I had a chance to meet a really cool guy. His name is John with twisted rotors... He is an Electrical Engineering student and has developed and is selling a cool rotary compression tester.

He sells the tester for about $250!!! Over $1500 cheaper than the mazda rotary tester..

Well I got a chance to give her a try on my rotaries......they should call it judge..jury and executioner... I had great news on one car....not so great on my other one.

Anyhoo... if you like...give him a shout! BTW he will be at seven stock selling these too! www.twistedrotors.com



OK here is the basic component...a magic box and a screw in transducer...



ready to test



Screw the transducer into your trailing plugs....make sure your ignition is disabled...floor the gas pedal and roll over for 5 seconds...



here is the front rotor on my 1980 SA22...shows all three pulses compression and the cranking RPM...cool



rear rotor.... all numbers good and even/equal



Here is where I wrote down all the compression figures for my 1980 SA22...all looks good!



Here is the bad news....my 1984 autocross racer has two weak pulses on the front rotor... Rear rotor OK...front has one good pulse and two weak ones... Wonder if I have a damaged apex seal...messed up corner seal or what???!! probably what ever the problem is causing issues with two pulses....since the one reading is consistently good, I do not think it is a housing issue....

What do you think??? I wonder if I do the seafoam trick if it might dislodge a stuck apex or something???? Car runs good and strong, but it could probably do better......

Ideas????

 

I had this in the "technical" section but it got moved here....still trying to figure out what is "non-technical" about my thread.....

Compression tester.....technical
Use of a compression tester.....technical
Results from the compression tester....technical
Asking advice why my compression is low.....technical
Asking if I should seafoam my engine or what to do to mitigate my low compression....technical

I am not one to nit pick but I am not talking about seat covers or the "f-stop" on the camera of the latest picture I took here....

 

Seafoam never hurts, so you can try that.

 

And nice tester! On your track car, are the front rotor's wooshes an audible difference between the low and high compression sides?

 

I will have to listen with a more discerning ear... I heard woosh woosh woosh out of the front....the tester shows it is weaker.... I tried the tester two times...got repeatble results..

 

That tester would be nice to have indeed. I'm going to talk with OGTA and see if we can get 6 or 8 folks to go in on a group buy!

 

yes, very noticeably sound difference.

 

Cool...let me know.. I can help to work out the details with him. He is part of our local RX-7 club of Houston.

 

worth a try. maybe a broke seal that has yet to be puked out.

 

yeah I will try the "old school" tricks with seafoam, marvels etc. car runs good.... I would like to get the compression better...if not, I will dig into the engine next year...

 

prpb a dumb idea but it would be bad *** if one could find a way to havihg it working at all times like while driving it would be pointless but cool

 

Just stumbled on this thread, thanks for the kind words Old School! My .02 is a cracked or chipped apex seal on that front rotor in the autox car. But some bad carbon might do the same thing. I have more experience with turbo engines, so I'm used to seeing broken parts.
While developing the TR-01, I pulled apart a 13B-REW and ground a mm off of the corner of one of it's apex seals. Stuck it back in, closed the engine up and turned it over. Very very noticeable difference. I'd have to look at my old records to see, but it was surprising to see what that little damage did.
As for why your thread got moved, the only comment I'll make is: helpful and technical information be damned, it all comes down to money.
-John

 

John...UPDATE.... the last time we had the RX-7 out autocrossing, scott and I drove the dogfuck out of it..... I then did the FULL seafoam treatment and went out and drove the car hard on the highway...

Brought the car back and the compression ratio is FINE now.. The front is basically what the rear is now and she is really running strong!!

I think I possibly had an apex or a seal stuck... Maybe the seafoam is a miricle worker!!!

BTW John, I know what you mean about the "technical/money" thing you are talking about!!! I kinda thought this was one of the MOST technical posts in a while....shows what I know....

 

John: I have thought of building one of these for myself for the past several years. I think it would be a cool project. I would just buy yours, but I like to tinker with stuff like this.

Just wondering if this is AVR based or PIC or something else. I was planning to use AVR for mine. I have a been of an electronics background, but most of my education has been mechanical/nuclear engineering. Electronics has been more of a hobby for me. This is why I didn't want to get a career in it because then it would be work instead of fun. It seems as everytime I want to pick this project back up, something else pops up and takes all my time. I have only minimal experience with microcontrollers and such, so it would be a good learning experience for me. Hopefully I can ask you some coding questions if I get hung up.

Looks like a good product and well worth the cost. I'm really glad that you are making these.

Kent

 

If i had spare money i'd love to get one of these. Overall great invention!

 

Also don't forget Old School when doing the test to pull the fuel pump fuse also. You don't want to be dumping fuel everywhere

 

Thanks for the heads up...on a carby car the fuel still stays nicely in the carb and just bypasses back to the tank (nikki)

But you are 100% right for all the folks running fuel injection....

 

GSL-SE addict.... I may be speaking out of line, but John put a lot of effort into this compression tester and is now selling them..

Asking John discrete details about his tester might be like Iran asking the United States how to enrich plutonium better....

At the ridiculous low price he is selling these at, it is way worth it to buy one and enjoy a perfected tool!!

 

Last time I tinkered with the idea of making something similar, I found that the appropriate pressure transducer by itself would cost about half what these complete units are selling for.

 

Thats what I found as well. Just wasn't worth my time. IIRC the chip isn't a PIC. I want to say Motorola but I can't remember.

 

great tool and an awesome saving!

 

Same here. My brother used to work as a nuclear reactor operator (ET Nuke) in the Navy and now works as engineer with emmisions on big non-nuke powerplants. He said the same thing about the transducer being about $125 for the pressure a rotary motor would require. It would be neat to build my own, but for the price, a pre-built one is the way to go. Plus, I bet he's has some sort of warrenty.

 

At the vary least, he's got the "We know this design actually works " warranty that you never get with a DIY job, until it's all done!

 

I'm not asking that. Just curious on what it is based off of (AVR, etc.). There are a whole bucketful of microcontrollers that could do the job. Saying the type does not disclose anything. They have to be programed and that is where the work is involved.

I wasn't saying to give me his code. If I ever get around to building one, I was just hoping I could say "Hey, this is how I wrote my code. Does this look good to you?"

I know it is a good deal and I know he spent a lot of time. I would still build it myself because I am a hardcore DIY type of person. I figure that everything you do yourself is a leaning experience and it is hard to put a price on that.

Oh, and Pu doesn't need to be enriched (it can be chemically separated), but Uranium does (for reactors or bombs).

 

GSL_SE addict...you make me laught about the Plutonium/Uranium thing.... My wife is the Chemical Engineer.... I am just the block head Mechanical Engineer....

You got me!!!