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100Bhp And How To Get There


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#1 tom1

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Posted 23 September 2013 - 05:52 AM

Hi , I would like to achieve 100 BHP, with the bits I have, from an old engine,it only ever did less than 1k road miles.

 

1293 block 

MED head (I think 31/ 36 vales)

kent cam 286?

S crank and rods (no pistons)

 

So to get there, which of these bits is not up to the job and what other bits do i need to buy? This should be looked at from a pounds to bHP ratio but with limited fund.Things like, can I get away with a cheaper set of piston or do I need a good set.



#2 Carlos W

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Posted 23 September 2013 - 06:00 AM

ContractorsPyramid.jpg

Attention to detail is one of the keys to producing power!

What is the car going to be used for?

#3 holmesy

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Posted 23 September 2013 - 09:04 AM

the block head and cams are fine for making that power. what you will need is a pair of twin 1 1/2 su's or weber, a compression ratio around 10.5 or slightly more. a good set of cast pistons will be fine such as the hepolite high compression ones ( cant remember the part number 5352 or summit but cooperman will be along to correct it)

but like said what is the car gonna be used for?

#4 diogoteix

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Posted 23 September 2013 - 09:35 AM

If you're not sure of the cam, check it! It's the starting point of your setup.

You'll need an exhaust that copes with the job LCB and side exit 1.75 inch RC40 would be my choice.



#5 coopdog

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Posted 23 September 2013 - 10:22 AM

That's a very revvy cam,

It will be terrible at low revs and very lumpy on idle :L


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#6 Cooperman

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Posted 23 September 2013 - 10:34 AM

If that is for road use it will be quite simply horrible to drive and its cruising speed will be low due to the need for low final drive ratio, close ratio gears and very high revs.

The engine won't last long before needing a re-build and to build it properly will be very expensive.

As is continually being correctly stated on here (does no-one read earlier posts) the 286 is a competition cam and is not really suitable for road use. It needs to be revved to 6800 rpm due to maximum power being delivered at 6400 rpm and a SC CR gearbox is needed to keep the power within the power band. A centre-main bearing cap is needed and the engine must be fully dynamically balanced. In fact, the OP's engine will need to be stripped and completely re-built to begin with as everything will need to be improved and/or replaced.

It is, effectively, a full special stage rally cam.

For a road car it's not 100 bhp that's needed, it's good mid-range torque and, maybe around 85 to 90 bhp. That will give optimum on-the-road performance and a wider ratio standard gearbox will ensure good cruising speeds at sensible revs. On a road car it should not be necessary to use over 6000 rpm.

The ideal road cam is a Kent 266 or equivalent Piper or MG Metro cam.



#7 tom1

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Posted 23 September 2013 - 11:12 AM

Sorry for the delay in stating that this is a hill climb mini that will be road legal but not in a road going class. Tax free so may as will could be a advantage. The gearbox is with John guess as I type, fitting higher final drive and a 4 pin diff, no SC unless you think different ? The cam did come out of mini that I build for rallying but never used.

#8 Cooperman

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Posted 23 September 2013 - 11:27 AM

If you are hill-climbing and have a 286 or hotter cam, you'll need a SC CR gearbox and a lower, not higher, FDR. I would suggest a 3.9:1 or even a 4.1:1.

With a 286 cam and a high FDR you simply won't get off the line cleanly and the acceleration will be poor. Without CR gears you'll struggle to keep it in the optimum power band. Don't forget to fit a centre main strap and get everything fully balanced so that you can safely use 7000 rpm.

The X-pin diff will work OK, although some hill-climbers use an LSD.

If you are not fitting SC CR gears, then don't go further than a 266 cam, but to be competitive you'll need a 286 with SC CR box and low diff.



#9 tom1

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Posted 23 September 2013 - 11:50 AM

When I said lower I ment higher it's that daft thing ,the higher the number lower the drive! it was all balanced last time and will be this time,I have gone from a center main ,to a set of big end caps from swiftune

#10 tom1

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Posted 23 September 2013 - 11:54 AM

Pressed the rong button. As for being competitive not the most important thing to me I just want to get out and do something

#11 Lennyliverpool

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Posted 23 September 2013 - 11:57 AM

Its interesting to read the above as i to would like to get to the magic 100 - i am on 90 bhp

listed below is the spec as is for now

 

Interested to read that the 286 is not good for road use? - mine is docile and the car is a daily driver?

As for revs i cannot tell you what i get because i have the wrong Rev counter in my mini! O_O which means

i have to halve the figure - consequently i am also around 6000 (actually 3000) so not sure what its meant to be as i have 

no more space on the counter!!

 

•Re conditioned metro 1275 gearbox (done about 1500 miles) 3.2 differential

•Re conditioned metro 1275 engine (done 1500 miles), +60 pistons, 286 cam, stage 4 head (Robert Walker) , orange non verto clutch, ultra light flywheel and back plate, 1.75 inch SU, Aldon distributor, (approx 90 BHP)

•New clutch master + slave cylinders

RC40 mini exhaust 

•Maniflow manifold (larger centre pipe)

 

Cheers

Lenny



#12 Cooperman

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Posted 23 September 2013 - 12:23 PM

Are you sure it's a 286. The 286 gives peak power at 6400 rpm and needs to be kept between 5000 and 6800 to give of its best. If not driven like this, then it's the wrong cam for the application.

As for a 3.2:1 FDR with a 286 and, presumably, a standard, that is a serious mis-match for best performance and the cam will not allow the car to perform as it could with a softer cam, like a 266, fitted.



#13 Cooperman

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Posted 23 September 2013 - 12:25 PM

When I said lower I ment higher it's that daft thing ,the higher the number lower the drive! it was all balanced last time and will be this time,I have gone from a center main ,to a set of big end caps from swiftune

 

Ok, I understand.

It sounds as though the engine will be fine, but do address the gearbox by fitting a SC CR set as you'll be disappointed if you don't

When you get out there you'll want to do as well as possible, of that you can be sure, and if you are 'bogged down' by wide gear ratios, despite having a good engine, you'll be angry with yourself for not doing it right.

God luck with the hill climbing.



#14 The Principal

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Posted 23 September 2013 - 01:01 PM

When I said lower I ment higher it's that daft thing ,the higher the number lower the drive! it was all balanced last time and will be this time,I have gone from a center main ,to a set of big end caps from swiftune

 

As a tip - are you referring to changing the centre main cap to a steel type? If your changing one or more of the main caps then they will need line boring, the thrust faces will need checking/machining and you may need two new holes for the four hole centre steel cap. Last time I did that about 6 months ago it cost me over £400 at Gosnay's in labour 



#15 Guess-Works.com

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Posted 23 September 2013 - 01:07 PM

As you might gather I know a wee bit about what is planned...

 

My theory is, if you're embarking on a competition type series, try an do it a cheaply as possible from day one, if you enjoy it then there's reason to increase the budget, if you don't then there's not much loss...

 

Gearbox wise, my suggestion is run a standard helical gearbox with a 3.6 final drive, this gives Tom the off the line speed and in reality 3rd gear will be the same overall ratio as 3rd in a SCCR gearbox with a 4.1 final drive, 3rd being the most likely gear used. The x-pin is a worthwhile investment upfront and will see him through to the point of needing a ATB/LSD.

 

As for the engine spec, I'm aware of the block Tom is using and that'll see him through, as you have the 286, use it...

 

The cooper S crank will need some special thrust for the block, and the S rods will be fine... again if you have them use them... then later on I'd be tempted to sell them to fund an upgrade to a forged crank and H rods.

 

Induction wise... Weber or one of SC's fuel injection systems.... if you have neither of those a a good HIF44 will be fine.






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