Any one towing much with their HTB2? I had hoped for more than what I'm getting. With the Mach 1.6's, I have to turn the TST off to keep temperatures at or under 1200. I haven't had it in the mountains yet, but even on the flats, I still have to watch the guages carefully and temper the right foot. And this is only with 6,000 pounds.
The only setup I have to compare this to was my PDR HX35 and RV 275's. Absolutely no temp problems there.

 

which exhaust housing are you running the 12 or the 14.

Jake

 

Your experience is like mine with the sps62, does not cool real well when towing.

 

And how much boost are you seeing????

 

Brett at II was telling me today that the only trucks they recommend the 12 on is a 1st gen 12v. I know the thread on htb2's but I thought that was interesting.

 

The HTB2-62 is the best all around high performance turbo I've ever seen, other than a vgt. It's able to start building boost at 1200 to 1400 rpm, which makes it very good for towing, can handle well over 500 hp with no problems, has a drive ratio of 1:1 or better up to 40 to 45 psi, and is safe to 50 psi. I've seen a 700 hp 3rd gen only give up 35 hp when going from a Silver Bullet back to a HTB2-12, and pickup a whole lot better driveability, especially in towing situations.

Maybe 1200 degrees is too low of a temperature to hold a 62 to. A completely stock ETH will easily see 1350 or 1400 degrees while towing.

Are you running a 62 or 64? A 64 will probably run hotter on a mildly fueled truck used for towing, than the 62.

 

I'm running the 62-14. Unloaded on the street, with the TST turned on, its unleashed. Down right scary actually. I have a manual boost controller set at 45psi, and it will peg that. For a large single, it does spool quickly.
Under load (6,000 lbs), I'll typically see 15-20 psi if boost. And yes, its a ETH engine. Perhaps the sticks are too much, which would surprise me being they are made specifically for towing.

 

From what I see in you sig, you have probably the ultimate tow combination using a single turbo. I would guess that you would dyno at about 450hp.

As far as EGT's, on of the nice things about your setup is that you have options. You can turn the box off, drop a gear, or back off on the throttle a little.

There are ways to lower the EGT. One of course you could add an S400 under your 62/14. It makes a great combo. Two you could add water/meth injection. Three under towing conditions you might have slightly lower EGT's with a 12 housing instead of the 14. I would not chance it though, because you could get into surge issues.

My preference would be the S400 of course...

Congrats on a nicely setup rig!

Paul

 

Paul,
Your freaking killing me. I didn't know that there was a twin combo using my HTB2. Tell me what the driving/engine response characteristics are like.
How will it handle 20,000 lbs? Are you studded (or fireringed)? What boost is usable? Realistic?....without creating another giant round of headaches?

 

Twins do drive differently then singles. For example if you use your 62/14 as a top turbo, the spoolup will be slower, but the total amount of air delivered at a given RPM will increase. This sounds like a contradiction, but it's not. For example if you are at 1500 rpm and accelerate the initial rate of boost increase for the single will be quicker. However at a constant 1500 rpm, the amount of air that the twins will move is greater. Now once you have the bottom turbo producing about 5psi, then the spool of the twins is amazing. I make 5 psi on the bottom turbo at about 15psi total boost.

IMO 450hp is about the max usuable when towing. It's not just about keeping EGT's down. I can make well over 550hp and keep EGT's in check. The cooling system, diff temps, trans temp, etc have a hard time keeping up with over a constant 450hp. Not to mention when you are towing something and get on it to pass someone, and it spins the tires as you pass them...

I have ARP studs and o-rings. 50psi is usually a pretty good number before you need to stud the head. Maybe 60psi before needing to o-ring. I ran 48psi on a single without studs. As far as what boost is usuable, I have run as high as 75psi, but did not see any improvement over 65psi at my fueling level. Either in EGT reduction or in 1/4 E.T.'s.

Hope this helps...

Paul

 

Paul,
I couldn't care any less about HP! To me, its all about useable torque. Getting the load moving, and keeping the engine cool for long distances is the ticket.
I really don't want to "lag" my driveability any more than I do. I have become accustomed to the initial lag of the HTB2 (compared to a Hybrid 35/14), because when the HT lights off, hold on! Even when towing, this combination pulls very well. The engine is already studded (@125ft/lbs), but I have no desire to pull the head and O-ring it. I have a manual boost controller set at 45psi, but actually rarely see that because I keep the TST at/or below level 3 usually.
What would be the ticket is, will the S400 keep the EGT's down while towing in the mountains? If maintaining 15psi from your upper turbo to make 5psi from your lower turbo, then making 20+ from your upper in the mountains equals that much more cooling? Is it truely beneficial from my standpoint to do this?
Thanks for the conversation!
Jim

 

Bart, was this 700hp 3rd gen, cobalts?

 

I've seen Pauls truck and those twins work awesome! he makes almost no smoke on the track.

 

Jim,

I have had a few different turbo combinations on my truck. I would have saved a lot of money had i gone straight to twins. I had a Dodgezilla (35/40 hybrid), that as you probably also found out, worked pretty well for spool, but lacked with keeping things cool. It was a great turbo, but I out grew it. I then went to a large single (flowed about the same as a sledpuller 66), and though it cooled at the dragstrip much better, it really didn't work well towing, or driving on hot days at high altitudes (I live at 4600'). I then went to the twins I have now. Night and day difference. I have a test hill that I use (as I'm sure most do). All the tests I did were with an empty truck. With the Dodgezilla going 62mph it would make 10psi, and 1000 degree EGT. With the large single it would make 7psi and 1150 degrees. With the twins it does 10psi and 950 degrees. Basically if you compare the Dodgezilla and the twins, they both made the same boost, but with the twins the EGT's were lower.

I have my truck setup for drag racing. It is also my daily driver, even though I have other cars I could drive. All the towing I do, is towing my travel trailer to and from the drag strips. Of course I do haul fire wood with it from time to time... Race car

For what I use my pickup for, the twins are night and day better then any of the singles I tried. Do I think a set of twins would lower your towing EGT's? Absolutely. Will you have to beef other things up? If you are like me you will, because having low EGT's means, "not enough fuel"! If I turn my power down, to about where your max power is, and keep my RPM at 1700 or above, I'm hard pressed to break 1100 degrees. I would never tow using that much power for an extended amount of time. Water temps would get to hot, not to mention the rest of the drive train.

Hope this helps...
Paul

 

Huh? I had never gotten my temps that high when mine was stock?!!