I figured I'd put this question up to see if my logic is correct or not.

The purpose of tuning with a wideband and adding fuel during boost is to cool down the cylinders. Running lean makes more heat (to an extent) and by adding fuel, you are cooling the cylinders and preventing detonation. That is why certain AFR's work better, because you are running at a certain temperature where power is maximized with the amount of risk of detonation minimized.

My car typically runs with EGT's around 1,300F (approx. 1,200F city and 1,400F on the freeway).

Based on this, can I go a step past tuning with a wideband and tune via EGT's? If what I said above is true, I should be able to pick an "ideal temperature" (say 1,300F) and as boost increases, I will have to add fuel anyway to keep the temperatures in check.

Let me know if my logic is correct regarding this.

 

Many people tune by egts. You are only looking at fuel and not timing as timing has alot to do with it as well!

 

Gotcha. Is it better to set timing or fuel first? If you set your timing, then fuel would be easier to tune by EGT. Then, once you get fuel tuned, go back and fine tune the timing?

I'm just trying to wrap my mind around all of this. haha

 

I understand.. But i myself can not teach you how to tune.. And i ve found out helping people on here can be dangerous!

i could write a book on what you just asked me!

 

Haha, understandable.

 

Tuning should be done by a certified tech but just to answer your question when tuning always start with fuel,air, and timing last in that order exactly.

 

i was told that combustion temp should be around 1750 degress F. that is the best mixture and most power. that what should be coming out of the combustion chamber. and that's if you placed the egt before the turbo somewhere on the mani. anything after the turbo would be reading approximately 200 or more/less degrees, less do to heat transfer through the turbo itself. This is what i was told. Don't take my word for it. look it up. And yes tunning should be done by someone who has experience and the fundamentals behind it. just my two cents

 

you tune fuel before timing.........all the professional and recreation tuners tune fuel first..........they say pull one degree of timing per 10psi of boost........once you get your afr at 11.5 in boost then you can start doing timing........you pull timing....your egt's will go cooler......you add timing...they get hotter........go to www.efi.com and read up on some of their stickies.....ive learned alot from just reading that website

 

I think you mistyped. EFI.com is color print management software. Did you mean the EFI101.com forums?

 

yea my bad....efi101.com

 

Can anyone else confirm this? Where should EGT's be on our cars?

 

EGT or Exhaust Gas Temperature is a direct reflection of how efficiently combustion has taken place.

1750 should be your max at any time on most piston engines. I personally like to tune to about 1650-1700. I find that if I can stay within that range during a full 4th gear pull I can make the most power. This is on 93 octane and different fuels have different burn characteristics so it depends on your fueling.

However here is a good read on it.

http://www.sdsefi.com/techegt.htm

http://forums.evolutionm.net/general...-tuning-2.html

 

Thanks Don. I'll probably get a rough tune trying to hit around 1,500F and work from there. Thanks for the links.

 

EGT with AFR and ignition tuning will be great, just make sure you detect knock closely as it critical too..

yeah usually you tune fuel first then ignition.. but make sure not to pull (retarding) timing too much it will sky rocket your EGT, in severe case may cause misfires that may cause false lean afr readings..

 

Aight can anyone post their EGT reading on different conditions? I just wanna compare how good or close mine are.

My cruising is 990-1020F, slight throttle could make it as high as 1150 while staying off boost. Idle is around 500-700F.. Havent looked at my EGT at boost yet but I think I saw once its like on 1200-1300 up to 4500rpms.

 

That seems really low. On the freeway, I am typically running between 1,300 and 1,400. City driving is typically in the 1,100 to 1,200 range.

 

im not sure if its the location of my sensor but its before the turbo before the manifold to turbo flange.. i guess its just my tune

 

Yea, manifolds can make a difference. I am using a log style mani and my sensor is in the collector about 1 1/2 inches before the turbo.

 

I have a tubular manifold, the probe is at the collector too, i think its more of my tune since my ignition map is not optimized on the dyno.. im curious whats the stock tc egts are

 

Your EGT sensor should be placed no more than 2 inches from the exit of the cylinder head exhaust port. It should be placed on the hottest cylinder.

Typically and keep in mind many factors effect this, idle should be around 850-1000F, cruise 1300F, WOT no more than 1725 F.

Volumetric efficiency plays a key role in EGT and thus affects timing and other things.