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Discussion Starter #1
I am in the middle of an engine rebuild on my 85 and I can't seem to find any good info on the 5MGE. I have done some measurements with a graduated cylinder and clay on the piston but I just wanted to check and see if anyone had these numbers or has done any measuring so we can compare numbers.

Serviceable limit (How much material can I remove) on the Cylinder Head or Engine block? ( I have seen 0.006" for cylinder head, but that seems tiny)

Piston Dish/Dome volume (measured about -1.5cc)

Combustion Chamber volume (measured about 50cc)

Factory gasket thickness (1.2mm or 0.047")

Piston to valve clearance (measured between 0.110" exhaust and 0.105" intake and this was with a 1.4mm or 0.055" head gasket)

These numbers are usually not that hard to find on other engines, but I guess that's what makes the 5MGE so special!
 

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Have you looked at the engine section of the online TSRM yet???
 

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Discussion Starter #3
Yeah, I have looked throught the EM section and the EM portion of the Service Specification section and I don't see any of the numbers that I am looking for. It does give some specs on warpage, but that seems to be about it for the cylinder head and the block surfaces.
 

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See previous post from him. No help here, he already looked.
 

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Sounds like you've figured out some of the "race engine" info. that's missing in the TSRM. :lol: :good: Now all you/we need is the specs. for the stock valve timing and cam profiles. :cool:
 

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Discussion Starter #7 (Edited)
Well, I wouldn't take any of the numbers I posted as exactly accurate. I am going to repeat the combustion chamber volume and piston dish/dome volume measurements so I can validate the first round of measurements. I am preparing the supra for scca ITS and there is a very detailed set of allowed engine modifications. The one I am working on at the moment is raising the comp. ratio by 0.5. I don't think it is going to take much to do that but I don't want to raise it more than the allowed amount and I also want to keep the valves from hitting the pistons. So if anyone else has any of the measurements it would validate my results.
 

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Discussion Starter #8
If anyone is interested, I repeated the combustion chamber volume and piston dish/dome volume measurements.

Combustion Chamber Volume = 52 cc

Piston Dish/Dome Volume = -3cc

These numbers are for a stock 5mge.
 

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Hi Russell,

I am very interested in these numbers.

I have been measuring the intake manifold plenum volume, runner volume, head intake volume, head exhaust volume to see about how efficient the intake manifold is.

I have been planning on measuring the combustion chamber volume, but have been busy with doing taxes.

Unfortunately my engine seems to be the 8.8:1 motor so I won't be able to do a direct comparison. I don't think that the head combustion chamber shape/volume changed, but who knows.

I've never cc'd an engine before, so I would like to know how you are measuring it.

How have you been sealing the valves when cc'ing the head? How have you been sealing the rings when measuring the piston top volume?

When measuring the piston/dome volume are you measuring with the rod/piston on the crank? I'm assuming that with the higher compression piston you have a significant pop-up so that the head may stick up above the block deck height. How do you handle this?

On my 8.8:1 motor, the piston is almost a flat-top with valve relief cutouts and the gap between the piston and the combustion chamber wall down to the top ring being a positive volume. Without assembling the motor yet, I assume (that word again) that the piston stays below the block deck so that measuring the volume is not too hard.

I'm not questioning how you're doing the measurements, I just want to be able to duplicate them.

Regards,

Dale
 

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Discussion Starter #10
Dale,

I learn something new everyday about the proper way to measure engine volumes, today I learned a recipe of ATF and mineral spirits is the best fluid to use....who knew. So my particular way may not be the best but it is getting more repeatable.

Combustion Chamber:

use the cam pulleys to actuate the valves out of the cylinder head
take some grease and apply it to the valve seat (just enough to make a seal)
actuate the valves back to their seats
apply a ring of grease around the combustion chamber and place a piece of clear plexi glass over the combustion chamber
the plexi glass needs a whole in it so you can add your fluid of choice (I used water with a little dish soap in it which breaks the surface tension)
I use a 100cc or 100ml graduated cylinder to measure the fluid
I start with the cylinder at 100cc and then subtract whatever is left over from 100 to get the volume of fluid that filled the combustion chamber

I forgot to put grease on the valve seats last time I measured.

The pistons on my 85 have a small dome and two valve reliefs.
The piston flat portion is basically at zero deck, flush with the top of the block.

To measure the piston dish/dome volume: (I still had the short block assembled)

Move the piston about 2 inches into the bore
apply a ring of grease around the bore just above the piston
move the piston up so the rings catch the grease and create a seal
I left my piston about 0.24" below the top of the block, that number doesn't really matter as long as you know it.
then apply grease on the top of the block around the bore
place the piece of plexi glass on top of it and make sure the grease seals to the plexi glass
Use the graduated cylinder and find out how much volume you have

Then use the 0.24" and the bore to calculate the volume of a cylinder (basically what it would be if you had a flat top piston)
Then take your calculated volume minus your measured volume and you should have a good idea of the dish/dome volume.

There are probably better ways to measure it, but this is how I found those numbers.
 

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Russell,

That makes perfect sense.

Okay, what is the recipe for the ATF and mineral spirits?

On the aluminum head it probably doesn't matter, but in the block I can sure see the advantage of not using water.

I won't be doing it today, but I'll try to get some numbers within the next week to compare to what you have.

Dale
 

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Discussion Starter #12
I don't actually know yet, I just mentioned how crappy water is becuase of the surface tension and its amazing ability to form air pockets and he just mentioned the ATF and mineral spirits thing, I was in a hurry so I didn't get the ratio. I will get the ratio from him probably on Friday.
 

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This kind of stuff should definitely go in the FAQ when measurements are completed. Great job.
 

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rwhite said:
If anyone is interested, I repeated the combustion chamber volume and piston dish/dome volume measurements.

Combustion Chamber Volume = 52 cc

Piston Dish/Dome Volume = -3cc

These numbers are for a stock 5mge.



What spark plugs did you use when measuring the combustion chamber volume? The stock heat range ND/NGK's, or something different??
 

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Discussion Starter #16
I talked with the guy at work about the mixture of ATF and mineral spirits for cc'ing the combustion chamber. He said something around 70% ATF and 30% mineral spirits will work just fine. He said it doesn't need to be exact, so just more ATF than mineral spirits should work just fine.

The spark plugs were Bosch Platinums WR8DPX.
 

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hmm, i wonder if there is an effedtive way to cc the domes on my forged slugs without them in the block. any ideas? thy are 85mm pistons so id have to get a block bores before i could use the mentioned method. im sure there is a way without using the block. any ideas?
william
 

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Discussion Starter #18
I haven't tried it, but if you have a piston ring compressor you might be able to get a decent measurement. I have one from sears and it fits pretty tight around the piston. Just put some grease around the rings to try and seal it and then measure how far the flat part of the piston is into the ring compressor and give it a shot. It may be hard to seal the top though..... The other way I had thought about measuring only the dish part was to fill the valve relief’s with clay, let it set up and then take the pieces of clay out and put them into the graduated cylinder and see how much the water level goes up. Just an idea.
 

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good idea, and ill then spray it down with pam while the clay is in the releifs, and use clay around the dome and let it harden then measure the volume, then subtract the releifs from the volume of the dome(its a pretty big dome) thnx.
 

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you can also check your measurements by weighing the clay X its density to give a volumetric value to get the density # just force some clay into a know volume cup like ones used for baking and then weight the amount and dived one by the other you could also do this with candle wax by melting first of course

brendan
 
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