New Product from 928sRus - Enhanced Intake System
04-18-2010, 11:27 AM
#121
Race Car
I can see a reason why the graph is leaner with more air. Yes, the MAF is registering more air and sending more volts to the LH brain, but how do you know what the LH map looks like? Even if there is enough air for the LH to drop down a row in the table but that row has the same values, the same amount of fuel will be injected even though there is more air present.
It would be very easy to verify this with a SharkTuner.
Dan
'91 928GT S/C
475hp/460lb.ft
It would be very easy to verify this with a SharkTuner.
Dan
'91 928GT S/C
475hp/460lb.ft
04-18-2010, 11:59 AM
#122
I can see a reason why the graph is leaner with more air. Yes, the MAF is registering more air and sending more volts to the LH brain, but how do you know what the LH map looks like? Even if there is enough air for the LH to drop down a row in the table but that row has the same values, the same amount of fuel will be injected even though there is more air present.
It would be very easy to verify this with a SharkTuner.
Dan
'91 928GT S/C 475hp/460lb.ft
It would be very easy to verify this with a SharkTuner.
Dan
'91 928GT S/C
475hp/460lb.ft
Just don't know when we will have the time to accomplish that though.
04-18-2010, 12:48 PM
#123
Inventor
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It's leaner because the LH WOT map is flat, using RPM only. (WOT map values are added to the base RPM/MAF scaled map.)
The stock WOT map is very rich at high rpm, (low 12's) so any airflow improvement will pull it closer to 13:1 for higher HP.
Torque is what SharkTuning will help most. The stock low/mid range is already lean (for economy) so the same improvements need more fuel to take full advantage of. A stock+ chip would just need a little tweaking to the WOT map.
The stock 19# injectors are getting flaky at high rpms because they are near max'ed out. Inconsistent or wavy AFRs are an indicator of this. S4+ need a 24# chip...
The stock WOT map is very rich at high rpm, (low 12's) so any airflow improvement will pull it closer to 13:1 for higher HP.
Torque is what SharkTuning will help most. The stock low/mid range is already lean (for economy) so the same improvements need more fuel to take full advantage of. A stock+ chip would just need a little tweaking to the WOT map.
The stock 19# injectors are getting flaky at high rpms because they are near max'ed out. Inconsistent or wavy AFRs are an indicator of this. S4+ need a 24# chip...
04-18-2010, 12:56 PM
#124
Rennlist Member
If the ID of the MAF is larger than the ID of the Throttle Body the size is big enough. If the voltage from the MAF reaches above 4.6v at WOT, but never reaches 5v it is the correct calibration range.
From my experience with the 944 Turbo, frankly, I am surprised supercharger users aren't running out of MAF range when running boost. You don't have to crank up the boost very much on the Turbos to run out of metering capability with the stock meter, especially if you are going to bigger injectors. When going to bigger injectors and bigger MAFs we also found the voltage from the MAF combined with throttle position determines when the engine is under load to advance the timing.
From my experience with the 944 Turbo, frankly, I am surprised supercharger users aren't running out of MAF range when running boost. You don't have to crank up the boost very much on the Turbos to run out of metering capability with the stock meter, especially if you are going to bigger injectors. When going to bigger injectors and bigger MAFs we also found the voltage from the MAF combined with throttle position determines when the engine is under load to advance the timing.
04-18-2010, 12:57 PM
#125
Rennlist Member
I doubt a bigger MAF would gain any improvement on a 5 or 5.4 engine. The inlet manifold is the main restriction.
Mark Anderson does use a special MAF which has the std MAF sensor and electronics, in a larger housing.
Mark Anderson does use a special MAF which has the std MAF sensor and electronics, in a larger housing.
04-18-2010, 01:04 PM
#126
Rennlist Member
The inside of the std MAF body is very smooth, no advantage there.
My interpretation of the EIS results is that the MAF is registering LESS volts at a given airflow, volts for any air mass is lower therefore mixture is weaker over the whole range.
This helps at the top end but is making the mid range rpm even weaker than normal.
Ken, LH ECU uses base fuel map (rpm and load) PLUS WOT map values (rpm only) to determine fuelling at WOT. So fuelling is load and RPM based. Std procedure for SharkTuning is to zero out all WOT map values, and tune soley on the base fuel map
My interpretation of the EIS results is that the MAF is registering LESS volts at a given airflow, volts for any air mass is lower therefore mixture is weaker over the whole range.
This helps at the top end but is making the mid range rpm even weaker than normal.
Ken, LH ECU uses base fuel map (rpm and load) PLUS WOT map values (rpm only) to determine fuelling at WOT. So fuelling is load and RPM based. Std procedure for SharkTuning is to zero out all WOT map values, and tune soley on the base fuel map
04-18-2010, 01:05 PM
#127
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04-18-2010, 01:14 PM
#128
Thanks for the educamating me.
04-18-2010, 01:18 PM
#129
Burning Brakes
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So unless intake is extrude honed or someone comes up with different intake
no gains on bigger MAF on 5 or 5.4liter.
04-18-2010, 01:23 PM
#130
Rennlist Member
However I have never measured the pressure drop across a MAF when it is breathing 350HP or so.....
04-18-2010, 01:27 PM
#131
Inventor
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For a basic companion (stock+) chip to the EIS, a minor revision to the WOT map would be sufficient.
04-18-2010, 01:47 PM
#132
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I was wrong about the WOT map fueling at high rpm, though. The WOT map values get smaller at high rpm because the base map is quite rich at the highest rpms. Most of the low/mid-range enrichment comes from the WOT map.
Some of the AFR change could be attributed to heat soak on the dyno (while the intake was changed).
As the engine compartment, intake, MAF, fuel, etc. heats up, AFRs will start getting leaner.
Some of the AFR change could be attributed to heat soak on the dyno (while the intake was changed).
As the engine compartment, intake, MAF, fuel, etc. heats up, AFRs will start getting leaner.
04-18-2010, 03:42 PM
#133
Rennlist Member
I was wrong about the WOT map fueling at high rpm, though. The WOT map values get smaller at high rpm because the base map is quite rich at the highest rpms. Most of the low/mid-range enrichment comes from the WOT map.
Some of the AFR change could be attributed to heat soak on the dyno (while the intake was changed).
As the engine compartment, intake, MAF, fuel, etc. heats up, AFRs will start getting leaner.
Some of the AFR change could be attributed to heat soak on the dyno (while the intake was changed).
As the engine compartment, intake, MAF, fuel, etc. heats up, AFRs will start getting leaner.
The main point I was trying to make is that at the top end the load value from the MAf is dominant so fuelling is not just rpm based.
The mid range with this intake is interesting as there is more power even with the weaker than optimum mixture. Some figures before an after Sharktuning will be very interesting. Should also be extra potential by remapping the igntion as well.
04-20-2010, 07:00 PM
#134
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"It looks awfully similar to 928 specialists "Blackbird" to me"
Good question and I am happy to provide an answer.
Yes it does have some similar traits to the Blackbird. Unfortunately the Blackbird is not available and has not been available for nearly two years. I had 6 on order - one for myself and the rest for local 928 owners here in DFW. DR told Jim M and me that we would have ours in July 09 at the OCIC - for some reason that did not happen. Not my business to know why they are not available - they just are not. I have stated publically that I wanted a Blackbird on my GTS. Everything was done on my car apart from the intake kit soooo after some others put together their own kits and the numerous emails asking me to put together a kit - we did.
Already sold 8 kits plus the 3 we have on test at the moment.
Dyno runs next week to see if any gains can be made power wise.
Would have loved to have a "Blackbird" but !!!!
Good question and I am happy to provide an answer.
Yes it does have some similar traits to the Blackbird. Unfortunately the Blackbird is not available and has not been available for nearly two years. I had 6 on order - one for myself and the rest for local 928 owners here in DFW. DR told Jim M and me that we would have ours in July 09 at the OCIC - for some reason that did not happen. Not my business to know why they are not available - they just are not. I have stated publically that I wanted a Blackbird on my GTS. Everything was done on my car apart from the intake kit soooo after some others put together their own kits and the numerous emails asking me to put together a kit - we did.
Already sold 8 kits plus the 3 we have on test at the moment.
Dyno runs next week to see if any gains can be made power wise.
Would have loved to have a "Blackbird" but !!!!
04-20-2010, 07:03 PM
#135
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Terry,
Just email me at Roger@928sRus.com and I will add you to the list for the second batch.
We will be doing a further two cars on the Dyno on Thursday.
Roger
Just email me at Roger@928sRus.com and I will add you to the list for the second batch.
We will be doing a further two cars on the Dyno on Thursday.
Roger
__________________
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014
928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."
Does it have the "Do It Yourself" manual transmission, or the superior "Fully Equipped by Porsche" Automatic Transmission?
George Layton March 2014928 Owners are ".....a secret sect of quietly assured Porsche pragmatists who in near anonymity appreciate the prodigious, easy going prowess of the 928."