90 GTU engine compression?
 

Hi all. What is the minumum compression reading for a healthy 1990 Non-Turbo GTU Engine? In addition, the compression reading of my current engine is #1) 80 and #2) 95 How is this reading? Lastly, what is the recommended oil viscosity for the 1990 13B non-turbos?

shouldnt you post this in the 2nd gen tech forum?

If those are PSI numbers they are not that good.Even though they are lower than i like to see, They have too much diference between the two rotors compression. Is there any mass amounts of smoke comeing from the engine? My 90 GTU non turbo had 100= psi on each with over 110k miles . Then the coolant seal just let go on me on the way home at a stop light. As for viscosity you will probably get a million different answers here. I use 20w 50 VR1 motor oil. 10w 40 is OK as well. hope this may help. And you will probably get more responses in the second gen section. FWIW.

There is no smoking at all. However, I just bought this car and i seen, from a past repair invoice, that the car 's radiator hose blew out a few years ago causing the engine to become overheated. So maybe that might have diminished the engine's strength somewhat.

Yes, if the engine has overheated there is a strong possibility that some of the housings have warped causing bad compression sealing. Also when the housings get really overheated the metal actually gets hardened( turns the metal a blueish black color) which in turn weakens the metal .Usually if you/past owner noticed the coolant gauge move up it was probably too late for the engine( keeping it from overheating) Keep your fingers crossed and watch your vital signs,...( oil pressure ,aftermarket wtaer temp gauge,etc..)

I see, I will monitor it closely. The motor is smooth running, however, it just doesn't have a strong pull acceleration, only in lowend power.

If it only feels like it pulls in the lower Rpm's then here is a situation I had that was similar......Have you checked the operation of your six port sleeves? They operate off the Airpump on the S5's. If you have removed the pump you need to either remove the six ports and the Variable valve in the upper manifold by the throotle body,,OR Wire them open. My engine did not pull hard either in the upper RPM's. I looked into the six port system and how/where it operates from. The hose off the back of the airpump had come off and was not feeding pressure to the six port actuators or the one in the UIM.( And related system components) The six port actuators are located above the exhaust manifold, next to the Air Control Valve(ACV, Emissions) The solenoid valves by the oil filler neck control the operation of the system Get a Factory Service Manual if you don't already have one and familiarize yourself with the components. Then order some gaskets and pull the intake manifolds and inspect all the vaccum hoses and connections and such, Sometimes the six port sleeve's can get carbon build up and other sludge that will keep them from opening even if the rest of the system works properly....( Of course this is ONLY if you are haveing a problem with the system.!!)Hope this may help and I'mnot sending you in the wrong direction. I ended up removing the airpump,six port sleeve's and all emissions crap since we don't have smog rules here. Idles a little rough but runs really nice up in the RPM's