KahnQuistador

I'll agree that the ECU will be "ok" and it might not throw codes but we're still talking about altering sensor readings that WILL affect how the ECU performs. You may not notice the little things, but there will be a difference.

If you want to mod the intake, the Motordyne system is the way to go. I had it on my G35 and it worked fine. As I recall, it had a valve on it where you could turn the bypass on and off. I left mine off, no bypass.

The difference is an engineered system vs. a "hey, ya'll, watch this!" system.

The inital question was how much gain was achieved and the answer was "none".

With respect to the S2000 dyno results, our test system ALWAYS issues a warning to operators about letting the vehicle return to normal operating temp before repeating certain tests or shutting it down after certain tests. It sounds like the S2000 dyno operators didn't do that. Bad practice.

My previous post simply said "consider this", not "don't do it". I did the plenum mod on my G35 because it had a known problem. It seems the G37 doesn't have that problem.

For those who must, mod away... After all, it's your car.

ironchef2008

iTrader: (4)

I and numerous others have used the Motordyne bypass with no ill effect and no codes. It's probably more beneficial for the FI guys, but it does reduce the temperature of the throttle body on G35's.

The reason why it makes no power difference in our application and many others, and is ultimately useless in all honesty, is because the density of oxygen between a 150 degree throttle body and a 110 degree throttle body is of no effect upon combustion. People love to speak of "heat soak" and "colder is denser" but they're using those terms somewhat improperly. Heat soak in automotive terms is meant to define when you attempt to place non-intercooled air via forced induction into the combustion chamber. Turbo's and superchargers significantly heat the air and without proper cooling, the amount of oxygen present per volumetric measure is reduced. But in a naturally aspirated engine, that 40 degree difference yields near identical density of oxygen. The key to an intake is mainly flow. If it flows better, and the ECU will account for it consistently, then there will be gains with or without the forty degree difference.


I couldn't agree more!

I understand but that's why I elaborated here on the effect of temperatures on an NA car. I didn't want anyone to falsely think that they would damage their vehicle via an ECU reading. Nissan has very aggressive ECU software but the coolant bypass has, to the best of my knowledge, not caused any sensor malfunctions, codes, or issues.

Agreed! But everyone should be realistic about their expectations with mods. A coolant bypass would not be high on my list of mods. If the throttle body was 250 degrees feeding into a metal manifold like the G35, perhaps.

C6Zhombre

the coolant/tb bypass is nothing new. I ran a coolant bypass on my 02 Z06 for about three years while living in Dallas. Yes, Dallas is somewhat hot, but I saw snow there at least once a year and had no issues with the tb blade freezing open or leaking coolant if installed properly.

but what is interesting, if I recall correctly, was the fact some chevy tuners claimed the tb blade could hypothetically freeze open in even 32+ degree weather....all it took was the right combination of moisture/density in the air to have this happen. Like I said, I never had an issue, and knew of many LS1/LS6 owners that were running the same without incident (and in even colder climates). I think on the chevy motors it proved to be about a 5 rwhp mod. Not much to tell you the truth, when you figure most of these cars were already making 350-450 depnding on mod state. Not a "material" percentage variance for most. I would expect even a less aggregate gain on this nissan motor thats only putting down 265ish, but when you're pursuing naturally aspirated power gains, maybe even a few is worthwhile. NA power is tough to come by on a big ci motor, much less a 6.

3des

^^ I did the TB bypass on my LS1 as well mostly because of minute leaks at both ends dropping orange coolant on my pretty block. Also I thought the purpose of shooting coolant through the TB was not to prevent the blade from sticking open but rather from sticking closed.

As far as mods go there is none easier than a TB bypass.

ppc

You are not sending bad data, nothing is being done to the sensor, the sensor is acurately measuring a lower temp in the intake.

Yes, ratios and net variances may be used but does not produce "GIGO". A ratio doen't change any accuracy in sensor readings. The ratios may not be in a range expected, but that is what we are looking for aren't we? The answer is yes, something that increases performance. It may cause the ECU to react differently having a lower intake temp. What nobody has data on as of yet, what happens to the intake temp when the ambient temp is 20F?

Sounds like you want to selectively apply your reasoning. The ECU works in a "closed loop" where it examines all of the sensors to make decisions on how to adjust the inputs and controls. As an example the O2 content in the exhaust is measured to compute the A/F ratio and adjust the injector pluse width to keep everything within predetermined limits. When the engine can no longer make the adjusts or some data is unobtainable the engine goes into "open loop" operating against tables instead of 100% sensor readings. I'm sure that the HFC are going to impact O2 values and temps as well.




First you say the Motordyne system worked, but then you state there was no gain. I quess I'm missing your intent here. Do you mean in didn't cause any harm but it didn't give you increases in peformance etc. that was expected or claimed by the company or others?

Just because you have a company of some stature providing an "engineered system" versus a home garage fabracation doesn't make one better, last longer, higher performance than another, just more expensive and a little more bling.

KahnQuistador

The bad data I refer to has nothing to do with the sensor. It has to do with the data the ECU receives. Anything you do to "fool" the ECU qualifies as "garbage in" and usually, that results in garbage out. Some garbage just smells worse.

How does the ECU respond to "bad" data? Well, it depends on the guy that programmed it. After all, this ECU is new and you will NEVER convince me that they got it all right the first time. My car has the "throttle surge" problem like others on this forum. That, my friend, is a programming error. We'll have to deal with it until they come up with a new ECU reflash. Now we're talking about intentionally feeding the ECU incorrect data.

You're not understanding what I'm saying about the HFC CEL issue. Agreed the ECU will note the out of range O2 input and might try to adjust the fuel injector performance to compensate. Or will it try to alter response to the throttle position? Maybe something else? Maybe all of the above?

When my CEL happened after installing the headers and HFCs, I noticed a slight drop in performance. In my case, because I know exactly what and where the problem is, I'm going to mod the sensor position to compensate. Of course, the right way to fix it would be to tweak the ECU data and leave the sensor position alone.

You can't make a blanket statement about what the ECU will do when a sensor fails or you intentionally alter the data unless you have intimate knowledge about the ECU which is not likely. I don't know because I'm no expert on the G37 ECU. I'll leave that to the folks at Technosquare.

The "no performance gain" comment refered to another members' statement about this mod, not the Motordyne package. The Motordyne system worked fine but I couldn't say how much it contributed to the performance gain from the whole package I had installed.

What I'm saying is that "fooling" the ECU is NOT a good idea. Sure, you CAN do it and MAYBE you can get away with it. Maybe the ECU will change the parameter you want it to change. Will it also change other parameters at the same time? I can't count the number of times I've heard programmers say "the changes I made couldn't have affected this or that". But the changes DID affect this or that and trouble soon followed. Usually about the time the General walked through the door.

What blows me away is that you have people driving a $40K vehicle trying to save a few dollars in an attempt to squeeze out another tiny fraction of power. If you can't afford to do it right, don't do it. We are not talking about fixing Granny's '49 Ford with chicken wire and spit.

You can mod your car any way you want. It's your car and I don't really care what you do to it. I'll stand by what I said because, like it or not, it's all true. BTW, some of what you said actually backs up what I said. Think about it.

Quote: "It may cause the ECU to react differently having a lower intake temp. What nobody has data on as of yet, what happens to the intake temp when the ambient temp is 20F?"

Now, that's exactly what I said. No?