4th Gen MAF mod
02-08-2006, 01:04 PM
#1
4th Gen MAF mod
I've been playing with trying a 3.5" intake on my 3.5 swap vs the stock 3".
Probably won't max out the stock MAF but this should reduce the air speed somewhat and I like playing. May be a good mod for FI vs swapping MAF's.
As you all know the 4th Gen MAF won't just plug into a hole like the 5.5 Gen will so I had to do a bunch of cutting to reduce it to about the same size as the 5.5 one and will next try to fit it into some 3.5" aluminum tubing. Have thought about this before but after seeing the MAFci made by CP-E for the Altima I thought I would have a stab at it.
My one concern is the placement of the sensor. The sensor is not going to be centered in the larger tubing. Any comments on issues with this? I don't think it should be because they are doing it on the Altima but I would like to hear some comments.
As soon as I get my 45 deg 3.5" tubing and 3-3.5" silicon adaptor I will take some pics. My Son picked up the stuff last week from Vibrant when I was in Fla I just have to go and get it.
My plan is to take both to the dyno in the spring and compare stock to mod.
Obviously anyone who tries this will have to have a/f adjustment capabilities.
Any ideas or complications etc you see would be appreciated.
Jim
Probably won't max out the stock MAF but this should reduce the air speed somewhat and I like playing. May be a good mod for FI vs swapping MAF's.
As you all know the 4th Gen MAF won't just plug into a hole like the 5.5 Gen will so I had to do a bunch of cutting to reduce it to about the same size as the 5.5 one and will next try to fit it into some 3.5" aluminum tubing. Have thought about this before but after seeing the MAFci made by CP-E for the Altima I thought I would have a stab at it.
My one concern is the placement of the sensor. The sensor is not going to be centered in the larger tubing. Any comments on issues with this? I don't think it should be because they are doing it on the Altima but I would like to hear some comments.
As soon as I get my 45 deg 3.5" tubing and 3-3.5" silicon adaptor I will take some pics. My Son picked up the stuff last week from Vibrant when I was in Fla I just have to go and get it.
My plan is to take both to the dyno in the spring and compare stock to mod.
Obviously anyone who tries this will have to have a/f adjustment capabilities.
Any ideas or complications etc you see would be appreciated.
Jim
02-08-2006, 01:42 PM
#2
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I doubt you're going to see the benefits of this until you run a matching throttle body. You'd an 80-85 mm throttle body instead of the stock 70 mm. Any plans for the TB?
02-08-2006, 10:54 PM
#4
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MAF SIGNAL CONDITIONING
CP-E just flow tested the same MAF sensor in the stock and larger tubes to come up with a MAF voltage correction curve. The "ecu" they supply with their MAFci is just a signal conditioner to apply this correction so the stock ecu sees the correct voltage for the actual air flow.
This "ecu" is not like an AFC which only takes over at large throttle openings. It is modifying the MAF output all the time.
Without this continuous signal conditioning, I think you will have
drivability problems. We are talking about roughly a 30% decrease in the mean flow velocity that the MAF will see.
During normal driving, the ecu is constantly switching back and forth between open and closed loop operation. Any time you decelerate or accelerate (except for very gradually) you are open-loop. As the ecu is only feeding fuel based on MAF output, you will be roughly 30% lean.
SENSOR POSITIONING
For turbulent flows, which any WOT blast will be, the positioning of the sensor in the airstream is not that critical. Even with the sensor only a 1/4 of the way across the tube diameter, you will still pick up >90% of the maximum flow velocity.
The positioning problem occurs at part throttle where the air flow is more laminar. In this situation there is a substantial change in the velocity profile across the diameter of the tube. The maximum in the centre is approximately twice the mean flow velocity. This is not a problem for the CP-E unit as they would have developed their correction curve for flows from idle right up to beyond redline at WOT.
CP-E just flow tested the same MAF sensor in the stock and larger tubes to come up with a MAF voltage correction curve. The "ecu" they supply with their MAFci is just a signal conditioner to apply this correction so the stock ecu sees the correct voltage for the actual air flow.
This "ecu" is not like an AFC which only takes over at large throttle openings. It is modifying the MAF output all the time.
Without this continuous signal conditioning, I think you will have
drivability problems. We are talking about roughly a 30% decrease in the mean flow velocity that the MAF will see.
During normal driving, the ecu is constantly switching back and forth between open and closed loop operation. Any time you decelerate or accelerate (except for very gradually) you are open-loop. As the ecu is only feeding fuel based on MAF output, you will be roughly 30% lean.
SENSOR POSITIONING
For turbulent flows, which any WOT blast will be, the positioning of the sensor in the airstream is not that critical. Even with the sensor only a 1/4 of the way across the tube diameter, you will still pick up >90% of the maximum flow velocity.
The positioning problem occurs at part throttle where the air flow is more laminar. In this situation there is a substantial change in the velocity profile across the diameter of the tube. The maximum in the centre is approximately twice the mean flow velocity. This is not a problem for the CP-E unit as they would have developed their correction curve for flows from idle right up to beyond redline at WOT.
02-09-2006, 04:35 AM
#5
Originally Posted by eng92
MAF SIGNAL CONDITIONING
CP-E just flow tested the same MAF sensor in the stock and larger tubes to come up with a MAF voltage correction curve. The "ecu" they supply with their MAFci is just a signal conditioner to apply this correction so the stock ecu sees the correct voltage for the actual air flow.
This "ecu" is not like an AFC which only takes over at large throttle openings. It is modifying the MAF output all the time.
Without this continuous signal conditioning, I think you will have
drivability problems. We are talking about roughly a 30% decrease in the mean flow velocity that the MAF will see.
During normal driving, the ecu is constantly switching back and forth between open and closed loop operation. Any time you decelerate or accelerate (except for very gradually) you are open-loop. As the ecu is only feeding fuel based on MAF output, you will be roughly 30% lean.
SENSOR POSITIONING
For turbulent flows, which any WOT blast will be, the positioning of the sensor in the airstream is not that critical. Even with the sensor only a 1/4 of the way across the tube diameter, you will still pick up >90% of the maximum flow velocity.
The positioning problem occurs at part throttle where the air flow is more laminar. In this situation there is a substantial change in the velocity profile across the diameter of the tube. The maximum in the centre is approximately twice the mean flow velocity. This is not a problem for the CP-E unit as they would have developed their correction curve for flows from idle right up to beyond redline at WOT.
CP-E just flow tested the same MAF sensor in the stock and larger tubes to come up with a MAF voltage correction curve. The "ecu" they supply with their MAFci is just a signal conditioner to apply this correction so the stock ecu sees the correct voltage for the actual air flow.
This "ecu" is not like an AFC which only takes over at large throttle openings. It is modifying the MAF output all the time.
Without this continuous signal conditioning, I think you will have
drivability problems. We are talking about roughly a 30% decrease in the mean flow velocity that the MAF will see.
During normal driving, the ecu is constantly switching back and forth between open and closed loop operation. Any time you decelerate or accelerate (except for very gradually) you are open-loop. As the ecu is only feeding fuel based on MAF output, you will be roughly 30% lean.
SENSOR POSITIONING
For turbulent flows, which any WOT blast will be, the positioning of the sensor in the airstream is not that critical. Even with the sensor only a 1/4 of the way across the tube diameter, you will still pick up >90% of the maximum flow velocity.
The positioning problem occurs at part throttle where the air flow is more laminar. In this situation there is a substantial change in the velocity profile across the diameter of the tube. The maximum in the centre is approximately twice the mean flow velocity. This is not a problem for the CP-E unit as they would have developed their correction curve for flows from idle right up to beyond redline at WOT.
I do plan on using this with the Emanage Ultimate, shouldn't that give me continuous signal conditioning?
The other thing I want to compare it to is using the MAP sensor and eliminating the MAF altogether. I realize it will have to run from a preprogrammed map all the time so may not be that great for gas mileage. I guess I could use the MAF on the street and swap over the the MAP sensor at the track if it would help my consistency. What I am really trying to achieve is consistency not necessarily maximum power, so I am hoping with the EU I can control timing, fuel etc so nothing changes between runs except the weather which I have a weather station and ET prediction software to compensate with.
I need to be able to put together runs that only vary in 100th's of a sec not tenth's. The class I will be running in consists of all v8's (auto's) mostly running in the 10-13 sec range. Last year I did ok but couldn't keep the consistency even with the weather station stuff. I think it was caused mainly by the computer which the v8's don't have and I'm hoping with the EU I can control the timing and a/f to be the same every run.
The weather setup I am using is capable of predicting runs to within 5-10 100th's and many times I have seen it within 2-3 100th's with my friend's 10 sec Chevy. Do you think thats possible using the EU or is it a hopeless task?
PS Where do you think that most of CP-E's claimed 20 HP is coming from, their intake or the modified a/f?
02-09-2006, 07:05 AM
#6
Jim here's my thoughts:
-First of all, having somewhat of an engineering background myself, I agree with most everything Eng92 said. From a fluid mechanics standpoint he's right on in my opinion.
-Yes you could develop a conditioning curve across all rpm/load points (ie all driving conditions) with the EU. However I think to do this properly you'd have to drive around with both MAF setups on at the same time. The EU would datalog the voltage output from both and then from that log you'd develop the translation map. If you have a spare stock MAF then this wouldn't too big a deal. Just some wiring and getting them physically located properly in the intake piping so the flow regimes are as similar as possible.
-I would suggest that if you're doing all this to remove restrictions due to the MAF, then it is worth trying the MAP and removing the MAF altogether. The process would be similar, the downside being the extra tuning time and effort required to adjust for temperature changes (since the MAP doesn't compensate for this automatically like the MAF)
-As far as consistency goes, without a true standalone you cannot expect to have perfectly consistent control over and output of timing, fuel etc. The stock ECU will adjust for several variables, eg- coolant temps etc. HOWEVER I think you can control it and improve it quite significantly with the EU as compared to an ECU (even a JWT or TS), since you can influence not only the outputs themselves but the input of variables that would modify the stock ECU's outputs. I have found doing a lot of runs on the dyno and the street last fall that I was getting very consistent curves (power, fuel etc) by controlling some key inputs. Don't know if you've seen my dyno but the curves are decently smooth. But if you wish we can discuss more about this when I come up there.
-I think CP-E's gains are a combination of things. If the A/F was way off to begin with there could be 1/3 to 1/2 the gain there. But I'd say the other major factor is just that they upsized the tubing and made a whole new free flowing intake to replace the restrictive stocker. It's just like getting a good aftermarket intake to replace the stock one. You're bound to see an increase. How much the MAF by itself contributes, not sure, but my gut feeling is that of those 3 improvements it's the smallest pie slice.
-First of all, having somewhat of an engineering background myself, I agree with most everything Eng92 said. From a fluid mechanics standpoint he's right on in my opinion.
-Yes you could develop a conditioning curve across all rpm/load points (ie all driving conditions) with the EU. However I think to do this properly you'd have to drive around with both MAF setups on at the same time. The EU would datalog the voltage output from both and then from that log you'd develop the translation map. If you have a spare stock MAF then this wouldn't too big a deal. Just some wiring and getting them physically located properly in the intake piping so the flow regimes are as similar as possible.
-I would suggest that if you're doing all this to remove restrictions due to the MAF, then it is worth trying the MAP and removing the MAF altogether. The process would be similar, the downside being the extra tuning time and effort required to adjust for temperature changes (since the MAP doesn't compensate for this automatically like the MAF)
-As far as consistency goes, without a true standalone you cannot expect to have perfectly consistent control over and output of timing, fuel etc. The stock ECU will adjust for several variables, eg- coolant temps etc. HOWEVER I think you can control it and improve it quite significantly with the EU as compared to an ECU (even a JWT or TS), since you can influence not only the outputs themselves but the input of variables that would modify the stock ECU's outputs. I have found doing a lot of runs on the dyno and the street last fall that I was getting very consistent curves (power, fuel etc) by controlling some key inputs. Don't know if you've seen my dyno but the curves are decently smooth. But if you wish we can discuss more about this when I come up there.
-I think CP-E's gains are a combination of things. If the A/F was way off to begin with there could be 1/3 to 1/2 the gain there. But I'd say the other major factor is just that they upsized the tubing and made a whole new free flowing intake to replace the restrictive stocker. It's just like getting a good aftermarket intake to replace the stock one. You're bound to see an increase. How much the MAF by itself contributes, not sure, but my gut feeling is that of those 3 improvements it's the smallest pie slice.
02-09-2006, 09:18 AM
#7
Jime,
IMO, do NOT eliminate the MAF instead run a hacked MAF. Driveablility and more importantly consistency will suffer especially since running a MAP only car requires an IAT map and the EU only offers a 16x1 map, so resolution isn't great.
Also, have you considered running a bypass tube(SR/240SX guys do this) or dual MAF(one dummy ala 300ZXTT) type setup?
IMO, do NOT eliminate the MAF instead run a hacked MAF. Driveablility and more importantly consistency will suffer especially since running a MAP only car requires an IAT map and the EU only offers a 16x1 map, so resolution isn't great.
Also, have you considered running a bypass tube(SR/240SX guys do this) or dual MAF(one dummy ala 300ZXTT) type setup?
02-09-2006, 10:18 AM
#8
Originally Posted by DandyMax
Jim here's my thoughts:
-First of all, having somewhat of an engineering background myself, I agree with most everything Eng92 said. From a fluid mechanics standpoint he's right on in my opinion.
-Yes you could develop a conditioning curve across all rpm/load points (ie all driving conditions) with the EU. However I think to do this properly you'd have to drive around with both MAF setups on at the same time. The EU would datalog the voltage output from both and then from that log you'd develop the translation map. If you have a spare stock MAF then this wouldn't too big a deal. Just some wiring and getting them physically located properly in the intake piping so the flow regimes are as similar as possible.
-I would suggest that if you're doing all this to remove restrictions due to the MAF, then it is worth trying the MAP and removing the MAF altogether. The process would be similar, the downside being the extra tuning time and effort required to adjust for temperature changes (since the MAP doesn't compensate for this automatically like the MAF)
-As far as consistency goes, without a true standalone you cannot expect to have perfectly consistent control over and output of timing, fuel etc. The stock ECU will adjust for several variables, eg- coolant temps etc. HOWEVER I think you can control it and improve it quite significantly with the EU as compared to an ECU (even a JWT or TS), since you can influence not only the outputs themselves but the input of variables that would modify the stock ECU's outputs. I have found doing a lot of runs on the dyno and the street last fall that I was getting very consistent curves (power, fuel etc) by controlling some key inputs. Don't know if you've seen my dyno but the curves are decently smooth. But if you wish we can discuss more about this when I come up there.
-I think CP-E's gains are a combination of things. If the A/F was way off to begin with there could be 1/3 to 1/2 the gain there. But I'd say the other major factor is just that they upsized the tubing and made a whole new free flowing intake to replace the restrictive stocker. It's just like getting a good aftermarket intake to replace the stock one. You're bound to see an increase. How much the MAF by itself contributes, not sure, but my gut feeling is that of those 3 improvements it's the smallest pie slice.
-First of all, having somewhat of an engineering background myself, I agree with most everything Eng92 said. From a fluid mechanics standpoint he's right on in my opinion.
-Yes you could develop a conditioning curve across all rpm/load points (ie all driving conditions) with the EU. However I think to do this properly you'd have to drive around with both MAF setups on at the same time. The EU would datalog the voltage output from both and then from that log you'd develop the translation map. If you have a spare stock MAF then this wouldn't too big a deal. Just some wiring and getting them physically located properly in the intake piping so the flow regimes are as similar as possible.
-I would suggest that if you're doing all this to remove restrictions due to the MAF, then it is worth trying the MAP and removing the MAF altogether. The process would be similar, the downside being the extra tuning time and effort required to adjust for temperature changes (since the MAP doesn't compensate for this automatically like the MAF)
-As far as consistency goes, without a true standalone you cannot expect to have perfectly consistent control over and output of timing, fuel etc. The stock ECU will adjust for several variables, eg- coolant temps etc. HOWEVER I think you can control it and improve it quite significantly with the EU as compared to an ECU (even a JWT or TS), since you can influence not only the outputs themselves but the input of variables that would modify the stock ECU's outputs. I have found doing a lot of runs on the dyno and the street last fall that I was getting very consistent curves (power, fuel etc) by controlling some key inputs. Don't know if you've seen my dyno but the curves are decently smooth. But if you wish we can discuss more about this when I come up there.
-I think CP-E's gains are a combination of things. If the A/F was way off to begin with there could be 1/3 to 1/2 the gain there. But I'd say the other major factor is just that they upsized the tubing and made a whole new free flowing intake to replace the restrictive stocker. It's just like getting a good aftermarket intake to replace the stock one. You're bound to see an increase. How much the MAF by itself contributes, not sure, but my gut feeling is that of those 3 improvements it's the smallest pie slice.
As far as the other variables, what I have tried in the past is a fixed resistor for intake temp, coolant etc, what I haven't been able to hold at a constant is the timing which I think is being affected more by the MAF than the other inputs. I was hoping the MAP would help because I don't want it to adjust for temp changes, I will adjust my ET according to weather station prediction. Bracket racing is a lot different than trying to get the quickest time possible. Although I do plan on running in the All Motor class in the Sport Compact Series so I do want quick as well, but my main and first concern is for the Bracket stuff.
I don't mind the time taken to tune, I have plenty of that and back roads, so if the MAP will produce more consistent results (excluding temp changes) then thats what I want. I did pick up a 1 bar a while back on Ebay.
Yes I did see your dyno runs, NICE. Where did you go? I've on been to the dyno once with my old 95 but plan on spending some time there in the spring once I get everything setup on the street.
02-09-2006, 10:21 AM
#9
Originally Posted by IceY2K1
IMO, do NOT eliminate the MAF instead run a hacked MAF. Driveablility and more importantly consistency will suffer especially since running a MAP only car requires an IAT map and the EU only offers a 16x1 map, so resolution isn't great.
I'm more than willing to be proven wrong, and if I am, so be it, but even having the 16x1 temp map I think I can tune it/get it to work pretty well. Who says you have to run a MAP in the winter. The range of temperature adjustment is relatively small for the racing season and 16 points resolution isn't so bad then.
Originally Posted by Jime
I don't mind the time taken to tune, I have plenty of that and back roads, so if the MAP will produce more consistent results (excluding temp changes) then thats what I want. I did pick up a 1 bar a while back on Ebay.
Yes I did see your dyno runs, NICE. Where did you go? I've on been to the dyno once with my old 95 but plan on spending some time there in the spring once I get everything setup on the street.
Yes I did see your dyno runs, NICE. Where did you go? I've on been to the dyno once with my old 95 but plan on spending some time there in the spring once I get everything setup on the street.
The dyno I use is located locally here in Kitchener. Where have you gone in the past? I can provide more details outside of this thread if you'd like.
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