When using JDM ITR pistons with a gsr head, is the quench area much too little? Would USDM ITR pistons be a better choice with a gsr head?

 

I dont think there is such a thing as too little a quench area. It can be shaped incorrectly or be too little in spots but as far as total quench area the smaller the better. The combustion chambers are not too different from GSR to ITR so as long you should be ok.

 

It would be the same with both pistons pretty much.

 

The reason I ask is because I noticed that my car pings at low rpms. I have the JDM ITR pistons in my gsr. Is the CR too high for 91 octane?


[Modified by lopey, 10:46 PM 1/4/2003]

 

JDM ITR pistons in your motor should give about 11.4:1 CR.
I would look at either tuning, or poor a/f mixture(ie contaminatoin from oil etc)

 

If you have ping problems that are really ping problems I would look at the fuel you are using and timing settings you have first. If those are in order you have other issues my friend

 

Not so fast there buddy.
the combustion chambers between the C1 and C5 are quite different indeed.
The C5 uses a perfectly round shapped chamber while the C1 uses a round chamber that has been reduced at the intake and exhaust ends.
Kind of like this , but on both sides (_)

 

I was just saying they are not different enough to make quench area an issue. They are both from the same cast but the C5 has chamber qualities that cater to high compression and has better swirl characteristics. Piston surface would not cause the problems he's having either way. Sorry I didnt clarify.

 

They are very different chamber designs
They are NOT from the same cast
You need to do more homework before responding it seems

 

You are confusing the issue with trivial matters. The heads are all modified versions of the smae cast. I know this hurts your feelings but honda does not go re-designing every single head they build from scratch. The basic Bseries design head was modified to make more power and flow and then that head was recast into the ITR head. It really does not matter though because the head design and the combustion chamber design will not cause the problem this guy is having. Im trying to help him out here.

 

No. The ITR head uses a B16A casting. Its no different in design. Its only
difference is in the valvetrain and seat transition which is finished after the fact.
The B18C(1) cylinder head is a completely different casting that is not
related and was designed completely separate of the B16A/ITR.

 

Youre still missing the point.

 

No, they are absolutely, positively not from the same cast.
The B series heads started way back in 89 with the B16.
then in 93 I believe, Honda redid the B series head with the GSR (B18C1) engine. That head was a totally new head casting. The intake ports are different, you cannot bolt a B16/B18C5 intake manifold on a B18C1, and the combustion chamber was also a totally new design. It was built to better take advantage of the dual intake runner the B18C1 intake manifold uses.
When Honda raided its parts bin to make the type R motor, they went with the old B16 head, Why? I don't know.
They updated the valves, specially the intake valves which have a shaft with a narrower diameter near the bottom of the valve, and the head at first, was hand ported and polished. Later generations of B18C5 received a mechanical p&p.
They also use dual springs on both the intake and exhaust valves. The B16 only had them on the intake valves.
About compression, the C1 is better designed for high compression than the C5.
One of those paradoxes of life I guess.



[Modified by Spaceballs the lunch box, 3:38 PM 1/6/2003]

 

All that filler, and this bit went un-explained!

First one needs to define a "quench area", it's function, how to optimize it and why!

JMHO


[Modified by Zygspeed, 6:52 PM 1/6/2003]

 

Ok, here is an explanation for you.
Copied from theoldone.com. When the piston is compressing the mixture, as the piston nears the head, the flat areas on the head and piston come together and force the mixture from those areas to "squish" into the chamber, where the spark plug and burning mixture reside, so you achieve a more complete burn.
The quench area also runs cooler than the rest of the chamber / piston. These lower temperatures are where the "quench" comes from.
The C1 head has a better shaped quench area than the C5. you need to look at a picture of a C1 and C5 to really understand, it's hard to put into words.

I forgot I had this picture.
this is a B18C5 head my friend David welded the cambers to make the quench areas work better. the combustion chambers used to be perfectly round, but he added material on the top and bottom of the combustion chamber then shaped them to the shape you see now. The C1 head sort of looks like this but the C1 head goes straight rather than having the pointy parts you see. It is not rounded as the C5 head. On the lower part of the combustion chambers (exhaust) you can see the outline of what the chamber used to be like. Better now?





[Modified by Spaceballs the lunch box, 4:40 PM 1/6/2003]

 

I think youre being just a little naive if yo think that honda designed the GSR head from a blank page. It is most certainly a "Modified" version of the B16 head.

 

Sure buddy!

 

Believe what you want, the fact is the internal cumbustion engine is not new technology and any anufacturer no matter who it is doesn't just start over every time they need to redesign something. They take from what they know and build. Im not saying this to hurt your feelings its just the truth. I have been working for Honda for 12 years and I think I have learned a few things about how they operate.

 

How does it work better??? What's the theory behind the clover-leaf pent-roof design???

 

The reason is this.
when the piston is at TDC, there is too much space between the combustion chamber and the top of the piston in the stock engine. Ideally, that area should be as small as possible to help push/direct the mixture towards the center of the combustion chamber; where it burns more rapidly and evenly, since there is less wasted space for it to expand. This also helps to rise compression, thus power goes up.
What he did with the welding was to fill in that void.
Do some searching on the net, there is plenty of info about this.