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-   -   Lowest compression on engine you were able to get running. (https://www.rx7club.com/2nd-generation-specific-1986-1992-17/lowest-compression-engine-you-were-able-get-running-491589/)

idsigloo 12-16-05 01:15 PM

Lowest compression on engine you were able to get running.
 
I'm gonna be working on my car tomorrow to see if I can get running but it has low compression. Like 50 on back and 55 on front. Really shitty for a rebuild engine. Anyways, I'm wondering what the lowest compression engine you've worked on and were able to get running and how long has that engine lasted?

13b4me 12-16-05 01:20 PM

60-0-0 front
80-90-10 rear

Didn't run for long, but I was able to do a couple donuts in it... (87 TII) :D

bigdv519 12-16-05 03:31 PM

S5 Vert, with 189,xxx miles. I took it out of comission although it was in running order, but smoking on deceleration. Front ~70-70-70, rear ~65-65-65. The actual motor hasn't been taken apart, and it is sealed, so it might still turn over.

vaughnc 12-16-05 03:46 PM


Originally Posted by idsigloo
I'm gonna be working on my car tomorrow to see if I can get running but it has low compression. Like 50 on back and 55 on front. Really shitty for a rebuild engine. Anyways, I'm wondering what the lowest compression engine you've worked on and were able to get running and how long has that engine lasted?

Ok you listed the cold compression numbers, what's the hot compression numbers (using a ROTARY ENGINE compression tester).

RotaryRepair 12-16-05 04:25 PM

last month 0-0-0 and 0-0-0

This customers car had a little excess pressure buildup, oil covered the entire engine bay, and the exhaust ports were caked with wet oil deposits.

engine was only 30k miles old, all I had to do was clean clean clean, and replace the oil control rings.

idsigloo 12-16-05 05:21 PM


Originally Posted by vaughnc
Ok you listed the cold compression numbers, what's the hot compression numbers (using a ROTARY ENGINE compression tester).

I don't know yet, haven't started the car yet. Tried to start it but didn't work. Wasn't able to do much else, will be working on it tomorrow.

walken 12-16-05 06:16 PM

I had an s5 block with 63 on the front and 68 on the rear dyno at 210hp at 12psi, lol

KompressorLOgic 12-16-05 07:17 PM

managed to get my turbo II to start with 0-0-0 front and 75-75-75 rear, barly when its cold, hot it wouldnt start unless you push it down a big hill when hot.

i managed to get the car up to 100 mph took quite a while! , i hit 13 psi on 1 rotor!! haha my boost gauge was bouncing back and forth like somethin was gonna xplod!!

vaughnc 12-16-05 08:43 PM


Originally Posted by idsigloo
I don't know yet, haven't started the car yet. Tried to start it but didn't work. Wasn't able to do much else, will be working on it tomorrow.

Put 2 capfulls of ATF into the lower sparkplug holes, clean the plugs, trickle charge the battery for 2-3 hours and then switch your battery charger "start" mode", and then work the car starter on & off for 30sec at a time until the "oil film" is re-established (assuming it's a flooded compression, not Apex seal compression issue). Also I'm assuming your plugs, plug wires, fuel filter, fuel injectors, & gas-tank fuel strainer are good/not gunked up. Assuming you're getting spark on both leading plugs.

Schmitty 12-16-05 09:56 PM

Mine ran with 25-25-25 in the front and 35-35-35 in the back

BlueTII 12-17-05 06:19 AM


Originally Posted by vaughnc
Ok you listed the cold compression numbers, what's the hot compression numbers (using a ROTARY ENGINE compression tester).

Impossible to give hot compression numbers if he can't get the car started. Besides those are really low, when it gets hot they will only go lower. Most people do not have access to a rotary compression tester, a piston tester will give PSI or BAR and give a good idea of what is wrong.

You need to put some ATF or 2 cycle oil in the spark plug holes to see if you can raise the compression. Also make sure you have a strong battery, if it is weak the compression numbers will be lower due to decreased engine RPM.

Eternal_Gamer 12-18-05 01:52 AM

i got 75 front 50 rear

GoldRX-7 12-18-05 01:27 PM

car runs on 80 80 80
and 60 60 80


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