Grizzly

What should the Compretion be on a 90 T2?

I think my car is in need of a rebuild, between 40-60psi and 105 max on the first rotor and basicly the same on the second?

When i turn it over with the plugs out it they make one loud noise and too quiter ones. this to me sounds like Tips?

I am having problems starting it as well but the odd thing is yesterday i did the same test and they where all around 60psi and 100 max, today there seems to be a bigger drop.

Does this sound like tips?

SaabGuy

Try the ATF trick before it really busts
BTW I'm following you!

My rx7 is sitting in ATF right now

SaabGuy

What are you using to test the compression anyways?

Erik

i'd say anything above 90 psi is good...

Grizzly

Is that per Compretion stroke or Max?

HAILERS

http://teamfc3s.org/info/articles/compression.html

Grizzly

yeh i know how to do the test its the results that get me.

Does it make alot of diffrence when the engine is hot and cold?

I dont get why i cant get the indvidual readings over 60 spi but the max is over 100 does that mean its ok or not?

HAILERS

Results are crummy. Engine should be HOT. The pedal fully depressed. You should get 6.0 kg/cm, 85 psi at 250 rpm... The differential limit of chambers: 1.5 kg/cm, 21psi at 250 rpm. That was out of the fsm that is online at http://www.iluvmyrx7.com/Technical_I...ice_manual.htm
Well, maybe not crummy, but suspect. Like it says, a minimum of 85 psi, and they are talking all three sides of the rotor, and without a differential of 21psi b/t the faces. But like Six Rotors says and the book implies with a graph, the rotation speed makes a bit of a difference. But that isn't going to make up for the difference b/t the faces. Have a fully charged battery and a fully warm engine with the throttle wide open. The thing must be idling a little on the rough side or at least irregular.

Grizzly

Its genraly playing up, the idle is set to 1000rpm and it seems to be smooth it does'nt misfire (when its warm). The main problem is it is hard to start if left for more than 10 minutes.

i have done the compretion test quite a few times and ever time its diffrent, is this usaly the case?

Do you have to remove both of the plugs on the rotor you are not testing or will just one out do? and would it make much diffrence it takes me 5 minutes to move the tester to the other rotor?

Grizzly

Does this sound daft? i have just been told that my car might need an oil change? the idear is that if the oil is old and thin it will reduce the compretion as the oil is less efficant.

I personly would'nt think oil would make that much diffrence it is low (on the min mark) but surly it still has oil to pick up?

Grizzly

Does it make much diffrence what Compretion Tester you use?(does it have to have the valve removed?)

Can i leakage test a Rotary?

HAILERS

Yo. That article that I pasted says take the valve stem out of the hose, then screw it(the hose) in the hole. I take both top plugs out at the same time, and have taken both lower plugs out in lieu of the top plugs. I can't see any difference whether the two top plugs or the two bottom plugs are taken out. So I'm saying take the top two plugs out, put them on the table, screw the compression gauge hose into one hole or the other, and have someone crank the engine while you watch the needle bounce up and down. You watch the needle at its highest point, on each pulse. They should all be within twenty psi. Hot engine or at least warm. Oil change? I sorta squinch my face up when read that, but what the heck, can't hurt is the way I look at that idea(doubt if it helpe either). Maybe your engine is not as I described before(crummy). If you have no one to help crank the car, you can take that BLUE connector hidden down below the trail coil assy, and pull the jumper off it, and insert a wire into the BLACK AND WHITE wires socket, and touch the other end of this new wire to the positive terminal of the battery, to spin the motor while you hold the compression gauge in the other hand.
http://teamfc3s.org/info/articles/compression.html

Grizzly

yeh what i was trying to say was i dont know what speed the thing is turning at (250rpm) if i took both plugs out of the other rotor would'nt it help release the compretion quicker to help it turn faster?

I have removed my Valve but the tester i have is oil filled and does not react that fast my pal has on that is the nads but he wont let me take it apart (hence the Question).

Tomorow i will do the test again doing it to the letter. change the oil get it red hot then do the test, No Puffing about this time.

Does the ATF trick work?

HAILERS

I think I forgot to mention to disable the fuel pump and the ECU. Either pull the fuse in the engine bay or pull the white plug off the cas. Don't wanna get shocked but even more important, you don't wanna be injecting fuel into the rotor housing while doing a compression check, and washing the rotor seals with gas.
I've never done the atf trick. I do have an opinion about it. Mom said if you don't have anything nice to say, keep your mouth shut. I be quiet. Keep mouth shut.

Grizzly

Right its a last ditch atempt to save your engine (and lots of cash?)

Looks like i'm going there AGAIN!, sorry this is suppost to be the reliable one that had an engine rebuild 10k ago, you would expect a Partail bridge running 450rwhp to be more of a problem would'nt you? (aaaarrrrrr thats it blow that too now B****H.)

Grizzly

HAILERS i take it you are an Engine builder or somting related to Rx7'ns i own 2, done loads of work on them and i could'nt tell you what colour the wires are on my car let alone anyone elses? you realy do know your sevens.

Thanks for the Help.

HAILERS

No, just a owner of three FC and just trying my dead level best just to be able to get to work on time and back home. Got the 87 factory manual with the wiring diagrams in the back. Similar to the 88 manual that is on-line, except better. It helps(?????) to own a car that has had every conceivable problem asscociated with RX-7's. Found out I like to rebuild rotary engines. Six Rotors and Irv taught me 90 percent of what I understand about acv. Article by Paul Stoakes showed me everything I know about BAC, man's best friend. Just a hobby. One engine failure. Water seal groove collapsed resulting in a air cooled rotary engine. Ego collapsed at the same time the engine went, until I took it apart and saw what the problem was. Partly my fault for not seeing the corrosion when I did the rebuild.

Turbo Timmy

it's spelled compression

compretion is what the japanese masseuse gives you at the end of a session.

Grizzly

Thanks for puting me right?

Grizzly

Yeh looks like i'm up for a rebuild to, my cars compression seems to be between 40-70psi per rotor.

When you rebuilt your did you do it for power or just to fix it?

I have lots of Gen 3 bits knocking about so i'll proberly street port it and fit Third gen rotors and Housings. Do you think its worth fitting Stantionary gears too?

Turbo Timmy

I guess you didn't get my joke... o well

FJ

Maybe he didn't, but it made me grin.

-John.

Grizzly

Sorry i'm very slow once it gets late on? Yeh dont worrk it took me abit but i got it.