Graphed head & cylinder mods - a good read.

[Keg]

So ive finished measuring up NSE.ONE's GG300 and put all the data through my software... glad i only have to do it once for each model bike cause it takes a bloody long time to measure and re-measure everything... There are a number of things that require you to get pretty creative in order to get a measurement and there is always the possiblity of human error so i try to measure everything several times to get a good average, but the results are usually pretty reliable... probably within 5% or so.



Theres no question that the bike does what its designed to do very well, power is very smooth and tractable, but its no mxer. Basically they have done this by using a small exhaust port, low compression, large squish and very little blowdown. Basically there is a lot more power to unlock out of the engine with some pretty easy porting changes... thats if you need more power!



The Black line is the stock engine, in this case 2.5mm squish, 11.9:1 comp, 1.3mm base gasket stack, piston level with port floors at bdc

The Red line is the cylinder dropped by 0.7mm to give a squish of 1.8mm, no further changes other than what occurs by dropping cylinder.... comp increases, exh duration drops, transfer duration drops

The Green line is the cylindner dropped by 1mm to give a squish of 1.5mm, no other changes.

The Blue line is dropping cylinder a bit but then doing some basic mods to the exhaust port to bring the top end power back... best of both worlds... better bottom without the loss on top. You can take this much further to get better top end if you want.


This engine has low exhaust TA and by dropping the cylinder to correct squish you reduce that further, making it fall flat up top... green line shows this. This is why its usually not advisable to use base gaskets to alter squish cause you can mess up port timing if you take it too far... with this engine though there is not enough blowdown TA and it could do with a larger exh port and lower transfers, particularly the boost port which opens 2.5 degrees before the others... so there is actually some beneift in droppping the cylinder on this bike, but its really only beneficial if you then raise the exhaust back up a bit to increase exh TA and blowdown TA.


Thread stolen from here ..... http://www.dirtbikeworld.net/forum/s...ad.php?t=82850

[Bailey28]

It looks like these "free" mods are a good bang for the buck. Swapping out base gaskets or shuffling what you have to get the cylinder .7-1.0mm lower is free, and if you have a flex dremel you can smooth and contour the transfer ports and clean up the casting flaws yourself.

Look at the difference between the black and green line... A 1mm base gasket swap alone will get you 4 horsepower at 6500 rpm? Damn 4 hp is a big difference on these bikes.

I will wait until my top end needs to be done, at which point I will attempt to do the above mods.

[john01]

I'm a little confused...does the black line show a stock bike at 52 hp and the green line show less peak hp at 47?

[Jakobi]

Disregard the power figures John. They are based on ideal scenario regarding fuel/air etc. The graphs are a calculated representation of how port timing/shaping and compression/squish effect the power curve/delivery.

Whas has happened is an engine builder in Australia has measured up a 2010 EC300 Euro model and punched the figures into some fanastic software that crunches the numbers and graphs the results.

[john01]

Oh.....thanks. Man I read free 4 hp and got all excited.

[Jakobi]

Originally Posted by john01

Oh.....thanks. Man I read free 4 hp and got all excited.

Depends how many base gaskets and where your ports are set now.. they could be available!

[Skidad]

Why no reading of just leaving the cylinder as is with the thicker gasket stack and adjusting the squish just using a head mod? Perhaps that might give the best all around results?

[Jakobi]

Originally Posted by Skidad

Why no reading of just leaving the cylinder as is with the thicker gasket stack and adjusting the squish just using a head mod? Perhaps that might give the best all around results?

Exact same question I asked on the original thread

[Jakobi]

]

BLACK line is stock engine

RED line is 1.6mm squish, 13.2:1 compression, done by machining head only
cause Jakobi asked for it

GREEN line is cylinder dropped by 0.7mm to give squish of 1.8mm, same as red line in first graph

BLUE line is same as blue line in first graph... cylinder lowered but then exhaust raised a bit


Doing the squish by machining the head shows a small gain everywhere without a loss of top end[/QUOTE]

[Skidad]

Originally Posted by Jakobi

]

BLACK line is stock engine

RED line is 1.6mm squish, 13.2:1 compression, done by machining head only
cause Jakobi asked for it

GREEN line is cylinder dropped by 0.7mm to give squish of 1.8mm, same as red line in first graph

BLUE line is same as blue line in first graph... cylinder lowered but then exhaust raised a bit


Doing the squish by machining the head shows a small gain everywhere without a loss of top end

[/QUOTE]

Thank you Jakobi, looks good to me.