what mods will be ran with this motor?

What pulley, intercooler, cam, exhaust setup.. head.. injectors etc.. I am very curious about the output of the engine.

Also - what clutch will you be running and will this be a street car or a track car for RnD purposes?

 

Sounds like a lot of work... for very few buyers. Thanks for the info. No need to do this on my account unless you guys are board and need something to do, which I am sure is not the case. It's too bad that there aren't more R50 owners out there that would make all your work worth your while.
Craig

 

Too much work? Not worth while?

Since when have those been reasons not to find out what you could do with an engine? What's next? Impractical? Too expensive? Too risky? Bad example for the children? A big bore R50 is not something the world needs, or wants, or deserves. Let's all agree on that. But you could say the same about cars in general, Minis definitely.

Now, putting aside all these "reasons" to not do it, hold my beer...

 

Lol.... Preachin' to the choir here....

This is exactly why one of my favorite responses is...
"What's NEED got to do with it?"

 

I would love it if they did this but for the vendor, it doesn't make for a good business model. Spend dozens of hours and perhaps a few grand in R and D for the 5 people that will buy it. Now, if it takes like a 15 min to figure out what is needed, sure, I'm tempted to buy one for 12% bump in base bhp. With bigger injectors and fuel pump, intake, header and exhaust it may even hit as high 15% gain with the right conditions.

 

that's the power of new technology, if the piston size is known, and the pin distance is known.... crank stays the same..... should be an easy calculation to get the appropriate rod length for the r50..... possibly a day at most. custom rods are always made and im sure they have cookie cutters in the big places, just input crank diam, pin diam and distance between centers

 

How does increasing the displacement 6% amount to a 12%+ power gain?

 

Displacement increases power output by increasing the amount of air the engine can consume. When you put in the correct amount of fuel with the increased amount of air you get a bigger explosion which makes more horsepower.

 

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I think you missed the point I was trying to make. I understand why increasing displacement makes more power....basic combustion engine theory. But I don't understand why a 6% increase in displacement would yield a 12% increase in power. If you said a 6% increase in displacement made 5-6% power increase it would make sense.......but if the only thing you do to a motor is increase the displacement by 6%.....why would it make 12% more power?

Also, on a forced induction motor like the R53's where you have a fixed displacement supercharger.....if you increase the displacement of the motor but the displacement of the supercharger stays the same....won't you lose an equal about of boost (6%) to make up for the added engine displacement that needs to be compressed? So when you are all said done.... the gains from the added engine displacement get canceled out by the loss of boost the supercharger is building?

Just basic physics.........right?

Have you dyno'd a stock r53 at 1.6 liters and then at 1.7 liters with the big bore kit and no other changes? Just wondering if there is much HP gain if any.

 

I'm no scientist, but I'm thinking that displacement and horsepower aren't directly proportional to each other. Like if you have a pipe with a 2 inch diameter, if you double the diameter to 4 inches, the amount of fluid that can flow through that pipe increases exponentially. So even though you only doubled the size of the pipe, you get more than double the flow.

Hopefully someone who knows more about engines can provide more info, but when he claimed a 6% displacement produces 12% more horsepower, that's the principal that came to my mind.

 

i look at it like this..

air lines for air tools. 120psi with a small air fitting does the same amount of work as a 80 psi line with a huge air fitting strictly based off of the huge increase in volume. (obviously my numbers arent correct but with air tools more volume means you can drop air pressure and do the same amount of work)

so the motor is the fitting, the supercharger is the psi in the line. motor becomes bigger, supercharger no longer has to be ramped up to do the same amount of work, and in our case since it is ramped up it does more work.

again, values arent correct just using it as a comparison. i highly doubt youd see more than a 30whp gain with an all stock S vs an all stock 1.7 with a tune on it.

 

I don't under stand this part (in red). The supercharger puts out a fixed amount of air at a given RPM......if you reduce the volume it has to fill up (cylinder area) boost pressure goes up, if you increase the volume it has to fill up, boost goes down....right?

 

Isn't that the argument against a BVH, or a ported head?

I think what is missing is that an engine is not a steady state machine. Air flows in discrete amounts as it fills the intake plenum, head, and cylinder. This generates pressure spikes and drops, and reflected pressure waves. The boost gauge reads a relatively long term average pressure.

 

Correct, possibly a better way of saying it would have been this:

And like the change in displacement, there's not a direct 1-1 correlation. Which is one of the things I'm going through, I may not actually be chasing a boost leak, the boost just may end up being this much less, problem I have is that since no-one else has done this exact combo, there's no other data to refer too, as too how much boost I "should" lose with the changes that were made. But again, the loss of boost doesn't "directly" translate into the ratio of power. Too many other factors to do a direct comparison with just that data.

Yes, and while you may see a loss of boost, it doesn't mean a loss of power, just a change in the way and where the power is made. And in most of the ported heads you can buy for the Mini, without having custom porting done, you most likely won't see much of a change, since intake ports aren't really touched much, mostly exhaust ports and valves, but this is also why choosing the amount and type of porting for your application also matters. A one size fits all ported head won't suit everyone.

Oops, now back to Displacement....

 

On my phone so this may be a bit odd.

It takes power to drive the supercharger. I would imagine it is roughly exponential to get more boost, ie to get 1 more psi takes 1hp, the next is 2hp, the next 4hp etc. With the increase in displacement (assuming perfect flow etc) you get more units of air in per stroke so yes the boost goes down. BUT, the supercharger is working against less pressure so takes less power from the crank to turn.

Same number of air molecules at less pressure + less parasitic loss of churning the air through the pump = more power.

Hope that makes sense.

James

 

try to make a comparison to help people understand.. only make people more confused hahahah!

im sure people with more experience will pitch in soon enough

 

The increase in power is from the increase in displacement. On a stock r53 engine rated at 160hp at the crank then 12% is 19.2hp.
The supercharger is an M45 which stands for 45cid of air per rev. The engine is 1.6L or 97.6cid. The intake of a 4 stroke engine is 1/2 its displacement per rev or 48.8cid. That is almost the same as the supercharger so if the supercharger was driven one to one with the crank then it would make 0 psi but we dont run the supercharger at 1 to 1, we run it at 3 or so to 1 ( i'm going to keep the math simple). Now the supercharger is producing 135cid to the engines need of 48.8 and you have boost.
If you increase the size of the engine then the engine will consume more air and if you made the engine big enough then you would see a drop in psi with a same supercharger drive ratio. But only at the max vol point not max rpm which is where most people think is max boost level is.
In real life theres no drop in psi on the gauge going from 1.6 to 1.7 or to a ported head or bigger cam or all of that together because the supercharger is already making way more than the engine can consume and the boost gauge just isnt that accurate. Your talking about maybe 1/2 a psi here at max vol efficiency which may not be max rpm so you wouldnt know where to look for the drop anyway.

So in the end all of the mods that make the engine bigger or flow more air make more power because they make the engine more efficient so it can make more power with less boost. Boost is just a measure of air backing up in the intake that the engine cant use. Boost is not a measure of engine power.

 

tl;dr

jk

 

dollar for hp the 1.7 kit is a steal, as long as you are building the engine yourself

when my track car needs a rebuild, this is gonna be going in.

I have not done a big valve head yet because the cost per hp is just not worth it for me I feel better off putting that nearly 3000 $ towards a spec-e36/e46 or similar car

 

@Sneed4speed - I am so sorry for brining up the HP debate... I should have just asked if it would work on a R50 and left it at that.

 

It's been a good discussion and pretty interesting. I've certainly learned a few things.

Nothing to be sorry about.

 

Nothing to be sorry about. Glad to answer questions.

 

Drat. Sorry.

James

 

Thanks for the technical answer! That explained a lot of the questions I had.

 

Sorry I havent updated this build thread in a while. The car is complete and out driving now. Everything is good. Lots more torque and power I have attached the final dyno sheet. As you can see the 1.7 kit makes a lot more power everywhere.