How do I get 80 to 85 bhp
Nomen Nescio
to get 80 to 85 bhp out of a Mini Cooper 1.3 carb engine. Maybe the
international newsgroup can give the final verdict.
I have a stage 1 kit fitted. The cat is removed. So I'm looking at 70
bhp (right?, never tested it).
Should I buy a new cam (276?). A stage 3 head (wich one). A new carb
(weber?). And where should I start? Some say a new cam would do it.
Not so expensive but the engine must come out to do it. Some say I'll
only need a stage 3 head. More expensive but easier to fit. And a
third one said a big weber would easily get me my 85 bhp for a price
somewhere in between the cam and the head...
Confused? I am. Any light on this matter would be much appriciated.
Eric
Andy Murray
DCOE weber should get you some decent power. Guy in my club has 1380
with all the above (also sc gears) and puts out over 100bhp at the
wheels (tested by Pete Baldwin Rolling Road).
--
Andy
998cc Appreciation Society
http://www.mininut.demon.co.uk/
Tom Parker
>There's a discussion going on in the Dutch Mini Mailing list about how
>to get 80 to 85 bhp out of a Mini Cooper 1.3 carb engine. Maybe the
>international newsgroup can give the final verdict.
The international mailing list has a wider audience than this newsgroup...
>I have a stage 1 kit fitted. The cat is removed. So I'm looking at 70
>bhp (right?, never tested it).
Sounds about right, similar to the MG Metro. However it depends a lot on where
you measure it. Measuring at the wheels will yeild a significantly lower
value. Also dynos vary significantly between each other. You would hope that
they don't vary much between concecutive runs, but if they aren't maintained
then they will....
>Should I buy a new cam (276?). A stage 3 head (wich one). A new carb
>(weber?). And where should I start? Some say a new cam would do it.
>Not so expensive but the engine must come out to do it. Some say I'll
>only need a stage 3 head. More expensive but easier to fit. And a
>third one said a big weber would easily get me my 85 bhp for a price
>somewhere in between the cam and the head...
There are many ways to skin a dog... A cam, something like a 276 or a 286 will
still be easy to drive (aparently, I've only driven a 296, which is a handful
but EXTREMELY powerful in combination with the right other bits), and should
give you the power you want.
A head will give you power if done properly, and possibly will be a nicer
engine to drive than one with a wild cam. The head is more likely to wear out
your gearbox and diff due to more torque than a cam.
A big carb won't deliver. First it will give you poor drivability, then it
will give you poor fuel consumption until you spend a lot of money on a
rolling road (this is true for all modifications, except perhaps a stage one
kit, they all have to be set up on a rolling road).
A big carb isn't necessary for a mild engine, only for a real screamer does it
become useful. By big I mean a twin choke 45 sidedraft. A little downdraft
might go well, but it is very difficult to beat an SU.
--
Tom Parker - par...@ihug.co.nz
- http://www.geocities.com/MotorCity/Track/8381/
mike
<N_Ne...@nospamhotmail.com> wrote:
>There's a discussion going on in the Dutch Mini Mailing list about how
>to get 80 to 85 bhp out of a Mini Cooper 1.3 carb engine. Maybe the
>international newsgroup can give the final verdict.
>
>I have a stage 1 kit fitted. The cat is removed. So I'm looking at 70
>bhp (right?, never tested it).
>
>Should I buy a new cam (276?). A stage 3 head (wich one). A new carb
>(weber?). And where should I start? Some say a new cam would do it.
>Not so expensive but the engine must come out to do it. Some say I'll
>only need a stage 3 head. More expensive but easier to fit. And a
>third one said a big weber would easily get me my 85 bhp for a price
>somewhere in between the cam and the head...
>
>Confused? I am. Any light on this matter would be much appriciated.
>
>Eric
Certainly fitting a bigger carb without changing aynthing else will be
a huge waste of time. With a standard head and cam, the carb is not
the restrictive component.
My advice would be to get the best head you can afford. Breathing is
everything, and the standard ports and valves are the biggest
bottleneck in a standard mini. A decent head will give you more
torque and power all the way. Don't go silly and get a race head with
ports so huge you can stick your head in them. That will ruin low
speed performance with little or no gain in top end. Go for a
reputable modifer such as Longman, Bill Richards etc and you won't be
dissapointed.
After a head swap, if you still want more power, then is a good time
to start thinking about cam's and carbs. IMHO the 276 isn't a
particulary good cam. It seems to combine the idle characteristics of
a 286 with the top end of the 266. I would be more than happy to
recomend either of the latter cams. The 266 in particular give an
excellent idle and very strong low and midrange power and a healthy
increase at the top end. The 286 makes a lot of power from around
3500 rpm up, and idle is still pretty good.
A HIF44 carb should be good for 90 or so bhp, maybe even 100. If you
are going to want more than this, a 45 DCOE is certainly one way to
go, although you will have to start chopping the bulkhead away for
airfilter clearance.
Regards
Mike Rigby-Jones
TVS
> a huge waste of time. With a standard head and cam, the carb is not
> the restrictive component.
Could'nt agree more. You could even get that power with a HS4. If its
modified and ifted with a rampipe it will flow about 180CFM. The gas
velocity will be very high helping to make plenty of torque.
>
> My advice would be to get the best head you can afford. Breathing is
> everything, and the standard ports and valves are the biggest
> bottleneck in a standard mini. A decent head will give you more
> torque and power all the way. Don't go silly and get a race head with
> ports so huge you can stick your head in them. That will ruin low
> speed performance with little or no gain in top end. Go for a
> reputable modifer such as Longman, Bill Richards etc and you won't be
> dissapointed.
>
Keep away from anything with BIG ports. A std MG Metro head is exelent if
you are on a budget and should be capable of 85Hp if used with a warmish
cam.
> After a head swap, if you still want more power, then is a good time
> to start thinking about cam's and carbs. IMHO the 276 isn't a
> particulary good cam. It seems to combine the idle characteristics of
> a 286 with the top end of the 266.
Ive got a 276 in my 1293. It woulnt pull untill over 2000 RPM and is a pain
in trafic. Top end is'nt wonderfull ither.
TVS
jimboooo
highly tuned race engines, with the levels of power you are looking at it
will be a swine to set up.
stick with the good ole 1 3/4 su and a good filter.
the cheapest way to get nore horses is to fit a stage1/2 head and a 276 or
286 cam, but you need a decent carb/filter and a 3 into 1 and ye olde rc40
odd comment about the torque.......
more torque= more power.......... any increase in power will mean more
stran on the transmission. My opinion..... and it is that an opinion,
is that much more than
90Bhp and you will want straight cut drops and watch the driveshafts,
watch the revs too, more than 7000 sustained can make the iron flywheels
wobble a bit,
Tom Parker
>odd comment about the torque.......
>more torque= more power.......... any increase in power will mean more
>stran on the transmission. My opinion..... and it is that an opinion,
>is that much more than
>90Bhp and you will want straight cut drops and watch the driveshafts,
More power puts more strain on the transmission, but you can get more power in
several ways. You can increase your torque near the maximum torque point,
which is usually at lower speeds. This puts more strain on the gearbox because
you are increaseing the maximum torque going through it. You can also increase
the torque at higher revs. This gives you comparatively more power because the
engine is going faster, but it puts less stress on the gearbox as you have
less torque than what you have a maximum torque...
I haven't explained that well.
>watch the revs too, more than 7000 sustained can make the iron flywheels
>wobble a bit,
I've seen a backplate blow up at 8200rpm... not pritty.
mike
>
>> After a head swap, if you still want more power, then is a good time
>> to start thinking about cam's and carbs. IMHO the 276 isn't a
>> particulary good cam. It seems to combine the idle characteristics of
>> a 286 with the top end of the 266.
> Ive got a 276 in my 1293. It woulnt pull untill over 2000 RPM and is a pain
>in trafic. Top end is'nt wonderfull ither.
>TVS
>
his and he has an ultralight steel flywheel as well. I smugly ordered
a 276 thinking that his engine would idle like a bag of old nails,
whilst mine shouldn't be too bad, and I shouldn't lose too much on the
top end. How wrong can you be? As wrong as a Mr Wrong, winner of
this years Very Wrong competition. His actually idles very well,
consideribng it has a very silly amount of compression (about 11:1).
What I will say though is that in my experience, getting a good idle
with an SU on a modified engine is way harder than with a Weber or
Dellorto. I had an HIF44, which was set up on a local rolling road,
and it certainly gave the goods in terms of power and economy wasn't
that bad. I swapped over to a 28/36 DCD Weber after manageing to get
my hands on one the the very rare downdraught manifolds that DV
mentions. Idle was instantly better, and that was before being set
up. The carb had come off some old Ford van according the guy at the
autojumble!
My brother runs a 45 DCOE with a loooong manifold BTW.
Mike
TVS
SU manifolds don't tend to be very long and the port/phlenum (o.k. I
can't spell!) chamber is big... so with a long duration cam, flow reversal
can easily take place.
I've flowed Vizzards instructions about modifying SUs and with a GOOD
ram pipe I can get nearly 195CFM out of a HS4 carb. Nearly as good as the
204CFM of the HIF6. (I, and another book I've read, don't agree with Vizards
clamed 240CFM for the HIF6!!)
But with such a high gas velocity there should be plenty of inertia
ramming! TVS
mike <mi...@dont-type-this.clara.net> wrote in message
news:38273a8a...@news.clara.net...
jimboooo
with multi jet carbs like the weber and dellorto's its easier to set up at
lower revs,
with the SU it takes a lot more practice/expertise to get the needle profile
right
there is only one man and one rolling road to use.......... Pete Baldwin
on CFM figures you can get a lot more than 240cfm from the HIF6/44
if you spend a lot of time with a grinder and remove all the lumps,
our race series restricts us to a standard inlet manifold and carb body but
modifications are free,
the manifold from the mg metro (non turbo) is not bad in standard from
albeit a bit short, but with 3 spacers and a lot of careful shaping it
works.........
last time on the rollers i saw 118 @ 8250 at the wheels, which probaby
equates to 135ish at the flywheel, using the 2.2 CFM per BHP rule that
suggests that a max flow of nearly 300 can be achieved. but please dont ask
me how many bodies, manifolds, spindles and butterfly's i trashed to get a
set that works.
if you are interested the rest of the lump is a (ahem) allegro 1300
overbored short stroked
310 scatter with roller tips 1:1.5 rockers carbon rods and a very sexy head
from Steve Whitton at MED. and yes its a bitch to drive unless its flat
out,
it will tick over at 2000 but you dont let the clutch up with less than
4000 cos it makes you look silly when you stall.
J
Siftah
par...@nospam.ihug.co.nz wrote on 6/11/99 10:54 am:
> A big carb won't deliver. First it will give you poor drivability, then it
> will give you poor fuel consumption until you spend a lot of money on a
> rolling road (this is true for all modifications, except perhaps a stage one
> kit, they all have to be set up on a rolling road).
Here here, There was some specs in Mini Mag/ MiniWorld a while back
concerning flow rates and maximum bhp's, the standard carb was good for
something like 100bhp (off the top of my head...)
And definitely get a rolling road tune, whatever you do, even a stage one
benefits, I gained an extra 5-10 from a proper set-up, unless you're some
kind of demon tuner who can sniff c02 levels and guess the correct needle
profile, or 40quid or so it's worth it.... :)
Siftah
wrote on 10/11/99 11:55 pm:
> interesting note on that
[snipped sexy spec & interesting flow rate stuff]
> equates to 135ish at the flywheel, using the 2.2 CFM per BHP rule that
I just love the way a thread asking for 80-85bhp can become a thread about
130+ engines, :)
I presume this engine was a 1275cc by the way ?
I'm interested to know what the max for a 998cc is tho ?
John (who's making a comparitively piti-ful 70bhp at the flywheel from
998cc) :)
jimboooo
sounds like the old mine is bigger than yours thing.................. rofl
its not what i intended
the point i was trying to illustrate is that it is a common assumption that
a BIG carb = big power
on the sensible 80 85 bhp fast road lump i really dont think its worth
bothering with a twin choke,
and that the su is capable of giving a lot more than most people will credit
it for. including some of the "reputable pro tuners" who incidentaly happen
to sell for a knock down Ł150 a nearly new dellorto or weber with jets from
a '72 transit v6 thats nearly right for your mini mate....
JIm
jimboooo
assuming 240cfm which you can get from the later HIF44 still (1 3/4 inch)
you get 100bhp however thats a flywheel figure, and with a standard box and
helical drop gears
that could be as low as 75-80 at the tyres.
which i think goes to show that the carb is not the restriction to the sort
of level that the original poster wanted,
i stick by my originaal opinion, go get a 276/286 and a (ahem) cleaned up
larger valve head..
which leaves me on another of my pet hates
what is the difference between a stage one and a stage two head? and a stage
three for that matter??
maybe its time for a new thread on that one??
yours Jim the opinionated one........
Siftah
wrote on 12/11/99 12:28 am:
> which i think goes to show that the carb is not the restriction to the sort
> of level that the original poster wanted,
> i stick by my originaal opinion, go get a 276/286 and a (ahem) cleaned up
> larger valve head..
> which leaves me on another of my pet hates
Sounds good to me, I've never risked lifting the engine out yet tho', I
think a new cam will be my next mod, along with a set of 1.5 roller rockers,
save my valves, the original ones are a bit noisy, little bit of play in
them too. Means investing/borrowing/begging/stealing/making/ a lifting
thingy to pull the engine out.
> what is the difference between a stage one and a stage two head? and a stage
> three for that matter??
About £100 :)
I've never seen a stage one head advertised, I always thought stage one was
just doing the exhaust and inlet manifold ?
Stage Two is supposedly some polishing and flowing work
Stage three = Stage Two + Bigger Inlets,
Stage Four = Stage Three + bigger inlets/exhaust
Stage Five = custom made with bigger everything!
I think it's pretty open to interpretation tho'
> maybe its time for a new thread on that one??
Yeah, always hard to get any definite power figures on these things,
Stage three made a decent difference to my 998, about 20bhp when all told,
but there again, other things were changed at the same time so it's hard to
say exactly what happened and for what reason.
TVS
> if you spend a lot of time with a grinder and remove all the lumps,
> our race series restricts us to a standard inlet manifold and carb body
but
> modifications are free,
> the manifold from the mg metro (non turbo) is not bad in standard from
> albeit a bit short, but with 3 spacers and a lot of careful shaping it
> works.........
Vizzards book states that a std HIF6 flows 240CFM at 25" of H2O. However,
'How to Build. Modify &Power Tune Cylinderheads' by P. Burgess/D. Gollan
states that the HIF6 flows 204CFM. I also get 204CFM on my homemade
flowbench. Whats going on?!
>
> last time on the rollers i saw 118 @ 8250 at the wheels, which probaby
> equates to 135ish at the flywheel, using the 2.2 CFM per BHP rule that
> suggests that a max flow of nearly 300 can be achieved. but please dont
ask
> me how many bodies, manifolds, spindles and butterfly's i trashed to get a
> set that works.
I haven't tried modifying a HIF6. I'll give that a go when I get another!
TVS
jimboooo
home made flow bench....... I tried that a few years ago with a borrowed
flow meter and a cone made of GRP the problem i had was getting enough air
through it, 300ckm is a hell of a lot of air to move compare it to a 1000
watt vacuum cleaner which at best moves about 60cfm....
There are two concentric 1 3/4 carbs fitted to metro's etc the HIF 6 and
the HIF 44, the numbers relate to the size the 6 being the older one and
the 44 being the newer one, the 44 being 44 mm
hence the 38 = 38 mm or 1 1/2 inch. there isnt much difference to look at
between HIF6 and HIF44
but there are a few subtle changes inside the throat.....
Its very difficult to establish the figures because we dont know the test
details, ie what manifolds were used, was there an air filter on its etc.
in standard trim the air filter and casing is a big problem, go out and get
one of the dirty great big ones from K+N, the one that means bending the
bulkhead back about 6" should be ok......
to modify the carb start with the butterfly and shaft, if you ever want one
doing, I can skim the butterfly's but send me two wrapped in a £5 note, and
expect one back cos they are buggers to mount. remember if you do reduce the
shaft to be careful of the return springs at each end, cos the shaft will
twist......
another thing to watch, when you are looking in the scrappies, dont even
think of wasting your time on any of the auto choke bodies, they just dont
work....
jimboooo
believe me its a lot easier to lift the car off the engine,
but then i suppose for every one who says its easier to lift the car off the
subframe,
there will be 3 people who will say its easier to lift the engine outta the
car..
on 1.5 rollers. they do make an engine a bit cammier if thats a proper
word.
when i did it, it was one of the last mods i made, it did give me more
power, but at the cost of low end driveability, not that i had much anyway.
the bit to be cautios of is that because of the higher lift, the valve
accelerates and closes faster,
get them noisy valves sorted my son....
jim the opinionated one
Nomen Nescio
but it won't be a bigger carb. Probably the new head with bigger
inlets and maybe a new cam at the same time. I'll let you know.
Eric
Andy Laurence
>'How to Build. Modify &Power Tune Cylinderheads' by P. Burgess/D. Gollan
>states that the HIF6 flows 204CFM. I also get 204CFM on my homemade
>flowbench. Whats going on?!
Home made flow bench... Sounds good, how did you manage that. I
would be intrigued to know how you made it. I would love to have my
own in the garage to 'tinker' around with.
Andy