Things we learned on Dyno & 03 555 HO

[DLeno]

no worms, Ted, keep it up. this is good straight info. We need more of that and less of the laminar flowing spiro nitro turbo sucking pseudo rocket guiding resonating nonscience.

 

[Jengle]

What??? You mean you can't induce a tornado in the muffler to suck all the suck all the exhaust out? I thought I was going to get away with a smaller turbo with that device on there. Now what am I to do?

 

[InThinAir]

So I guess for selfish purposes, I need to clarify some things since I am a little slow on the up take



I would guess that since I do alot of my driving in high elevations, that I am defueling because of the boost on my stock 03? Is that correct? The thinner air would cause that? Or is that backwards? Is my boost lower at elevation and I could help myself with opening up the intake and exhaust, which would be correct for a non turbo application?



I have noticed that towing the same loads between my mostly stock 01 and my completely stock 03 that the 01 outpulls the 03. I attributed it to the BHAF and Full 4" exhaust on the 01. And was gonna make those upgrades to the 03 after putting in an EGT to get some baseline numbers.

 

[Flores]

How much boost does it take before it defuels?

 

[JRG]

This can also be corrected by backing off on the wastegate adjustment by lengthening the rod by a turn or 2.

Could you please explain a little more ie. location?

It wouldn't surprise me in the least that even stock trucks are experiencing some defueling on hard pulls up a mountain with a big trailer, this happens because as the turbo temps climb and stabalize at full temp it pumps more air.

I know I have injectors but my truck seems to do this.



JRG

 

[Ted Jannetty]

At higher elevations it will have less boost so it shouldn't be as much of a problem for us flat landers.



I haven't checked yet but I would guess around 24 psi, someone else is welcome to jump in here.

 

[DLeno]

first, let me say that I don't intend to open up worm cans myself. I'm just a practical analytic the prefers to avoid pseudo science -- and I'm not picking issue with anyone who feels that a coat of paint gave them 20 more HP. as long as we know we're talking about feelings and subjectivity, not objective science



second, I note that (if memory serves) your 01 had an HX-35 turbo and 12cm housing. thats a lot more turbo than today's little HY-9, and I expect (the HX) would not suffer from this de-fueling problem and would greatly benefit from air upgrades.



As for elevation and boost, I'm no expert but I'll talk through the electronics part anyway (boost detection). First of all, the ECM makes decisions based on Manifold Absolute Pressure (MAP). this name is precise because its meaning is precise: absolute barametric pressure, or "stick a barometer in the intake pipe". Boost is simply a relative value that we are accustomed to measuring, and our gauges are calibrated in. But the ECM reads MAP, not boost (boost is the pressure difference between the intake manifold and the outside air). Whatever air pressure is present at the MAP sensor is what the ECM will react to.



the reason I think this is important is that at higher elevations, MAP will not be as high as at sea level. So to me, the ECM wouldn't see the high numbers and won't be as apt to perform Ted de-fueling . Of course, the other traditional things will happen with high elevations, though -- higher EGTs especially. I just don't think the particular phantom de-fueling phenomenon would be as likely.

 

[XcumminsX]

Why the hell didnt cummins just use a bigger turbo... less heat... make it so computer doesnt send the message to de-fuel. .



Nick

 

[Ted Jannetty]

Injectors would definately drive your boost higher which you need so I would suggest a boost fooler in this instance rather than backing off the wastegate.

 

[JRG]

I was wondering about that. I also was waiting for the "fully modified" B-lite as well, guess a boost fooler is in order, just now to pick one. Would backing off the wastgate do anything in the mean time?



JRG

 

[RankRam]

Originally posted by Nick Sommer

Why the hell didnt cummins just use a bigger turbo... less heat... make it so computer doesnt send the message to de-fuel. .



Nick

It's emissions, bigger turbo = more lag.

 

[lmills]

Originally posted by JRG

I was wondering about that. I also was waiting for the "fully modified" B-lite as well, guess a boost fooler is in order, just now to pick one. Would backing off the wastgate do anything in the mean time?



JRG

Hey JRG, What the heck are KAX injectors? I have never heard of them

 

[KLockliear]

What is STP corrected power?

 

[Ted Jannetty]

Standard Tempurature and Pressure

60 degree, dry air, 29. 92 barometric pressure.

This is the Standard figure that the computer corrects to so if you bring me your truck in the middle of winter or the middle of summer you will get the same numbers.



Extremely accurate

 

[KKlepfer]

Thanks Ted for taking the time to post to this site, your results are based on numbers and not feelings and that is refreshing.



Also thanks DLeno for adding your expertise and knowlege. I now have a better understanding of boost pressure and MAP.

 

[bulabula]

I'd guess that the MAP converts manifold pressure to a voltage then sends that voltage signal to the ECM - like almost every other sensor on the engine. And that the higher the pressure, the higher the voltage signal. And when the pressure&voltage reaches a predetermined point - the ECM commences defueling to protect the engine. Is that voltage range the typical 1-5 volts?



I'm thinking it would it be possible to create a boost fooler simply by wiring in a resister in the MAPs circuit to reduce the output voltage signal.

 

[nickleinonen]

oh, nick: a zener diode and a series resistor is all you need ...

yeah i know that is all i need really, but the ecm will see the factory values until the zener diode clip's the voltage off. i am thinking of something that will ramp the voltage up real quick to my preset clip point so the ecm will see say 20psi almost instantly giving the engine more fuel while you only have a few pounds of boost. will give a little smoke, and make the turbo spool a bit quicker... i can't however, figure out how to make it work with cruse control on???

 

[rbattelle]

Originally posted by nickleinonen

yeah i know that is all i need really, but the ecm will see the factory values until the zener diode clip's the voltage off. i am thinking of something that will ramp the voltage up real quick to my preset clip point so the ecm will see say 20psi almost instantly giving the engine more fuel while you only have a few pounds of boost. will give a little smoke, and make the turbo spool a bit quicker... i can't however, figure out how to make it work with cruse control on???

I assume this is how most boost foolers work.



Does anyone make a box that is just a boost fooler? I mean one that will allow you to take advantage of higher-flowing exhaust without "dialing in" more horsepower/torque by messing with injector timing and/or fuel pressures?

 

[DLeno]

rbattelle: boost foolers in production boxes today range from very simple to fully mapped. In the simpliest form, TST uses the zener diode method (or something similar), simply passing factory boost levels to the ECM so that the factory fueling curve is left "factory" but capped at some value before the ECM gets unhappy. Then TST of course applies their own duration stuff on top of that.



In the more complex forms, boost fooling involves reading the factory levels and re-mapping them to new ones, similar to what nick is targeting.



The only thing required to do "boost fooling" that will fulfill the objectives you mention is a trivially simple electronic circuit consisting of a dollar's worth of parts at Radio Shack. well maybe $2. Its the TST method that caps MAP, prevents de-fueling, and preserves all factory fueling curves.



nick, tell me about the problem with cruise control. my first thought is to simply insert an op amp (into the MAP circuit) with a simple linear gain of (determined by experimentation). put some bias in there so that the ECM reads some minimum boost perhaps. I haven't looked at this in detail but it seems this could be done without the cruise control knowing about it. the challenge will be driveability -- you really don't know what will be optimium, if this will really work well, and with an analog circuit it will be difficult to change the transfer function easily. A more fancy method might be to perform A/D, put in a look-up table , then do D/A back. that way you have complete control over the affect of boost on the fueling curve by changing numbers in a table. the bonus is that you can call this (numbers in a table) step "programming".



anyway, without the fancy digital circuitry, you're stuck with whatever analog circuitry capabiilty you have at your disposal (which may or may not work and will be hard to change if it doesn't) you might get lucky and the op amp with gain of . 5, 2 or 3 (who knows) might work. clamp the output by limiting Vcc directly or zener the outout. This might be fun: I can't wait to hear about your results!

 

[JRG]

Hey JRG, What the heck are KAX injectors? I have never heard of them

http://www.kaxmotorsports.com



JRG