Yeah, that's the ticket - a four barrel with accelerator pumps! This setup would likely dyno at 195 HP, maybe more depending on how motivated the dyno operator was!
Skyactiv Intake Valve carbon build up - Anyone taken a look at intake valves?
- Thread starter johnygfunk
- Start date
Yeah, that's the ticket - a four barrel with accelerator pumps! This setup would likely dyno at 195 HP, maybe more depending on how motivated the dyno operator was!
- :
- RDX Aspec Adv.
Yep. I actually had an EFI car that I converted to carburetor. I picked up a bit of peak power, at the cost of area under the curve and driveability.
- :
- San Antonio, Texas
- :
- '15 CX-5 Miata AWD
You still seem to think the role of a dyno operator is to meet some kind of number goal. The owner of the car may be after a number, based on whatever change they made. The operator is not paid for what number the machine produces, he is paid for the use of the machine. If you ever actually utilized the services of a dyno shop you would understand this and quit acting as if a posted dyno chart showing a gain is automatically altered by the operator (according to some prior posts).
- :
- RDX Aspec Adv.
But he has a point. It very well can be. I've seen it done. Strap the car down a bit harder, cool it very well with a fan in front. Over/under inflate the tires. There is a ton of trickery that can be done. You can very easily show a customer a 5-10whp "gain" any time you like, by manipulating the dyno setup and the car prep. I've also seen dyno operators sand-bag things. Such as not locking the TQ converter and dynoing in a gear other than 1:1 and tuning only the A/F ratio and the hell with power output numbers. This resulted in an 11 second car laying down "well under 400rwhp", lol. It was done this way because a ton of people were watching on dyno days and the owner didn't want to tip his hand for the drag strip later on, as the same crowd would be there, too.
Ultimately, a dyno never won a single drag race. So to hell with it. It's nothing more than a tuning tool. Absolutely nothing more, and the numbers is shows are absolutely worthless except in context to the process of tuning that specific vehicle.
Last edited:
I've done some extensive dyno testing and you both are right. The operator can certainly skew the results. If it's done in an apples to apples way on the same day in controlled conditions and on the same dynamometer than the results can be comparable. I've swapped parts with the vehicle still strapped to the dynamometer so that the results are as comparable as possible. A dynamometer is a tool just like any other tool, if it's not used properly, the results will not be the same for comparison purposes.
4G63T, as a former ASE master certified technician, I can tell you with absolute certainty that the positive crankcase ventilation system has a lot to do with oil leaks if it's not working properly. It's as simple as negative pressure versus positive pressure inside the engine. If the PCV valve system isn't working properly than eventually positive pressure, however so slight, will build up. Once positive pressure builds inside the engine, it will eventually push the oil past the seals.
Mike has a good point, there is no evidence that there is a problem with the Skyactiv engines. So I don't understand why anyone would mess with it. From what I have learned, carbon buildup on the intake valves was a problem when direct injection first came out. Only the early adopters of this technology had this problem. As far as I know, manufacturers have mostly solved this problem.
I'm on my second Skyactiv powertrain with a total of 80,000 miles cumulatively. Based on my experience, these engines are very well engineered and in my opinion bulletproof. The Skyactiv family of engines in my opinion are some of the best I have ever experienced. If Mazda made a Skyactiv V-8 engine and put it into a pick up truck then I would buy it in a heartbeat.
Mike has a good point, there is no evidence that there is a problem with the Skyactiv engines. So I don't understand why anyone would mess with it. From what I have learned, carbon buildup on the intake valves was a problem when direct injection first came out. Only the early adopters of this technology had this problem. As far as I know, manufacturers have mostly solved this problem.
I'm on my second Skyactiv powertrain with a total of 80,000 miles cumulatively. Based on my experience, these engines are very well engineered and in my opinion bulletproof. The Skyactiv family of engines in my opinion are some of the best I have ever experienced. If Mazda made a Skyactiv V-8 engine and put it into a pick up truck then I would buy it in a heartbeat.
I've never said any dyno chart showing a gain is automatically altered by the operator. I said the gain is not proven simply because the vendor has a dyno chart showing a gain. Only an extremely nave and gullible person would think otherwise.
And lots of car enthusiasts and people in the industry know this and agree with me:
http://www.superstreetonline.com/how-to/additional-tech/0402tur-dyno-tricks-problems/
http://www.nicoclub.com/tag/chassis-dynamometer
http://www.hotrod.com/how-to/engine/hrdp-1103-chassis-dyno-testing/
http://www.superstreetonline.com/features/news/9907scc-technobabble/
A lot of "enthusiast" shops want a dynamometer but they are very expensive tools costing tens of thousands of dollars on the low end. Not every small shop can justify the cost as there are only so many people who want to pay good money to know how powerful their car is and each dyno owner must compete with any other shops in the area with chassis dynamometers. The manufacturer is often glad to sell it on a monthly payment plan but it's still up to the purchaser to get enough business to make the monthly payments. So Joe Racer brings in his heavily modified ZXRXW super turbo'ed speed coupe into one of the local performance shops to see what it will do. After a few dyno runs Joe Racer is told his pride and joy makes 225 hp. Joe is not sure what to make of this because last spring, at the shop across town, his coupe made 255 HP (and that was before he bolted on the super duper air intake which was supposed to make 8 more peak HP). He should be seeing numbers up around 268 HP, not 225 (which is more of an insult than a real test). Before you know it, Joe has told all his performance car friends that Honest Bob's Tuning Shop is not to be trusted. At the very least you will get dyno numbers that are real low. And why pay good money only to have all your hard work insulted? Pretty soon Honest Bob is losing customers to the two shops on the other side of the river (who apparently are more clued into their customers "needs") and is having trouble making payments on his shiny new dynamometer.
But read the articles I provided, my perspective is supported by all of them.
Thats like saying tinting the windows will keep the in-cabin area slightly cooler and it will some how cool the motor even more? Your comparing apples to oranges, two different parts that operate in different ways.
Your statement is correct regarding leaking gasket when there is positive pressure build up in the crank. But vacuum is not needed. Also, some motors the dip stick pops out first.
For the other topics in discussion:
This modification does not gain horsepower or take away horsepower. Its only main purpose is to stop vapors from entering the intake/manifold. Only time this modification would give you any type of gains is if there is crank pressure build up due to clogged PCV and doing this removes the clog.
My car had factory internals with tight piston to wall clearances. Some of the engine builders/vendors built motors may have looser tolerances than factory so there was more crank pressure created. This required two things. One was to run thicker oil and two for some people’s setup the factory pcv wholes were not big enough and they either made the existing valve cover holes bigger or drilled more holes on the valve cover to allow more volume of crank pressure to be relieved. No one had oil leaking issues running 20-40 psi but they did have their oil dip stick pop out.
After closer inspection the CX-5 motor has one vent on the valve cover (no PCV valve on the valve cover). The PCV valve is actually on the block, in which I think seems to release pressure straight from the block/crank case area. Now that is a much better spot to relieve crank pressure as it does not have to pass from the block to the head through the same area that the oil is to drop down from the head. The oil separator might just be doing the job of stopping the oil slushing around from exiting but not completely stoping oil vapors. I dont know the design of the cx-5 oil separator but I was looking at some picks of other Mazda Speed Turbo ones and didnt seem like it was designed for oil vapors, unless the baffles are casted on the block itself...?
Also want to add:
The dyno testing I did was by me. It was not on the actual rollers. It was street dyno that is pretty accurate as far as back to back runs data logged on the same road. It may not be configured to read the same as an X dyno but it was close to Mustang Dyno configuration. Whats important if any changes where made from the baseline runs not the actual whp numbers. I did numerous pulls with PCV system in oem configuration vs venting. So no there was no Dyno Operator skewing the results from tire pressures etc...
Last edited:
You are correct if there is crank pressure build up. But venting out should not create crank pressure build up. Also if deciding to vent its good idea to remove the PCV valve or gut it out as there is usually a spring that holds it closed slightly when no vacuum to pull or pressure to push out. Also want to add some motors will pop out the dip stick as well way before any leakage of the gaskets. The Evo 4g63T motor never leaked just popped out the oil dip stick. Maybe thats dependent on motor design and dip stick popping out gave just enough relief to not need to push further and leak through the gaskets like some other cars may do.
I’m not saying this is a needed modification. I just dont want oil in my intake manifold. And I personally feel its better not to have oil in the intake manifold rather than having it. Thats another area of discussion though. That is all.
When the pressure is such that a dip stick is popping out, usually its an indication of excessive blow by gases. Given that your Evo engine was turbocharged and I'm guessing it was probably modified with higher boost than stock, I would guess there was more combustion gas getting by the rings than normal.
Are you actually seeing oil in your intake manifold of your Mazda? How much?
Are you actually seeing oil in your intake manifold of your Mazda? How much?
I would agree that turbo motors might create more blow-by due to the higher cylinder pressures with the turbo. For the record I never had the dip stick blow out. Those were people either running real high boost and recirculating or upgraded internals with loose tolerance vs oem and recirculating.
I havent checked the Mazda to see how much oil is in the PCV tube. The location is hard to reach, I’ll be checking it later when I get a chance. It would just be a remove tube and see how much oil residue is around the inner walls. No real “test” . If its bone dry, Ill be happy. If not I will probably figure a good way to change from recirculating to venting.
- :
- San Antonio, Texas
- :
- '15 CX-5 Miata AWD
Those articles address a lot of relevant things, using different dynos among them...One also mentions a mustang trying out different dynos for results, which is not the case when you are comparing tunes on the spot (ECU flash from a laptop).
I'm talking about dynos posted by different people in different states/countries comparing the stock tune to their aftermarket tune (and achieving similar results); where a difference and trend can be seen, regardless of how accurate the reported output actually is. I'm not talking about the dyno from the manufacturer of a part and what they claim, and certainly not people who just go in and dyno their current tune against itself (or drive around to see which dyno get's them the highest number to post on a forum). It doesn't matter if a mazda3 sky dynos at 140tq stock and 160tq tuned and then dynos at 150tq and 170tq on the next; what matter is the gain is about 15% from each dyno. I could say this tune gives about 15% increase in tq at this rpm range or I can say (based on published crank hp of 155 of a 2.0, gives ~20hp. Of course the % will vary based on what fuel you tune with, and your environment.
I agree about not taking all of the posted numbers for face value. I didn't put my intake on my car and insist I gained 10hp. Same with the exhaust. However I know (from data) in conjunction with my tune, my car is able to flow more air g/s with my intake compared to my stock filter (or even the jbr drop in highflow filter, which I tried on both my 2.0 and 2.5).
- :
- San Antonio, Texas
- :
- '15 CX-5 Miata AWD
I need to get my hand on a Service manual for the 2.5. I was looking at removing the intake mani to look, but unless there is a bolt that is out of reach without a lift (or jacked up but I don't want to go into the engine bay from below with jacks), then it may have changed slightly from the 2.0
That's all well and dandy. But what you actually said was this:
Chris_Top_Her said:
And I pointed out that I never said all dyno results were automatically altered by the operator (although the attached articles pointed out just how tightly integrated the operator is with the machines output). The same articles all talked about operator bias and even cheating as if it was assumed this was commonplace. At least one article discussed how the results could be unconsciously biased by the operators own desires even when that operator was trying to be conscientious. That's why scientists developed the double blind technique for experiments, a technique that is almost never used when a dyno is put through it's paces. But one article showed that, even when the dyno operator was fooled as to the source of the car, and the intent of the car owner, the results still varied widely, sometimes even on the same machine and on the same day.
Most dyno results, even on the same day on the same machine are not the scientific result you make it out to be. To get that you need a dyno costing in the vicinity of $2 million USD, the type that only government agencies, well funded development companies and auto manufacturers have access to. These are the kind of dynos that were used to develop your vehicle and it's programming in the first place, not some little $35,000 "toy" at your local enthusiast auto shop that arrives via a shipping company. And, even the machines costing upwards of a million dollars can be "gamed" by the operator if his/her motives are not noble.
Last edited:
Just went and messed with it again. The pcv and oil separator are right above the starter under the intake manifold . I can reach the pcv hose with my fingers and maybe pull it out but that's about it from the top . I don't think I can put it back if I pull it out from the top .
I think there are only two possibilities at the moment. We need to access it from under the car or remove the intake manifold. I do not want to remove the intake manifold so under the car on jack stands or ramps is what I'll probably do when I have the time.
We have a really weird looking intake manifold. I'm not even sure why there is a sponge/cushion thing under it?
- :
- RDX Aspec Adv.
This is HUGE! So many people want to use non-SAE corrected numbers and compare their dyno numbers on the internet. It's absurd. The dyno is FOR TUNING. That's it.
Ok tried again from the bottom. I was able to pull the pcv hose off the intake manifold. I used a napkin to shove inside the pcv hose and found there was oil in it . Please note my car has about 200 miles at the moment. I'm trying to imagine how much oil would be going in and costing the intake manifold or head if the car had 20,000+miles etc... I think that the purpose of the oil separator is to stop oil slushing around but not oil vapors like a deal good catch can would.
There is not enough room for me to reach in and mess with it further, so I hooked the hose back in to the manifold . In order to mess with it more, I think one would have to either remove the starter from underneath or remove the intake manifold.
There is not enough room for me to reach in and mess with it further, so I hooked the hose back in to the manifold . In order to mess with it more, I think one would have to either remove the starter from underneath or remove the intake manifold.
- :
- San Antonio, Texas
- :
- '15 CX-5 Miata AWD
I believe JBR and/or corksport sell an oilcatch can.
I would think that anyone wanting to undo decades of progress in making vehicles clean, drip free and with vapors contained would be better served using a Campbells soup can (extra points for leaving the label intact). Just poke two small holes near the top and wire it on with a short length of bailing wire so it hangs above the dripping oil. The Tomato Soup exudes authenticity and captures that spirit of American ingenuity in a way the other flavors simply can't. The solutions from JBR and Cocksport are too expensive (for what you get is basically a fancy looking soup can) and instead of conjuring up that endearing American ingenuity, appears haughty and elitist. Lord knows the Campbells Soup can is just as effective and has proven itself over 100 years. (wink)
Last edited:
I should also point out that there is not a single documented case of excessive carbon on the valves of a Skyactiv GDI engine. At least not a stock engine. Start messing with various tuning parameters and/or breather hoses/valves then all bets are off.
In other words, there is no reason to worry about carbon build-up on the valves.
In other words, there is no reason to worry about carbon build-up on the valves.
