I can't seem to find any information about this anywhere. I've read a few posts how people increase the boost and retard the timing so that they ultimately are running a safer tune. Could someone elaborate? If possible, please tell how to achieve this. Or at least explain the theory behind it.

Thanks!

 

More boost certainly doesn't make a safer tune. Adding fuel and retarding timing will make a safer tune but retarding the timing too much can cause excessive cylinder temperature which isn't good either. Having a good standalone and a good tuner are the keys to a good tune.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecD &raquo;</TD></TR><TR><TD CLASS="quote">More boost certainly doesn't make a safer tune. </TD></TR></TABLE>

Actually to achieve the same HP it does make the tune have the ability to be more conservative. Lets say you make 350whp @ 15psi with MBT being the guiding point for you timing retard (always good), but if you want it safer then you can always add a tad more boost, say 2-3PSI and retard the timing EVEN MORE then normal to avoid "peak" cylinder pressures and getting a better average cylinder pressure instead of a peak. That's the theory and the theory works in real life too . The downside is two fold here. 1.) Higher EGT's because the burn is started later and 2.) More boost means more lag and more fuel needs even though the tune is safer.

This is why people never should base things off boost and just shoot for horsepower. The tuner will make the decision on MBT and if he feels safe tuning there. Hope that helped

 

"This is why people never should base things off boost and just shoot for horsepower. The tuner will make the decision on MBT and if he feels safe tuning there"


WOrd


Modified by bigdaddyvtec at 12:11 PM 2/3/2006

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecD &raquo;</TD></TR><TR><TD CLASS="quote">More boost certainly doesn't make a safer tune. Adding fuel and retarding timing will make a safer tune but retarding the timing too much can cause excessive cylinder temperature which isn't good either. Having a good standalone and a good tuner are the keys to a good tune.</TD></TR></TABLE>

Can you explain why retarding timing increases cylinder temps? Think about it, overretarded timing would mean that peak burn rate would occur too far after TDC, which simply means that less of the pressure generated by the burn would contribute to pushing the piston down, as the piston would tend to "run away" from the burn. However, the burn *should* still be complete. Perhaps this delay in burn, when delayed too far, can cause the burn to happen into the exhaust stroke, which would mean *much* higher EGT's. HOWEVER, this is really not detrimental to the actual combustion chamber and should NOT have an effect on peak cylinder temps, as the peak temp is still the same (possibly less). The only real effect is that the EGTs are higher b/c the burn happened closer to the exhaust stroke...

 

You can have high EGT's from too much timing retard or too much timing advance.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">

Actually to achieve the same HP it does make the tune have the ability to be more conservative. Lets say you make 350whp @ 15psi with MBT being the guiding point for you timing retard (always good), but if you want it safer then you can always add a tad more boost, say 2-3PSI and retard the timing EVEN MORE then normal to avoid "peak" cylinder pressures and getting a better average cylinder pressure instead of a peak. That's the theory and the theory works in real life too . The downside is two fold here. 1.) Higher EGT's because the burn is started later and 2.) More boost means more lag and more fuel needs even though the tune is safer.

This is why people never should base things off boost and just shoot for horsepower. The tuner will make the decision on MBT and if he feels safe tuning there. Hope that helped </TD></TR></TABLE>

Nicely put. I think I'm actually starting to understand the theory. So I guess my next question would have to be how to implement this in real life.

Can this "safer tune" be done with street tuning? If so, what egt temps would be ideal, since it would be running a lot hotter. Or what egt temps should be a red flag that the timing is too retarded? And also, how much added retard are we talking about here? Is there any rule of thumb?

I'm sure there are a lot of other people out there that wouldn't mind a more conservative tune for their daily drivers. But I bet the're also worried to push more boost and retard the timing achieve the same results with a more conservative tune. So keep the comments comming.

Thanks

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by .nate &raquo;</TD></TR><TR><TD CLASS="quote">You can have high EGT's from too much timing retard or too much timing advance.</TD></TR></TABLE>

I dont think this is correct either, according to this post on pgmfi: http://forum.pgmfi.org/viewtop...bf8a4

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote &raquo;</TD></TR><TR><TD CLASS="quote">originally posted by calvin
Generally you can bring the egt down with higher ign values and higher afr's. If you start knock (I didn't test/see that (Dave told me)) you egt will go way down. So basically when you tune with egt and don't know knocking sound you play with fire. But tuning with egt isn't easy. But I hope I shed some light on egt temp/tuning stuff. I could find any real answer in different topics. So I hope this helps other. </TD></TR></TABLE>

EGT's actually decrease a LOT under detonation...

Ive only heard this from a few sources, but I doubt many who have posted on here actually have an EGT probe to be able to talk about.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by bigdaddyvtec &raquo;</TD></TR><TR><TD CLASS="quote">The tuner will make the decision on MBT and if he feels safe tuning there</TD></TR></TABLE>

What is MBT?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by cobra2326 &raquo;</TD></TR><TR><TD CLASS="quote">

I dont think this is correct either, according to this post on pgmfi</TD></TR></TABLE>

No that's right. It's kind of an upside down bell curve. There is a sweet spot for EGTs. But no one should tune of EGT's. Use a dyno and a wideband sniffer to tune. Everything is else is for safety like oil pressure EGT, fuel pressure ETC. EGT is nice because on a hot day you can see if you have detonation or you can see if you are placing too much load on the engine.

Yes EGTs decrease on detonation. Think about it....it makes sense.

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asianspeed &raquo;</TD></TR><TR><TD CLASS="quote">
I'm sure there are a lot of other people out there that wouldn't mind a more conservative tune for their daily drivers. But I bet the're also worried to push more boost and retard the timing achieve the same results with a more conservative tune. So keep the comments comming.
Thanks</TD></TR></TABLE>

This is a great thought, but you need to learn the principles and theories on your own by reading/taking classes because so much **** flies around here and other forums that NO ONE should trust it. Don't even listen to me. Find out and understand for yourself then you won't need anyone

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by flood &raquo;</TD></TR><TR><TD CLASS="quote">

What is MBT?</TD></TR></TABLE>

Minimum Best Timing. The point where peak cylinder pressures are around 15-20* after top dead center (ATDC). Increasing timing will no longer yield any gains. If you know a little physics this is where the rod angle is the best to "push" on and provides the most power. Like a seesaw you want to be on the farthest end to have maximum power right? Sometimes this can't be reached for reasons of detonation or fueling or other things, but it's where the most power is still being safe. After that point there is no reason to advance even if you can because power just isn't available. the ONLY way to see this is on a dyno

 

adseguy, I'd like to street tune my car before taking it to the dyno. What timing/egt temps would you recommend for a safe street tune?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asianspeed &raquo;</TD></TR><TR><TD CLASS="quote">adseguy, I'd like to street tune my car before taking it to the dyno. What timing/egt temps would you recommend for a safe street tune?</TD></TR></TABLE>

The ones that fit your car . Can't say.....every car is different and reacts differently. That's why there is no one map for a certain engine and PSI . Get someone with the knowledge to do it or learn EVERYTHING yourself so you can do it

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">

The ones that fit your car . Can't say.....every car is different and reacts differently. That's why there is no one map for a certain engine and PSI . Get someone with the knowledge to do it or learn EVERYTHING yourself so you can do it</TD></TR></TABLE>

How do you tune your timing then? I thought that you adusted your timing according the egt temp readings. But if those readings aren't consistent, then those numbers are useless. Can you help me understand how professional tuners adjust the timing and why?

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by asianspeed &raquo;</TD></TR><TR><TD CLASS="quote">
I thought that you adusted your timing according the egt temp readings.</TD></TR></TABLE>

No one should tune using EGT.....it's not a tuning tool but a safety tool. Check EGT's to make sure everything is OK, don't make adjustments to suit EGT temps just use it to make sure everything is OK like an oil pressure gauge or fuel gague (Lik eI said before ).


This is where it gets complicated. Many factors are addressed here. Tuning on the street is easy, cheap, and safe for low boost/low power levels. Any real tuning for best performance AND safety should be done on a dyno. Now ideally you adjust timing until the torque curve stops going up (that's MBT), but if it were that simple anyone can do this. So many factors including gas used, IAT's, compression, quench, OMG I could go on....hahaha. I could write for days and days and days and days on why to put timing where, but it's a lot to learn and soak in. This is where you pay money for a tuner that knows all these things and understands the limits of an engine or you can study it yourself to understand why ignition values and fuel values are the way they are. Speaking of fuel did you know that 12.0AFR isn't ideal? . I'm going off on a tangent here, sorry.

But this is where the thread ends because of the severe technical stuff that can be talked about. Here's a thread on tuning started my Mase. not too bad and lists some good things without getting too technical.

https://honda-tech.com/zerothread?id=979788

 

Ummmmm, MBT stands for Maximum Brake Torque, not minimum best timing...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecD &raquo;</TD></TR><TR><TD CLASS="quote">Ummmmm, MBT stands for Maximum Brake Torque, not minimum best timing... </TD></TR></TABLE>

it can be both...it's t00ning thing

 

ive only heard of maximum brake torque

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Mase &raquo;</TD></TR><TR><TD CLASS="quote">ive only heard of maximum brake torque </TD></TR></TABLE>

Who are you n00b?! STFU you don't know WTF your talking about....and I drink more then you

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nonvtecD &raquo;</TD></TR><TR><TD CLASS="quote">Ummmmm, MBT stands for Maximum Brake Torque, not minimum best timing... </TD></TR></TABLE>

..or Mean best timing

 

good thread

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">Who are you n00b?! STFU you don't know WTF your talking about....and I drink more then you </TD></TR></TABLE>

Um, this is a joke right? Mase is a well known tuner...

Anyways, when people talk about MBT, it refers to maximum brake torque, not minimum best torque. Why would you want torque to be minimum? Jeff evans is very knowledgeable on this subject, and tunes cars to find their MBTT (maximum brake torque timing). Basically, you start with a conservative retard per psi of boost, and slowly advance on the dyno until torque starts to drop, or detonation threshold is reached. Once you find MBTT, usually you pull back about 1* for longetivity.

 

my vote goes with maximum brake torque, and thats my final answer

 

edit: drunk GF post...ignore


Modified by adseguy at 5:13 PM 2/7/2006

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by adseguy &raquo;</TD></TR><TR><TD CLASS="quote">I'm drunk right now and this **** is even makin my girl laugh. I love H-T. Here she is gonna talk:

Adrien is really gay. I hate him. He is a huge homo. But I like making out with him. He's a pretty good kisser for being gay and trying to kiss a hot girl in Rolla....

I sometimes don't know about this kid. I guess it's just bc he's from france....</TD></TR></TABLE>

Hahahah, this is my thread that's supposed to make people smarter and ****....BUT I'M DRUNK NOW TOO! And your girlfriend is funny! Drink up!!! Let's continue this thread sober in the morning!