Engine/Transmission (1994 - 1998) muffler and high egt's

[dlefebvre]

Hello all



I had to put a muffler on my 95 CTD last week before I went on vacation towing my 6000# fifth wheel. The drone in the cab was pretty annoying when I pulled the trailer through the mountains on the may long weekend. The egt's would slowly climb to the 1200* mark on a 8% grade of about 10 miles. No problem, I could hold the truck at 70 mph in fifth gear. Outside temp was around 10 degrees celcius.



Put the muffler on and headed out, outside temp around 25 degrees celcius. Egt's climbing higher than expected pulling the trailer on the same route as in may. Thge only way to get them down was more boost which means gearing down to fourth to get the rpms up. Its not that big of a deal, but my question is, is the high egt's caused by the restriction in the exhaust because of the muffler? Or is it because of the higher ambient temperature meaning less dense air? Can the waste gate line to the pump be pinched off to give you more boost?



I had to hold the truck back going up alot of grades because of the high egt's. The pulling power itself had not seemed to change.

Anyone run across this before?

 

[Deezul1]

The muffler will cause EGTs to be higher as cool air cant come in when hot air is in the way, kind of simple explanation but you get the idea. Try a straight through Walker muffler as a lot of members have had good results with them, I dont know the part #. Yes the boost line can be plugged for more boost, just pull the rubber hose off the steel ine and plug it

 

[dlefebvre]

If I plug the rubber line from the wastegate, is there a chance of overboost? I guess the next mod is the boost guage



The muffler I put on is a dynomax superturbo, the muffler shop assured me it is a high flow, but I'm not so sure now. The damn thing was $ 175 canadian! But if it hinders performance, I will get rid of it. Anyone have any muffler suggestions? I was going to post on muffler suggestions before I left on the trip, but time restrictions resulted in a hasty purchase.



Back to the boost issue, how much is normal for the 95 ? how much is too much?

 

[Deezul1]

I can hit 40lbs boost for a few seconds and then it backs off to about 37lbs. I think thats about max for the HX35 turbo. Check out Rip Rooks web site for a decent muffler, the guys that have tried it have seemed mostly happy with it.

 

[Mark Craig]

Muffler and EGT's

Depending on the muffler design, (OEM vs Good performance type) there shouldn't be much if any EGT change. I can run our system with or without a muffler on Fords, Dodges and GM's and I can't ever see a difference in EGT's on the gauge. Ours is a straight thru design, with our Spiral Louver core, what type of muffler did you install?



Mark @ DPPI

 

[illflem]

I feel the only problem you have is the change in outside temp. I don't have a formula but the relationship between intake temp and egts for sure isn't 1:1, more like 1:3 to 1:5. In other words the difference from an outside temp of 50F(10C) to 77F (25C) could raise your egts 81-135F. If the A/C is running the effect is even worse since hot condenser air is passing over the intercooler.

 

[ewcmr2]

I agree with Bill

Ambient temp makes a large difference. In cool weather <60* my truck will rarely get up to 1200*. If it is >90* 1300* is just a throttle pedal to the floor away.



Eric

 

[dlefebvre]

thanks for the ifo guys, thats what I like about this site! You ask and you recieve!