The most you've sprayed in front of the MAF?
The most you've sprayed in front of the MAF? Just wondering what others have done? Wondering how big I can go safely? I would like to be around 100 - 150hp at the tires which is about 600 wheel where I'm going to run out of fuel pump. Injectors will have tons of room left.
At 925psi on the dyno, dual 28s in the lid (NOS 5177 style) was worth 45hp/60tq at the wheels, and dual 38's only gained 76hp/110tq rear wheel. Seems like I should have picked up a little more, right?
Tuner said everything looked good (I assume he was talking about fuel pressure, a/f, MAF scale).
At 925psi on the dyno, dual 28s in the lid (NOS 5177 style) was worth 45hp/60tq at the wheels, and dual 38's only gained 76hp/110tq rear wheel. Seems like I should have picked up a little more, right?
Tuner said everything looked good (I assume he was talking about fuel pressure, a/f, MAF scale).
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From: Berkeley, California
Spraying ahead of the MAF is a hit-or-miss kludge. The IAT-table trick is a far superior alternative - simple, reliable and predictable. Spray after the the MAF and let the MAF work as intended.
Not to thread hi-jack...but could you elaborate on this "IAT-table trick"...or point me towards a thread that explains it...???
(This nitrous stuff is pretty new to me...any advice or info would be appreciated.)
1) Car came with the kit.
2) Laziness. I love the idea that a hot bottle, cold bottle, empty bottle, un purged system can be hit at will and can provide results somewhere between good and great. No rich/lean condition, etc.
Seems the IAT tricker method would pretty much remove the "flexibility" I enjoy so much since it would lock me into a constant fuel enrichment, right?
Not a race car so a smallish shot size for street play is really all I want. Do you feel the MAF method may not be repeatable compared to what we saw during dyno tuning?
Does 76rwhp gain from dual 38's on a full bottle at 925psi sound right? Most jetting charts put that at 125hp (I assume rear wheel).
During tuning I was hoping to see at least 100 wheel, but felt like cramming bigger jets than what should be required was not a good idea.
During tuning I was hoping to see at least 100 wheel, but felt like cramming bigger jets than what should be required was not a good idea.
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Joined: Nov 2002
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From: Berkeley, California
Not at all. Done properly, the IAT- resistor trick uses a part of the IAT table that I've never seen used in normal driving (IAT above 85 degrees C). Maybe if you're stuck in traffic, in Summer, in the Mojave desert. Otherwise no enrichment. By saying "done properly", one of the things I have in mind is using the normal IAT sensor when the nitrous system is disabled.
Last edited by Gary Z; Aug 15, 2014 at 03:11 PM. Reason: Spelling error
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I understand it's momentary and not always active.
I was suggesting (I believe) once the tricker is activated it basically acts like a wet kit (consistent fuel enrichment whether or not the correct amount of nitrous is there). No good for low/high bottle pressure seen during random, unplanned, unprepared nitrous hits I would like to be able to do.
Am I mistaken?
I was suggesting (I believe) once the tricker is activated it basically acts like a wet kit (consistent fuel enrichment whether or not the correct amount of nitrous is there). No good for low/high bottle pressure seen during random, unplanned, unprepared nitrous hits I would like to be able to do.
Am I mistaken?
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From: Berkeley, California
The IAT trick essentially gives you two separate tunes. The PCM includes tables that modify spark advance and fuel enrichment in response to changes in intake air temperature. We take advantage of the fact that the range of these tables extends beyond normal operating temperatures and therefore parts of the tables are normally unused. We can modify the IAT tables in these normally unused areas to reduce timing and add fuel as needed during nitrous injection. When nitrous is activated, a relay in the IAT sensor circuit, forces the PCM to read a false temperature that falls in the modified areas of the IAT tables. Normally, intake air temperature is measured by a thermistor (IAT sensor) in the mass airflow sensor (MAF). When nitrous oxide is activated, a relay switches a fixed 300 ohm resistor into the IAT circuit in place of the thermistor. This forces the PCM to read a temperature of approximately 85 degrees Centigrade. The modified table areas then take over. The highest true intake air temperature I’ve seen is 59 degrees C, well outside the modified table areas. When nitrous is disabled the modified areas of the IAT tables have no effect and the normal timing and PE tables are used.
-Gary
-Gary
So 76hp might be a little low but not crazy. Instead of spraying nitrous right at the valve you are fogging the lid and letting the motor suck it in from a few feet away.
Hold your hand 2' from the bottle and open it, then hold it 6" and open it.
(don't really do that) but you get the point.
If the A/F and timing are where you want it then just put the jets in that make the HP you want. Who cares what "everyone else" says it should make.
From what I have seen that kit (5177) is limited to about 125hp.
The IAT trick essentially gives you two separate tunes. The PCM includes tables that modify spark advance and fuel enrichment in response to changes in intake air temperature. We take advantage of the fact that the range of these tables extends beyond normal operating temperatures and therefore parts of the tables are normally unused. We can modify the IAT tables in these normally unused areas to reduce timing and add fuel as needed during nitrous injection. When nitrous is activated, a relay in the IAT sensor circuit, forces the PCM to read a false temperature that falls in the modified areas of the IAT tables. Normally, intake air temperature is measured by a thermistor (IAT sensor) in the mass airflow sensor (MAF). When nitrous oxide is activated, a relay switches a fixed 300 ohm resistor into the IAT circuit in place of the thermistor. This forces the PCM to read a temperature of approximately 85 degrees Centigrade. The modified table areas then take over. The highest true intake air temperature I’ve seen is 59 degrees C, well outside the modified table areas. When nitrous is disabled the modified areas of the IAT tables have no effect and the normal timing and PE tables are used.
-Gary
-Gary
Thanks alot Gary. I appreciate the reply.
If your running a 99-02 (896/411 pcm) then you could run the custom nitrous operating system with efi live. It adds nitrous timing and fuel tables and works very well. No tricking sensors or anything like that involved.
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From: Darien,ga
so is it okay to run the wet system on my stock 6.0 thru the air flow mass sensor without tuning or should it be tuned to be safe.im only wanting a 100 shot.i have the nitrous express pn20110 system
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-Garrett
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The IAT method is for pulling timing, the maf would still be adding fuel with the injectors for the dry shot.
your not getting enough fuel. I bet that thing on a wide band is super lean. You are going to need to trick the iat or use something like a (maft old school tuning).
you can try to relocate to a single nozzle spraying on the iat sensor. those 5177 kits use the small powershot noids so even with no jets max spray is going to be whatever the orfice size is.
I know someone who use to run no jets in one of those kits back in 99.
you can try to relocate to a single nozzle spraying on the iat sensor. those 5177 kits use the small powershot noids so even with no jets max spray is going to be whatever the orfice size is.
I know someone who use to run no jets in one of those kits back in 99.