for reference, i have an aem afr, electric boost gauge, and the aeroforce scangauge...
when logging and making sure everything is tuned safely, is it necessary to know what the egt's are? or is afr adequate?
is it possible that the egts would become dangerous even if no kr is being shown?
the reason i'm asking, is because it would seem that the internal temps would be different at the same afr if you were running more timing...
insight? thanks!
There are several schools of thought on this but it's my opinion that in general, lower EGT's are almost always better for reducing knock. Why? because generally lower EGT's mean lower cylinder temps...
first of all if your reading EGT's from the scangauge then take with a grain of salt.
If you have a probe, then still dont look too much at it. EGT is a poor way at determining anything unless you have a known value/temp to go off. Also with only 1 EGT probe it doesnt mean very much, having one per cyl would give you info about how each cyl is on fuel/timing/flow.
Best bet is to look at the wideband, if you go to a dyno and note the EGT when making max power(on a certain fuel), then you can use this later when you modify something, try to get back to that same EGT while using the same fuel.
Also if your EGT's are high it doesn't mean that you cyl temps are high, if could mean that you have fuel still burning in the exhaust, meaning you need more ignition advance.
EGT's can help if you have no way to monitor knock by itself. If your PCM starts to pull timing back due to knock you will see it on an EGT gauge with your EGT's rising above the generally safe zone.
EGT's can help if you have no way to monitor knock by itself. If your PCM starts to pull timing back due to knock you will see it on an EGT gauge with your EGT's rising above the generally safe zone.
ok... so if i can monitor knock i'll generally be alright?
also... that link speedeuphoria posted said that retarding the timing will generally raise egts... i was under the impression that by advancing timing you'd be raising your chances for knock thus higher egts... ? no?
ok... so if i can monitor knock i'll generally be alright?
also... that link speedeuphoria posted said that retarding the timing will generally raise egts... i was under the impression that by advancing timing you'd be raising your chances for knock thus higher egts... ? no?
thats my question also . if a/f's are good an no knock do you have to worry about egt's ?
__________________
stage0,cca bfmic, needswings dp no cat, mccord electric opener , agp wga ,dtec fc/bc , front an rear strut bars ,progress front an rear sway bars an springs, tripple pillar pod with auto meter volt an oil pressure guage , turbo xs wideband, turbonetics cold side pipe raptor bov , aem cai,return line ,255 walboro fuel pump, Granatelli wires , 4306 plugs
No IMO EGT is pretty pointless unless you have one in each cyl to compare to the others. This way you could (hopefully) spot a cyl that is running richer or leaner than the others.
More timing advance = lower EGT's, less timing advance = higher EGT's.
So if your getting knock retard like Jon stated, then timing is pulled and the EGT's will rise.
Another thing to think about is pump gas, when pushing the limits, you should have less timing advance which means higher EGT's, so its basically a compromise between Knock threshold and high EGT's. The thing is that many motors dont display the same EGT's so if you have no concrete temp for YOUR motor then comparing to a friends EGT even w/ similar mods is not an exact science.
Cam timing also effects EGT's as do other factors, thats why its hard to compare to others. Fuel still burning in the exhaust has higher EGT's so if you have more overlap or other things. Anti Lag/spool type setups like a 2 step that severely retards timing cause high EGT's while spooling the turbo at a stand still.
Your better off looking at the wideband and reading the plugs, then you are worrying about EGT's
If you do look at EGT's WOT is the only thing to consider for the most part as cruising EGT's can be high also but dont worry. The melting point for aluminum is a known values but you will see people go well beyond that in some applications w/o issue, so like I said its not an exact science.
Last edited by SpeedEuphoria : 07-15-2008 at 05:56 AM.
No IMO EGT is pretty pointless unless you have one in each cyl to compare to the others. This way you could (hopefully) spot a cyl that is running richer or leaner than the others.
More timing advance = lower EGT's, less timing advance = higher EGT's.
So if your getting knock retard like Jon stated, then timing is pulled and the EGT's will rise.
Another thing to think about is pump gas, when pushing the limits, you should have less timing advance which means higher EGT's, so its basically a compromise between Knock threshold and high EGT's. The thing is that many motors dont display the same EGT's so if you have no concrete temp for YOUR motor then comparing to a friends EGT even w/ similar mods is not an exact science.
Cam timing also effects EGT's as do other factors, thats why its hard to compare to others. Fuel still burning in the exhaust has higher EGT's so if you have more overlap or other things. Anti Lag/spool type setups like a 2 step that severely retards timing cause high EGT's while spooling the turbo at a stand still.
Your better off looking at the wideband and reading the plugs, then you are worrying about EGT's
If you do look at EGT's WOT is the only thing to consider for the most part as cruising EGT's can be high also but dont worry. The melting point for aluminum is a known values but you will see people go well beyond that in some applications w/o issue, so like I said its not an exact science.
the reason i ask is i had my car tuned at like a 23.3 spike in third an i had the gain on the dtec adjusted to were i only droped 2-3 psi by redline . a friend told me my egt's were probely through the roof . so i retuned it to to drop to about 16-17ish . yea i got scared of melting down my motor . but my a/f's never went above 11.3 at redline , knock i was using the dtec an i know it's not very go but it never went above 6 . i've been told there super sensitive an not to worry until it gets up around 20 .
EGTs will increase with timing advance (not decrease like he said)...this will happen to a point. Once timing gets too advanced and the engine starts knocking then the timing will decrease. Make sense?
To the original poster...I"m map clamped and I just watch AFR, knock, and timing. I set my scan gauge (Aeroforce) to have the annunciator light flash at me if KR goes 3.0 or higher so I can just not watch it and keep other info on the gauge. I know if it lights up I have to adjust the tune that's all. Timing I already dealt with that in the past when I was tuning my map clamp. Now honestly...I know timing is running well (30-34deg from 5000rpms to redline and the track times tell me it's running damn well) and I have the knock light set so to speak so I really only watch air fuel and just make sure my knock warning light doesn't go off.
EGTs will increase with timing advance (not decrease like he said)...this will happen to a point. Once timing gets too advanced and the engine starts knocking then the timing will decrease. Make sense?
yup... that's what i was thinking...
To the original poster...I"m map clamped and I just watch AFR, knock, and timing. I set my scan gauge (Aeroforce) to have the annunciator light flash at me if KR goes 3.0 or higher so I can just not watch it and keep other info on the gauge. I know if it lights up I have to adjust the tune that's all. Timing I already dealt with that in the past when I was tuning my map clamp. Now honestly...I know timing is running well (30-34deg from 5000rpms to redline and the track times tell me it's running damn well) and I have the knock light set so to speak so I really only watch air fuel and just make sure my knock warning light doesn't go off.
i have my aeroforce set up the same way... kr on the warning light, advance and injector % on the screen...
i have a seperate afr and boost gauge...
i need to get a new fmic soon... i'm spiking to 19.5 ish and settling to 16/17ish but my timing is down in the high teens during the spike, then raises towards redline, which is where i get some knock... oh... and my mapclamp is set at 4.82 - as high as it can go without allowing stage1 to see too much boost...
i have my aeroforce set up the same way... kr on the warning light, advance and injector % on the screen...
i have a seperate afr and boost gauge...
i need to get a new fmic soon... i'm spiking to 19.5 ish and settling to 16/17ish but my timing is down in the high teens during the spike, then raises towards redline, which is where i get some knock... oh... and my mapclamp is set at 4.82 - as high as it can go without allowing stage1 to see too much boost...
teens...yikes mine never is that low. I just read the boost from the MAP sensor to get an idea where I'm clamped (it's around 15.3psi give or take)...spike 19-21psi (depending on weather conditions) and fades to 14psi at redline. I'd play around with the wastegate arm and map clamp settings until you find a happy medium.
teens...yikes mine never is that low. I just read the boost from the MAP sensor to get an idea where I'm clamped (it's around 15.3psi give or take)...spike 19-21psi (depending on weather conditions) and fades to 14psi at redline. I'd play around with the wastegate arm and map clamp settings until you find a happy medium.
yeah... our fmic is quite a bit smaller than yours...
let me know what you think:
-i'm boosting 19.5 down to 16
-afr's are waaaaay rich... i'm talking flat 10's
-timing is 19ish and quickly goes up through the rpms...
-map clamp is set at 18 psi
-depending on weather, i get maybe 2/3 points of knock... sometimes i don't see any
i was thinking about starting to clamp down slowly while keeping an eye on the knock...
what do I think first...I always ask are you using the stock boost gauge to read boost...if so that can be off and you may be boosting differently than you think (I had a stock gauge tell me 16psi fade to 12psi which was in reality 23psi fade to 15psi...I almost died considering I ran it that way for about 2 years no map clamp and kept getting spark cut)...doh
Anyways I continue...
I think if you're on stock fuel 16psi @ redlne is too high w/o a return line or someway to increase fuel delivery.
I think it's a game of trial & error (and that's why I got an in-cabin MAP clamp) so I can adjust it while driving and quickly floor it again and check and keep adjusting from there.
If you can't control the knock then LOWER the boost and tune down there. You'd be amazed how much power can be made on lower boost with good timing... Boost isn't everything...
That's what I say...I'm running 19psi (mostly...if it's cold out I may see 20/21psi) but like I said 19psi hold and tapers to 14psi at redline I'd give that a shot and go from there.
Plus peak efficiency of the turbo is 19psi anyways...go higher you're making a good amount of heat. Will you make more torque/power...sure...but gains won't be as much, you'll be increasing temps (both intake temps and exhaust gas), pissing off the ECU by possibly seeing knock and further hurt your timing...plus added strain on the turbo. Someone like me plans on keeping stock turbo forever so I drew the line at around 20psi being my limit for a spike.
Last edited by N0sferatU : 07-15-2008 at 09:54 PM.
AutoForums.com is the premier network of enthusiast-owned
enthusiast-operated automotive communities.
We operate more than 100 automotive forums where our users consult peers for shopping information and advice, and share
experiences and opinions as a community.
EGT vs KR
Linear Mode
