1.0 Pistons in the 1.3.

H

Hyundai

Buy & Sell Member
Could someone explain to me how this would uprate the power? - I find it hard to understand as I thought this was one of the main differences between the 1.0 and 1.3 as they're nearly identical. :eek:
 
Hyundai said:
Could someone explain to me how this would uprate the power? - I find it hard to understand as I thought this was one of the main differences between the 1.0 and 1.3 as they're nearly identical. :eek:
Click to expand...

if im right then 1.0 pistons will increase compression ratio thus increasing the combustion in the chamber, not sure if its beneficial as ive never done it

main diference is pistons, crank, rods and cams
 
Broony said:
if im right then 1.0 pistons will increase compression ratio thus increasing the combustion in the chamber, not sure if its beneficial as ive never done it

main diference is pistons, crank, rods and cams
Click to expand...

i have sort of done researh on this as a cheap way of tuning a cg13.

the 1.0 pistons are flat top and the 1.3 pistons are dished.

the 1.0 rods are a diffrent legnth to the 1.3s do to a diffrent crank.

iirc the 1.0 pistons are smaller the 1.3's.

if you was to fit the 1.0 pistons into a 1.3, ither there wouldnt be engough compression, or the pistons would hit the head lol.

and you would beable to fit the rods, pistons in a 1.3 ither due to the crank beeeing diffrent...

therefor it would need custom rods i think?

best bet is to a) stick 1.3 cams in and be done (a nice gian :)

b) stick in a 1.3

c) spend alot of money lol

dan
 
frank said:
the 1.0 pistons fit a treat, and raise the compression (giving you more power):cool:
Click to expand...

well said mate(Y) except that it does make it sound slightly more simple than it is:D i would recormend honeing the bores and you will need new rings and all the kit to rebuild the engine.
 
squarepants said:
i have sort of done researh on this as a cheap way of tuning a cg13.

the 1.0 pistons are flat top and the 1.3 pistons are dished.

the 1.0 rods are a diffrent legnth to the 1.3s do to a diffrent crank.

iirc the 1.0 pistons are smaller the 1.3's.

if you was to fit the 1.0 pistons into a 1.3, ither there wouldnt be engough compression, or the pistons would hit the head lol.

and you would beable to fit the rods, pistons in a 1.3 ither due to the crank beeeing diffrent...

therefor it would need custom rods i think?

best bet is to a) stick 1.3 cams in and be done (a nice gian :)

b) stick in a 1.3

c) spend alot of money lol

dan
Click to expand...

Those highlighted above are incorrrect, 1.0 are the same size as 1.3 pistons only difference is the dish because as frank said 1.0 fit into the 1.3 bore.
You wouldnt need the rods or crank as that would turn it into a 1.0 with 1.3 cams.
 

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So all I would need is the piston heads from the CG10 and install them on the CG13 Rods?

What are the power gains for this? What is the difference in compression?
 
Hyundai said:
So all I would need is the piston heads from the CG10 and install them on the CG13 Rods?

What are the power gains for this? What is the difference in compression?
Click to expand...

yes, and dunno, 10.5 : 1 ?
chrismo has just done it to his (and skimmed the head a little too :eek:)
you could work out the c/r mathmatically, because 1.0,s and 1.3,s have the same c/r eh
 
Right. If you put the 1.0 (flat top) pistons into a 1.3 engine with 1.3 crank and rods. you will have a compression ratio of 11.8:1 this is with a standard cylinder head which has 24cc's in the port, a deck height of 1.4mm, iirc a 80.5 stroke crank and cant quite remember the bore. It will give you quite a power gain but to get the most you will need to run the 773 cams and another engine management something like omex, dta or equivelent.
 
Hyundai said:
Will the rise in compression pose any damage to the engine or affect it in the long run?
Click to expand...

if you use the extra power you will probably affect the life of the engine, but a decent inlet cam will backflow a lot of the compression anyway :)
 
The CG13 engine has a standard ratio of 9,5:1 Now the thing I've heard is when you change the 1.3 pistons for 1.0 pistons the ratio would be anywhere around 10.5:1

11.8 sounds way to high! Where did you get these numbers from? I have placed 1.0 pistons on my 1.3 rods, and placed them inside my CG13 engine, together with the NME cams from Matthew. I also did some port-grinding myself, and skimmed a little bit off the head.

Yesterday I changed the oil, after 500 km, and yesterday I did some serious full throttle work....... and I must tell you: There is NOT much power gain to be honnest! Did a measurement 0-100 km/h in 10 seconds....;-(

So all about the 1.0 pistons inside a CG13, I don't know why, but I notice almost NO gain! Soon I put some 773 cams in, and hope there is some gain noticable. A/F is 12:1 all the way, so the engine runs righ enough.

One thing also: Now when I want to drive from stand, I have to push the throttle a little, as the car wants to stall if I don't. Idle is 750-800 rpm.

Long story, but the main thing is: Don't think putting 1.0 (flat) pistons inside a CG13 engine will help you getting a lot more (cheap) power. But the swap is 100% safe, 0,0% chance the pistons will hit the valves.





gr Chrismo
 
It's a lot of labour if there isn't much power gain. Replacing all the gaskets and rings seems a bit trivial now. Thanks for the information.
 
Must give you that! But it is also possible........and I hope not.........that the port-grinding I did on the head (done it myself, and never have done it before) is the reason my engine is not making the powergain it should be making with these modifications.






gr Chrismo
 
i make it a c/r of 12.2 : 1 fwn
250cc (1 cylinder) divided by 9.5 (stock c/r) = 26cc (size of combustion chamber + head gasket)
319cc (1 cylinder, of a 1.3) divided by 9.5 = 34cc (size of same combustion chamber + head gasket + dish in piston)
so with a 319cc cylinder and the smaller 26cc combustion chamber + head gasket = 12.2 : 1 compression ratio ??
 
One more thing: The 1.0 pistons are FLAT, giving a 10cc differende between the 1.0 and 1.3 piston. But also than the cr. will be 11,8:1 Also the engine will be no 1275cc, but 1235cc. This less volume will also infect the power gain I assume. (perhaps this clears why my engine is NOT running lean with the original injectors??)

Hmm Young Nav was right! Or do we make a mistake calculating these numbers??





gr Chrismo
 
Chrismo said:
One more thing: The 1.0 pistons are FLAT, giving a 10cc differende between the 1.0 and 1.3 piston. But also than the cr. will be 11,8:1 Also the engine will be no 1275cc, but 1235cc. This less volume will also infect the power gain I assume. (perhaps this clears why my engine is NOT running lean with the original injectors??)

Hmm Young Nav was right! Or do we make a mistake calculating these numbers??





gr Chrismo
Click to expand...

no chris, the swept volume is still 250cc and 319cc (whichever piston you use) :)
 
I can't explain it, and I'm probably wrong, but something about franks maths doesn't make out the added stoke for the 1.3, as well as the dish in the piston.
 
I must say I don't think you're right about that, Frank! The hollow 1.3 piston has at BDC MORE cc as the 1.0 piston in the same engine! The difference is more or less 10cc.
 
swept volume remains the same the engine is still 1275cc! Their is actually 8cc in the dish of a 1.3 piston not 10. The head i have to go on my rally car has 24cc in the head and so does most of the heads i ve ever measured. All these figures i have worked out myself but all have been agreed by peter vaughn he is Mr micra man and used to build some of the NME engines and also engines for Geoff Jones
 
You are right again.....the stroke remains the same, so the volume too. But why is there almost no power gain noticeable in my CG13, with 1.0 pistons, NME (Peter V) cams and a flowed head? I don't get it!
 
Chrismo said:
You are right again.....the stroke remains the same, so the volume too. But why is there almost no power gain noticeable in my CG13, with 1.0 pistons, NME (Peter V) cams and a flowed head? I don't get it!
Click to expand...

i think you have a fundamental problem chris, you should have 100+hp with your spec (and a 0 -100kph of less than 8 sec,s) fwn

Manny said:
is the left the 1.0 piston?
Click to expand...

yeh, manny :grinning:
 
I agree with frank you should be seeing 100bhp and a big difference in performance. Will try and find my working tomorow aint got a hope in hell of working it out off top of my head not a chance of remembering the formulas lol.
 
Giving some more info about my mods: I have the oem intake, including airbox. And have a custom made exhause manifold, with I think, a bit too small pipes (28mm inside).

If above should be no problem, I truely start to believe the port-grinding I did is the problem! Why is it possible to run 12:1 at full throttle with standard injectors?



gr Chrismo
 
Chrismo said:
Giving some more info about my mods: I have the oem intake, including airbox. And have a custom made exhause manifold, with I think, a bit too small pipes (28mm inside).

If above should be no problem, I truely start to believe the port-grinding I did is the problem! Why is it possible to run 12:1 at full throttle with standard injectors?



gr Chrismo
Click to expand...

i doubt it,s the porting chris fwn,
with the headskim too, you should have a c/r of about 13 : 1 imo (and cylinder pressures of well over 200psi :eek:)
are you sure the cam timings are ok ? (post a diagram of the dipstick measurements like i did), and have you done a compression test ?
 
What RON fuel are you using Chris - are you sure that you ren't getting pre-igntion?
 
the stroke is the same which means the swept volume is the same (as frank said) but the 1.3 pistons have a dish and the 1.0 dont meaning if you fit the flat topped pistons in a 1.3 engine the cr will increase as the swept volume is being compressed into a smaller space as there is no dish in the piston any more.

figures/math

1275/4 = 318.75 cc swept volume per cylinder.

318.75 / 9.5 (current cr) = 33.55cc combustion chamber.

so if we go with the 8cc dish in the 1.3 piston, if were putting flat topped ones it we subtract 8.

33.55-8 = 25.55cc new combustion chamber with 1.0 pistons.

therefore new cr should be,

swept cc / combustion cc = 12.47:1

if we were to go with the 10cc dish that someone mentioned then the cr would be 13.5.

that is of course if the 1.0 and 1.3 pistons are the same height.
 
they are the same height as the outer skirt on the 1.3 piston crown is level with the deck at TDC. same as the 1.0 pistons.
 
The 773 cams are on it's way!

Compressioncheck is not done, but with new rings this should not be wrong.

Timingcheck done as you did (more or less), and checked the degrees on the pulley. These numbers where almost the same as the original numbers suitable with the cams.








Chrismo
 
on 773 cams i think you need to run timing at 22 degrees fully adavnced

Also make sure you run tidy fuel like V power with octane booster i suggest plutoline if running at those sort of cr's...... Then let her RREEEEEEEEEVVVVV
 

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