31 replies to this topic

[valve bounce]

evening all

im building a 1275 engine for my mini, so far ive got a relinered 1330 to take the bore back to 1275 with high compression pistons and a very good condition crank. i have a 12g940 head with 35mm inlets and 29mm exhausts the ports have been played alittle, ive got a set of vernier ajustable timing gear. for fueling i have a 28/36 weber or twin hs2's, for exhaust i was going for maniflow 1.75 ich lcb twin box system, ignition i was thinking mg metro dissy. the gearbox is standard 998 a serise with a 3.44 diff with hardened diff pin.

my biggest porblem is deciding which camshaft to use i was thinking 276 kent, 270 piper, 731 or 544

the car will be a weekend warrior with the odd summer drive to work and back so something managable in traffic would be good, i had a mg metro in my 998 and would like something similiar in my 1275, the car will also be used for the odd auto test and posibly a navigational rally to 2.

thanks rob

[bmcecosse]

544 all the way! But forget the 28/36 - and twin 1 1/4 are too small. Single HIF 44 or twin 1.5" SUs on a GOOD (ie weber like) manifold - not the BMC item with daft balance pipe!

[Cooperman]

Let's consider your cam options as you've stated them. The 544 is very similar to the Kent 286, but not quite as good although you would probably not notice the difference. The 286 is a fine cam and comes on at around 3000 rpm with little below that and it peaks at 6400 which may be a bit high for a road engine. I always use the 286 in my 'S' rally car, but that's a bit of a screamer with no bottom end really, just lots above 5000 rpm right up to about 6800.
The 731 is a really old design rally cam, but it is not as good as the MG Metro or Kent 266.
I don't know much about Piper cams, although I hear they are very good, so their 270 is probably excellent (I've never worked with one). I like the 276, although some are not so convinced. I built a 1275 with that cam, twin HS4,s and a Rob Walker head, etc, which ran beautifully and gave 92 bhp at 6100 rpm (that's peak power). For a road rally car it is excellent.

[bmcecosse]

Yes - the 286 cams by various suppliers are 'modern improvements' on the good old 544 which is a fabulous cam. I suppose they couldn't just copy it - could they!!
As for the 28/36 - aye right!

Edited by bmcecosse, 04 January 2011 - 11:18 PM.

[Cooperman]

I like the 276, although some are not so convinced. I built a 1275 with that cam, twin HS4,s and a Rob Walker head, etc, which ran beautifully and gave 92 bhp at 6100 rpm (that's peak power). For a road rally car it is excellent.

Just out of interest which rolling road do you use ?

I go to my old friend Peter Baldwin.
I worked with the 731 cam years ago and there really doesn't seem to be much by way of comparison with the 276. I had a Mk 1 rally 'S' with the 731 back in 1969, but soon changed it for the super 544 and got better results.
I also built a 1275 Historic Rally 'S' engine with a 276 plus all the other bits and that gave 94 bhp at Peter's RR. Went well on the rallies it did and still does. The owner loves it and I built an 1100 Sprite Mk 1 engine also with the 276 for him for Historic rallies.
I like the 276, but it's just a personal preference really. For my own cars I use a 286 and I've even built a 998 rally Mini with that in. Very cammy and 74 bhp at 6400-ish, but the gearing was low. Didn't like the 998, so fitted a 970 'S' lump, again with the 286. It gave 84 bhp at 6800 rpm from memory. It was a 'class winner' too unless there were any hot Imps entered (twin 40 DCOE's, 108 bhp at 8000 rpm, well a 'poor man's Porsche' really). Didn't enjoy competiting in it as much as my big 'S' though.

[valve bounce]

well i think im going to use the kent276 or piper270 i think then, i decided to not use the 286 as i thought it would be to agresive/cammy for road use so by that theory the 544 is out and the 731 sounds like it would make a good paper weight so its out also, the 266/mg metro is abit tame.
does anynody have any other ideas on camshaft or any of the other spec

thanks rob

[danrock101]

94bhp is quite feasable, so I'd say that's right

Edited by danrock101, 05 January 2011 - 08:13 PM.

[valve bounce]

what sort of power would my engine spec be around 70-85 bhp @ the fly? or is that abit optamistic

[danrock101]

94bhp is quite feasable, so I'd say that's right

LOL but then again you also said this:

Personally though, I wanted a 130bhp n/a engine and decided to go 5 port

All these figures need to be taken with a large pinch of salt.........

I was talking about the engine cooperman built, not the OPs engine.

What's wrong about going for a 130bhp n/a motor?

[danrock101]

Depends what you're idea of fun is, I did say 'personally' not, YOU SHOULD. I've already paid for everything now, just waiting for it to be built. The power will 'come on' at 3k and rev all the way to 8k and beyond but I'll set the rev limter at 8k. As it's a long stroke engine it will have more torque throughout the rev range, I will be moding the valves to help the power when it's 'off cam' and the megajolt will help with 'off cam' power massivly. The only problem is the weber but I'll be using the shortest manifold I can get away with, without loosing top end power, to help 'off cam' power.
Put it this way it will have alot more power than my 850 when it's 'off cam', some people actually like' bwap bwap bwap bwap bwap' a cammy engine makes, then the weber roar at 8k. It will last alot longer than a month, I've been pesturing lots of different people who have a high spec n/a engines, if worst comes to worst I will have to change the cam and then the engine will be more 'driveable'.

I do plan to go turbo eventually but the main reason is the tourqe, so I can use a 3.1 diff and still have good off the line performance... cheaper than a 5 speed box

[danrock101]

Ive done plenty of research, spent months and months deciding on a spec. The current head is only a MED rally head that I'll use just for running it in, but MED said it will still be good for 125bhp. Then I'll sort out a full race head... either experiment with one I grinded myself or get one made. I already have all the parts I need for my n/a engine apart from megajolt. At first I'm aiming for 100 at the wheels with the MED head, with s/c drops + box it shouldn't be too much to ask for.I know it will be a dog to drive to some people, and I might not get 130bhp but either way it will be epic fun for me, and it's something I would like to experiance, just because someone else didn't like a high powered n/a a-series engine, doesn't mean I wont, but if I don't I'll change the engine round.
The reason I'm aiming for 130 is I thought it would be rougly touching the limits of the cam I wanted to use, I think the 'bottle neck' of a engine should be the cam, for best tourqe. Not because I plucked a figure out of the sky, but because I wanted it to be revvy, if I wanted it to be smooth and only rev to 6k and last over 5k miles then I would of chosen a SW5 and aimed for 100bhp. It's just something I'd like to try, same as a dog box. The first mini I bought had a SW5 in and I thought it was a standard cam untill I stripped the engine down, I was pretty shocked to be honest lol.

[valve bounce]

right then ive been offered a kent 274 scatter cam, it has been put in and engine set up, then decided not to use and was taken out without even been run.
the specs are:
Power band 1500-6500rpm
Cam lift (mm) inlet 7.23 exhaust 7.13
Valve lift (mm) inlet 8.85 exhaust 8.71 with standard 1.22 rockers
inlet 10.84 exhaust 10.69 with high lift 1.50 rockers
Timing 16/52 71/27
Full lift at 108 degrees

so my question is, it a good choice or not?

[Paul Wiginton]

Ive done plenty of research, spent months and months deciding on a spec. The current head is only a MED rally head that I'll use just for running it in, but MED said it will still be good for 125bhp. Then I'll sort out a full race head... either experiment with one I grinded myself or get one made. I already have all the parts I need for my n/a engine apart from megajolt. At first I'm aiming for 100 at the wheels with the MED head, with s/c drops + box it shouldn't be too much to ask for.I know it will be a dog to drive to some people, and I might not get 130bhp but either way it will be epic fun for me, and it's something I would like to experiance, just because someone else didn't like a high powered n/a a-series engine, doesn't mean I wont, but if I don't I'll change the engine round.
The reason I'm aiming for 130 is I thought it would be rougly touching the limits of the cam I wanted to use, I think the 'bottle neck' of a engine should be the cam, for best tourqe. Not because I plucked a figure out of the sky, but because I wanted it to be revvy, if I wanted it to be smooth and only rev to 6k and last over 5k miles then I would of chosen a SW5 and aimed for 100bhp. It's just something I'd like to try, same as a dog box. The first mini I bought had a SW5 in and I thought it was a standard cam untill I stripped the engine down, I was pretty shocked to be honest lol.

I sorry mate but you haven't done any research, if you think any of the above is true. That or your just going on the BS you've been told over the phone. A true 130 horsepower A series will just be getting into it's stride at 5000rpms and forget your redline of 6k, as I said earlier you'll be needing 9000rpms at least and a full steel bottom end.
For a true 130 horses your looking at a 10k engine.........
Another word of advice, when people are trying to help you drop the attitude.

DILIGAF, I dont believe what you are saying. My 1380 has run over 130 bananas for the past 11 years with a 310sp cam. Power pulls from 3,200 in 4th gear and peak power is at 7,200. It will poodle along at 30mph happily and it certainly did not cost £10k.
Also, you say long inlet makes torque - thats wrong mate, short inlet makes torque and long makes power. Thats from 15 years of my experience, countless years of Swiftune experience and hundreds of years of Pete Baldwin experience.

Paul

[valve bounce]

right then been reading and thinking ive been looking at the piper 270 here are the specs:
Part No. Application Power Band Power Increase Duration Valve Lift Timing Full Lift Lift @ TDC with clearance Valve Clearance
Inl Exh Inl Exh Inl ATDC Exh BTDC Inl Exh
BP270 FAST ROADThe BP270 cam is a straight forward installation with none to light modification and parts needed depending on vehicle. Generally referred to as the stage 2 of cam tuning this profile performs well when used in conjunction with other stage 2 tuning products such as free flow exhaust systems and remaps, giving a good torque and power increase in road cars.
(Approx 270° duration) 1500‑6500 10BHP 276° 276° 0.385″
9.78mm
0.385″
9.78mm
31‑65
65‑31
107° 0.082″
2.08mm
0.080″
2.03mm
0.012″ / 0.30mm
0.012″ / 0.30mm

the kent 276 specs are:
Application Power Band Cam Lift(mm) Valve Lift(mm) Duration Timing Full Lift VC (mm) LTDC Required Parts
Sports ' R ' 1500-7000 I 7.43 E 7.99 I 9.14 E 9.84 I 270 Deg E 280 Deg 29/61 66/34 106 Deg 0.40 I 2.16mm CF1 / VS2
Part No Part Type Description
MD276 Camshaft Sports ' R '
Product: MD276

so in the real world whats the diffrence between the 3 cams ive just writen up the specs for?
im still really strugling to make a decision on which cam to use can anyone shed anylight on which to use?

[Paul Wiginton]

To be perfectly honest you wont notice any difference in any of those cams, theyre all so similar. Id go for the Kent as their machines are newer and more accurate, making a better cam