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How To Get 100bhp From A 1275 Block


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#16 Massey

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Posted 17 December 2009 - 02:15 PM

well its like your trying to get some thing stupid like 200bhp

they are 70 bhp standard

if they are set up properly and dyno tuned so the fueling is spot on and the timing is correct then its not impossable to get 100bhp from a 1275,1293,1340
ex... it depends on the set up

as im going to use a weber on my set up as well

#17 Guess-Works.com

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Posted 17 December 2009 - 02:31 PM

As has been said many times by many people in many threads...

Building an engine is a compromise between Cost, Performance and Reliability...

#18 t25dave

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Posted 17 January 2010 - 02:53 AM

Massey is on the riight track!

Get reading the BIG YELLOW BOOK, tuning the A-series by david vizard, it doesnt matter to much if its not the newist edition, read it to clue yourself up so you know the basics of what it takes to make a reliable drivable a/a+ & it'll clue you up on what the basic parts you need to make that 1293 100bhp motor

a good engine is not the sum of the parts you see in shiney box's or the pages of a magazine! which is where the ££££ come from

you can get 100bhp from a 1293

you can get 100bhp from a "1275" YES thats right you read that correctly 1275!!! & it will be drivable (sw5 cam i'll keep what edition to myself) & reliable by use of a paticular electronic distributor, & not cost the earth

but..... you need to do some study of the vizard book!

ask yourself first what you want from your engine? & what do you use the car for for the most part?

speak to anyone with "experiance" of various types of engine &............a well built,
well tuned, by use of a rolling road session or two at a rolling road that is very familer with the a/a+ series engine,
carburetter or fuel injected engine will be the most "Daily" drivable choice that will give the most instant acceleration!
this route will also give you the best MPG

turbo or supercharger conversions do decrease MPG,drivabuility,reliability on the A/A+ engine, yes you can get a more instant result in BHP numbers but at a cost!!!
it is an old pushrod engine that is'nt the smoothist in its operation

there are many factors to building a good motor, the bhp numbers are not the factor you should be looking at!

there is a chap that does the Mini Showdown at avon park/shakspere county raceway most years with a grean mini that competes in A class,1000cc or less & he cross's the 1/4 mile in just over 15 seconds, you put that mini on the street with the "right" gearbox ratios/final drive it would out accelerate a subaru imprezza or mitsubishi evo in the short distances you have in built up town areas,

so you may partially understand the potential you have with a 1275, nicely put together engine, on the "right" gearbox/final drive, running carburetter/s or fuel injection

carefully consider wah t you actually need from your engine/box & study what you Dont need, not what you think you need, dont spend thousends when you dont have too!
Many people around can "assemble" an engine or box, & speak big numbers in the bhp & torque department & how strong there engine & box's are!
building a good engine is not the assembly of parts that are new & shiney! to extract the most you have to really know how to put an engine together properly

speak to people like longman, calver, bill richards about what you'd like to achieve from your engine! Not your local wannabe-pro-engine ASSEMBLY chump!
Get advice from the right people before paying your money!!!

if you dont understand what the person is talking to you about ask them to explain!

there are many many tricks to gain alot of bhp/torque that dont cost the earth! these are the things you should look into before looking a rebored blocks & modified heads, & these tricks dont need to be notified to your insurance!!! as your engines some of parts is still OE-ish ;OP enough from me for now!

#19 Ouster

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Posted 17 January 2010 - 09:33 AM

Show me how to build a 100 HP n/a 1275 motor that doesn't cost the earth then.

#20 R1minimagic

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Posted 17 January 2010 - 09:48 AM

Stick an R1 in it!

#21 bloomers

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Posted 17 January 2010 - 10:43 AM

I want to know how you get 100bhp, out of 1275, and it not costing the earth too :goaway:

Show me show me!

Bloomers

#22 pdaykin

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Posted 17 January 2010 - 12:19 PM

Not costing the earth is clearly a relative term.

Many years ago I had my first 1293 "100bhp" motor built for me. First of all, it didnt make 100bhp despite the claims. Secondly, it generally ran like a pig around town. Thirdly, it cost in excess of £1k 20 (ish) years ago.

To actually get 100bhp, and it be just about usable engine cost several thousand pounds. More importantly, in my experience driving a decent 90bhp A series is better than a 100bhp+.

I hear stories of them being done on the cheap - and to be honest, I think it is mostly bar talk. Look in the pages of Miniworld etc and see how many engines actually produce 100 bhp. Not as many as you would think by looking at the spec of them.

Unless you have a well equiped workshop and are skilled, I do not believe that you will get 100bhp for less than 3k - which is why supercharging looks good on paper. Until you remember that you will probably need some remedials on your base engine to get the most out of a supercharger.

Bolt on power is generally pretty cheap. In my opinion, reliable bolt on power doesnt exist to get you 100bhp. It doesnt matter what book you buy, or how often you read it, as others have said you will need proper, specialist A-series advice. They will also advise you on appropriate induction, gearboxes, diffs, etc - but again, unless you are lucky none of this is cheap but whats the point of having 100bhp on the hard shoulder ?.

#23 Wil_h

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Posted 17 January 2010 - 12:27 PM

Massey is on the riight track!

Get reading the BIG YELLOW BOOK, tuning the A-series by david vizard, it doesnt matter to much if its not the newist edition, read it to clue yourself up so you know the basics of what it takes to make a reliable drivable a/a+ & it'll clue you up on what the basic parts you need to make that 1293 100bhp motor

a good engine is not the sum of the parts you see in shiney box's or the pages of a magazine! which is where the ££££ come from

you can get 100bhp from a 1293

you can get 100bhp from a "1275" YES thats right you read that correctly 1275!!! & it will be drivable (sw5 cam i'll keep what edition to myself) & reliable by use of a paticular electronic distributor, & not cost the earth

but..... you need to do some study of the vizard book!

ask yourself first what you want from your engine? & what do you use the car for for the most part?


I agree with this, it's all about the VE of the engine, which basically means spend money on a head and chose a suitable cam.

turbo or supercharger conversions do decrease MPG,drivabuility,reliability on the A/A+ engine, yes you can get a more instant result in BHP numbers but at a cost!!!
it is an old pushrod engine that is'nt the smoothist in its operation


But I disagree with this. I know some turbo motors pushig over 150bhp and still returnibg 40+mpg and covering as many miles between rebuilds as any other A series.

there is a chap that does the Mini Showdown at avon park/shakspere county raceway most years with a grean mini that competes in A class,1000cc or less & he cross's the 1/4 mile in just over 15 seconds, you put that mini on the street with the "right" gearbox ratios/final drive it would out accelerate a subaru imprezza or mitsubishi evo in the short distances you have in built up town areas,


Well I weighed this car and it was around 460kgs with a 4.1 diff. So maybe it could keep up with subaru to 60 but that's it, it's a massive compromise to get it this fast and is only ever used at Avon park.

#24 R1minimagic

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Posted 17 January 2010 - 12:31 PM

A turbo is a very efficient way to get more MPG out of an engine, why do you think most manufacturers are downsizing engines and sticking turbos on?

They are using energy from the exhaust which is otherwise wasted.

However, if you increase BHP a lot then you are bound to use more fuel!

#25 samsfern

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Posted 17 January 2010 - 12:37 PM

how much pounds you got ???? have a lookie at this, 16valve twin overhead cam head 8 port, im going to be doing it when funds allow, http://www.specialis...hantPageDisplay

Edited by samsernie, 17 January 2010 - 12:38 PM.


#26 t25dave

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Posted 17 January 2010 - 02:02 PM

pdaykin & will=h show they have some good knowlwdge!

willh, i usned the green mini thou thats seen at avon as an example, maybe i should made clear that it is! "granted" at the more extreme end of mini 998 tuning in the standard 5-port, i know you can go down the forced induction, twincam form with the small bore also but at a comprimise, mostly a comprimise on money spent as there is more cost involved "to the novice"

if a good majority of the tuning thats been applied to the green mini thou at avon park is applied to the large bore a/a+ will make a superb motor

cost is relitive to an point, if your prepared to put a little time aside to do some of the work yourself such as modifying your carb for example, there are many areas where small tricks can be applied to get the most from a mini engine, there are a few books i personally feel mini owners should read before putting hard earned cash into a "production-line" 1380 kits/builtengines that dont give you what you actually want as said in an above post

loosing hard earned cash is a hard to swallow lesson people!

as willh i'm sure will agree, a good "road & weekend track action" motor is the sum of a good gearbox with the right gearset/final drive, & a properly matched camshaft & cylinder head, & a few tricks in the right areas will get you 100bhp large bore, & with a good a/a+tuner making your carb adjustments on the rolling road you can get these results on a SU hiff carb!

the minis biggest problom is its gearbox/ratios, invest in that 1st, put it aside & do your research & take it from there

AC dodd is a decent fellow as is dave walker of emerald ECU's & tuning, there are some very knowledgeable chaps in the grass tracking arena

what comprimise are you willing to make with your mini, as pointed out, how much driver comfort do you want to keep, reducing weight is a perfect way to gain a quicker car & in the initial stages can cost close to '0'
what sort of motorway speed are you happy to drive at to shows, track events etc??? this will dictate many factors in your engine build choices
do you carry passengers or do you want your mini to be a selfish indulgance
is it a daily driver or weekend/high days vehicle
what are your aims for your mini, ie road track, do you want to drive it on the road even?
how many miles do you actually do in your mini

my "PERSONAL" choice for a quick daily driver is a small bore block with a large bore head pushing around 80bhp,
getting the gear ratios right is the hard part!
this for me has proved to be the most "Abusable" setup as the small bore will take higher rpm far better than the large bore, cam choice is is a balance betwen the head & carb used, i tend to go for a hiff44 or a twin 1.25" carb setup, i dont do motorways in my mini i stick to the smaller roads & cruise to venues at no more than 60mph, my top speed is only 95 maximum, i used to have a 3.1 final drive & had just over 100mph but it was near about the limit 7 working the motr hard!!!

if i Wanted to spend a good chunk of cash for a more allround gearbox i'd have a 5speed, 5th would be more like a overdrive/motorway gear! & also to increase daily drivability/reliability i'd go down the route of fuel injection,

but i'm a skin-flint so i stick with electronic igniton & a carb or two, as i say, keep it simple!

i can give a basic spec list of what it would take to get 100bhp from a 1275 but as a list of specification it does'nt look much, it does'nt look much on paper/or type, there are a good few factors that will give you the 100bhp your looking for but some of those factors can be gained for free by putting in some work & time yourself!

do you want 100bhp with plenty of comprimise or do you want a "reliable" genuine 100bhp,

as many older tuners undertand, its about Bang for your Buck!
a good engine builder/tuner will build what you want!
not a spec sheet to shout about in the pub or a chat forum or to print on a piece of paper to put in a frame in front of your car at a show! but

quote: A turbo is a very efficient way to get more MPG out of an engine, why do you think most manufacturers are downsizing engines and sticking turbos on?
very true but they have put their money into "fully" developing strong reliable efficant engines,
the a/a+ engine is an old engine with which modern techniques are being applied through a loyal following, so in a forced indution guise it will have many comprimises as a daily driver, & as you state the higher state of tune of a turbo motor you do loose mpg, as many of the chaps who have & tune the A/A+ turbo motor it was'nt the best devloped & highly comprimised engine but we're glad they did, i say this as i have a turbocharged "just about" road legal mini

also i do feel that when more so called experianced people try to give advice to their friends or on a chat forum they get to technichal! this is what pushs the less experianced/novice/younger people to making the wrong choices & hearing the fancy spec sheets speak to them louder than "actual fact" i must say i am a true A/A+ fan & dont think a mini is a mini if it has a powerplant from a differant manufaturer

Edited by t25dave, 17 January 2010 - 02:20 PM.


#27 Sprocket

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Posted 17 January 2010 - 02:55 PM

Very few SW5 cammed engines get near 100bhp ;) though there are some, just not many

I managed 107bhp with my 1275, its nice and dosile in heavy traffic and around town, but when you open it up, its a bit of an animal right up to 8000rpm :goaway:

It does have one of those bike 16v heads though, but I don't think I will ever go back to a five port head, its such a different drive, you have to try it to know where im coming from :)

Edited by Sprocket, 17 January 2010 - 02:59 PM.


#28 t25dave

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Posted 17 January 2010 - 03:34 PM

sprocket, i read a build up somewhere of your white mini & its a cracking build, your a chap that does hs research!!!!!
i know what you mean about a 16v, i have drove a 16v mini but it was'nt a=series, a 16v is a different animal! & a good one at that, i'd like to go down the bmw 16v head in the future!!!

quote: Very few SW5 cammed engines get near 100bhp though there are some, just not many, as it just takes those few tricks that are in a oule of a/a+ tuning books that are out there!

#29 danrock101

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Posted 17 January 2010 - 03:39 PM

get a nice stage 4/5 head with massive vavles, decent cam, hiff44/twin carbs or a webber. stage 2 LCB, depends what's people's idea of exspensive

#30 Wil_h

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Posted 18 January 2010 - 11:29 AM

The requirements of a turbo engine are much mis-understood. I firmly believe (well I can give examples) that a 130bhp turbo engine (as in block, crank) could be built to a much lower spec than a 130bhp NA motor. Especially if rpm is kept sensible.

I use my 998 turbo daily, other people who have driven it said they hardly noticed it was turbo'd. I can't see any compromise (to reiterate a point I make a lot, my engine had done 70,000 miles before I turbo'd it, still going strong)




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