anywhere to have compression checked that's cheaper than a mazda dealership?
really wondering if the compression of my car is off of what it should be and is affecting my hp.

 

Why not just go buy a compression tester at a car parts store for like $40?

If you are super cheap just remove your spark plugs and see how she sounds. If it sounds like a horse galloping down a driveway of mashed potatoes you have a problem.

Do you have cold or hot start problems or something? For an NA engine, it is not worth rebuilding because you have slightly low compression and may be losing 10 of you 140 hp. Sorry but, from the sound of this post and some of your past ones, doing your own compression test may be way out of your league.

GL,
~Tweak

 

lol damn, well at least your straight forward with the guy.

If you really feel the need to check your compression, explain whats going wrong with the engine/car. That is unless you woke up just dying to know what your engines health condition and need to know for curiosity

 

How much is "cheaper than a mazda dealership"?

I have a homemade one that was "cheap", but not too simple and it requires an oscilloscope.

 

DAMN oscilloscopes are just in everyone arsenal of tools? lol used em to measure sound, keep amps from clipping. never for auto work. thats nuts and thye arent cheap by a long shot...

could always buy a rotary compression tester i know a guy who knows a guy that makes them. for cheaper than mazda seeing as a mazda one cost $600. lol he can do it for a third of that. not that theyd sell you one anyways...


the piston counterpart somebody else mentioned isnt very accurate for testing all the faces of the rotor but it will give you a roundabout figure that can help. sort of...lol just divide by 3 i guess but definitely the cheapest route

 

A "piston" type compression tester will work JUST fine. What do you need to see, 84.764565 psi? 85 isn't accurate enough? It measures pressure through the spark plug hole, not piston, rotor, or jet engine specific compression. Hold the button down to release the air while ur cranking to see each side. Wow, you guys are really starting to worry me.

 

^...or take the schrader valve out

 

Been using piston tester just fine.

First reading without valve, to see if the compression is consistent.

Second reading with valve in, to measure the maximum compression.

 

never said it didnt work... but there are more accurate methods out there. but because cost is a factor is a viable solution.

 

i just want to know my compression ratio is 9.7 : 1
as my owner's manual explains is the correct ratio for stock conditions
tweak, it's an s5 so that's 160 hp and yea 10 does mean something to me if it's gone from poor compression

 

common man lets get real........

160hp rated to the fly back in 91'................dont think your even close to that number for hp now. ask if you dont understand what i just said.

 

i have no idea what you're talking about :/
never said i was the rotary god or anything but the motor was rebuilt by the previous owner and there's like 30k on it i think. right now i definitely don't have 160 probably like 120 or something by y pipe and mufflers are absolute ****, i haven't taken my car up past 5k rpm in a very long time because it feels/sounds like the exhaust can't take it so im just nursing it for another month until i get a tax return and can the corksport power series. after that i would really like to think it would be somewhere close to what it was in 1991, whatever that was...

 

If you are having a problem at high RPM look elsewhere than "exhaust not taking it" what ever that could possibly mean. Unless you literally have a kinked pipe it is more likely a sad fuel pump from weak voltage, or clogged sock, fuel filter, or spark plugs. You need to wrap it out every so often to avoid carbon building up then coming loose and chipping an apex. Then you will really need a compression test.

 

use a piston gauge type compression tester and get the fitting for the rotary size spark plugs. pull the 40amp fuze in ur fuze box and have someone turn the key. the needle will bounce on every face. gives u a decent idea of what ur workin with. if it hits 90. 30. 31. or sumthing u have a problem. if its consistant and over 90 ur engine still has some decent life.