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Sooted engine. Any experience with MMO? Any advice?
My engine has ran about 2-3000 thousand miles after rebuild. basically newely overhauled. Single turbo, big streetports. 1000 and 2000cc injectors. ViPec V44 ECU. It has a supermild basic map up to 0.5-0.65 bars (8-10psi), but uses aaaaaloooot of fuel. waay too much, It ran on very cold sparkplugs (4x 10s) and only on the street with few hard pulls (I have changed the plugs to 7's and 9's t the moment and it responds much better for street). The 10-plugs were sooted bad. The engine has drowned in fuel a few times as well , and because of a superhard clutch and 2-way differential is has died quite a few times in intersections.
It has good vacuum, runs well, and starts excellent on warm engine. However, when I did a compression test the numbers were awfully low (considering freshly built engine), but they were very even. almost same compression on all sides. SEE PICTURES.
I installed direct water injection with the smallest nozzle, changed to 7's and 9's, and put Marvel Mysteri Oil in the fuel tank and ran the car pretty hard for around 100 miles with full water pouring in to see if it got any better. But the numbers are exactly the same. not worse. not better. I want to try and pour MMO oil inside the rotor housing, let it work with manually turn it around with 6-8 hours for about 24hours.
Do you guys have any experience on how to remove soot? what did you do that worked? and if you have used MMO, how long do you suggest it should work inside the engine before you clean it out and start the engine?
I lost a strong motor once as a result of tuning that caused my timing to be too retarded. It ultimately resulted in a strong motor losing compression. Depending on who did your tuning and how that happened it *could* potentially be something to look at.
That said, a great way to remove carbon build up (what you're referring to as soot) is to get the motor fully up to temp and ingest 1 gallon of distilled water through the vac nipples on the UIM (half in front, half in rear runner). I'm not sure if your engine has enough miles on it to really build up that much carbon yet though, the water injection will certainly help combat that!
Just to be safe, are you still running the OMP or premixing enough oil? I may have missed it, but I didn't see that detail.
You need to let the screen of the compression tester keep showing you results, you need to get the corrected to 250 RPM numbers to have a solid apples-apples number to look at.
With a big street port, do you have a brap or lope at idle? If so that means you have a lot of overlap and compression numbers will NOT line up with a stock motor. There are times the exhaust and intake ports are both open at the same time so some of your low speed compression is going out the exhaust port.
That said, the water injection trick just stated should be the best bet, but remember you will never make amazing compression numbers. Big thing is the motor should start hot and cold and idle, if you have that and it makes good power you are good.
You also may want to look into an RX-8 starter to increase cranking speed, that will help if it does ever seem tough to start warm. The faster an engine cranks the more compression it makes and the easier it is to start. That's how Mazda band-aid'ed a bunch of RX-8's with weak engines.
Thanks a lot for the replies, guys. Appreciate it. Do you guys think that the low compression numbers on this relatively freshly built engine can be because of carbon buildup?
Originally Posted by fendamonky
Just to be safe, are you still running the OMP or premixing enough oil? I may have missed it, but I didn't see that detail.
I'm not runnig the OMP, I'm premixing. Wil the water injection remove any carbon buildup , or will it only help prevent it to get more? The rotors are lightened/lighter than stock and have 3mm apex seals if that is of any useful information. The tune was made by a very experienced rotary tuner. But the engine only had around 400miles on it when I tuned it, so the tuner kept it at Wastegate spring 0.5 bars and limited the RPM to 6000 and told me to drive it more , before I can later change to higher springs and then do a more aggressive tune. but then the Covid-19 came and I never got to tune it. I drove it in the streets to enjoy it a bit but Im affraid it has had too much fuel, too cold sparkplugs, and drowned too many times and choked too many times. hence my theory about the low compression numbers.
Originally Posted by DaleClark
With a big street port, do you have a brap or lope at idle? If so that means you have a lot of overlap and compression numbers will NOT line up with a stock motor. There are times the exhaust and intake ports are both open at the same time so some of your low speed compression is going out the exhaust port.
That said, the water injection trick just stated should be the best bet, but remember you will never make amazing compression numbers. Big thing is the motor should start hot and cold and idle, if you have that and it makes good power you are good.
Dale
I cant say I have a brap idle, no. However, it sounds more "rough" than a stock idle, and It needs to stay in high idle RPM , minimum of 1000, or it will die. I have found out that when the engine is run really warm I need to adjust the idle to be held at 1300-1400rpm for it to not die when I put my feet off thottle and the RPM needle fall down. (maybe this is more a tuning-issue?) According to the previous owner the engine has the largest street ports available. I'm not sure if that really is the case. But if it has the largest street ports, the argument about 'a lot of overlap' might be the reason why I have to low compression on such a "new" engine.
When starting cold, I have to help the engine with some throttle to fire, also I need to hold throttle for a while to keep RPM over 1000rpm, until it gets a little warm. After holding the throttle for about 2 minutes or so It can hold idle at 1000rpm. When it gets warm the idle is up to 1300-1400rpm. But when the engine is warm it starts quick and instantly and holds idle without any assistance. (I dont know if that is a ECU tuning issue. I dont have the tuning-knowledge.)
I think you have partially a tuning issue with idle and partially the large street ports. What are you using for an ECU?
Also 3mm apex seals don't seal as well at low RPM so you have that against you as well. That's why it's super rare to find people running 3mm seals at this point, there are a lot better options out there. There are 2mm seals that can take a world of abuse.
What all is done to the engine? Do you have a big turbo/shooting for big power?
What fuel injectors are you running? Some fuel injectors (like running stock 850's as primaries) just don't idle well and don't do low pulse widths well.
That is good information i did now know, thanks Dale.
The setup is 10 years old (but all the parts were brand new before startup), because the project was never finished by previous owner it has been many years before I was able to make it run.
The ECU is ViPec v44. The injectors are Injector Dynamics 1000cc primary, 2000cc secondary. The fuel rail is a 4 injector in a row fuel rail. The turbo is a Garrett GTX35R. The previous owner apparently chose the parts/setup for fast spool and responsive power. Big streetport and lightened rotors with 3mm apex seals.
i have had some Marvel Mystery Oil poured inside the engine, through the leading spark plug holes. I have turned the engine manually a few times and will continue to do so for 24h , then i will remove plugs and blow clean by running the starter. I'll try and start the engine again and run it warm, and inject water at high rpm. Then ill try and make a new compression test and see if there is any different numbers.
I don't know if letting the engine sit with MMO and turning it over will do anything in particular. If you think it's carboned up you have to get that carbon out of there, the steam clean method would be the way forward there.
So I'm not totally understanding your fuel rail setup - do you have an aftermarket intake manifold with 4 injectors straight across, the middle being "primary" and the outers being "secondary?" That will also give problems, you want the primary injectors close to the intake port, that's why the stock primary injectors are where they are. That gives better low speed atomization.
Big secondary injectors, having them upstream, big street port - that's going to be a bitch to get to idle well and idle at a lower RPM. That setup is less about response and more about big power.
I don't know if letting the engine sit with MMO and turning it over will do anything in particular. If you think it's carboned up you have to get that carbon out of there, the steam clean method would be the way forward there.
So I'm not totally understanding your fuel rail setup - do you have an aftermarket intake manifold with 4 injectors straight across, the middle being "primary" and the outers being "secondary?" That will also give problems, you want the primary injectors close to the intake port, that's why the stock primary injectors are where they are. That gives better low speed atomization.
Big secondary injectors, having them upstream, big street port - that's going to be a bitch to get to idle well and idle at a lower RPM. That setup is less about response and more about big power.
Dale
Yes , that is the type of fuel rail I have.. And yes, I agree its probably more for big power and a headace to drive in the streets 🙈 I know the setup is redicilous, but I bought the project cheap with all parts unused and new buildt engine 10 years ago. Thats why im not spending money on other set up, yet. I just have to make this work as well as possible.
I have to do some research on how to perform the steam clean method. I will post the compression test result after i have done the MMO procedure.
to be honest recent experience from the BP perspective, if you’re going to put the boost to it, lower compression is not necessarily the hindrance it would be for NA or as some would suppose. You could even argue to just turn it up some more. Though shorter oil change intervals might be considered.
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I have had some Marvel Mystery Oil poured inside the engine, through the leading spark plug holes. I have turned the engine manually a few times and will continue to do so for 24h , then i will remove plugs and blow clean by running the starter. I'll try and start the engine again and run it warm, and inject water at high rpm. Then ill try and make a new compression test and see if there is any different numbers.
Ok guys, so I did the steps above. The white smoke was everywhere and took about 15-20 minutes before it was all gone. After the smoke was much less and the engine and oil temp reached operating levels I revved to 4000-4500rpm and injected water with the AEM WI test-button (5-6 seconds of squirt) about 10 times. Then I did a new compression test under the same circumstances (on cold engine) as the first compression test to get more accurate comparison. I think this is the first picture-documented before/after thread on trying to remove built up carbon inside rotary engine. Here are the results after the MMO procedure:
Sparkplugs were cleaned before the test:
Compression test 3. October 2021:
As regards to the RPM on the test (I have a very small (weak) battery because of the v-mount setup), I connected a larger battery before I did the rear-test. Hence better RPM on rear test
Seem like it worked a little . The compression got better, but are there more potential for better results?? My question is , would it work/help to do this procedure one more time? Or, do you think it will get better/cleaner after some driving with boost and water?
Also you need to let the compression tester show you the corrected readings. Just keep watching the screen after it does the test. You can't compare numbers that were taken at different RPM, it has to be corrected to 250 RPM to have an apples to apples comparison.
Also you need to let the compression tester show you the corrected readings. Just keep watching the screen after it does the test. You can't compare numbers that were taken at different RPM, it has to be corrected to 250 RPM to have an apples to apples comparison.
Dale
Ok. I dont think this older version of the tester does that but I will try and see next time.
Also, what size nozzle do you have in the water injection kit? Might not be enough water just using the test button on your AI kit.
I'm using the smallest of 3 nozzles that came with the Aquamist big WI kit.
I have been told that less is more when it comes to Water injection. Ive heard people pour in so much water it affects the poweoutput negatively or sometimes drownes the engine. My engine is tuned at only 0.65bar.
Originally Posted by TeamRX8
you can just plug the numbers in using this link to compare the before and after readings
09-30-21, 11:30 AM
Though shorter oil change intervals might be considered.
. The compression got better, but are there more potential for better results?? My question is , would it work/help to do this procedure one more time? Or, do you think it will get better/cleaner after some driving with boost and water?
