Ideas for engine power

[Lawrence832]

Heya people.
Don't know if anyone knows about my little micramini but I though I would introduce her here she has a nice little k11 cg10 engine



It's the 998 engine but running honda cbr 600 bike carburettors with bigger jets. Also using megajolt controlled ignition with two maps enabling on the fly testing exhaust is a 4,2,1 dual silencer no cat system modified from a rover k series engine.

Not sure of the power output but she is fairly nippy when you put your foot down and bounce of the hard Rev limiter at 8000 revs!

Today tho it's time for a change. I have purchased a 1275 k11 cg13 engine
My plans however are not set in stone of what to do yet and would like some ideas from you chaps on here

Exhaust will work fine for the 1275 as it is probably to large for the 998 as it is
Carbs can be rejetted to a larger size, already have the jets
Megajolt can be tuned for the 1275

Now my issue is with engine hardware.
What do people think of getting a head skim to up compression? And if I do what sort of power/reliability will I get?

Comments are much appreciated
Lawrence

 

[pollyp]

hi lawrence, k just focusing on the engine side

Intake:
Teflon insulating inlet manifold spacer: prevents engine block heating the manifold, keeps the air cooler till it enters the inlet port.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-50#post-510149

CAI box: shield the carbs from engine heat and supply with air from a cold high pressure region.

Compression:
if the head & block is skimmed alot from original thickness, it will retard timings of both inlet & exhaust cams. best to precisely check and adjust the cam timing to match factory cam timing and tune em from there.

Combustion
clean white oxide off the dizzy cap points if fitted
check spark gap
orientate spark gap towards inlet port

Exhaust
smooth out the ports
match head ports to gaskets & inlet/exhaust manifolds

Weight
lighten flywheel
balance crank assembly
knife edge crank counterweights

Oil control
windage tray: prevent oil sloshing/foaming against the spinning crank during rapid cornering.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-66#post-536819

trap door pickup: keep the pickup surrounded by a valved tank of oil at all times to prevent oil starving during high g-force.
https://www.micra.org.uk/threads/pollymobiles-rebuild.35251/page-63#post-530476

dual catch can: reduce amount of oil vapours recirculating back into the inlet manifold, keeps the system cleaner with less oil contamination.

reliability depends on many factors including:
condition of all bearings, seals, rings, fuel quality, service intervals,
aggressiveness & accuracy or combustion afr mixture & timing,
driving load & distance, mostly urban driving or mostly WOT racing?

 

[Lawrence832]

Cheers pollyp, my intake is simply a metal tube belended to the inlet port but I don't think I have space to add a Teflon spacer.

I'll bear the timing in mind when skimming the head then, don't want wasted power there

Is it worth going for copper core hg leads and Philips 4 point spark plugs. The spark should be good from megajolt tho

Exhaust is already smoothed and matched

I was thinking of lightening the flywheel but worried about stalling from lack of inertia. I shall contemplate it.
Not planning on balancing the crank and going that much into it tbh

I shall look into oil control also.

Afr ratio should hopefully be spot on and driving is generally calm until I fancy booting it and playing about

Many thanks for that and your links also, shall give me something to read
Lawrence

 

[pollyp]

Cheers pollyp, my intake is simply a metal tube belended to the inlet port but I don't think I have space to add a Teflon spacer.

I'll bear the timing in mind when skimming the head then, don't want wasted power there

Is it worth going for copper core hg leads and Philips 4 point spark plugs. The spark should be good from megajolt tho

Exhaust is already smoothed and matched

I was thinking of lightening the flywheel but worried about stalling from lack of inertia. I shall contemplate it.
Not planning on balancing the crank and going that much into it tbh

I shall look into oil control also.

Afr ratio should hopefully be spot on and driving is generally calm until I fancy booting it and playing about

Many thanks for that and your links also, shall give me something to read
Lawrence

the teflon gasket can be as thick or thin as u like, 1mm sheet can work. I used 5mm as a test.

not tried copper HT leads yet but a previous member once tested & dynoed em with success. my standard ngk plugs work fine so sticking with that for now.

lightening the flywheel shouldn't be a problem at all.
I once had a 3.4kg JUN flywheel with helix 3-pad clutch and idles perfectly fine cos the heavy crank has enough inertia to sustain itself. frank has an even lighter flywheel and was superbly responsive.

only issue with superlight flywheels is lack of clutch inertia dampening between each firing so the clutch engagement or drivetrain backlash may stutter when driving off.
plus easier to stall driving off cos the revs change alot faster than usual with the rapid release of clutch ur used to, but that's all down to relearning clutch & throttle control, give the clutch time to propel the car before fully releasing. soon get used to it.

 

[Nelly_mini]

I have a frankspeed lightened flywheel on my mini micra and had no stalling issues at all. she is a 1.3 and happily spins the wheels in 3rd gear, shes a bit of a monster, you may need to take some more cooling precautions such as using water-wetter and a
water tank before the radiator (i cannot for the life of me remember the name of it!!)

 

[Lawrence832]

Cheers nelly. Be nice to see what you do for cooling, and you mean a header tank, I am contemplating fitting one also, have you got a blog or anything I can investigate?

But here are my plans,
Get the new 200mm flywheel skimmed and hopefully get a lot taken off. Not gunna go to town and drill holes etc but a hefty weight loss

Head skim for 2.5mm to raise compression and I'll make the cam timing adjustable by either removing the dowels or giving them an ark to move in.

Cams to be reground and I'm going to run double shims.

And may look into the Teflon gasket also

Keep the ideas coming guys but I don't want to do massive work like forged internals etc as only going NA

Lawrence

 

[l_jonez]

Best advice I can give is to ditch the carbs and go injection. I'm sure @Skinner_87 would agree as well

I loved my carbs but its a different animal with ITB's you can get the Afr perfect, where as carbs are just close enough.

 

[Lawrence832]

Thanks for your imput l_jonez. I had thought about throttle bodies and injection but it's just the wiring and getting it all setup that I'm really worried about, In all honesty I don't think I have the skills to go custom injection, hence why I went carb . I'm planning on getting an AFR wideband to weld in so hopefully that will help with my carbs and fueling.

What happened to your build too mate? Last thing I saw was a post about an alternator a while back, life got in the way?

Lawrence

 

[Nelly_mini]

Im on the mini forum as 666junky and have a thread on there but it does not contain any recent pics at all for a few reasons. The reason i mentioned the cooling is because im at the same stage myself, it runs, but the car runs keeps overheating..getting a new rad and thinking of running an auxillery rad down the front too

 

[Lawrence832]

Yh I found it after a Google search. I was going to get one of those cheap alloy rads as that allows me to modify the piping as I can then learn to weld aluminium. Will get a nice header tank too for that coolent movement in the rad

 

[l_jonez]

Thanks for your imput l_jonez. I had thought about throttle bodies and injection but it's just the wiring and getting it all setup that I'm really worried about, In all honesty I don't think I have the skills to go custom injection, hence why I went carb . I'm planning on getting an AFR wideband to weld in so hopefully that will help with my carbs and fueling.

What happened to your build too mate? Last thing I saw was a post about an alternator a while back, life got in the way?

Lawrence

My mini is off the road, just because it wasn't getting used and now life has got in the way but I'm hoping it will be dusted off in the summer

 

[fuzzy-hair-man]

I have a frankspeed lightened flywheel on my mini micra and had no stalling issues at all. she is a 1.3 and happily spins the wheels in 3rd gear, shes a bit of a monster, you may need to take some more cooling precautions such as using water-wetter and a
water tank before the radiator (i cannot for the life of me remember the name of it!!)

What weight flywheel did you end up with Niki? Just at the same stage myself looking at something near 4kgs, ie. remove any easy to get off don't lose any strength. I figure a lighter mini should have even less downsides to a light flywheel than a micra.
There's a modern 2 core radiator that's supposed to be quite good, better than the 4 core rads the cooper s had apparently. Afaik copper conducts heat better than aluminium so the traditional radiators which use copper should (all things being equal) be better than the aluminium ones. Aussie minis needing more cooling often plumb in a spare clubland or later mini heater core somewhere around the engine bay...
http://www.minispares.com/article/T...2&perma=cooling-controlling-water-temperature
The radiator part listing should be at the bottom of the page.

 

[Nelly_mini]

Best to ask Frank on here - i bought it from him and didnt really ask too many questions as i was so excited to buy something for the mini lol. its not stupidly thin / weak but it is certainly alot thinner than others ive seen! - it does have a few drill holes but it is for balancing purposes and not for further lightening.
Ive bought a new rad purely because my old rad is blocked up and covered in soot, grease and oil so really should have gone before i even started this project lol.
My setup has the temp sensor in the thermostat housing (mk1 mini part) - which means i dont get a reading til it opens - huge bummer as i think the stat is pooped - hence my overheating issues! I may have to look into lower temp stats (if there is such an option) or even remove it totally.
anyone here heading to L2B this year? i know its very soon but im going to try and get there lol.
Please be careful with temp senders / gauges as some dont tally up - mine under reads massively, i thought it wasnt even half way but really it was boiling over.. eek!
Injection is awesome, even if you dont go down the ITB route a decent single throttlebody teamed up with good ECU and custom inlet will get some great results. Im running a custom inlet and the torque is amazing + it starts on the button!