998, std head, SW5: how many HP did you get ?
Turbo Mini Forums

Hi,
All the projects I see here use 12H heads. As this route was too easy I've used the std Metro 998 head that I ported a little bit.

With SW5 I got 40HP at 4000RPM, then power stays flat up to 5000RPM and then falls down. Torque is almost flat from 1500 to 4000 (max 70Nm @3500), then falls down.
Numbers were the same with carb and MPI injection.

The engine was rebuilt less then 5000km ago, so I suspect there are still lots of mech loses. However I find that level rather low.

Once turbocharged the engine feels the same except the power is higher. I still have not measured HP.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

Does seem a bit low, but std 998 heads are crap. an SW5 with a 12G295 will make 60 bhp.

Fastest 998 mini in the world? 13.05 1/4 mile 106mph

www.twin-turbo.co.uk

last head i did (12G202) ported to a very limited budget made
these numbers at my usual dynoshack

stock short block sw5, hif44. thrown together (I just did the head for a guy).

56.9DIN HP @ 5613rpm and 87Nm @3614rpm.

but it made 56 banana at 4600 rpm and still 56 at 6000.

whurlies..85 @ 1750 rpm and 4200
65@6k

all the heads i have done tend to have this plateau thing

dyno reads quite low on the bananas and curleywhurlies (sp?)

a 1310/sw5 i helped out with with all usual suspects makes 90 banana there but the curve is pretty much the same shape..just higher up and it will rev to near 7 k due to the 1.45 rockers.


should be good charged i guess. btw there is a turbo version of the sw5 as well

Edited by Sir Yun on 8th May, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

It looks like std head is very limiting.
What I like with it is the absence of pockets, since I've switched to MPi (so cyl richness is better balanced) I have not been able to make engine ping (N/A, not turbo) and I believe pockets like any cavity is a great source of pings.

With a turbo ping resistance is more important. Anyway I leave in 2.5 months, I won't change the head now.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

the stock head is as Will_h states crap.

i ended up with the shape that was pretty much a similar to a ported 295 head
(there is a lot of metal in a std head).

i'd use a 202 as a base (unless you can find a unmolested 295) as it is quite easy to lower compression and fit bigger valves.

porting is a bit of a nightmare as the ports are tiny near the valveguide and cramped so it is hard to keep the burr from producing very angry/scary tool chatter when you start off.

i port the with the guides in as the hole otherwise is a perfect spot to jam a burr in ( with 700+ watts that is not good). after that i press the guides out and fit new ones.

i had some pics but the upload section is down.



but you won't need to pocket the block.

Edited by Sir Yun on 13th May, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Where did you guys time the camshaft in? I'm about to do the same spec engine.

i think i used 106 (from memory (!)the lca is 104.5 so that seems about right)

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

My SW5 is retarded by around 5 degrees (opens/closes later).

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

that seems quite a lot.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Why ?

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

well it is a bit further retarded than is the norm (3-4 degs). but i have mostly installed this cam in 1275 and up

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

I retarded it to extend the power band a little bit.
I actually prefer the MD256, even with turbo. I have measured profiles of both and found MD much more clever, a well elaborated like Schrick profiles I saw. SW5 is just an improvement with too much lift, a very usual profile for a modern market cam. But I sold MD with my other Mini 1000.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

My experiences with the sw5 (NA) are just about all good. IMHO a lot of people complain about power dropping off at higher revs and blame the cam, but i'm pretty shure that is down to the headwork (as i have never had trouble, a 1275+ is exactly the same shape as this graph just the scale is differnt and with 1.5 rockers it will rev a bit higher)

Powerband should be extended as is, but the head needs to be ported to make use of the extra lift (duration is as you know limited).

btw this head was not all that much ported and there is more potential in the exhaust port as this was not modded all that much




the sw5 is indeed akin to quite a few cams these days.

Schrick does a A series cam ??

never used a MD 256 so i can't comment

I'm now running a RE13 profile..but that is more like a md286 but with some bottom end. should work with a 998.

i think Russell engineering do a turbo version as well . our australian cousins should be able to comment about it.

Edited by Sir Yun on 16th May, 2008.

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Schrick does not work for Mini but their Porsche cams are very good, clever not symmetric profiles with little overlap, high lift accel and good power band.

The torque curve is close to the one I was getting, however with std head it falls down even more (possibly due to mech losses of a freshly rebuilt engine). I've used Swiftune valve springs which are rather stiff, the next time I'll put std springs, if I decide to keep SW5.

Here are cam profiles I measured. Both SW5 cams are exactly the same and symmetric, MD cams are different.

Edited by alpa on 16th May, 2008.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm

it could be mechanical losses ( what was the torque needed to turn with pistons in?) but most engines i have had a hand in go on the dyno at about 750km after a rebuild not 5000 km. torque will be relatively higher after a more miles than peak hp ( at least on stuff i have seen).

the head is choking the cam's extra lift.. a MD256 would work better with a std head

That sir, is not rust, it is the progressive mass reduction system

http://aseriesmodifications.wordpress.com/

Sure SW5 has too much lift for std. However this makes more port choked duration, same as if cam was square shaped. In theory :) .

I could feel real difference at high RPM between 1000 and 2000 km.

Edited by alpa on 22nd May, 2008.

std 998 A+, g295, MD266, RHF4, 109hp @0.8bar/5400rpm