I some cases. However I have several cars in the shop right now for rebuilds where that does not hold true. One is a single turbo that starts good cold, will lay down 400 on our dyno but will not restart hot since the compression is around 60psi per face. Another is a low mileage twins car with a one chipped apex seal. Just because a car starts and runs does not mean the engine is healthy.


Nice work on the spreadsheet Arghx.

 

None of this is of much comfort to those of us with no access to any sort of compression tester in our home state/country. Even my Mazda dealership doesn't have anything, and if they did, they would not be allowed near my FD.

The compression testers I've seen online that are reputable, cost an arm and a leg, let alone currency conversion and then monstrous international shipping costs worth more than the price of the unit itself.

I'd be all for someone making a cheaper compression tester that was easier to acquire. I said that ten years ago but still in the same boat today.

 

They don't have basic compression testers at auto parts stores there, that you could use on say a small engine?

Of course, here I am being an American and assuming auto parts stores are a thing in Australia, when in the US they are on every corner. Why not Order off Amazon? Here I am assuming that Amazon has a local division for you and doesn't charge international shipping...

 

The old school approach is still a great way to determine engine health.

If it idles at 700 or 750 flat and even with good vac when it's hot (like 90c and up) it's a good engine.

 

Pretty sure different types of ported engines run differently though correct? Most engines in these cars are rebuilt nowadays and alot actually get them ported since they are apart. How would you even know the type of port when it is in and running? And then you never know about small vacuum leaks to throw off the vacuum readings.

 

FYI, my company makes a great Rotary compression tester, with a quality sensor, cranking indicator and rpm.
I ship these all over the world.

 

Nice looking product!

 

Filling a hole in the market for sure

 

The motor must also be warmed up to get an accurate compression reading. A motor with fatigued seal springs will often compression test in spec when cold, then read low once warmed up. We only use the Mazda OEM tester in my shop. I've used others over the years and found the Mazda tester to be the most accurate and reliable.

 

have you tried rotarycompressiontester system? without actually data I'd hate to say other units aren't as accurate

 

I've used just about everything out there, way back to the original mazda tester that had the thermal paper. I'm not saying that some of the aftermarket testers are bad, I just have had the best results with oem.

 

Thanks, I have worked hard to make it the best product I can.
Here is another unit with new LCD, getting ready to ship.



Here in the near future you will be able to choose how you want your results displayed I'm having software written for each.
In PSI, Kg/cm like Mazda tester or some have asked for bars.
Also working on a new board design with Bluetooth so it can be linked to my compression calculator app I have a couple Purdue university engineering students working on.

 

Some of us down here in Houston have made our own units for about $200.
I went one step further and purchased a very accurate mechanical pressure gauge to calibrate my pressure regulator pressure output to my unit.

See attachment for parts.
They now have a faster logger for a little more in cost with USB outputs.

 

MIne don't ever need calibrated, software was written to match our high performance sensor.
I have a dial gauge I check every sensor with from my manufacturer.

 

People keep asking me which plug hole to use. Mazda says Top plug hole, does it really matter?
Here is a pic of one of my compression testers sensors plugged into the leading plug hole and one in the trailing plug hole on the same rotor.
Same crank cycle and same Rpm, within 1 psi difference between the two plug holes.
Was testing some units and thought I would share.
I will have RCTV5 Digital handheld rotary compression testers in stock the coming week.
Steve

 

you can build your own with a dataq logger and a 150psi transducer for about $75. it does require a laptop though and calculating the engine speed by the graph manually, for those who are complaining about access to these testers or prices.

took me less than an hour to build my own shop tester and calibrated on the nose to 100psi with my shop air supply.

 

My RCTV5 wasn't hacked together in some garage with misc. parts.
It was developed and tested over an 18 month period.
The V5 is actually the 5th version designed before ever being released to the public.
This was developed by an engine builder and drag racer.
This was engineered on his own Rx-3
1000hp (4) rotor, semi peripheral port, twin turbo methanol burning 4 door. Video of car running on my Facebook page.
So accuracy was his main focus when developed and easy operation.
No laptop needed, no sensor adapter causing dead volume.
He designed this to take to the drag strip.


Been tested against TR tester, Mazda tester by some of the best engine builders in Australia.


There are dozens of race teams and Rotary shops all over the world that use my tester.
Software was written by Classified Performance in Australia, he also writes ECU software for Factory race teams.
All electronics are done by Custom Circuit Board Design - Excel Electronics Inc
Then I final assemble and test both testing unit and sensor on 1 of my 2 Banzai Racing rebuilds in my 7 and 8.
Chris and Elaine rock!



Bluetooth version able to connect to my own compression calculator app is coming in the future for iPhone and Google play.

 

just simply stating for those who couldn't afford your prebuilt kit or who enjoy building things themself.

 

If a DIYer can't afford this pre built kit, then they need to sell their car and use public transportation. Now building their own because they like that sort of thing is something else.

 

in all honesty i like my tester, as it gives me a curve of all the pulses and can even pinpoint a intermittently sticky seal or variations on even a single chamber. uneven pulses do happen and can show a potential problem and cause.

the thread about building a digital tester was actually here in the 3rd gen section already.

 

Sorry I wasn't trying to be rude in anyway.
I should of started my reply differently,
I would of been one of the people trying to build what you use. I always wanted my own in the past.
Just trying to pass on some info.

 

it's alright, we all get defensive when there is an investment involved. just mentioned it for those who like to tinker with electronics and there's more than a few around here. your tester is good for those who don't have the time, knowledge or patience for such things. it's nice and portable and quicker and easier to use, i run mine through a laptop since it really is more of a datalogger so it's not always practical for something like checking compression between racing runs.

 

The original Mazda tester was mechanical and designed to use the trailing plug holes.

The electrical ones will read a little lower pressure from the training holes due to the small opening for the pressure to flow through. I use the leading holes as they give a 100% actual response to pressure change.

 

I was just curious that's why I asked what the deal was.
The pic of the two testers above was because I wanted to see the difference between the leading and trailing, same rotor on the same crank cycle.
I hooked up 4 sensors and testers the other day and tried them all at once just for fun.

This is easy enough to use if I disable the ignition and fuel. Put in the sensor, that my 7 year old boy gets a kick out of taking a tester out and helping me test it.
I tested a 04' Rx-8 6 speed with 120k original motor, upgraded starter, and Sakebomb coils and wires.
With compression of mid 70's on both rotors that still started in less than 2 seconds.

 

^Hmm seems it's a perfect time to rebuild that Renesis before something actually breaks and causes more damage. Them apex seals are gonna be short. That's just me though.