18 replies to this topic

[Baeumchen]

hi

i own a 1275cc single carb engine with k&n, manifold, and a basstuck exhaust

now, my plan is to bring it up to about 90 driveable hp

since im not into tuning that much, i wanted to know what i could or should do to bring it to around 90 hp

new head?
camshaft?
double carb?

what would be the cheapest way?

i will be glad for every tipp

[mambaman]

as long as the base unit and box are in good condition, i would suggest getting a stage3 head from a good source (i.e not minisport/minispeed/minispares). Then add to it a sw5 and a set of 1.5 roller tip rockers. A hif44 will do a good job, but a set of twin 1.5"s will do it better.

This would be my recomendation from what people have told me, ive never tried the combination personally myself. 90bhp is easily possible from a sw5 and high lift rockers, but it will vary massively on the head.

[Guess-Works.com]

are we talking 90 at the wheels or 90 at the flywheel... as there is a BIG difference..

but the cheapest way is to do what ever it is yourself !

Edited by GuessWorks, 19 July 2005 - 03:12 PM.

[Sprocket]

Completely standard 1275 bottom end with Stage three head, 1.5:1 rollr tip rockers, Maniflow LCB, MG Metro inlet, K&N bolt on filter, RC40 single box exhaust and a tune on the rollers will put out around 80 bhp at the flywheel and that is with the cat. Thats the max you can do with the engine in the car. The next thing to change is the camshaft and fit a lightened flywheel, then the only thing left is an over bore with lightening of the crank and rods, this is where it starts to get expencive. Dont forget to put it on the rollers or all the expensive engine bits you fitted will have been a waste.

Oh and if you change the final drive ratio from the 2.9:1 or 3.2:1 as seen in the late models to 3.4:1 or if you can bear loosing top end speed 3.7:1, this make much better use of the power.

[Alburglar]

You'll never get to 90 with out a weber, good head, hi lift cam, high lift rockers, lightened everything, rc40 straight through. rolling road session. Most of your money should be spent on the head

[Alburglar]

I have a swiftune 1380 road rocket (stage 3 head), sw10 cam, HIF44. LCB.
Only just 90bhp at the flywheel.
76bhp at the wheels

[Alburglar]

However, still on standard rockers and my exhaust is too big

[Guess-Works.com]

You should be able to clear 100 easy at the fly with a 1380, and not far off with a 1275.

Tuned, I hope my 1330's going to be clearing 100.

adn I don't think a webber is necessary, I'm running an HIF44

[pdaykin]

To put this in perspective, 90 BHP is a high figure

Just see the rolling road reports on any of the John Coope Garage Conversions - none seem to make it despite their claims.

Two vital elements yo have missed are PRICE and RELIABILITY.

90 bhp from a 1275 AND driveable - unlikely. The only way this is going to happen is if the rolling road reads on the high side.

[Guess-Works.com]

I disagree, an MG Metro 1275 was designed to provide 72/73 Hp as standard..

If you strap onto that, a ported head, decent cam (286 etc) & vernier timing gear, high compression, well tuned HIF44 with K&N, decent LCB & exhaust system, and if you can afford a nice lightened flywheel, then I'll be well surprised if you not touching 90.

Any "at the wheel figure" has to take transmission into account, and later coopers are using such silly diffs ( like a 2.95 or 2.7 ) its no wonder that the engine cannot perform.

[Bluemini]

You'll be stretching it trying to get 90 @ the wheels from a 1275, its going to cost you a fair big of money! You can get 80 fairly easily with a good head ( ), cam roller tips or full roller rockers, good inlet and exhuast system and a HIF44 carb on a good manifold.

I had 104 @ the wheels in Blue and that was with a 1380, 296, stage 3 head, 1.5 roller tips, lightend fly, decent sized exaust and good inlet system with a HIF44 and of course - s/c drops to improve the engine to trany ratio. But there are more things that need to be improved on or uprated when your dealing with big power like the 'box and clutch, bushes and mounts, etc etc.

Big power costs money!

[Sprocket]

turbominihaha is quoting 156bhp at the wheels on his turbo'd mini

http://www.theminifo...?showtopic=9835

[Guess-Works.com]

Hence My original question, 90 at the fly or wheels.. 90 at the fly is achievable.

[Sprocket]

Completely standard 1275 bottom end with Stage three head, 1.5:1 rollr tip rockers, Maniflow LCB, MG Metro inlet, K&N bolt on filter, RC40 single box exhaust and a tune on the rollers will put out around 80 bhp at the flywheel and that is with the cat. Thats the max you can do with the engine in the car. The next thing to change is the camshaft and fit a lightened flywheel, then the only thing left is an over bore with lightening of the crank and rods, this is where it starts to get expencive. Dont forget to put it on the rollers or all the expensive engine bits you fitted will have been a waste.

Oh and if you change the final drive ratio from the 2.9:1 or 3.2:1 as seen in the late models to 3.4:1 or if you can bear loosing top end speed 3.7:1, this make much better use of the power.

Surely from the spec I was running above I could get another 20bhp easily enough, by lightening internals and flywheel, an over bore( being conservative) of +60 thou, a 276 or 286, a twin choke carb and still be very reliable and driveble in town traffic.

You could get more power and reliability from the gearbox by using straight cut transfer gears and final drive on the standard helical gear set to keep the noise down. and as I said before change the final drive ratio to 3.7:1 to free up some of that power and turn it into acceleration but not sacrificing a great deal of top end speed, who needs to go faster than 80 on the public roads anyways

[Sprocket]

Hence My original question, 90 at the fly or wheels.. 90 at the fly is achievable.

Yeh, he hasn't answered that one How big is your wallet