 

Out of interest, at going market rates, how much would it cost to buy the 1275 engine, and all the mods (cam, inlet & exhaust manifold, head? etc) in today's market? Would it actually be cheaper to tune my 998 seeing as Ive already got it?...

 

Car will be fast road/summer toy type setup.

 

Jim

[LukeH]

Pricing this up using minisares or minsport etc.. is quite straight forward. I good used 1275 is going to set you back anything between £200 - £600 depending on age/spec/condition. You are then looking at £600 - £1000 'ish in parts e.g. pistons, cam, head, rockers, gearbox components, then you'll need all the machine work doing approx £500-600 and assembly £500 - £1000 unless you do the latter yourself. 

 

There are quite a few engine packages out there with varying degrees of modification that would probably be a better route to take in my opinion or purchase a good used tuned engine as and when one comes up.

 

The head is the best place to start on the mini for any sort of tuning but the 90bhp you are mentioning will take some fairly serious engine modifications to achieve even with a 1275.

[JimF]

Brill - cheers!
To be honest 90bhp was a figure I pulled out of thin air. Would I need to overbore? Machining isn't a problem I work in engineering. Do tuned engines come up for sale very often?

[Bubblebobble]

http://www.minisport...abs_description

 Something like that , then you are going to need a decent head and matching cam from somewhere as well .  Then inlet and exhaust , plus  a carb or carbs . Then a decent radiator . 

[JimF]

To be honest I'd rather build the engine myself. Thats a lot of money and I dont think that with my engineering contacts it would cost that much, especially if I'm buying a cyulinder head & cam on top of that £1800.

[LukeH]

If you have the necessary skills and equipment to build yourself I would do that. I considered a rebuild of my MPI myself but I would need to pay for the machine work plus the parts so I decided to go Yamaha R1 route and I picked one up last week.

 

My standard 1275 MPI engine is a Rover claimed 64bhp or thereabouts, so quite a bit of work needed to get decent bhp increase. An overbore to 1293 (+20thou) plus a decent head, cam and roller rockers plus the carb(s) as Bubblebobble has suggested would be a nice setup and you will still have a few more overbores to go. 

 

Probably worth getting a decent gearbox built and select a final drive to suit how you want to drive it i.e. revvy or motorway cruising. I would personally check out Guessworks on here for gearbox work (haven't personally used his services but a lot have)

 

Luke.

[JimF]

Fantastic help! Thank you!

[Cooperman]

To take a Mini 1275 engine from its standard power and torque output to around 80 bhp is not expensive. Just a good clean-up of the head including finishing-off processes in the inlet & exhaust tracts, removing the step around each valve, smoothing out the combustion chamber surfaces and having the 35.6 mm/29.5 mm inlet & ex. valves. Then fit a better cam like a 266 or MG Metro, an HIF44 carb on a smoothed out alloy inlet manifold, fit a decent ex. manifold and a 1.75" exhaust system plus a better distributor and you'll have 80 to 85 bhp if assembled accurately.

To go from 80-ish to 90+ will cost a lot more as you'll need a much better gas-flowed head and a 'hotter' cam. This in turn leads to the need to drop the FDR so that it stays 'on cam' through the gears.

Don't be seduced by bhp figures unless you are using the car for competition. For a road car it is better torque that's needed and then it will just be better to drive. You can chase bhp with your cheque book, but all you will achieve is to make the car 'less nice' to drive on normal roads.

For a classic car what is ideal is to have a car which is pleasant to drive on the roads.

[JimF]

Fantastic advice thank you! I'm well aware of torque being more important as opposed to BHP figures (my daily is a very drivable late model STI with 'only' 330bhp, but bags of midrange). I wasn't aware of this 85bhp glass ceiling, I just didnt want to spend a load of money tuning an engine and end up with only a 10bhp improvement or something. 85bhp will do me fine! Naturally my brain thinks "Lets just squeeze a bit more power out of this 998" but Im being realistic - I'll only end up upgrading at some point or another.

[Bubblebobble]

If you could score a mg metro engine or cooper you would be set up well to start with .

[JimF]

Duly noted

[mk1leg]

go for the cooper head set up from minisport.....its 80bhp     http://www.minisport...conversion.html

[AVV IT]

I've got a rebuilt MG metro engine with a stage 1 kit, it gives BHP of around the mid 70's, and it probably wouldn't take much in terms of a bit of extra head work to push that up to nearer 80bhp. By comparison to the 50ish BHP I had before, from my low compression 1275 Sprite engine, the rebuilt MG was a massive improvement. If you're used to a standard 998, then you're effectively doubling the power, so that would undoubtedly feel like an even bigger leap.

Now you can call me a "big girl" if you like, but when "giving it the beans" even that amount of power can be a bit unnerving in a rusting twenty year old tin box with, ageing brakes and suspension. To be honest, I rarely get the opportunity to fully "open her up" and "see what she can do" anyway, so I certainly wouldn't be bothered about an extra 10 bhp or so on top, especially if it was going to cost thousands to achieve. My advice would be to go for a "warm" spec 70-80 bhp 1275, like Cooperman suggests, and then consider further mods at a later stage if you feel that you still want/need even more power.

Another thing to be aware of is your insurance. Some insurance companies have an issue with you exceeding double the standard BHP. When I put the stage 1 MG unit in my sprite (an increase of appx 52-74bhp) they weren't bothered, but when I put the same spec MG unit in my former 998 Mayfair (increase of appx 36-74bhp) they refused to insure me. Meaning I had to go with another insurer who would accept over double the BHP and pay almost double the premium for the privelage!

[Cooperman]

I built a 'standard' engine for a 1300 cc Endurance class rally Mini. It was a 1991 1275 Cooper and I did a bit of work to the engine as follows:

 

MG Metro head & cam, bored to +0.060" with 21253 pistons and 0.027" skimmed from the head with the block decked to bring the pistons absolutely level at TDC.

It was balanced and the flywheel was very slightly lightened (technically not allowed under the regulations). I did a bit of discrete 'cleaning up' inside the head, particularly removing the steps around the valves, taking a bit off the valve guide bosses and smoothing out the 'short-side radius'. I used the standard HIF44 carb and removed the 'casting flash' in the alloy inlet manifold.

The cam was very accurately timed-in and I used original-type Cooper 'S' forged rockers.

It gave 84 bhp at 5700 rpm, but best of all it had super torque right through the rev range which was important as the gearbox had to be standard. i FITTED A 3.44:1 FDR and it really went well.