Compression Number Format

Reply Subscribe

Thread Tools

Search this Thread

02-26-02, 02:02 PM

Gir

Full Member

Thread Starter

Join Date: Nov 2001

Location: Utah

Posts: 183

Likes: 0

Received 0 Likes on 0 Posts

Compression Number Format

I am considering a 93 base model with sunroof.
The compression numbers the seller gave me are
Front: 125-125-130
Rear: 130-130-130

Ive always seen compression numbers in 6-8 never the hundreds. Is this a bad thing?

Reply Like

02-26-02, 02:42 PM

rynberg

Lives on the Forum

Join Date: Dec 2001

Location: San Lorenzo, California

Posts: 14,716

Likes: 0

Received 8 Likes on 8 Posts

The minimum compression is 100 psi at 250 rpm. Your numbers look really good depending on the measurement conditions (rpm and altitude).

Reply Like

02-26-02, 03:30 PM

Gir

Full Member

Thread Starter

Join Date: Nov 2001

Location: Utah

Posts: 183

Likes: 0

Received 0 Likes on 0 Posts

Cool I will find out what rpm that was run at
is 250 rpm the standard?

Reply Like

02-27-02, 01:11 AM

Nathan Kwok

Rotary Enthusiast

Join Date: Feb 2001

Location: Huntington Beach, CA, USA

Posts: 1,025

Likes: 0

Received 4 Likes on 4 Posts

Yes 250rpm is standard. The numbers you are quoting are in psi, while the Mazda manual lists them in kg/cm^2, so its a simple unit conversion. FWIW, 125psi=8.8kg/cm^2 and 130psi=9.1kg/cm^2. These numbers are extremely good considering the factory new spec was only 120psi or 8.5kg/cm^2. Maybe the rpm was a little higher, or you just found yourself a cherry engine.