29 replies to this topic

[Buschur Racing]

Hello everyone,

 

Interesting testing done today.

 

We released our Pro Catch can a month or so ago.  The sales have been very good.  One thing I wanted to do was some real back to back dyno testing to see if power could be gained on an FBO car.

 

Today I had a customer come in who's car we built to a BR140.  It doesn't have our catback on it but the balance of the car is Buschur Racing, (BR)140.

 

First thing we did when Joe arrived today was to load it on the dyno to check to make sure the tune was still in check from the last time I touched it and get a good base number for today.  I made two pulls, boost on the stock turbos is maxed out over 5600 rpm.  Mid range the boost was hitting 19.25 psi and by 7000 rpm in 4th gear it had fallen off to 14.07 psi.

 

The car was here for our lightweight battery kit, coolant tank and the Pro Catch can.  The only part there possible of adding any change in power was the Pro Catch can.

 

Base line dyno and logs showed the timing right on the edge of where it needed to be with minor correction.  

 

We added the parts, loaded the car back on the dyno and started again.  

 

Now, something to add.  I logged the crank case pressure before adding the catch can.  The design of our new Pro Can uses the oil cap as a vent so I could not log the crank case pressure again as there is a fitting in the way.  (I'll have to make something else for doing this)  The crank case pressure with the stock set up hit .6 psi.  

 

The addition of the Pro Can dropped the actual boost in the car, peak stayed at 19.25 psi but at redline the boost wouldn't go over 13.6 psi.  In my own car this same thing happened, I was seeing 4 psi+ of pressure in the crank case and after adding the Pro Can it dropped to 0 and the boost dropped I was seeing also.  

 

Power went up much more than I thought.  YES, the car was tuned further but before the catch can the car was seeing some minor knock corrections and after it was gone.  AFR's and peak boost remained the same while the peak boost dropped about .67 psi.  (Interestingly enough the same amount of crank case pressure it has prior to the Pro Can).

 

Power went up 24 whp and 22 ft lbs when it was all said and done and to be honest, I believe I could have squeezed a little more out of it.  The engine, heads, cams are stock and Joe road races the car so I decided that would be enough.

 

The power was increased from 2500-7100 rpm.  

 

 

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[HiBoost]

Did you add fuel or just timing?

[Buschur Racing]

Did you add fuel or just timing?

Fuel too.

[HiBoost]

Correct my thinking if I'm astray... in a perfectly sealed piston/cylinder scenario crankcase pressure shouldn't impact this.  More fuel to get the same AFR and boost dropping both point to an increase in air consumed by the intake stroke, no?  So is it plausible that there is that much leakage past the rings (in the opposite direction as combustion gasses flow) that the extra 0.6psi in the crankcase partially fills the cylinder and prevents as much intake charge from coming in?  If that is happening then it also seems likely that leakage air would have some oil mist in it which could be why it accepts more timing now?

[Buschur Racing]

More oil will contaminate and certainly not allow more tuning. You asked if I added fuel, I said yes. I added it just to adjust the fuel trims to get them as close as possible, not because it needed it for the power gain.

[HiBoost]

Right but more fuel being added and the AFR staying the same means more air got added too, so I was trying to speculate on where that was coming from.  Without answering the fuel question it could have been possible that the extra power was just from more timing, not an actual increase in VE.

[Buschur Racing]

Right but more fuel being added and the AFR staying the same means more air got added too, so I was trying to speculate on where that was coming from.  Without answering the fuel question it could have been possible that the extra power was just from more timing, not an actual increase in VE.

 

For the case of this dyno test, I should have answered "no fuel was added".  The fuel trims were off in the base dyno runs.  The fuel I added was just to get them back to "0", not because of a change in the VE.  

 

You have to consider a few things.  There is a target AFR, let's say 12.0:1.  The car is constantly making changes, small if you did your job right tuning it, to keep it at 12.0:1.  So even on the best tune you are going to see a few percent plus or minus from "100", which would mean there was no trim at all.  A 20 hp gain on a 600 whp car is about a 3% gain in horsepower.  That is a very small difference and has a small effect on VE, depending on how close the fuel trims were to begin with it's small adjustment to the VE to get back to "100".  

 

I answered yes, the fuel was changed to be honest with you.  It was changed however to just make adjustments from it being off during the base line pulls that I did for the test.

[HiBoost]

I feel like we're miscommunicating here.  You posted that this was interesting, which implies that the result was somewhat unexpected.  I agree that it is interesting and I am trying to have a discussion about why a catch can may be adding 24whp.  I understand how fuel trims work, but whether you asked for 97 and the ECU added 3 or you just asked for 100 in the first place, in either case you are getting 100 and there's really no difference in the fuel quantity used.  The curious part to me is that on 2 cars you have seen the boost drop after adding the can.  My question would be is this boost drop present immediately or only post tuning?  If it occurs right away then why do we think that is the case?  If we take oil control out of the equation, which I can't see how that could effect boost level, then the only other thing that the can does is reduce crankcase pressure.  This is claimed to improve ring seal.  I can see how better ring seal can improve power but I was/am sort of grasping at straws as to how that could drop the boost pressure.  Seems like only a VE increase could cause that.

[Jared@SFS]

I wish the pressure could have have been monitored, that is a pretty fascinating change!

 

To help explain what David is saying that yes fuel was added, but not fuel was added due to VE when he said fuel trims were a bit off.

 

A GTR has a target AFR table. You tell it you want to run 12.4 AFR or .85Lambda

 

In the software, you tell it to inject a certain fuel unit. Lets say the fuel unit was 50 to run .85 Lambda. But the GTR using it's wideband AFR sensor detects that 50 fuel units actually runs at .90 Lambda. It will adjust its learned values until it hits the target. Lets say it needed to actually add 10% fuel to reach the target. The GTR has learned 55 fuel units= .85 Lambda, and learns 110% fuel trim from the base value.

 

David sees that, and being a anal tuner wants it to have 100% fuel trims and not have the car have to learn, so he corrected the programmed value from 50 units to 55 units. That way when the wideband sensors report back the computer does not adjust. And this is how you add fuel, but not actually add any fuel.

 

That either helped, or confused people a lot more. Hopefully both.

[Nissangtr10]

So with same tune no changes to anythin but a catch can what is the gain?

[UnaBomber]

I wish the pressure could have have been monitored, that is a pretty fascinating change!

 

To help explain what David is saying that yes fuel was added, but not fuel was added due to VE when he said fuel trims were a bit off.

 

A GTR has a target AFR table. You tell it you want to run 12.4 AFR or .85Lambda

 

In the software, you tell it to inject a certain fuel unit. Lets say the fuel unit was 50 to run .85 Lambda. But the GTR using it's wideband AFR sensor detects that 50 fuel units actually runs at .90 Lambda. It will adjust its learned values until it hits the target. Lets say it needed to actually add 10% fuel to reach the target. The GTR has learned 55 fuel units= .85 Lambda, and learns 110% fuel trim from the base value.

 

David sees that, and being a anal tuner wants it to have 100% fuel trims and not have the car have to learn, so he corrected the programmed value from 50 units to 55 units. That way when the wideband sensors report back the computer does not adjust. And this is how you add fuel, but not actually add any fuel.

 

That either helped, or confused people a lot more. Hopefully both.

 

that helped a ton actually thansk

[HiBoost]

To help explain what David is saying that yes fuel was added, but not fuel was added due to VE when he said fuel trims were a bit off.
 
A GTR has a target AFR table. You tell it you want to run 12.4 AFR or .85Lambda
 
In the software, you tell it to inject a certain fuel unit. Lets say the fuel unit was 50 to run .85 Lambda. But the GTR using it's wideband AFR sensor detects that 50 fuel units actually runs at .90 Lambda. It will adjust its learned values until it hits the target. Lets say it needed to actually add 10% fuel to reach the target. The GTR has learned 55 fuel units= .85 Lambda, and learns 110% fuel trim from the base value.
 
David sees that, and being a anal tuner wants it to have 100% fuel trims and not have the car have to learn, so he corrected the programmed value from 50 units to 55 units. That way when the wideband sensors report back the computer does not adjust. And this is how you add fuel, but not actually add any fuel.

I completely understand fuel trims, and summarized all of what you wrote above when I wrote this:

whether you asked for 97 and the ECU added 3 or you just asked for 100 in the first place, in either case you are getting 100 and there's really no difference in the fuel quantity used.

What is not being explained is the drop in boost. If the turbos are flowing the same air mass but the boost in the manifold is less, then more air made it into the cylinder. I.e. VE was increased. But if VE increases while not adding any "net" fuel (i.e. base+trims) and AFR stays the same, then what explains this? If we work backwards and say same fuel mass and same AFR, then we'd have to assume same air mass. But then why would boost go down? THAT is what I'm trying to figure out here.

[Jared@SFS]

I completely understand fuel trims, and summarized all of what you wrote above when I wrote this:


What is not being explained is the drop in boost. If the turbos are flowing the same air mass but the boost in the manifold is less, then more air made it into the cylinder. I.e. VE was increased. But if VE increases while not adding any "net" fuel (i.e. base+trims) and AFR stays the same, then what explains this? If we work backwards and say same fuel mass and same AFR, then we'd have to assume same air mass. But then why would boost go down? THAT is what I'm trying to figure out here.

 

You posted that after I had opened the topic and got into a bunch of phone calls, if it didn't help you, it helped someone else!

 

If boost goes down, but AFR and Fueling stays the same, there HAS to be a VE improvement. Part of the VE is the reduced crankcase pressure.  If I understand correctly, you are trying to find out where the VE came from?  If you picture a old hand operated piston style bicycle tire pump, it is much easier to push when it is not connected to a tire. When you connect it to a tire and start to inflate it, it becomes harder as pressure goes up. By reducing pressure in the crank case, it's just like operating the bicycle pump not connected to a tire.

 

 

Also, I think the reason you don't see David saying or claiming any magical improvements is he isn't a bullshit salesman. He presents observations to foster technical discussions.

Edited by Jared@SFS, 11 December 2015 - 11:38 AM.

[HiBoost]

I think you are confusing VE with parasitic and/or pumping losses. The latter would impact power measured, but the former would be the only thing that could impact the air/fuel relationship we are discussing. VE refers specifically to how much air gets ingested into the cylinder relative to its static displacement. A force acting on the bottom of the piston shouldn't impact this, but air leaking past the rings per my "reverse blow-by" SWAG might. This is why I also originally mentioned the theoretical perfectly sealed piston/cylinder vs what may actually be happening.

[Jared@SFS]

I think you are confusing VE with parasitic and/or pumping losses. The latter would impact power measured, but the former would be the only thing that could impact the air/fuel relationship we are discussing. VE refers specifically to how much air gets ingested into the cylinder relative to its static displacement. A force acting on the bottom of the piston shouldn't impact this, but air leaking past the rings per my "reverse blow-by" SWAG might. This is why I also originally mentioned the theoretical perfectly sealed piston/cylinder vs what may actually be happening.

 

 

In forced induction motors, you can exceed 100% VE (which 100% is the combustion volume ingested every 2 crank cycles). Pressure coming up around the piston rings, and pressure acting against the piston work together to reduce the volume of air coming in. I described them as one force when it is two, and you're right there. A VE improvement from the improved piston ring seal, and a parasitic loss reduction from the piston operating in a "vacuum"

[HiBoost]

Pressure coming up around the piston rings, and pressure acting against the piston work together to reduce the volume of air coming in.

The first part of this - pressure coming up around the rings - is what I was originally suggesting as the sole modifier of VE. But the second part, pressure acting on the bottom of the piston, I do not believe that this can impact the volume of air coming in. The volume of air coming in comes down to the swept displacement, the breathing potential (head flow, valve lift, etc) and the RPM. Even NA motors can achieve VE beyond 100% at certain RPMs where the intake is properly tuned to achieve super-filling. But, going back to our scenario, pressure on the bottom of the piston does not impact any of these things. The piston still goes down just as far so the swept volume is the same. The engine still achieves the same RPM so the charge velocities are the same. And of course the flow characteristics of the intake are unchanged. So that still takes me back to a drop in boost in this situation all coming down to less crankcase pressure leaking up and therefore allowing additional intake charge from coming in. That just seems like a shocking result to me as it would seem to require *really* leaky rings to allow there to be such a measurable change by getting rid of only 0.6 psi of crankcase pressure. So this is why I keep probing the topic to find out if I'm missing something or what.

[thehelix112]

If we assume there is positive pressure underneath the piston on the intake stroke, and we assume less than perfect ring sealing, then theoretically that pressure is acting against the charge flow into the bore.

Ergo, reducing that pressure could increase charge flow, and therefore VE.

No?

Dave

Edit: oh that was the last bit of your post Jeff. My bad.

Edited by thehelix112, 11 December 2015 - 01:22 PM.

[Tim]

I will tell you guys 1 thing this is a great discussion

[Buschur Racing]

I feel like we're miscommunicating here.  You posted that this was interesting, which implies that the result was somewhat unexpected.  I agree that it is interesting and I am trying to have a discussion about why a catch can may be adding 24whp.  I understand how fuel trims work, but whether you asked for 97 and the ECU added 3 or you just asked for 100 in the first place, in either case you are getting 100 and there's really no difference in the fuel quantity used.  The curious part to me is that on 2 cars you have seen the boost drop after adding the can.  My question would be is this boost drop present immediately or only post tuning?  If it occurs right away then why do we think that is the case?  If we take oil control out of the equation, which I can't see how that could effect boost level, then the only other thing that the can does is reduce crankcase pressure.  This is claimed to improve ring seal.  I can see how better ring seal can improve power but I was/am sort of grasping at straws as to how that could drop the boost pressure.  Seems like only a VE increase could cause that.

 

The boost has dropped the same amount on both cars vs crank case pressure measured and  immediately following the installation of the pro catch can.  I'd agree the decrease in boost is directly related to the decrease in crank case pressure.

[Buschur Racing]

So with same tune no changes to anythin but a catch can what is the gain?

 

Good question, I have no answer because as the boost drops and other things change they all need to be re-adjusted to optimize what you are doing.  There is certainly ZERO down side to getting a real can on the car.