Ideal EGT's?

[Style]

Can't really find anything conclusive on this. Especially in a thread that isn't from nearly 20 years ago so what would be deemed a safe/ideal EGT at idle, cruise and WOT? This scenario would apply to an EGT probe mounted in the exhaust port. Basically immediately after leaving the head.

I've seen 550-650degC at idle thrown around which I'm quite happy to believe I guess. In terms of max at any given point, 950degC looks to be where ECU alarms should be set so again, happy with that. From what I've seen, some people reckon cruise EGT's should be higher than WOT as the AFR's will be leaner, promoting a hotter burn. So would that mean cruise EGT's are the highest to expect? WOT temps would be a touch lower than cruise? Or does the fact you're at WOT mean temps will rise like the rest of the engine bay does?

 

[Luxluc]

SRD removed my EGT sensor 2 years ago ; I wouldn't rely too much on EGT.

The only good location is in the exhaust manifold.

[Style]

1 hour ago, Luxluc said:

SRD removed my EGT sensor 2 years ago ; I wouldn't rely too much on EGT.

The only good location is in the exhaust manifold.

Thanks mate that’s reassuring.

I’m just a bit concerned as I’m running a log style manifold and turning the boost up. I think the car will either be limited by the actual flow through the manifold or the EGT’s. No ones taken it past 500hp so we’ll see. 

[Noz]

12 minutes ago, Style said:

Thanks mate that’s reassuring.

I’m just a bit concerned as I’m running a log style manifold and turning the boost up. I think the car will either be limited by the actual flow through the manifold or the EGT’s. No ones taken it past 500hp so we’ll see. 

With a log manifold. Probably worth having an exhaust gas pressure sensor. That'd be some sexy info.

[Swampy442]

1 hour ago, Luxluc said:

 

The only good location is in the exhaust manifold.

Its in the exhaust manifold...

By running a log manifold you're looking for a quick spool, but ultimately you'll be power limited because of it. EGTs build because you cant get rid of the exhaust gasses, which a tube manifold does well.  On cruise you're EGTs will be much lower because youre burning much less fuel, EGTs only really come into play at WOT and  repeated, long high load pulls. In the real world they're not much of an issue

 

Edited May 19, 2021 by Swampy442 (see edit history)

[Style]

49 minutes ago, Swampy442 said:

Its in the exhaust manifold...

By running a log manifold you're looking for a quick spool, but ultimately you'll be power limited because of it. EGTs build because you cant get rid of the exhaust gasses, which a tube manifold does well.  On cruise you're EGTs will be much lower because youre burning much less fuel, EGTs only really come into play at WOT and  repeated, long high load pulls. In the real world they're not much of an issue

 

Nice one, thanks for the explanation. So basically don’t pay too much attention to it unless you’re seeing temps flirt with 1000degC after thrashing it?

Main reason behind the question is the car was being mapped on the road and cruise EGT’s were 760degC. I was advised this was on the hot side. Yet to see a WOT temp so I wanted to get an idea of what to expect. 

[Style]

1 hour ago, Noz said:

With a log manifold. Probably worth having an exhaust gas pressure sensor. That'd be some sexy info.

My other concern with this manifold was dead-heading it at a certain point. Hopefully that should present itself by other means if it does happen and pressure would likely level off at that point.

It’s highly likely I’m overthinking it and it’ll be alright. I haven’t seen anyone push a Whifbitz NA-T mani past 510hp so it’s into uncharted territory 

Edited May 19, 2021 by Style (see edit history)

[Noz]

1 minute ago, Style said:

My other concern with this manifold was dead-heading it at a certain point. Hopefully that should present itself by other means if it does happen and pressure would likely level off at that point.

It’s highly likely I’m overthinking it and it’ll be alright. I haven’t seen anyone push a Whifbitz NA-T mani past 510hp so it’s into uncharted territory 

I've seen someone do 550 I'm sure. Can't remember who where or when. 

Might have been the Joshy. Hmmm.

[Swampy442]

10 minutes ago, Style said:

Nice one, thanks for the explanation. So basically don’t pay too much attention to it unless you’re seeing temps flirt with 1000degC after thrashing it?

Main reason behind the question is the car was being mapped on the road and cruise EGT’s were 760degC. I was advised this was on the hot side. Yet to see a WOT temp so I wanted to get an idea of what to expect. 

760 is pretty high on cruise, where is the probe located?

[Style]

5 minutes ago, Swampy442 said:

760 is pretty high on cruise, where is the probe located?

Cylinder 6 right at the manifold flange basically 

[Style]

12 minutes ago, Noz said:

I've seen someone do 550 I'm sure. Can't remember who where or when. 

Might have been the Joshy. Hmmm.

Yeah Josh is up there for sure. Just not sure I trust the dyno it was on 

[Noz]

1 minute ago, Style said:

Yeah Josh is up there for sure. Just not sure I trust the dyno it was on 

Easy cop out that. Sounds like shots fired.

NAt dyno day needed!

[Swampy442]

17 minutes ago, Style said:

Cylinder 6 right at the manifold flange basically 

You cant get more accurate, right at the hottest part of the engine 

[Style]

18 minutes ago, Noz said:

Easy cop out that. Sounds like shots fired.

NAt dyno day needed!

Bring it on I say! Log manifold bois only though 

4 minutes ago, Swampy442 said:

You cant get more accurate, right at the hottest part of the engine 

Yep, would’ve been nice to see all 6 but still think it’s a bit high. Maybe next move is to do some pulls and keep an eye on it. See where it goes 

[Frank Bullitt]

What compression are you running? Would you run WI?

[Mike2JZ]

Sensor placement in manifold & depth of the sensor into the runner etc will all have an effect on EGT reading. So take with a pinch of salt when reading people's online. 

On my car typical readings whilst on petrol. 

Warm Idle: ~400-500C
Cruise around town: ~500-600C
Sustained motorway driving for a few hours: ~650-750C
WOT: 800-950C

Every setup will be differnt but for idle and cruising you should never have to worry about EGT. I've leaned mine out a ton whilst cruising and couldn't get my EGT to dangerous levels. So long as you have enough timing in cruise areas, you will be fine in most cases. Obviously if you can make your manifold cherry red whilst cruising then you might have to reconsider your tune up or hardware combo. 

I typically only worry about EGT whilst got WOT. 800-900 is acceptable depending on boost level. Once I get close to 950 then I get ECU to cut power, or add fuel etc blah blah. 

@supradanturbowas having major EGT issues on his old log manifold with big boost on pump fuel. His wasn't NA-T but similar principle to the whifbitz kit. Can't realy get around the physics of high flowing 2J meeting small port exhaust manifold. It's gonna produce more heat then its worth at a certain level. I've yet to push an NA-T log manifold to the limit yet, but I'm gonna bet that 600whp will be the maximum on pump fuel. 

[supradanturbo]

Thanks for the mention @Mike2JZ 

egt was a massive issue on my old set up. 
Any real boost/power wasn’t really “safe” without a high percentage of ethanol. 
 

anything over 500hp on pump fuel was a major loosing battle to egt. 
 

at the drag strip with 30% ethanol. the logs showed Over 1000c sustained during a run. And a peak egt reading on decal of 1070c. 
I returned to the track, and ran 60% ethanol. This brought the peak sustained egt reading down to 920c 

 

I have monitored the egt problem, on a log manifold, probably more than most people, having 50+ runs all trying to tune my way around a problem. 
the fix for the problem is a good quality tubular manifold. I have recently swapped, also have egt set up on the the tubular manifold. Egt never saw over 870c at the track. Also the tubular manifold out performs the log manifold in every aspect. 
power output, spool time, egt 

[Style]

9 hours ago, Frank Bullitt said:

What compression are you running? Would you run WI?

Approximately 9:1 mate. WI is a good shout if I decide to keep this manifold setup. I think it'll be a choice between WI route or to cough up the £ for a quality tubular manifold.

8 hours ago, Mike2JZ said:

Sensor placement in manifold & depth of the sensor into the runner etc will all have an effect on EGT reading. So take with a pinch of salt when reading people's online. 

On my car typical readings whilst on petrol. 

Warm Idle: ~400-500C
Cruise around town: ~500-600C
Sustained motorway driving for a few hours: ~650-750C
WOT: 800-950C

Every setup will be differnt but for idle and cruising you should never have to worry about EGT. I've leaned mine out a ton whilst cruising and couldn't get my EGT to dangerous levels. So long as you have enough timing in cruise areas, you will be fine in most cases. Obviously if you can make your manifold cherry red whilst cruising then you might have to reconsider your tune up or hardware combo. 

I typically only worry about EGT whilst got WOT. 800-900 is acceptable depending on boost level. Once I get close to 950 then I get ECU to cut power, or add fuel etc blah blah. 

@supradanturbowas having major EGT issues on his old log manifold with big boost on pump fuel. His wasn't NA-T but similar principle to the whifbitz kit. Can't realy get around the physics of high flowing 2J meeting small port exhaust manifold. It's gonna produce more heat then its worth at a certain level. I've yet to push an NA-T log manifold to the limit yet, but I'm gonna bet that 600whp will be the maximum on pump fuel. 

Thanks Mike, great info in there once again

Good to see that 650-750degC is your ball park for cruising, even though relative to all the other variables like you've mentioned. It looks as thought this manifold is definitely a major bottle neck (pun intended) with my setup and a tubular manifold would solve every problem with regards to this. I've heard the PHR ones have gone up to ~900hp but they look to be a little more free flowing that the Whifbitz one and they're also US figures...so I'll take those with a pinch every time.

Cruising EGT's at a sustained ~70mph, 6th gear

1 hour ago, supradanturbo said:

Thanks for the mention @Mike2JZ 

egt was a massive issue on my old set up. 
Any real boost/power wasn’t really “safe” without a high percentage of ethanol. 
 

anything over 500hp on pump fuel was a major loosing battle to egt. 
 

at the drag strip with 30% ethanol. the logs showed Over 1000c sustained during a run. And a peak egt reading on decal of 1070c. 
I returned to the track, and ran 60% ethanol. This brought the peak sustained egt reading down to 920c 

 

I have monitored the egt problem, on a log manifold, probably more than most people, having 50+ runs all trying to tune my way around a problem. 
the fix for the problem is a good quality tubular manifold. I have recently swapped, also have egt set up on the the tubular manifold. Egt never saw over 870c at the track. Also the tubular manifold out performs the log manifold in every aspect. 
power output, spool time, egt 

Great, thanks for the info mate. Sounds like you've been through the problems I've got coming already if I keep this setup. So I think I'll jump over all of that and just aim for a tubular setup ASAP. Even a fast spooling 500hp on tap would be nice for now

[Mike2JZ]

Americans won't go anywhere near 900hp on log manifold without ethanol, so take that into consideration as well. On our pump fuel detonation & heat will be major restrictions in making power.