CG13DE volumetric changes

[MajikMarch]

Right so it turned out that the guy I was going to buy a 1.3 off was a Muppet and lets say pictures can be desceving! I currently have no Micra.. or car! but I still have a working CG13DE (Y)

By using the basic maths & phsyics rule of capacity ive decided to try to build a 1.6CC engine from a 1.3DE block (I am an A 2nd Year A Level A* Physics student :wasntme: )
Pi (3.14) x Radius of Cylinder(squared) x Height = CC of that cylinder! CC x 4 = Total Engine CC
CG10DE 1.0 = Bore 71mm, Stroke 63mm & Compression @ 9.5:1
CG13DE 1.3 = Bore 71mm, Stroke 80.5mm & Compression @ 9.5:1

I had originally decided to change the total volume of the CG engine By changing the Bore size, but on experimenting with numbers I've ditched the idea of a "bore-up/bore-out" and instead a stroker idea!
By using the standard bore size but changing the "height of the cylinder" (stroke) from 80.5mm to an whopping 101mm you can *theoretically* get a CG16DE, 91mm stroke would get you a "CG145DE" engine (1.45litres)

I also theorised if you changed the bore size to something marginal like 72 - 74mm (giant in terms on cylinders etc) and lowered the stroke to something a little more practical such as 91-96mm that you could gain the same gain (1.6) from a little less drastic stroke changes! I.e. 73mm Bore x 96mm stroke = 401.8cc per cylinder obsiously with this you would need to have alot of parts changed/custom and modified but I think technically speaking it might work.. lets see if I can convice the engine centre to help me try it!

Ideas, questions or even problems? post them up now

 

[Guy]

Only prob is, I think it was Frank who said that 1.0 and 1.3 Micra engines have ridiculously thin cylinder walls .

 

[frank]

Only prob is, I think it was Frank who said that 1.0 and 1.3 Micra engines have ridiculously thin cylinder walls .

yes 2mm thick
cga,s are 72mm dia bore, and about as big as you can safely go
and their longer stroke just about clears the side of the block too, so drastic machining needed for clearance for a longer throw (£1000 ?) custom/special crank fwn

 

[MajikMarch]

WillenhallEngines will machine you a crank up for about £500-1000 dependant on type of crank/design etc etc they can even do bottom end skimming/machining to lower the crank area.. but its all down to money.. shame theyre 2mm thick.. 8U66ER!
Not to far away from you frank (Y) I'm Wolves way

Edit; A little bit of modifying my equations mans if you could do a 72.25mm bore and a 90mm stroke you could get a 1475cc block?? thats an extra 10mm stroke though! You have to find that from some where?? Unless I can see what I can do with my workings out?

 

[superls]

all sounds nice on paper, id like to see it pulled off, i made a cg stroker engine, cg10 block, custom machined cg13 pistons and a cga crank, cant remember the exact figure of stroke but the final cc was 1311,

in my opinion, theres not much chance of you getting anywhere near 1450 1500 cc. but id love to be proved wrong

 

[MajikMarch]

Yes.. I'd love to try it! I just need to get it all designed up and speak to the local machine/engine shop! (Y)

 

[ibrooks]

It's possible to stroke engines by offset grinding the big-end journals to a smaller size and using a con-rod which originally went onto a smaller journal. It depends on the original size of the journals as to whether there is enough metal left when you've ground to the smaller size and finding a suitable con-rod of the right length with correct sized big and little ends.

Iain

 

[misterc123]

Hi all i see this is an old thread but did anyone have any luck with this? I'm thinking of doing something to try and get close to 1400cc for my rally micra (up to 1400 class).
I calculated if you use a almera 1500 cc crank with stroke of 88mm it gives you 1396cc........but does it fit?

anyone know?

cheers steve

 

[frank]

Hi all i see this is an old thread but did anyone have any luck with this? I'm thinking of doing something to try and get close to 1400cc for my rally micra (up to 1400 class).
I calculated if you use a almera 1500 cc crank with stroke of 88mm it gives you 1396cc........but does it fit?

anyone know?

cheers steve

no the GA crank is longer steve, a CGA crank and corsa xe pistons bring it up to 1367cc

 

[Tony Perks]

Actually I have just bored my cg10 to 73 mm, and there is 1.5mm left after finding a water damaged block i sectioned it and measured the liners, and mine were 3.5mm thick, but even bored out they are still quite sturdy as there is loads of Ally that overlaps the top of the bore and the bottom to support the liner, However I would not recomend turbo ing this larger bore, i will let you know next year how reliable it is when the new racing season gets under way. Dont mean to doubt you Frank youve done much much more than i ever will with these little busses, just reporting what i have found.

 

[frank]

the 2 blocks that i busted up tony (pics were in my deleted blog) had liners that averaged about 3mm, but were only about 2mm in places

 

[Tony Perks]

I guess i will have to see what happens then!

 

[frank]

I guess i will have to see what happens then!

we only differ by half a mil tho surely ? you have machined 1mm off the wall/liner (from 71mm to 73mm) and you say you have 1.5mm of liner left

 

[Tony Perks]

yes but maybe my section was through the thick bit?!

 

[misterc123]

no the GA crank is longer steve, a CGA crank and corsa xe pistons bring it up to 1367cc

Thanks Frank
But it was the QG15DE crank i was looking at replacing the GA crank, do you know what's longer? I see the main bearings are the same size and the crank seals also (cant find the big end sizes).
I dont know if the cranks line up or what is spaced differently.

Cheers Steve

 

[frank]

Thanks Frank
But it was the QG15DE crank i was looking at replacing the GA crank, do you know what's longer? I see the main bearings are the same size and the crank seals also (cant find the big end sizes).
I dont know if the cranks line up or what is spaced differently.

Cheers Steve

the QG has the same (bigger) bore spacing as the GA steve, the journal sizes are the same iirc, but that wont help as the block is longer eh

 

[misterc123]

Thanks for the info.
Just managed to source a low mileage CGA engine so going to pick it up tonight.
I have some cams so will put those in first and see what it's like.
Does £75 for it sound ok for a CGA?

Cheers Steve

 

[frank]

twas a good price steve, you,ll need to fit your head tho eh

 

[misterc123]

No problem.
Thanks for your help