Engine/Transmission (1994 - 1998) EGTs too hot? More timing or boost needed?

[JGheen]

So I am thinking my EGTs on the freeway and hill climbs are too hot for just general driving and not towing anything. My truck does have 37" tires on it and I think that may be a contributing factor but lately, maybe it's the hot weather, but I am thinking they are too hot.

My cruising temps on flat level freeway @ 75mph are about 900*F, sometimes a little hotter, like 1000-1100*F with a good wind in the trucks face. They also get extremely hot, really fast in 4th and 5th gears when putting some pedal to it. I can usually see 1500* in 4th gear fast and I have to get out of the throttle to get the temp back down, but with my timing and boost I would think they would not rise as fast but then again, with the amount of fuel I am running throught the EDMs, I am not sure what normal is. Is there anything I can do besides alternative fuel injection(water, propane, etc. ) to cool the temps? More timing, boost, perhaps a larger HTB2 compressor?? Are those cruising temps too hot for a highway cruise?



Thanks, Joe

 

[bkroupa]

I assume you have 3. 54 gears?

If you have no boost leaks, I'd guess your not spinning the motor fast enough to spool the turbo cruising. I think you'd be happier with a 12CM housing for most of your street driving with your truck geared that tall (assuming 3. 54's), but that wouldn't help your wide open EGT's.

There are a few post from people that went from a 14 to a twelve housing & were much happier with their HTT turbo's. I read several when I was deciding on a turbo for mine.

 

[JGheen]

Yes, I am running the stock 3. 54 gears but as you mentioned the 12cm housing would not help my wide open, top end EGTs which is something I am concerned about with how fast they climb to the dangerous temps as well as my questionable cruising temps.



Joe

 

[bkroupa]

I'm not running anywhere near the fuel you are, but I had to compromise on how far I slid the plate forward to keep from running too hot. If you like the temps in 4th gear & don't want a smaller turbo housing you may want to consider 4. 10 gears or try a set of smaller diameter tires.

I don't remember the guys name, but do a search for HTBG or HTB2 turbos & there was a couple of guys that did go smaller, ran cooler, spooled faster & gave up very little if anything on top. Single turbo's are a compromise, that's why you see the guys raving about twins.



BTW my 70mph cruising temps are ~800 degrees pulling a tall 30' travel trailer

running 70 empty is ~650

 

[Signal73]

My truck runs hot unloaded I can get it up to 1300° EASILY @ 45lbs of boost just accelerating on the highway from 55-80mph. I assume my turbo is undersized

 

[JGheen]

Well, my #100 plate is set full forward,so that could be a reason as to why the temps rocket to 1500* in 4th and 5th with all that fueling and no curve on the plate to de-fuel any. I guess I could move it back some and see how they react. My AFC housing is set full forward as well so I could probably move it back as well to lower the cruising EGTs some since there is little to no boost while cruising.

bkroupa, those are typical EGTs I read about that everyone else is seeing, where is your AFC set at?

Signal73, those temps your seeing are similar to how mine climb and the temps they reach, but with your 12cm housing that would probably explain some of your hot top end temps which is why I went with the 14cm since I knew I was going to be throwing more fuel at it in the near future. Where is your AFC set at?



Joe

 

[bkroupa]

I think the lower egt's cruising are mainly because of the smaller turbo I have & not pushing as big of tire or 4wd. When I run my camper shell, one of the tall industrial types my EGTs run ~50 degrees higher without the trailer. So big mirrors, big grill guards etc all add up on the cruising load. I've adjusted my AFC back & forth to get the best throttle response without ******* off the EPA. Forward or back did not seem to affect the hwy mpg much. I drive ~700 miles a week mostly 65mpg hwy & average 22 mpg running empty. 13-15 towing the TT (depends on the wind) I've gotten as bad as 12 driving 75 towing until I figured out how long it takes to stop going that fast.

I tow 65 now

 

[JGheen]

I could probably adjust mine a little back as well as backing off on the star wheel some with the amount of pre-boost smoke i put out. It's nice for those pesky tailgaters but I would have to believe that is where most of my mileage goes.

As for hot EGTs, I guess that my cruising temps should be around 900*+/- due to the weight of the truck with the large tires, bumper, tool box, etc. I think I am good on turbo size and air flow but does anyone know a wild guess of how much, if any, decrease in temps I might get by advancing timing more to say 17* or even 18*? Is there a good rule of thumb for how much timing to give it with a given amount of fuel..... example... . it seems most who run an injector that flows in the range of a 370 run about 16*-17* but that is just a common number I have seen on here.



Joe

 

[Matthug]

You have studs and O-rings, I would bump the timing to 18 in a heart beat. This may sound dumb, but I'd check your air filter and see if it's time for a cleaning.

Also, I did a lot of research and I've never heard anything good come from the twin ram intake, too many people had too many problems with them. This could be another.

 

[Signal73]

AFC+plate FF, starwheel about ½ way.

 

[Matthug]

The AFC kit from TST really helped my smoke a lot. AFC full forward, 0 plate full forward, starwheel cranked 100%, I can still acclerate faster than most traffic without a single puff of smoke... . well maybe just a slight one starting out but thats it.

 

[JGheen]

You have studs and O-rings, I would bump the timing to 18 in a heart beat. This may sound dumb, but I'd check your air filter and see if it's time for a cleaning.

Also, I did a lot of research and I've never heard anything good come from the twin ram intake, too many people had too many problems with them. This could be another.

I actually just cleaned my AFE about 4 days ago and before that only about a month ago due to some runny, old AFE oil I had used and it all drained to one side of the filter.

I would be curious to know some reasoning behind those problems with the Twin ram intake. Mine has been good to me ever since I installed it... . seems to distribute the air more evenly accross all cylinders and I have never had any problems doing plate adjustments with it installed on the engine, just as easy as with the original stocker.



I am thinking my top end EGTs are just so hot due to a combination of the amount of fuel I am running, the #100 plate being full forward and not de-fueling at that flat curve at the top of the plate as well as the HTB2 producing some turbulent air flow between 30 and 38 psi of boost. I would like to try that AFC spring kit you mentioned as that might clean up some of the bottom end smoke.



Joe

 

[Bob4x4]

The AFC kit from TST really helped my smoke a lot. AFC full forward, 0 plate full forward, starwheel cranked 100%, I can still acclerate faster than most traffic without a single puff of smoke... . well maybe just a slight one starting out but thats it.

I don't think you have near the fuel Joe has... ... ... ..... The afc spring kit comes with lighter springs than what Joe has now... ... ... that will equate to more smoke. Joe you might want to add a valet switch to save a little smoke .



Bob

 

[JGheen]

I don't think you have near the fuel Joe has... ... ... ..... The afc spring kit comes with lighter springs than what Joe has now... ... ... that will equate to more smoke. Joe you might want to add a valet switch to save a little smoke .



Bob

Thanks Bob, I was thinking about a valet switch too but nobody else but me drives this truck. For now I'm just gonna play with the AFC some to reduce the pre-boost smoke for a little mileage increase as well as back the #100 plate up some to try and lower those 4th and 5th gear EGTs.

Bob, do think I should try more timing or just back the plate up for a reduction on those top end EGTs?



Joe

 

[Matthug]

I don't think you have near the fuel Joe has... ... ... ..... The afc spring kit comes with lighter springs than what Joe has now... ... ... that will equate to more smoke. Joe you might want to add a valet switch to save a little smoke .



Bob

I think the AFC kit has a common mis-conception that the spring kit is lighter than stock. I actually bought it thinking thats what it's purpose was, thinking that the AFC arm would get full travel by like 8-10 PSI instead of the stock 18. It's purpose is too lessen smoke output, therefore it is a tighter spring. I've tested it with shop air, and of course a real world test actually netted me less smoke. The only way I can make it smoke as much as it did with the stock spring it to hold my foot on the brake while fooring it at low RPM's. Doing it that way I can black out a lane on the highway easily. The ''light'' spring is actually stiffer than the stocker and is longer to put more preload on. With the stock spring and the starwheel halfway the AFC arm traveled to full length at about 16-18 PSI. With the light spring in the AFC kit and the starwheel full forward it didn't reach full length until 30 PSI and didn't even start moving until 5-7 PSI. Remember, the starwheel full forward lessens the spring tension so I could even make it tighter and it wouldn't move until 10+ PSI. This is why TST recomends the heavier spring in the 215 trucks, to lessen smoke output even more.

The valet switch does help, mine works great. But since I have the AFC full forward and the smoke screw in the whole way it still can leave quite a puff of smoke if it's lugged. But with the valet switch cutting the boost signal atleast the exhuast is 100% clear at WOT and I still have 250 RWHP and 550 ft/lbs... . plenty for towing anything the truck can handle and my EGT's topped out at 1100 towing 8000 pounds up a very steep 2 mile long grade.

 

[Bob4x4]

Joe,I still say the best for your truck right now is to regear it. You will be amazed at the overall improvment. A side benefit will be your clutches will last a bit longer



Bob

 

[Bob4x4]

I think the AFC kit has a common mis-conception that the spring kit is lighter than stock. I actually bought it thinking thats what it's purpose was, thinking that the AFC arm would get full travel by like 8-10 PSI instead of the stock 18. It's purpose is too lessen smoke output, therefore it is a tighter spring. I've tested it with shop air, and of course a real world test actually netted me less smoke. The only way I can make it smoke as much as it did with the stock spring it to hold my foot on the brake while fooring it at low RPM's. Doing it that way I can black out a lane on the highway easily. The ''light'' spring is actually stiffer than the stocker and is longer to put more preload on. With the stock spring and the starwheel halfway the AFC arm traveled to full length at about 16-18 PSI. With the light spring in the AFC kit and the starwheel full forward it didn't reach full length until 30 PSI and didn't even start moving until 5-7 PSI. Remember, the starwheel full forward lessens the spring tension so I could even make it tighter and it wouldn't move until 10+ PSI. This is why TST recomends the heavier spring in the 215 trucks, to lessen smoke output even more.

The valet switch does help, mine works great. But since I have the AFC full forward and the smoke screw in the whole way it still can leave quite a puff of smoke if it's lugged. But with the valet switch cutting the boost signal atleast the exhuast is 100% clear at WOT and I still have 250 RWHP and 550 ft/lbs... . plenty for towing anything the truck can handle and my EGT's topped out at 1100 towing 8000 pounds up a very steep 2 mile long grade.

No smoke at 250 is no big deal,I have 350 with no smoke and Joe is double your number we are not talking about the same ball game... ... ... ...



Bob

 

[DBraunig]

Hey Joe,



i am sure Bob is right about the gears, but that won't be cheap. Wouldn't you benefit from a little more timing? The motor looks like you have it set up to take a little more. I have a real #10 plate if you want to try it and see if it helps with egts on top. The #10 cost me . 3 at the dragstrip so i stuck the #4 back in it, but it was cooler.



Dave

 

[Matthug]

Hey Bob, learn to read there buddy. I have 250 with the no boost signal to the AFC, I was talking about my valet switch being on. I have 350 RWHP when the AFC see boost I am running a 0 plate the most smokey of them all and I can accelerate with 0 smoke coming out.

 

[Bob4x4]

Hey Bob, learn to read there buddy. I have 250 with the no boost signal to the AFC, I was talking about my valet switch being on. I have 350 RWHP when the AFC see boost I am running a 0 plate the most smokey of them all and I can accelerate with 0 smoke coming out.

350 is still in a different field... ... ... ..... hx35 :-laf



Relax buddy

Bob