29 replies to this topic

[minisam92]

what can i do to get more power from a 1275 thats got a oil cooler big vavle poilshed ported and doublevalve sprung head with i think by the looks of it cooper s forged rockers decked head and block rally cam lightened steel flywheel orange diaphram clutch 3.4 diff twin 1,25 inch carbs and two crankcase breathers and what power would you expect from this engine with the mods mentioned on ?
and what could i do to get more power ideally i want 100 bhp - 115 bhp
ive bin told not to chwnge rockers as it prob wouldnt pass emissions with cam?
any ideas poeple?

[josh.evans]

re bore,webber maybe for 115bhp,straight cut drops maybe full straight box,286 or 296 cam, many things for a 115bhp a series will cost ££££'s

[minisam92]

re bore,webber maybe for 115bhp,straight cut drops maybe full straight box,286 or 296 cam, many things for a 115bhp a series will cost ££££'s

would fitting twin 1.5 su s help or not ? was also finking of the doing the g/box
and do you gain any power from eletric dizzy and upgraded coil ?
also do you gain anything from silicone hoses or a alloy rad ?

[Ethel]

More cc's .It would probably end up slower if you got 100+ hp out of a 1275 because you'd lose torque at driving rpm to make that sort of power at high rpm with the cam you'd need.

Coils add nothing, good electronic ignition can help but having the right ignition advance matters more.

[minisam92]

More cc's .It would probably end up slower if you got 100+ hp out of a 1275 because you'd lose torque at driving rpm to make that sort of power at high rpm with the cam you'd need.

Coils add nothing, good electronic ignition can help but having the right ignition advance matters more.

thank you for the help dont spose you would hazard a guess at wht bhp that engine should have ?

[minisam92]

by the way its a a + if that makes a difference?

[MiniLandy]

Turbo.

[01smartc]

I would say from that spec we would normally see around 90bhp on our rolling road.

Thats depends on how well set-up it is ... if the cam timing rights, how good the head is etc.

I dont think you would gain much from twin 1.5's to be honest.

What compression ratio has it got?

Chris @ Smart Performance

[minisam92]

I would say from that spec we would normally see around 90bhp on our rolling road.

Thats depends on how well set-up it is ... if the cam timing rights, how good the head is etc.

I dont think you would gain much from twin 1.5's to be honest.

What compression ratio has it got?

Chris @ Smart Performance

not to sure on compression ratio as i did nt build it i bought it off an old mini enthusiast it was his old race engine although it has been fully rebuilt and he is a trusted family friend lol would i gain from 1.5:1 roller rockers or not

and with regaurds to turbo i would like to build 1 using a mg metro turbo but for a mini as there origanally a turbo engine

[danrock101]

would i gain from 1.5:1 roller rockers or not

-5 to 5bhp,

[minisam92]

would i gain from 1.5:1 roller rockers or not

-5 to 5bhp,

ou can loose bhp with them !!!

[Ethel]

I don't know that you'd lose maximum power if they were set up correctly, but you could lose performance - it's not all about power. Road cars don't go everywhere flat out and have to cope with a wider set of conditions than a racer; having things happen when you push the accelerator across more of the rev range can make for a better performing car.

[danrock101]

yeah I don't think you'd loose any max power but it all depends on the current cam, Cooperman gained 2bhp and think he said he lost some low down, so imo on a road car they're not really worth it if you're going to fit them for power. You can put that money towards a better cylinder head.
If you want 115bhp you basicly need a strong bottom end, the more capacity the better, a kent 276 cam will do, not sure what you have at the moment.
Then you want a good cylinder head, I have no idea what the head is like on your engine at the moment, talk to a engine builder like smart performance and tell them your requirements and they will port you a head to suit.
Then I'd probably recomend a modified hif44

[ministar]

I think you at a point now where you need to read David Vizards big yellow bible. Its called 'Tuning an A Series'. Very helpful and I read it from cover to cover.....

[Cooperman]

yeah I don't think you'd loose any max power but it all depends on the current cam, Cooperman gained 2bhp and think he said he lost some low down, so imo on a road car they're not really worth it if you're going to fit them for power. You can put that money towards a better cylinder head.
If you want 115bhp you basicly need a strong bottom end, the more capacity the better, a kent 276 cam will do, not sure what you have at the moment.
Then you want a good cylinder head, I have no idea what the head is like on your engine at the moment, talk to a engine builder like smart performance and tell them your requirements and they will port you a head to suit.
Then I'd probably recomend a modified hif44

To get to 115 bhp will mean building an engine which won't really run well below about 3000 rpm and not pull strongly below about 4000+. That power will probably come at about 6400 rpm so, as 'danrock' says, you'll need a very strong bottom end. My 1310 'S' gave 117 bhp at 6400 the last time it was on the rollers, but that's OK as it has the EN40B crank of the Mk 1 'S'. It revs to over 7000 rpm safely, although I do rebuild it after every 6 or 7 rallies.
If you want to drive it on the road and have a decent cruising speed be careful of looking for absolute peak power rather than a good useable area under the torque curve with adequate top-end bhp.
A 115 bhp car will mean you need a close ratio gearbox to keep it 'on the cam'. This in turn means you have a high 1st gear which then means a low final drive. This then limits your cruising speed and makes the car 'nasty' in traffic.
Look at the Kent Cams power curves on their web site and decide what engine characteristics you want for the driving you actually want to do. If you want a competition car, then go for a 'full-on' competition engine with everything at the top end.
I did fit 1.5:1 roller rockers and gained 2 bhp at over 5700 rpm, but although I didn't measure it, I am sure it is now more lumpy low down, which doesn't matter on a rally car with a SCCR 'box and a 3.9:1 final drive. Cruise is about 58 mph at 4000 rpm or 72 mph at 5000 rpm. However acceleration is 0 - 60 in just over 7 seconds using only 1st and 2nd, or 8.5 seconds using 1st, 2nd & 3rd and changing up at about 6400 rpm.