Question for guys with a Comp box and auto tranny

[Zukifreek]

So now that I got my RV275s in and tapped the pump I have been running on level 3X3 to save my auto. The other day I started watching the EGTs and empty going up a bit of a grade I stomped it and my EGTs came up to 1200, thats the highest I have ever seen the gauge go but never had pump tapped and only ran on level 1 before. My boost was around 30ish and I was going about 75-80mph in a hurry. I have noticed since the RV275s that the EGTs seem to climb higher before the boost starts to come on. It will hit 800-900 and barely have any boost building. Does that seem normal? What level do you guys tow on? My trailer is a 30 footer and 9800lbs. I don't think I have a boost leak. Sounds like I need a bigger turbo now....I thought I was done spending money...does it ever end...lol.

[Wild and Free]

Sounds normal to me, nothing to worry about with what you describe.

[Zukifreek]

So I have never researched much on EGTs other than 1400 is BAD Is it safe to hit 1200-1300 all day long? It was a warmer than usual day and the plastic winter front is in so the intercooler wouldn't be helping me much.

[Mopar1973Man]

So I have never researched much on EGTs other than 1400 is BAD Is it safe to hit 1200-1300 all day long? It was a warmer than usual day and the plastic winter front is in so the intercooler wouldn't be helping me much.

Correrction... <1200*F can be done all day long without worry. 1200-1300*F - Are you willing to bet your engine that your gauge is accurate? >1400*F is dangerous period.

[Wild and Free]

Standard rule of thumb is for every degree of increased intake temp the exhaust goes up by 3 degrees.Having your winter front on does make a difference.Timing makes a huge difference in what is safe for exhaust temps also, advanced timing will result in higher internal cylinder temps heat soaking the piston valves block ect, as the heat is held in the cylinder longer, retarded timing results in hotter exhaust temps but lower cylinder temps as the fire is burning as it leaves the cylinder thus being a less damaging heat, you are reading it to be high but it is hurting nothing at that point.

[ISX]

If you have that HY35 then the exhaust housing is only 9cm and will hurt you as it becomes a bottleneck. High RPM's help EGT because of flow.. If you go the same speed say 55mph in overdrive up a hill and then downshift and stay the same speed, EGT's will drop. This is especially pronounced with a trailer. The pistons are moving faster so they are moving air in and out faster, along with having the mechanical advantage of being in a lower gear. With the 9cm housing, you can't shove that much air through it so at high load/RPM's you will start to the EGT's get high. If you had an HX35 you would be fine, an HX35 with a 14cm housing is even better (stock ones are 12cm). I have cheated in life with the 12cm HX by adding my own wastegate controller. I don't know if you have the wastegate still hooked up stock but if you do, then you hit 30psi while outflowing the wastegate. If you think about it, that means you are just wasteing drive pressure straight out the wastegate. So I have a boost controller that keeps the wastegate completely shut until I get to 30psi, then it opens. This means I don't have to outflow the wastegate and can get up to 30psi much quicker. A lot of boost is a cheat to keep from downshifting. With a lot of boost there is a lot of flow so the engine stays cool. I used to run over 1200 easilllly but since doing that I stay under it just as easily. Most hills around here with our trailer I only need about 20-25psi to fly up. By 30psi I am in the passing lane. If I want more, that means I will hit the 30psi set point and the wastegate will open and EGT will spike. This is fine for a very short period, so it's my last resort when I figure out my current rate of passing someone isn't fast enough, so I stomp it, get in front, then let it cool off. It's basically the heat soaking into the pistons that is the problem. The oil jets under the pistons can take away heat which raises the time it takes for the pistons to soak all that heat in, otherwise they would melt prettttty quick. If I were you, get an HX35 with a boost elbow or something and that should be enough to solve your issues. Though if you're buying a turbo I would get a better one. I am not a turbo expert so I wouldn't know which but there are definitely better options than the HX.

[diesel4life]

Do you have 3.55 gears? That is what Ive got with an auto and I personally think the combo is almost too high when your pulling heavy trailers. The trans wants to drop into OD at about 52 mph and the rpms drop to 1600 which is too low for towing. If your on a perfectly flat road and just have to maintain speed its OK, but any kind of grade or quick acceleration the egts will start going through the roof. My 98 is an HX turbo so I can imagine your problem is compounded even more. Ive learned to accelerate using the OD button which keeps the trans in 3rd and I will generally keep the converter locked. Depending on load/grade I will run in 3rd all the way to 2200 rpm sustained its actually easier on the engine, egts will be lower and according to my scangauage Im actually burning less fuel than if Im lugging it in OD.

[Zukifreek]

I did the HX35 swap in the summer, and it has a boost elbow in it cranked all the way in. My truck does have the 3.55 gears, but I was just empty rolling when I saw 1200 on the EGT. I will try it with the winter front out and see if it trys to climb any higher. When I tow the trailer I will probably just put the comp on level 1. Thanks guys.