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SC 998 help
https://www.ausmini.com/forums/viewtopic.php?f=5&t=35600		 Page 1 of 1
Author:  Kennomini [ Sun Sep 09, 2007 7:04 pm ]
Post subject:  SC 998 help
Hi all, I'm after some advice on what to do with my engine. I've already fitted the AMR300 supercharger (brackets & pipework) and the lump is at the mechanics getting striped. The head has been upgraded to 998 cooper spec and converted to unleaded, the rest is stock. I'll only be running a low boost due to the small SC. The engine befour the upgraded head did 30.9BHP (big I know :oops: ) so with the SC I think around 50BHP just a guestamate.
Will a standard spec diff & box do that power with no problems or should I look at 1098 or 1275 parts?
Also any susjestion on clutch and flywheel?
I don't want to rebour it if I don't have to, is it worth getting some low comp pistons?
What would be a good cam and is it worth changing from std?
Would one of those pulsar dizzy's be a good idea?
I asume it's a 3.44 diff, it has pot joint CV's and a rod change box (2 rods from box to stick) I use the car as a daily drive and I want to do 110km with out it screaming in pain but still be good at low revs, I don't want to rev over 4500-5000.
Any susjestions would be appricated.
Author:  willy [ Sun Sep 09, 2007 7:08 pm ]
Post subject: 
Standard diff and gearbox will easily take double that power, if in good condition.

Starting to look at lowering your compression is really going to be advantageous if you know what your compression ratio is at the moment... the lower the c/r, the more boost you are safely able to run (to a point).

3.44:1 diff ratio with 10" wheels will sit on around 100km/hr @ 4000rpm.
Author:  Mister White Keys [ Sun Sep 09, 2007 8:10 pm ]
Post subject: 
That sort of power is no problem with standard bits. I'm running a normally aspirated 998 that managed just under 50 horses at the wheels and is running standard gearbox and diff with no problems at all. As willy says it could probably take double the power.

I haven't had any experience with superchargers but I have had great responses with small bores after the addition of a more free flowing head (such as the 998 cooper head that you mention), a warm road cam such as the Wade 104 profile and a set of LCB extractors.
I have also found that twin 1 1/4" carbies make a huge difference but this obviously doesn't apply to a supercharger set up.

Good luck with it, there is a lot of satisfaction to be had in getting some decent power out of a small bore motor. These big bore people just don't understand :P
Author:  Spaceboy [ Mon Sep 10, 2007 6:11 am ]
Post subject:  Re: SC 998 help
Kennomini wrote:
Hi all, I'm after some advice on what to do with my engine. I've already fitted the AMR300 supercharger (brackets & pipework) and the lump is at the mechanics getting striped. The head has been upgraded to 998 cooper spec and converted to unleaded, the rest is stock. I'll only be running a low boost due to the small SC. The engine befour the upgraded head did 30.9BHP (big I know :oops: ) so with the SC I think around 50BHP just a guestamate.
Will a standard spec diff & box do that power with no problems or should I look at 1098 or 1275 parts?
Also any susjestion on clutch and flywheel?
I don't want to rebour it if I don't have to, is it worth getting some low comp pistons?
What would be a good cam and is it worth changing from std?
Would one of those pulsar dizzy's be a good idea?
I asume it's a 3.44 diff, it has pot joint CV's and a rod change box (2 rods from box to stick) I use the car as a daily drive and I want to do 110km with out it screaming in pain but still be good at low revs, I don't want to rev over 4500-5000.
Any susjestions would be appricated.


a standard gearbox should be fine, but an uprated clutch is probably a good idea.

if you run low boost, you can run standard pistons, but make sure the motor is healthy and not blowing past the rings or anything.

you suggest you dont want to rev the motor and you say its a daily driver., So a standard cam would be my first suggestion, a sw5 might be another option, theres a bloke using one with his supercharged smallblock here in adelaide.
my re-13T equipped mini doesnt get going until 3000rpm and has a lumpy idle.

a pulsar dizzy is a bad idea, it will not suit your engine without a lot of modifications.
I am running standard points no worries., but i will upgrade to a petronix or similar at some stage. Dont forget to have your car dyno tuned including ignition.

i'd guess at 60-70hp at the wheels.
Author:  sox61 [ Mon Sep 10, 2007 1:12 pm ]
Post subject: 
Hi Kenno,

I'm running a 998 with a blower. My specs are pretty standard. Standard dizzy (elec. ign.), standard pistons, rod change box, standard diff. If you drive it like you stole it, yeah, things will break. Just treat it with some respect.
The cam is a GR RE13T, and as spaceboy says, it does take a while to spool up. I think you will get away with the standard cam, depends what u want from the engine when finished.
My car runs boost from 8-10psi without too much trouble...

In saying that, I have just gone to a 1275 head because of blowing the head gasket on the 998. Made good power with it, but now I can run a metro turbo gasket and hopefully this will hold in better!
Low comp pistons are definately a good idea if you want to run big boost, it just wont have much poke until the boost gets going. If i did it again i'd run forged pistons and more boost, and a 1275 block... (and a turbo)(and efi) :roll: :lol:

Edit: Had to go to an orange dot in the box as the standard couldn't hold the power...
Author:  slinkey inc [ Mon Sep 10, 2007 5:43 pm ]
Post subject: 
I'd say that I think standard compression should be ok. As it's only an AMR300, it won't make a lot of boost anyways. Gearbox should be fine, I've been running mid-70s atws for quite sometime now without a hiccup, however, I have 1275, and a lot of Cooper S parts, (appart from gearbox which is 4 synchro remote). But I think you'll be alright.

As for ignition, it really depends who you ask, both my Mini's run Pulsar dizzys. Personally, I wouldn't go back to Lucas, or points- My preference. Advance wise, well total advance wise, the Nissan suits boost, as it's not really a big advance dizzy, makes less than a Cooper S dizzy, but has a simliar curve (almost the same over 2500rpm) and stops advancing at around 5000ish RPM. Unlike S which goes much over.

I think 123 ignition, or better yet, coil pack, ultimately is probably the way to go. Although costly.

Above all, which ever you choose, be safe! Until at least someone (possibly you??) sets the static timing it right. For safety, I'd set your dizzy to about 5* BTC so it doesn't detonate under boost.

As for diffs, I'd say 3.444 would be good, with about 50+ hp atws, or if you want a bit more go, try a 3.64 perhaps.

Lastly, as for clutch, Cooper S clutch (whatever colour that might be) is probably the way to go, it's worked for me.
Author:  Kennomini [ Mon Sep 10, 2007 6:31 pm ]
Post subject: 
I thought that I would'nt need many $$$ bits, pretty much a cooper S clutch and throw-out bearing, standard box & diff and a low comp 998 cooper spec engine should do 8) .
Any susjestions on compretion ratio that I should aim for?
Author:  Spaceboy [ Mon Sep 10, 2007 6:47 pm ]
Post subject: 
Kennomini wrote:
I thought that I would'nt need many $$$ bits, pretty much a cooper S clutch and throw-out bearing, standard box & diff and a low comp 998 cooper spec engine should do 8) .
Any susjestions on compretion ratio that I should aim for?


yeah standard is fine if you want to run low boost.
Author:  slinkey inc [ Mon Sep 10, 2007 7:10 pm ]
Post subject: 
Depends, is this motor just for fun now, or a long term project?

If it's long term maybe thinking ahead for big future boost might be the way.

I'm not exactly sure my compression, due to not knowing the cc's of the dish on my piston. But it's probably around the 9:1 area. And I run a max of 7 psi, of full go, at high rpm.

But usually I make around 5psi up hills, and on acceleration, it goes quick enough without flatten it everytime I move.

PS. Metro Turbo motors, stock, run 9.4:1 compression and about 7psi max boost.

Now as a rule of thumb, it is said (on the Turbominis forum) to run no more than 10psi, with 9:1 compression.

There's no point running low compression without big boost. But hey sounds like this is a homebuild, mostly, so have fun, and hopefully all goes well! There will be some issues that'll arise in which you'll need to figure, so good luck!

Enough mumbo-jumbo....

Yeah stock 998 should be quite OK, but I'm no expert on 998s, 1275s are my thing. :wink:
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