Boost drops, EGT increases. Is there a fix??

[Rollingon]

The Kennedy dyno runs, posted on his website (many thanks), demonstrate how EGT is tied to airflow and boost levels. Which raises a question.

As RPM approaches 3000, I notice how boost is tapering off and EGT rises. Is the stock wastegate opening early, and if so is there a simple/inexpensive/safe way to keep it from doing so? I suppose I could get a Banks Big Head, but I really can

[Kennedy]

Boost may help this, but my take on it is that a couple of factors play in:

1) HP level increases so BTU output will also increase.

2) Throughput on the exhaust side of the turbo increases and goes beyond the window of peak turbo efficiency. The wastegate uses with exhaust back pressure AND boost pressure so if the drive side pressure comes up it will activate the wastegate with less boost psi.

3)Timing/pilot injection etc. all can change at upper RPM's also.

In the future, I do have plnas of releasing a wastegate control, but that could be quite a while yet. I have definitely seen gains by increasing boost depending on the programming.

[madmatt]

ever try washer solvent????? :D see snow performance (http://www.snowperformance.net) they can help get your EGTs in check.

[Mark Heiken]

Have you used this Matt? Does it work as claimed?

[DmaxMaverick]

Originally posted by beeler:
Have you used this Matt? Does it work as claimed? AKA: WMI, or Water Mist Injection.

It is one form of charge air cooling, and works. Matt was refering to injecting washer solvent, which would contain methanol. Most WMI's only use water, but methanol adds a little bump in power, as well as the added benefit of water cooling the intake air. I've often thought of doing this myself, but haven't seen the need on my Duramax. A very good alternative to an innercooler, depending on your needs and available skill, time, money, and space. It would also be a good companion to an innercooler if EGT's became a problem. WWII fighter planes used this type of system for "War Power". Some injected pure methanol, and gained up to 50% more power for emergency evasion.

[madmatt]

oh yeah it's good stuff! it works great on long grades. the systems are getting really high tech and it's really tough to mess an engine up just spraying a little water down it's throat. most -20 washer solvent is mixed 70 water/30meth but some applications we run more like 50/50. it also comes in handy on pulling tractors were multiple turbos are ran and the boost is to high for any cooler.

[Jim Brzozowski]

Rollington, Kennedy it right on. The BTU's are what distinguishes the extra power available from diesel over gasoline. Gallon per gallon there are more BTU's available in Diesel. The other guys here are talking about water/methonal spray which I have done, but that only cools the intake charge which will make the air denser going in, but once the turbo compresses it, its up to the intercooler to get the additional heat out. That all being said, I don't think the water/alcohol will help exhaust temperatures. There are a lot of guys on this site that understand the turbo part better than I do, but somehow I suspect more boost will result in the computer telling the fuel "we need more fuel", and it won't solve the high exhaust gas temp. Bigger exhaust system probably would. Kennedy sells one.

[rjschoolcraft]

In the 6.5 world that I live in, more boost produces lower egt (intercooled, of course). In stock form, I used to struggle to tow my trailer at 65 mph running 1350 F egt. I'm in the midst of a new project build now, but my last configuration could tow at 75 mph all day long running 950 F egt. Max fuel rate went from 62 mm3 to 79 mm3 per stroke.

Boost is key.

[Kennedy]

Eventually,I should have a simple boost adder device available. Works good in all of my testing.

[DmaxMaverick]

Originally posted by SoTxPollock:
Rollington, Kennedy it right on. The BTU's are what distinguishes the extra power available from diesel over gasoline. Gallon per gallon there are more BTU's available in Diesel. The other guys here are talking about water/methonal spray which I have done, but that only cools the intake charge which will make the air denser going in, but once the turbo compresses it, its up to the intercooler to get the additional heat out. That all being said, I don't think the water/alcohol will help exhaust temperatures. There are a lot of guys on this site that understand the turbo part better than I do, but somehow I suspect more boost will result in the computer telling the fuel "we need more fuel", and it won't solve the high exhaust gas temp. Bigger exhaust system probably would. Kennedy sells one. In regards to lowering EGT's....
WMI WILL lower EGT's. Perceived or not. Water carries (transfers) heat, and will carry heat out of the combustion chamber more efficiently than air/gasses alone. A "perceived" EGT (gage reading) may show a higher indication, but that is indicating more heat being removed from the engine, not more heat in the engine. In many cases, EGT gage readings are unchanged before/after WMI. A more accurate judgement of WMI is the ECT. All else being equal, adding WMI will lower ECT, regardless of the EGT indication.

I have talked with several folks that tried WMI, then abandoned it after they didn't see any improvement. Same statement from most of them. "My EGT's didn't go down" It is important to watch your EGT's when under power, but you should know what the numbers mean, and know what is really going on before the end result is concluded.

[madmatt]

to see the full advantages of running water/meth you really need to get one on the dyno and compare EGT verus HP readings. the egts stay about the same but HP increases dramaticlly which translates into easier grade pulls which works the engine less and equals lower EGTs then you may normally see pulling the same hill. Sure you can still run'em up if you flat foot it, but you'll be making more power w/ little to no gain in temp.