Such a cool tool....Twisted Rotors compression tester
 

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

http://i378.photobucket.com/albums/o...r/P1040157.jpg

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

http://i378.photobucket.com/albums/o...r/P1040150.jpg

ready to test

http://i378.photobucket.com/albums/o...r/P1040146.jpg

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

http://i378.photobucket.com/albums/o...r/P1040147.jpg

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

http://i378.photobucket.com/albums/o...r/P1040145.jpg

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

http://i378.photobucket.com/albums/o...r/P1040158.jpg

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

http://i378.photobucket.com/albums/o...r/P1040159.jpg

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 ass 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!!! :)

Nuke engineer here. :) I've taken most of the ME classes as well. I've taken a few EE classes, but would have liked to have done more. I've always wanted to play with microcontrollers and I figured something like this would be an interesting application. I never really got to play with them in my EE classes.

While the key is on this is true, but once you start cranking with the pedal floored, that carb is dumping fuel unless the pump isn't running. Otherwise fuel would never get to the jets, it would just bypass all the time LOL

Do you understand the operation of a carb?? Even if you pull the fuse to the fuel pump, you have fuel in your fuel bowls.... Unless you can find a way to remove the ounce or two of gas in the bowls you run into this problem anyhow...

I can start my car and drive down the block with the fuel pump fuse pulled...

Just in case anyone is interested. I've made a converter to compensate for elevation, rpm and the dead volume of each engine type.

http://foxed.ca/rotarycompcalc/screenshot.png

http://foxed.ca/foxed/index.php?page=rotarycalc

Brilliant!

I'll throw it out there that John is a good guy. I got to meet him at Sevenstock this past year and can say that I would definitely buy his product (and more than likely will when I get my next FB)

Does anyone know if he still makes these? I've tried to pm him a few times now and he is not responding even though still active on the forum recently

website link in original post still active...
seems to be working on an even better one.

Stu Aull
80GS
Alaska

yes he still is in development of a newer version. he isn't currently taking any orders on them but they are in the works and R&D is being allocated. Hes a pretty busy guy im not surprised he didn't get back to you.

Hes a local member at out Houston club really cool guy, got to use one of these myself on my 85 original motor from the 1st owner at 150K mark tested 108, 110,108 front and back. :nod:

GROUP BUY:
.
I'm in for one.
DickGetty @ Hotmail . com

Cool rotary tool. Now it appears it is at V2.0?

Thanks guys he got back to me and is still making them but not for a while. Bought myself a rotary diagnostics one for now

Count me in for 2 on a group buy whenever the time comes

too bad he never seems to have time to get the next round rolling otherwise i would be in for one.

For everyone that isn't up to date with twistedrotors on facebook he has a new shipment ready to go and orders opened today on his website WWW.twistedrotors.com for his amazing tester

Sold out already.

Wish he could do kits if he's short on time so I could make my own like you can with a megasquirt.

just want to give you fellow rotarites that are not watching on facebook an update. twisted rotors has started selling these again he said he is making 5 a week and putting them available to buy every friday untill the demand runs out. he did the first round today and the first 5 sold in under 5 minutes lucky me i got one.when the 5 he has are gone it will show sold out again so keep your eye on the prize and like him on facebook for the times of when the link opens on fridays. i will update as i can for everyone too

Is there a way to contact him w/o going the facebook route?

Yeah I second that I don't have a Facebook account nor do I wish to have one.

Maybe through his site but not positive. As of now he is saying at 5pm centeral time every Friday he will make the link active again for 5 more testers. If he changes it I will post it up on here for everyone that doesn't want to deal with Facebook

5 more testers go up forsale at 5pm centeral time today 7/11/14. buy them from his site

TR-01 Rotary Engine Compression Tester

Ok, I got my order placed. Be aware however, PayPal won't cut it. You'll need an Amazon account to enable the purchase to go through.

As an update, I recieved my tester last week. Looks to be good quality with a rubber case / protector, simple and easy to use. As a point of reference, I tested my 31K mile motor which is completely stock and never been out of the car. I removed the rotor cap and both top plugs. The test was done with the sensor screwed in to the two top plug holes one after the other and using the starter to crank the engine over.

Ft Rotor = 118 / 116 / 124
R Rotor= 118 / 117 / 114

Cranking RPMs were 273 and 269 respectively.