Recommendations, boring, ballancing

[Guest]

Called cometic today for gasket prices

The base gasket will have to be 1.60mm (0.063)

putting the piston in the hole by 0.25mm (0.010)

That was the closest option to the 1.45mm (0.057) I could get in coper.

The head gasket now needs to be 0.25mm (0.010) smaller to get the 1.5mm squish.

That makes it a 1.27mm (0.050)

I called JE pistons to see if its ok to dish out the center of the piston the 1.7mm.(0.067)

Didn't get a call back.

 

[TeamDar]

Should have bought turbo pistons. They come already dished.

 

[Guest]

Didn't have much of a choice for a 78mm piston. There were two on the shelf and I didn't have to buy a whole kit so I saved some money there. Everything else was much higher compression than these.

 

[GregT]

If you do need to gain more chamber volume, the side walls could be laid back to match the bore size or the diameter of the piston dish.
Don't touch the front or rear squish areas.

 

[7981GS]

You can also enlarge/make deeper the valve reliefs to drop a cc or two.
Especially if you are installing over-sized valves anyway.
I have had them cut .040 deeper with no problems. You can probably go deeper safely.

Eric

 

[Guest]

This how much area the piston will take up. There is room on the sides to loose a few cc's

Its 15cc's stock
I need to gain at least 6cc's

There is already 2cc's in the valve reliefs.
I need another 4cc's at least,

Do you think I could get that from the sides ?

With the deck height back to 1.25mm(0.050) I need to get at least 21cc's to get below 11:1

You can also enlarge/make deeper the valve reliefs to drop a cc or two.
Especially if you are installing over-sized valves anyway.
I have had them cut .040 deeper with no problems. You can probably go deeper safely.

Eric

Never thought of that How much meat is in the valve seats ?
Since these heads have a habit of cracking what effect would recessing the valves in the seats have?

 

[TeamDar]

You could connect the valve reliefs in the pistons. Make one long pocket for the intake and one long pocket for the exhaust.

 

[7981GS]

In your case, you could un-shroud those valve pockets quite a bit also and increase flow.

Eric

 

[Guest]

In your case, you could un-shroud those valve pockets quite a bit also and increase flow.

Eric

Do you think there is that much room ?

You could connect the valve reliefs in the pistons. Make one long pocket for the intake and one long pocket for the exhaust.

I was thinking of just making a 67mm cylinder in the middle of the piston 1mm deep.
But now looking at the piston and valve reliefs and squish bands I would like to keep the triangles between the valve reliefs and just take out the material in the middle.

 

[7981GS]

Yes there is room. Look at where your valves are at the flat of your combustion chambers.

These, cannot be opened up any more as there is simply no room with these custom-made over-sized valves and pistons...

Those are for a 13.5:1 compression engine.

No, it will not run on 87 octane pump gas. LOL!!!


Eric

 

[ArttuH]

For example here are a couple of photos what I did for my 1150 engine to drop compression:

Just food for thought.

I guess that you can't gain much volume by opening the combustion chambers without re-shaping them completely. Though you have quite much material to remove on the sides due to increased bore size. So you may get few cc's from there. I wouldn't remove the ridges between the valves, they are there for a reason.

 

[Guest]

Just food for thought.

I guess that you can't gain much volume by opening the combustion chambers without re-shaping them completely. Though you have quite much material to remove on the sides due to increased bore size. So you may get few cc's from there. I wouldn't remove the ridges between the valves, they are there for a reason.

Thanks, Pictures really help

I just spent the last hour doing something like that on a spare head with a dremel .

Just doing the sides I managed to get 3 cc's

I agree with you about leaving the ridges in the center. this is one of the areas they crack.



Should I keep going and make the angle's sharper like the original design or keep it slightly tapered.

 

[Guest]

lol

 

[7981GS]

8.00 or a little under in the 1/4 mile (7.92 best). :twistedevil:

Eric

 

[Guest]

Very nice

 

[7981GS]

I lied.
This is the car that the engine came out of running...

http://www.youtube.com/watch?v=c49Wz4MWxM4

Eric

 

[Guest]

looks like its working good Eric


I was messing with the dremel and then I realized that there are more bits than I know what to use.


So what are all the bits designed for ?

Which ones would allow me to cut and shape aluminum the best ?

I've been using the small sanding tubes and small carbide tip for fine detail. Then I finish sanding by hand. ( all learned by trial and error on spare head)


What about polishing the combustion chamber when I'm done ?
(I started messing with the steel brushes bit)


How could I make both chambers the same instead of just by eye?



On the sides the transition is a sharp angle. Should I go for the same or just smooth it out so that its a gradual angle. In other words, should I make a bathtub shape or dome?

 

[Guest]

looks like its working good.


I was messing with the dremel and then I realized that there are more bits than I know what to use.


So what are all the bits designed for ?

Which ones would allow me to cut and shape aluminum the best ?

I've been using the small sanding tubes and small carbide tip for fine detail. Then I finish sanding by hand. ( all learned by trial and error on spare head)


What about polishing the combustion chamber when I'm done ?
(I started messing with the steel brushes bit)


How could I make both chambers the same instead of just by eye?



On the sides the transition is a sharp angle. Should I go for the same or just smooth it out so that its a gradual angle. In other words, should I make a bathtub shape or dome?

If it was me I'd employ the power of cardboard.

Make a template of the shape and use that to verify uniformity between the two cylinders. You can then measure depth at pre-defined points on both sides evenly as well to ensure the depth is the same.

Just my 2 cents anyway coz most of this stuff is going way over my head...

 

[gearhead13]

I find the carbide cutters the best for removing material. The pinecone shape is my favorite. The stone type wheels are kind of useless for alu because they load up. Sanding drums work good in different sizes and grits.

 

[mawg]

I've been looking into building a stroker motor for my car and have found some interesting things about quench and compression ratio and preignition. Quench is the distance between the flat part of the piston,excluding the dome or dish and the flat park of the heads combustion chamber.(the squish aeras) Apperently if the quench distance is about 1.1-1.2mm the engine can have a higher static compression ratio without detonation.So, here's my two cents worth.First, find a piston with enough thickness to be milled.Maybe you can use the JE's,how thick are they? You might have to go custon, witch are more expensive,but not that bad, maybe twice as much? .Adjust bottom base gasket for zero deck hight, use a 1.1-1.2 mm thick head gasket for the desired quench, and calculate the piston dish for the desired compression ratio,witch I'd keep to <11.0:1. the dish should not be round but shaped like an Altoids box, a rectangke with it's long side at the front and back of the piston where the squish aeras in the head are. Don't know what the dimensions should be but but the idea is to try to keep as much of the factory squish areas as possible. This keeps the TSCC design, witch I think works good,and avoids messing with the combustion chambers,witch I'd just polish and bowl port. Love this thread,can't wait to hear it run!