Engine/Transmission (1998.5 - 2002) Mach 1.5's and EGT's

[lkuykendall]

I recently upgraded my 2001. 5 from Bosh 275's to EDM Mach 1. 5's. At the same time I installed the HTBG turbo from High Tech Turbo with the 14 cm exhaust housing and 4" downpipe. This past weekend I pulled a 21’ bass boat through East Texas and my EGT’s are WAY up compared to what they were prior to the upgrades. In the rolling hills of East Texas with the cruise set at 65 mph, I am seeing EGT’s jump to 1050 or more (pre turbo). I never had this problem with the 275’s and HX35.



For those running Mach 1. 5’s, does this sound right? At one point, I was told that the 1. 5’s could even drop EGT’s which I found hard to believe but I never expected them to jump like this when pulling a light load.



Overall the pickup is much less drivable even empty with the current setup and there is no way I can use the additional power that the injectors provide over the 275’s due to EGT's. Running empty you have to bring the RPM up to around 2300 when shifting or it heats up to much between gears. My wife hates driving the pickup now because she has to constantly monitor the pyrometer when driving around empty. This is not what I was looking for when I upgraded!



If it isn’t the injectors could it be turbo related? I was seeing about 25 lbs of boost on the rolling hills while pulling my boat this past weekend. This is down from what I would see with the HX35 but if I understand this correctly, higher boost numbers do not always mean lower EGT’s so I assumed this was about normal. Cruising down the road empty I am seeing about 5 lbs on flat ground.



Any thoughts?



Len

 

[AggieJustin]

Len-



What's the max EGT you're seeing right now? Towing and empty.



You mentioned 1050, but that's not in the dangerous range. You can get up to 1250 pretty safely. You can go beyond that as well, but just don't stay there for long periods.

 

[lkuykendall]

Justin,



The reason I am concerned with 1050 is because I am pulling such a light load. With the 275's, EZ and HX35 grossing over 25,000 lbs I could pull hills going up the caprock in West Texas at 1100 or a little higher. I believe my current combo would force me to back off because I feel the temps would be out of hand with that load. If power isn’t usable for towing it is worthless to me, I don’t dyno, drag race etc…



I have not ran the truck hard since installing the injectors, I will play with it this weekend if I can and let you know how the temps climb when I get on it.



Len

 

[darkhorse]

If it isn’t the injectors could it be turbo related?



Any thoughts?



Len[/QUOTE]



First of all, I'm not a turbo expert but I have done a lot of reading on the subject. I recently purchased a Dodgezilla from Rip. He explained to me that I would likely see higher temps cruising & under light loads at partial throttle as the larger unit does not move as much air in those conditions. However, as loading increases& the turbo moves into it's efficiency range the peak temperatures are lower. Make sense? If you have your old 12 cm housing, you might try it on the HTGB or you could try the 14 cm housing on your HX 35

 

[Gary - K7GLD]

I have the 1. 6's, stock turbo, 4 inch exhaust, and running empty my EGT is about 200 degrees lower than with stock injectors at cruising speed/load - and also on upgrades as nearly as I can determine. Boost is much more rapid than before the 1. 6's - probably more due to exhaust mod than injectors, but the injectors undoubtedly do their share. Boost so far tops out at the same 32 PSI as before, but will know lots more when we hook on to the 5er in a few weeks and hit some grades. I suspect the turbo in your case - not enough air to "feed" the fuel...

 

[Boondocker]

Gary,



What's your SOP meter impression of the 1. 6 injectors - little grin, medium grin, big grin? Has the novelty subsided? If you got do-over, would you get a different size?



I know you've had the Comp for a long time and got the exhaust upgrade with the injectors, so can you distinguish the change due to the injectors?



Smoke - with the Comp set to low-smoke, can you avoid making smoke without having to light-foot it too much?

 

[PC12Driver]

It's absolutely the turbo. I just went through the same thing w/my Dodgezilla.



Bigger compressors take more exhaust energy to drive. Two things contribute to exhaust energy; RPM and expansion from fueling.



RPM because the engine is an air pump: more RPM = more airflow through the engine and out the exhaust.



The more fuel you burn, the more expansion you get in the combustion process, thus greater exhaust volume. But increasing fuel also increases egt's; increasing RPM's does not (to a point).



So you're cruising along at 65 mph pulling your boat. The horsepower required to do this hasn't changed, so roughly the same amount of fuel is used (fuel = power, boost = cooling). With the same RPMs and the same fueling you will have the same exhaust volume as you did before the mods. But now you have a more agressive compressor that takes more energy (exhaust volume) to generate similar boost (compared to the factory hx35). This is why you are seeing lower boost numbers for a given situation; bigger turbos need more exhaust energy to light them off. Factor in the larger exhaust housing that will extract even less energy than your factory 12cm housing and the problem is compounded.



Same idea when you start to climb a hill. The amount of horsepower that you needed to climb the hill before the mods is the same amount of power needed after the mods, therefore roughly the same exhaust volume. Again, the new turbo isn't as efficient down low as the stocker, so you end up with lower boost numbers. More fuel is added in response to the increased load from going uphill, but the less responsive bigger turbo can't generate enough boost to keep the egt's in check. Adding even more fuel might generate the needed exhaust volume to light the turbo, but flooring it up a slight incline isn't really practical.



Your comment about higher boost numbers not always causing lower egt's is correct - after a point. This is usually the case once the turbo's effective range is exceeded on the high side. 40 psi from a hx35 is significantly hotter than 40 psi from your HTBG; the HTBG is designed as a higher airflow compressor and the hx35 is working way to hard to generate that boost. At lower boost readings (like 25 psi for example) the hx35 is right in it's efficiency range and isn't superheating the air. The hx35 is good for about 30-35psi btw.



My suggestion would be to put the factory turbo back on and try things out; if the egt's stay below 1250 then you don't need a bigger turbo (with my 2's and the Comp on 1 the egt's easily stay below 1250 with the stocker). I experienced the same problems as you once I started towing with my DZ, and with the stock turbo back on all is better. It gets hot on the top end (like full throttle on levels 3 and above, which is rare for me), but the drivability with the trailer is worth it. Or, like darkhorse suggested, try a smaller housing on the HTBG to "extract" more of the exhaust energy, or try the 14cm on the '35 to relieve some backpressure (if your wastegates are compatible that is). But if your egt's aren't an issue with the stocker there's no reason to change the turbo.

 

[PC12Driver]

Whoops, just saw that the HTBG is a Schwitzer. The exhaust housing swap ain't gonna work I don't think.

 

[lkuykendall]

Thanks for the info. I spoke with Paul from High Tech Turbo this afternoon and what he told me seems to agree with what everyone is telling me at TDR. Paul said that I should really see the advantages of this turbo when pulling a heavy load, not when running empty or light. He even suggested using a boost elbow when running empty or lightly loaded to see if the additional boost would drop the EGT’s.



If the boost elbow doesn’t help, it looks like I wasted over $1,000 on this turbo. If so, anybody flowing lots of fuel need a turbo?



Thanks again for all of the suggestions and information, it has been very helpful.



Len

 

[Bob Wagner]

Len, when running empty at say 60 or 70 mph what is your boost pressure?



If you take a drive this weekend make a couple of notes.



say outside temp/ steady speed at 35 - 55 -65mph/ what are your egts and boost pressure's at those different speeds.



Thanks





I run Mach 4's and a dodgezilla 40/35 hybrid with a 14cm housing and have no egt issue's at all.

 

[Gary - K7GLD]

Gary,



What's your SOP meter impression of the 1. 6 injectors - little grin, medium grin, big grin? Has the novelty subsided? If you got do-over, would you get a different size?



I know you've had the Comp for a long time and got the exhaust upgrade with the injectors, so can you distinguish the change due to the injectors?



Smoke - with the Comp set to low-smoke, can you avoid making smoke without having to light-foot it too much?

1. I'm *very* satisfied with the 1. 6's - glad I didn't go to the 2's - around town, running empty, I've been running with the Comp off, or on 1x1 for better smoke control - more on that below.



2. I'm pretty sure the biggest difference in the better turbo spoolup is due to the turbo-back 4 inch exhaust - and it's really pretty hard to isolate the effects of the separate mods, since both were done at the same time.



3. And here's the main issue so far, WITh the Comp on 3x3 where I frequently ran it before the exhaust and injector mods, LOTS more power, big grins, and enough smoke in low RPM ranges to keep all Grant county mosquito free for the season, unless care is used on the loud pedal. But that smoke is only for the first short distance until the turbo spools from a dead stop (which it does MUCH faster than before!), and once up to speed and a few pounds of static boost - say from 35 mph on, very little smoke, just a haze as boost almost instantly jumps to 32 PSI or so and telephone poles start going by REALLY fast.



Nice plus with the Comp, is the easy ability to DEfuel with the settings down at the lower levels, like 1x1 or so for better smoke control around town - still all the power I could possibly want or use, and I still have 24 more levels on up above!



As it is, I pretty much rate the 1. 6's plus the 4 inch exhaust as about the same power level as the Comp alone used to be on 5x5 - and THAT was good for 311 HP and 835 TQ on the dyno - sure will be interesting to see how the upgrade dynos, and also what happens in heavy steep towing situations.

 

[Boondocker]

Gary,

telephone poles start going by REALLY fast.

Thanks for the update. I guess all your power is getting to the rear wheels



Neil