For one, I don’t have a wideband constantly hooked up to my car - I only have boost and EGT.
I would like to know a couple of things about my EGTs…
Besides running lean and/or retarded timing- what are other culprits for having your EGTs run higher than normal?
Why does cylinder 1 usually burn the hottest?
EGTs will run higher at the presence of knock because the car is pulling timing out and gas is being burned in the manifold rather than the cumbustion chamber and giving false readings to your EGT probe.
Another common cause of high EGTs is intercooler inefficiency. Sometimes the intercooler simply can’t effectively cool the volume and intensity of charge air it’s being fed.
Boost leaks are another. Most people forget how serious a boost leaks can be, but the way most boost control systems are set up the turbo will continue to generate your target boost level, or “try” to, even if a leak is present. Because there’s a leak, the turbo will have to spin that much faster to generate the same amount of boost. Overspinning the turbo often pushes it well out of it’s efficiency range and generates a ton of added heat which can cause serious problems such as detonation, melted pistons, etc. Of course turbos can also be pushed out of their efficiency range without a leak being present. I see people try to run too much boost pressure for their setup all the time.
You mentioned a lack of timing advance. I’d like to point out that this can be an issue under highway cruising at a constant speed as well as in boost. I’ve seen this several times on vehicles that have been poorly tuned elsewhere. Sometimes it’s a mail order tune and sometimes it’s a custom tune.
EGT gauges are excellent monitoring devices because they show there’s an issue caused by a wide range of things. If EGTs go dangerously high you have to do some investigating to find the cause, but at least you’ve been warned that something is wrong.
There are other potential causes of high EGTs and I’m sure others will chime in.
-Mike
it is the last cylinder to get air, and can run rich. that will up your EGTs
If you read the DSM forums there is some debate why the cylinder one runs the hottest… Some say that #2 actually runs hotter… I’ve read that it had something to do with the fuel delivery in the rail…
But who knows… I think the reasons are alot of speculation.
Why not just run 4 gauges. One for each cyl, then only look at the highest one.
Seriously though, I can only imagine that the difference in temp between the cylinders is not big enought to cause a serious issue. If you have a problem, you will notice it by soaring temps in all cylinders anyway.
It’s that reason why Magnus tapered the plenum on thier DSM and Evo intake manifold. By getting narrower, you up the air velocity into cylinder number 1 and thus compensate somewhat for it running with the least amount of air. I agree with you Joe, on an extreme race setup with oversized valves pushing tons of air, that can come into play, but with stock sized valves and stock cams, I can see it not being as much of an issue, especially when you are turning the boost up.
take a look at most aftermarket or custom intake manifolds for SKylines or Supras…they are mostly tapered to for air into that cylinder…i think Newmans is…maybe he will chime in
A. 4 gauges is expensive. While I firmly believe that running an EGT in EACH cylinder is a must for a competition engine, for the street tuner crowd any is better than none.
B. 1 cylinder can fuck up more than others, misfiring injector? bad spark wire? or even under a stock engine one cylinder could end up running to lean just because of the way air/fuel flow. EGT is a good tell-tale if something is wrong but ALOT of things can make them look bad. hard to say what is actually making it read badly.
If anyone is interested in running 4 probes, there are single aeronautical gauges designed to display the readings from 4 egt probes at once. The nicer ones show your choice of the average of the 4, the highest reading one, etc.
If anyone is interested in running 4 probes, there are single aeronautical gauges designed to display the readings from 4 egt probes at once. The nicer ones show your choice of the average of the 4, the highest reading one, etc.
-Mike