My R1's compression test results
03-22-06, 06:18 PM
#26
at the low engine speed, the overlap would allow the intake to back out the exhaust port. that would not allow enough air/fuel to compress, and giving low compression.
so yes a high overlap/agressive port motor would have lower readings
so yes a high overlap/agressive port motor would have lower readings
03-22-06, 06:26 PM
#27
Original Gangster/Rotary!
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Hey Anthony,
cranking speed was around 260 rpm each time. motor was warm. when I was testing front rotor, both plugs were out of rear rotor, and vice versa.
I didnt use the conversion chart......need to check and see if it's on the back. Tester cost about half the cost of a new unit.
Swolbynos, that is good info, and intuitively I figured as much. The car runs friggin' great, and is most definitely not down on power
.
cranking speed was around 260 rpm each time. motor was warm. when I was testing front rotor, both plugs were out of rear rotor, and vice versa.
I didnt use the conversion chart......need to check and see if it's on the back. Tester cost about half the cost of a new unit.
Swolbynos, that is good info, and intuitively I figured as much. The car runs friggin' great, and is most definitely not down on power
.
Originally Posted by AnthonyNYC
The readings depend on the cranking speed of the engine. It is impossible to say that it is low without knowing the cranking speed. The lower the cranking speed, the lower the readings.
The readings should not be a difference of 1.0 kg/? on each of the 3 sides.
On most mazda compression testers, there is a conversion chart on the back or some have it in the front. Mine has it on the back that will tell you what the compression is compared to the cranking speed.
Goodfellas, what was the cranking speed?
Did you use the conversion table?
If you don't mind me asking, how much was your unit?
What you tested the 1st rotor, were the plugs in our out of the 2nd rotor?
Was the car warmed up when you tested?
All of these affect the readings...
After using this tester on a number of motors and friends motors, I really do not like it at all. I think they are quirky at best. You have to stop cranking at the right cycle in order to get accurate readings and we have tested numerous times and get different readings.
I think if you are testing for a blown engine, they are great but you can do that with a piston engine one or just listen for the pulses.
Anthony
The readings should not be a difference of 1.0 kg/? on each of the 3 sides.
On most mazda compression testers, there is a conversion chart on the back or some have it in the front. Mine has it on the back that will tell you what the compression is compared to the cranking speed.
Goodfellas, what was the cranking speed?
Did you use the conversion table?
If you don't mind me asking, how much was your unit?
What you tested the 1st rotor, were the plugs in our out of the 2nd rotor?
Was the car warmed up when you tested?
All of these affect the readings...
After using this tester on a number of motors and friends motors, I really do not like it at all. I think they are quirky at best. You have to stop cranking at the right cycle in order to get accurate readings and we have tested numerous times and get different readings.
I think if you are testing for a blown engine, they are great but you can do that with a piston engine one or just listen for the pulses.
Anthony
03-22-06, 06:38 PM
#28
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My friend just ripped into me for my post. Let me rephrase.
MY MAZDA compression tester is quirky at times. We think there may be something that is wrong with the one I have but when we tested against his, his read perfect and gave no issues.
Sorry!
Anthony
MY MAZDA compression tester is quirky at times. We think there may be something that is wrong with the one I have but when we tested against his, his read perfect and gave no issues.
Sorry!
Anthony
03-23-06, 02:02 AM
#29
I agree that the mazda tester seems less reliable to me than a standard gauge. I've had the thing refuse to give readings when it's in a bad mood, and other times it gives readings off by 50% then a simple reset and retest 30 seconds later yeilds believeable results.
Not to mention that it has torn up twice now for no aparent reason, powers up fine but won't read pulses no matter how long you crank. The first time I paid to have it repaired, took 3 months and cost $275. Now, it's down again with the same failure. The manufacturer wouldnt tell me the problem or how to prevent it last time, and were generally hard to work with.
I plan to sell it, either as is or once I repair it, because honestly I trust myself interpreting a piston tester more than I trust that 1600 mazda tester.
As for the rest of the discussion, I've built hundreds of engines from stockport to bridgeport, some low compression rotors, some high compression. Some 2mm, some 3mm, variety of seals. Porting doesnt significantly affect compression readings at all. Neither does compression ratio. I can get the same 120psi out of an 8.5:1 motor as I can a 9.7:1 NA motor.
My current halfbridgeport motor in the FD tested 115-118psi last week with about 600 HARD miles on breakin. Basically breakin consisted of a drive around the neighborhood and then let 'er rip. I'm running OEM 3mm seals (which are said to drop compression, ha), 9.0:1 rotors with some material removed from the bevelling process (drops compression ratio even more), solid cornerseals (said to lose a few psi compression due to no rubber insert), and JHB cermet resurfaced housings.
Not to mention that it has torn up twice now for no aparent reason, powers up fine but won't read pulses no matter how long you crank. The first time I paid to have it repaired, took 3 months and cost $275. Now, it's down again with the same failure. The manufacturer wouldnt tell me the problem or how to prevent it last time, and were generally hard to work with.
I plan to sell it, either as is or once I repair it, because honestly I trust myself interpreting a piston tester more than I trust that 1600 mazda tester.
As for the rest of the discussion, I've built hundreds of engines from stockport to bridgeport, some low compression rotors, some high compression. Some 2mm, some 3mm, variety of seals. Porting doesnt significantly affect compression readings at all. Neither does compression ratio. I can get the same 120psi out of an 8.5:1 motor as I can a 9.7:1 NA motor.
My current halfbridgeport motor in the FD tested 115-118psi last week with about 600 HARD miles on breakin. Basically breakin consisted of a drive around the neighborhood and then let 'er rip. I'm running OEM 3mm seals (which are said to drop compression, ha), 9.0:1 rotors with some material removed from the bevelling process (drops compression ratio even more), solid cornerseals (said to lose a few psi compression due to no rubber insert), and JHB cermet resurfaced housings.
Last edited by RotaryResurrection; 03-23-06 at 02:06 AM.
03-23-06, 02:29 AM
#30
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Originally Posted by RotaryResurrection
I agree that the mazda tester seems less reliable to me than a standard gauge. I've had the thing refuse to give readings when it's in a bad mood, and other times it gives readings off by 50% then a simple reset and retest 30 seconds later yeilds believeable results.
Not to mention that it has torn up twice now for no aparent reason, powers up fine but won't read pulses no matter how long you crank. The first time I paid to have it repaired, took 3 months and cost $275. Now, it's down again with the same failure. The manufacturer wouldnt tell me the problem or how to prevent it last time, and were generally hard to work with.
I plan to sell it, either as is or once I repair it, because honestly I trust myself interpreting a piston tester more than I trust that 1600 mazda tester.
As for the rest of the discussion, I've built hundreds of engines from stockport to bridgeport, some low compression rotors, some high compression. Some 2mm, some 3mm, variety of seals. Porting doesnt significantly affect compression readings at all. Neither does compression ratio. I can get the same 120psi out of an 8.5:1 motor as I can a 9.7:1 NA motor.
My current halfbridgeport motor in the FD tested 115-118psi last week with about 600 HARD miles on breakin. Basically breakin consisted of a drive around the neighborhood and then let 'er rip. I'm running OEM 3mm seals (which are said to drop compression, ha), 9.0:1 rotors with some material removed from the bevelling process (drops compression ratio even more), solid cornerseals (said to lose a few psi compression due to no rubber insert), and JHB cermet resurfaced housings.
Not to mention that it has torn up twice now for no aparent reason, powers up fine but won't read pulses no matter how long you crank. The first time I paid to have it repaired, took 3 months and cost $275. Now, it's down again with the same failure. The manufacturer wouldnt tell me the problem or how to prevent it last time, and were generally hard to work with.
I plan to sell it, either as is or once I repair it, because honestly I trust myself interpreting a piston tester more than I trust that 1600 mazda tester.
As for the rest of the discussion, I've built hundreds of engines from stockport to bridgeport, some low compression rotors, some high compression. Some 2mm, some 3mm, variety of seals. Porting doesnt significantly affect compression readings at all. Neither does compression ratio. I can get the same 120psi out of an 8.5:1 motor as I can a 9.7:1 NA motor.
My current halfbridgeport motor in the FD tested 115-118psi last week with about 600 HARD miles on breakin. Basically breakin consisted of a drive around the neighborhood and then let 'er rip. I'm running OEM 3mm seals (which are said to drop compression, ha), 9.0:1 rotors with some material removed from the bevelling process (drops compression ratio even more), solid cornerseals (said to lose a few psi compression due to no rubber insert), and JHB cermet resurfaced housings.
Anthony
03-23-06, 06:02 AM
#31
Originally Posted by AnthonyNYC
Same exact problems with mine and one other one around the area that I know of.
Anthony
Anthony
Oh, and thanks for the info on cermet coating. I knew about ceramic coating but didn't know that was what it was called.
Anyone have hands on experience with these coating?? It quite costly.
Originally Posted by afterburn27
Last edited by Herblenny; 03-23-06 at 06:09 AM.
03-23-06, 07:16 AM
#32
development
Originally Posted by RotaryResurrection
I'm running OEM 3mm seals (which are said to drop compression, ha), 9.0:1 rotors with some material removed from the bevelling process (drops compression ratio even more), solid cornerseals (said to lose a few psi compression due to no rubber insert), and JHB cermet resurfaced housings.
the rubber insert is behind the "line" of the side seals...which seal to the side of the corner seals??
what is the reasoning behind wider apex seal lowering compression?? seems a wider seal shortens the compression face by 1mm (0.5mm on each side)
03-23-06, 09:30 AM
#33
fart on a friends head!!!
Originally Posted by herblenny
Anyone have hands on experience with these coating?? It quite costly.
Originally Posted by dubulup
what is the reasoning behind wider apex seal lowering compression?? seems a wider seal shortens the compression face by 1mm (0.5mm on each side)
03-23-06, 10:39 AM
#34
Originally Posted by dubulup
I'm not following how a solid corner seal...can lower compression
what is the reasoning behind wider apex seal lowering compression?? seems a wider seal shortens the compression face by 1mm (0.5mm on each side)
I just thought I'd throw in a comment that I'm making better compression with that combination of parts that the all knowing members of this forum claim should offer low compression, than most of them are making with their "recommended" setup.
03-23-06, 03:30 PM
#36
it sucks since you just bought it, but maybe the tester is off... have you done a test with a piston tester recently?
i've been meaning to ask you, rotaryresurrection, did you get NEW coated housings or get used ones and send in cores? how much did it end up costing in the end?
i've been meaning to ask you, rotaryresurrection, did you get NEW coated housings or get used ones and send in cores? how much did it end up costing in the end?
03-23-06, 04:07 PM
#37
Originally Posted by RotaryResurrection
Again, as the people that go around spewing this crap on this forum. "Oh, 3mm seals are shitty, stay with OEM 2mm". Seriously, anytime a member mentions getting an engine built and possibly using 3mm seals, a bunch of forking idiots flood the thread with useless misinformation. "Oh, a buddy of mine is a racer in puerto rico and he runs 69 psi boost on stock 2mm seals, there is no place for 3mm seals in a rotary". "Yeah, 3mm seals make poor compression and don't seal well, and they chatter a lot at high rpms too".
I just thought I'd throw in a comment that I'm making better compression with that combination of parts that the all knowing members of this forum claim should offer low compression, than most of them are making with their "recommended" setup.
I just thought I'd throw in a comment that I'm making better compression with that combination of parts that the all knowing members of this forum claim should offer low compression, than most of them are making with their "recommended" setup.
Paul, I guess I need to read little closer. I completely missed that.
03-23-06, 04:12 PM
#38
Originally Posted by alexdimen
it sucks since you just bought it, but maybe the tester is off... have you done a test with a piston tester recently?
i've been meaning to ask you, rotaryresurrection, did you get NEW coated housings or get used ones and send in cores? how much did it end up costing in the end?
i've been meaning to ask you, rotaryresurrection, did you get NEW coated housings or get used ones and send in cores? how much did it end up costing in the end?
it'd be pretty dumb to fork over the money for new mazda housings and turn right around and start grinding the perfect coating that you paid for off just to put your own. So yes, you use old worn housings and work from those, because the end result will be a perfect like new surface regardless of how it started...though, there is definitely a limit to what they're able/willing to repair, and deep gouges from apex seal damage is beyond that limit.
03-23-06, 07:20 PM
#39
that's what i had assumed, thank you. i agree with using used housings... it's also something like 2x the cost if you get it with new housings judging from the site. i guess the whole thing with new housings is there is no chance of cooling channel erosion and pinhole leaks, etc... but i'm sure used ones are inspected for that anyways... or i'd hope they do at least.
03-23-06, 09:02 PM
#40
THE C/P Number affect by Port. Cranking speed this is two major thing.
The car still starable under 5KG. and drive able. but I think it will loose some HP at mid range due to the seal is not seal good.
MY 13BPP with 2mm Carbon seal. got about 5.9KG of compression. this is normal for this type of engine with this type of seal. Start up fine. rev it fine. tons of power, infact I just make 310HP at 8500RPM on engine dyno.
But your number seen a little be low.. but along as it start up fine. and got power who care
J
The car still starable under 5KG. and drive able. but I think it will loose some HP at mid range due to the seal is not seal good.
MY 13BPP with 2mm Carbon seal. got about 5.9KG of compression. this is normal for this type of engine with this type of seal. Start up fine. rev it fine. tons of power, infact I just make 310HP at 8500RPM on engine dyno.
But your number seen a little be low.. but along as it start up fine. and got power who care
J
03-23-06, 09:51 PM
#41
Original Gangster/Rotary!
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Originally Posted by diyman25
THE C/P Number affect by Port. Cranking speed this is two major thing.
The car still starable under 5KG. and drive able. but I think it will loose some HP at mid range due to the seal is not seal good.
MY 13BPP with 2mm Carbon seal. got about 5.9KG of compression. this is normal for this type of engine with this type of seal. Start up fine. rev it fine. tons of power, infact I just make 310HP at 8500RPM on engine dyno.
But your number seen a little be low.. but along as it start up fine. and got power who care
J
The car still starable under 5KG. and drive able. but I think it will loose some HP at mid range due to the seal is not seal good.
MY 13BPP with 2mm Carbon seal. got about 5.9KG of compression. this is normal for this type of engine with this type of seal. Start up fine. rev it fine. tons of power, infact I just make 310HP at 8500RPM on engine dyno.
But your number seen a little be low.. but along as it start up fine. and got power who care
J
Just for the hell of it, I may try the tester again this weekend and see how consistent it is. Having no p/s and a/c makes it a piece of cake to swap out my plugs.
03-23-06, 10:46 PM
#42
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hey this might be something you already know but you need to hold the throttle wide open when turning the motor over on the test....just thinking, I have seen low numbers with the throttle closed
03-23-06, 10:50 PM
#43
Original Gangster/Rotary!
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Originally Posted by glenrx7
hey this might be something you already know but you need to hold the throttle wide open when turning the motor over on the test....just thinking, I have seen low numbers with the throttle closed
Time for round 2 on sunday
03-23-06, 11:00 PM
#45
Original Gangster/Rotary!
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Originally Posted by eatmyclutch
wow you're dad owns an FD? 
03-24-06, 04:33 AM
#46
Originally Posted by GoodfellaFD3S
If that is the case then I am an absolute friggin' retard, because my throttle was most definitely closed when I was cranking.
Time for round 2 on sunday
Time for round 2 on sunday
03-24-06, 06:43 AM
#47
Original Gangster/Rotary!
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Originally Posted by diyman25
oh DAM... YEP you need to hold it wide open !!. and you know you need to do C/P at hot!!. because cold test will read higher noumber. Any way hope to see some better result
03-24-06, 07:04 AM
#48
I definitely learned something new from this thead.
Since I'll be getting my tester in a week or two, I wondered about what is the correct procedure.
AnthonyNYC sent me this thread describing correct procedure when performing compression tests.
http://www.fd3s.net/compression_test.html
Since I'll be getting my tester in a week or two, I wondered about what is the correct procedure.
AnthonyNYC sent me this thread describing correct procedure when performing compression tests.
http://www.fd3s.net/compression_test.html
03-24-06, 07:27 AM
#50
Original Gangster/Rotary!
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Originally Posted by oorx7
This is all good info. Thanks alot. Not shure if I had the throttle open when I did mine last year. Although that would not explain uneven bumps on the compresion tester, right?
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