Engine/Transmission (1998.5 - 2002) What do ya'll think of this towing combo?

[caleb c.]

I use the truck primarly for a tow rig,and here is the mods I am planning to go with what I have now. Mach 2 injectors,Dodgezilla 14. cm gated,SBC con FE. Does this sound like a good towing combo?The Zilla' should be enough for Don's 2's shouldn't it?And I could probally get away with a con OFE,but thought I would get the FE since its a tow rig and I will probally upgrade the power more down the road. Sound like a good towing combo?

 

[Supermod56]

Sounds good, I have the Catcher ECM, a great towing mod!! Have Mach 1. 6's on the way, and I have an Con-OFE & NV5600 sitting on the bench, can't wait to get those bolted in! Not sure if I would go with the FE, the OFE is good to 1000lbs. tq.



Tom

 

[Wyatt 1]

I just installed an FE and it is grabby, it isnt very smooth, but it isnt bad either, I like it, and if planning more mods no need to take out the transmission twice, did that not to much fun the second time around.

 

[darkhorse]

The Zilla' should be enough for Don's 2's shouldn't it?And I could probably get away with a con OFE,but thought I would get the FE since its a tow rig and I will probably upgrade the power more down the road. Sound like a good towing combo?[/QUOTE]



Yup, the 'zilla is plenty of turbo for the Mach 2's. Bob Wagner is using one with his Mach 4's & he can do some towing. I just put in Mach 3. 8's & so far they are running cooler than my old 1. 5's True, I haven't towed with them.



I'd give South Bend a call before ordering & ask them for a recommendation on the clutch. They will be straight with you if they think the con ofe would suit you better.

 

[PC12Driver]

That's very similar to what I have. As a daily driver it worked great. Pulling a trailer it sucked (10k lbs, 27' 5ver). The turbo will not light under normal driving with a trailer 'till about 2000 rpm, and in sixth that's about 70 mph (3. 54 gears). So normal cruising at 55-65 mph in sixth is out on all but the smoothest roads, since I'm always under the turbo at that speed. The egt's rise sharply and the boost doesn't increase to anything useful if I encounter any normal hill, unless I downshift to get above 2000 rpm then boost comes up and all is good. In the mountains or on twisty roads I'm constantly shifting to keep rpms over 2k so I can get boost and actually accelerate.



The compressor on the DZ is large and agressive and it takes a lot of pressure to drive. A smaller 12cm housing would help pull the useful range down a couple hundered rpm, but then I wouldn't be comfortable with the drive pressures and heat on the non-wastegated side of the housing (since Holset only 'gates the back 3 cylinders).



As far as the clutch, the OFE is grabby when you're trying to manuver the trailer or start out on a hill. As in "I hope I don't break anything" grabby. Keeping it tached up while you slip it will help, but that can't be good for the clutch. I installed a 2-low kit, and that helped for parking the trailer, but not for normal driving. And you need a CAD front axle for the 2 low, which the 2002s may not have.



I'm comparing this to my truck with just an EZ. Pulling the same hills in sixth was effortless. I didn't have to downshift at all except for a few of the higher passes in Colorado, when egt's became a concern at altitudes over 8,000'. And with that power I could keep the stock clutch, which was great for towing.



So now when I tow, I swap back to the factory 35/12 to get my low end back and keep midrange egts under control (less that 1200* pre with the injectors and the box on level 1). Easily 10-15 psi more boost at 1700-1800 rpm and I can set the cruise and let her go. And as far as the clutch, I'm hoping some traction bars will take care of some of the clutch chatter/axle wrap.



So my advice would be to stick with a smaller turbo, like a PDR35 or the HTBG (check out Clmsnow's reviews on this turbo; good spool, good midrange, fully wastegated, and keeps 450hp at 1350*), or go with twins. And I'd go with the lightest duty clutch that will support your power, unless you're sure that you'll have more power in the future (the OFE holds 1000 ft/lbs).

 

[johncameron]

My OFE is fine for pulling. I have to back my 6000#+ trailer up my driveway which is quite steep and I have no problems with practice. When the clutch starts to engage let the pedal out and go. You can't slip them without twisting the cab off the truck! I'm really happy with my setup all around. I tow with just the DD2's and EGT's are never over 1250F with 30LBS+ of boost. The stock 12cm turbo has a great bottom end from 1400 up. With the banks box on I can hit 35LBS at 1300RPM!!!!! Yes I had to try!



JC

 

[JJ Jackson]

I have a set of Dons' Mach 2's with a stock HX 35/12, and the power is right where I want it and no EGT problems. When I run unloaded with the Comp on 5x5, I call it the Cummins eclipse of the sun.

Isn't the ConOFE the strongest? Thats what I have, but I wish it wasn't so grabby, I too feel like I'm gonna snap something sometimes. I thought SBC had a dual disk set-up to combat this problem, give them a call.

Good luck, ... Jim

 

[caleb c.]

If I do go the dodgezilla route,should I go with a 12 or 14 cm. housing?I also do have a drag comp box but it would be turned down low while towing. But which housing would be better for towing with 2's?

 

[PC12Driver]

For towing, the 12cm housing would be better. No question. Like I said above, the DZ with the 14cm housing lights off at 2000 rpm. The housing is what "tunes" the turbo to your application. The 14cm is awesome above 2k, but for towing you need the turbo to be "on" at or near your cruising rpms. The 12cm housing should bring the effective rpm down 200 rpm or so.



Look closely at the HTBG by High Tech Turbo. It costs a little more than a DZ, but it spools at a lower rpm, will run higher boost more efficiently, and you can run a 12cm housing with very little (or no) change in top end egts since it has a great wastegate that will bleed drive pressure from all six cylinders.

 

[caleb c.]

Thanks for al the help guys. I will also look into the HTBG as another option. And I guess go with a 12cm. housing on whatever I decide to use. Also,Isnt there a way to modify holset turbos to wastegate all 6 cylinders?

 

[darkhorse]

For towing, the 12cm housing would be better. No question. Like I said above, the DZ with the 14cm housing lights off at 2000 rpm.



Mabe it's may caTCHER, or my porting job, or something like that, but my DZ 14 puts out boost a lot sooner than 2k. I often climb hills at 1500 rpm holding 10 psi & a tickle of the go pedal sends the boost needle right up the scale.

 

[darkhorse]

Thanks for al the help guys. I will also look into the HTBG as another option. And I guess go with a 12cm. housing on whatever I decide to use. Also,Isnt there a way to modify holset turbos to wastegate all 6 cylinders?

Yes, some folks drill out the divider through the waste gate port. I'm not at all convinced that really accomplishes much though. The port itself can be opened up some & the edges radiused a little to help the flow.

 

[PC12Driver]

Mabe it's may caTCHER, or my porting job, or something like that, but my DZ 14 puts out boost a lot sooner than 2k. I often climb hills at 1500 rpm holding 10 psi & a tickle of the go pedal sends the boost needle right up the scale.

What size trailer are you pulling?

 

[darkhorse]

What size trailer are you pulling?

That's running with no tow & a light load, but it's not much different when I have the horses loaded. That only runs about 7,000 lbs though.

 

[Hohn]

With all due respect, PC12, you can't really comment on JUST your turbo as you have so many other mods that may affect the outcome. You can't attribute your results solely to the turbo, can you?



When sizing a turbo, the proper way to do it is to look at your hot side and cold side separately. First, you need a compressor that can move enough air to support your HP needs. Will a DZ's 60mm compressor support the 450hp or so that Don's 2 can make? Probably not WOT, but with the box down or off, you can probably achieve reasonable EGTs with the DZ's 60mm compressor. The compressor determines total turbo airflow capability.



The turbine side or "hot" side determines WHERE in the powerband your compressor will operate. If you go too big, you will have a laggy charger that won't stay spooled when you need it. If you go too small, you will have a surging, barking nightmare that lack driveability.



I ask *this* question: why would a DZ/14 be a lag pig if a HX35/14 is NOT??? Sure, the DZ will spool slower in a drag race (more inertia), but this is TOTALLY different than the ability to MAINTAIN BOOST, like you would want for towing. To illustrate this, just imagine a turbo with a VERY tight turbine housing, but also with a VERy heavy inertia. This kind of fictional turbo would be slow to spool because of the heavy internals. You could make the turbine side tight enough to kill the engine and STILL not have good spoolup!



However, this same fictional turbo would SUSTAIN boost quite well in a towing situation-- it would go to very low rpm and keep boost. Obviously, it would choke quickly on the top end, but the point stands.



So, we come back to the Dodgezilla and its relevance to your application. The compressor side will flow enough air to cool the M2s on lower to middle range box settings.



So we come to turbine size. The 12CM housing is too small, even for an HX35. It's fitted to as factory equipment for the main reason of EMISSIONS. That means that EGT control is sacrificed in favor of spoolup. Banks supplies a 14CM housing with their PowerPack, and this IS NOT AN ACCIDENT. Even with the somewhat modest hp gains a Banks kit provides, a 14 housing is a must. Keep in mind that this is with an HX35!!!! How much more flow does an HX40 compressor need from the turbine side?



So when you increase compressor size, you MUST increase turbine housing size as well. *Rate* of spoolup will be slightly slower due to the heavier compressor wheel, but SUSTAINABLE boost should be fine.



In short, if you go with a DZ, the 14cm housing is the very smallest you should consider! I'd encourage you to try an 18. 5 with the combo-- you'd be surprised at its performance, I bet. Surely a first genner will part with the 18. 5 for cheap!



JMO, as always.

 

[Clmsnow]

I recently installed the HTBG of my truck, with DDII's and Edge Comp. I started with the 14cm and then switched to the 12cm. I have yet to find a situation where the 14cm was better. EGT's are the same, boost is up and most importantly, spool up is much faster. Many people told me to keep the 14cm but I wanted to find out for myself. The 12cm was the best thing I did, along with adjusting the wastegate. I also noticed it ran better at elevation(ie-7000ft). HTT is selling most of their new HTB2's with 12cm FYI.

 

[PC12Driver]

To respectfully respond to your respectful response...



About a year ago I would have agreed with you 100%, and that is the common thought process here on the TDR about turbo selection. But, when I was trying to figure out why my combo was so laggy for towing and was talking to everybody trying to figure it out, it was Van Haisley that turned on the light for me.



I look at it this way; there's two types of lag. The first, and the one that you bring up in your reply, is the time it takes a turbo to reach zero to full boost. Inertia plays a big part here, which is related in a big way to compressor diameter. More rotating mass = more time to reach boost. Important for 1/4 mile times, but not an issue for towing.



The second, and lesser talked about, is the lag that you have in steady-state mid-throttle operation. It has to do with the blade pitch on the compressor wheel. The larger diameter compressors also will typically have more blade pitch. More blade pitch means more resistance, and more resistance takes more drive power to overcome. In steady-state cruise, with all other factors remaining the same (ex turbine size, engine rpm, fueling level) an increase in compressor size/pitch will result in less boost and less charge air volume. The engine will generate roughly the same exhaust volume (energy) to drive the turbo, but the increase in load from the compressor will prevent the turbo from spinning up as high and generating as much boost (charge air volume).



In your DZ/14 vs. HX35/14 comparison you are only referring to inertia. Factor in drag from the blade pitch, and put it in a partial throttle scenario, and the DZ will not generate as much boost as the '35, thus resulting in higher egts.



With the trailer in tow, my DZ/14 will consistently run 5-10 psi less boost and 200* higher egts than my HX35/12.



The efficiency range of a compressor has two sides. There the top side that everybody seems to focus on (maximum useful boost), but don't forget about the bottom side. If the compressor isn't turning fast enough to get into it's efficiency range it will not move as much air as a properly sized compressor in it's efficiency range. So to get a larger compressor into its efficiency range at mid throttle, you'll need a tight housing with a wastegate. The small cross section will extract more energy from the exhaust and get the compressor into it's map sooner, and the wastegate will bleed off drive pressure once the compressor reaches the upper end of its map. But this is where the Holset's fall short, since they only 'gate 1/2 of the cylinders and they can't keep up with big HP. This is why I'm starting to favor the HTB series from HTT; they can 'gate all 6 and keep up with the flow.



I don't know if you followed the discussion about Clmsnow's HTBG. He started with the 'BG/14 and went to the 12 cm housing. There was a bunch of opposition to the change because the 12cm housing is "way to small" for the HP and egts would be high. But the end result was a slight decrease in egts, since the compressor was driven into its map sooner and the fully wastegated housing could keep up. So you can't say that the 12cm housing is too small. The key to running small housings is a good wastegate. HTT is even running 12cm housings on their larger HTB2. Suggesting the 18. 5cm non-w/g housing is a bit extreme. That would result in a very narrow useful range waaay up in the rpms.



Caleb's mentioned that the truck would primarily be used for towing, and that's how I answered. His mods are almost identical to mine, so I answered in light of what I would do to mine to improve its towing ability (based on my actual experiences). If towing wasn't the primary function of the truck, I would have suggested the DZ/14. It performs well when empty and playing around, and it will keep 460hp cooled down to <1400*. But when you put a load on the truck everything changes and you really can't apply drag racing or dyno racing knowledge to towing needs. You need to select a turbo based on how you intend to use your power, not just how it cools on the top end.

 

[HeavyHauler]

After talking with Everett at HTT for a while about what I do with my truck and where I'll be at HP-wise, he STRONGLY suggested that I go with a 12cm2 housing on the HTB2 with Mach 5s and the EZ, which will probably yield close to 450 HP.



I always like to stick with the manufacturer's (the experts) opinions on matters like this. They do this stuff for a living, and I figured if anyone knew what turbo I needed to be running, it would be them.



Good luck.

 

[bkroupa]

I wound up with a DZ with a 12CM housing & it "lights" alot earlier than 2000rpm, like 1400.

For 1600 rpm & up towing & empty cruising it works very well. My towing mileage has improved by over 1mpg & my empty mileage has improved by . 5mpg. The spool up is not noticably any slower than stock with the 12cm housing.

 

[darkhorse]

I wound up with a DZ with a 12CM housing & it "lights" alot earlier than 2000rpm, like 1400.

For 1600 rpm & up towing & empty cruising it works very well. My towing mileage has improved by over 1mpg & my empty mileage has improved by . 5mpg. The spool up is not noticably any slower than stock with the 12cm housing.

My DZ-14 lights around 1400 also. I have yet to have any egt troubles but then I don't tow more than 6 or 7K pound.