Compression

[ThompsonRacing17]

hi i have a 1g eclipse with the 4g63 2.0 n/t ... i bought this car for a dirt track car and its race ready... it sounds really mean and we did a compression test and the compression is 250 psi... i was wondering if that is really good? or what should it be to be considered as "high compression" pistons say "63dM". any help would be greatly appreciated... note... in my division your suppoed to be stock... i know 250 psi cannot be stock...

On the top of my pistons it say 63dM... are these stock or?? Its a 4g63 n/t

 

[iwillnotbleed]

Way over. If I remember correctly a stock n/a runs around 180 psi.

 

[ThompsonRacing17]

What kind of work could possibly be done to get 250 psi?

 

[BogusSVO]

Milled head, decked block, bigger cams, tighter centerline of the cams (less over lap) A smaller CC cylinder head, flat top or dome pistons. Stroker crank.

Just to name a few.

If you are supposed to be stock, pull the VC, and check the cams, there should be a large letter on the cam just behind the #1 cam journal.

Also check the back of the head and see if there is a casting number.

 

[sauminator]

OK so most likely its got alot of work...?

Was there any indication of such from the previous owner?

 

[Pauls99Gst]

Have you seen this compression on a gauge for yourself or is this someone's word? Don't believe it until you see it.

 

[northernawd]

If you didn't witness the compression test or didn't do it yourself. Than do one yourself or ask the mechanic to perform one infront of you and show you the numbers on the guage.

 

[BogusSVO]

This is your 3rd thread on the same topic, the 2nd with an improper title.

I have responded in the other thread you started a couple days ago.

 

[DSMnoobsause]

Reading the guage wrong?

 

[BogusSVO]

http://www.dsmtuners.com/forums/newbie-forum/451825-compression.html

You have not gone and looked and posted the info I asked you to do in this thread....

http://www.dsmtuners.com/forums/newbie-forum/451825-compression.html


Here is the first thread you started on this topic.
http://www.dsmtuners.com/forums/newbie-forum/451777-need-help-please.html

 

[boost97gst]

What the hell? What kind of pistons do you have? Didnt know they made that high a CR. You must have 11:1s or something really high.
Mine is at 180, stock CR 2g mahles

 

[Cdc1221]

What kind of fuel is this thing running? Diesel?

 

[BogusSVO]

http://www.dsmtuners.com/forums/newbie-forum/451841-63dm-pistons.html

Sounds like he has the stock pistons, from what I have read in the above thread.

Just guessing, I would say the head has been milled way past min spec.

 

[JusMX141]

Merged all four threads you started on the exact same topic into one. Please only start ONE thread per topic.

 

[ThompsonRacing17]

No its not its a dirt track car and most the fast cars got about 165 horsepower. I'm hoping to beat that. And I doubt just shaving the head would give me that much compression. And I don't think whoever did the work would put the motor in jepordy by shaving it that much seeing how its raced every Saturday

 

[BogusSVO]

How do you know that the head has not been milled past min spec?

Have you measured it?

http://www.dsmtuners.com/forums/cyl...how-measure-4g63-cylinder-head-thickness.html

Or they may installed a Huyndai cylinder head from a 1.6 or 1.8 that has a smaller combustion chamber.

 

[undefined0000]

What kind of fuel is this thing running? Diesel?

Literally laughed when I read this. I'm wondering now if that would actually kinda work. Run the car on gas for a while, heat it up. Drain the tank, diesel it up, disable ignition and go. .

One of the many things I've wanted to do to a car.

 

[ThompsonRacing17]

By the way. Pretty cool u live in Pensacola.. I was born in fort Walton and spent most of my life in Crestview! Small world!

 

[BogusSVO]

I have been in Pcola since 1986.
I do machine work for those along the Gulf Coast.

If you will go look, and maybe get a few pics of what I have asked you in the posts above, I may be able to help you figure why you have compression in the 250psi range

 

[undefined0000]

Cdc was right:

http://www.waybuilder.net/sweethaven/MechTech/Automotive01/default.asp?unNum=2&lesNum=7&modNum=6

"Diesel engine compression readings average approximately 275 to 400 psi"

 

[Cdc1221]

Cdc was right:

http://www.waybuilder.net/sweethaven/MechTech/Automotive01/default.asp?unNum=2&lesNum=7&modNum=6

Lmao he could put a hx40 on it and call it a 4g6what cummins?

Literally laughed when I read this. I'm wondering now if that would actually kinda work. Run the car on gas for a while, heat it up. Drain the tank, diesel it up, disable ignition and go. .

One of the many things I've wanted to do to a car.

In all seriousness though, i doubt that would work on a stock 63 rotating assembly. They already fail miserably when knock occurs. A diesel engine is knock city

 

[undefined0000]

Lmao he could put a hx40 on it and call it a 4g6what cummins?



In all seriousness though, i doubt that would work on a stock 63 rotating assembly. They already fail miserably when knock occurs. A diesel engine is knock city

You know more than I do when it comes to that aspect. I'm just now learning gas, don't know more than the basics about diesel . I'd have to tear down a volkswagen TDi to see what the differences really are. I really am interested in how his compression is that high. Its kind of impressive.

 

[Cdc1221]

Yea im just wondering what its running on. Would have to be straight meth. As for a diesel, to do the conversion would involve machining a cast head for a set of diesel injectors where the plugs normally go, setting up an injector pump, locating the glow plugs in the head. Diesels inject the fuel after the intake valve is closed, when the piston is already coming back up on the compression stroke so that it takes in as much air as possible on the intake stroke

 

[undefined0000]

Yea im just wondering what its running on. Would have to be straight meth. As for a diesel, to do the conversion would involve machining a cast head for a set of diesel injectors where the plugs normally go, setting up an injector pump, locating the glow plugs in the head. Diesels inject the fuel after the intake valve is closed, when the piston is already coming back up on the compression stroke so that it takes in as much air as possible on the intake stroke

Basically A LOT of work. I did some reading up on diesel engines a while back, just out of curiosity on how they can run 60psi without exploding.

What would be ample pressure for gas to detonate at full operating temperature?

 

[Cdc1221]

Basically A LOT of work. I did some reading up on diesel engines a while back, just out of curiosity on how they can run 60psi without exploding.

What would be ample pressure for gas to detonate at full operating temperature?

Too many x factors i would think. But that would definitely be worthy of a write up for the tech articles if someone could come up with an equation. Say (x)Crx(y)xIATx(z)fuel amountx(a)mass air