Why do bigger injectors run hotter while towing?

[Vaughn MacKenzie]

Yep, that's what I'm saying. With heavy throttle the HTB2 will run cooler, but for normal cruising/rolling hills with a trailer, the stocker will move a bunch more air mid-throttle. The HTB2/12 is just barely waking up at cruise rpm/fueling while the HX35/12 was "on" and making good boost. If a hill sneaks up on me and I don't have my rpms up, my egt's will climb right past 1250 and boost will just sort of hang in the low 20s. If I hit the hill at the proper rpms (1900+) the HTB2 will light off and keep temps in check. The HX35/12 was already pulling hard by 1700rpm. Since my gearing and tire size puts me at about 1800-1900 rpm on the highway, that would put me right in the sweet spot of the '35 and just tickling the bottom end of the 'B2. For me, the HX35 was much easier to tow with.

I don't know how big the HTB2/12 is compared to a DD Jammer turbo (HX40 based) but I have no trouble with mine coming up while towing, even below 1600 RPM. I think mine has a 16cm exh. housing, not totally sure. I suppose that's because it's already riding at 6-8psi on the level and essentially somewhat spooled all the time. I do have to roll into the throttle a bit slower than with the stocker, but it does spool well. While towing my EGTs quickly come up to 800F, but between 800-900 the boost comes up and the turbo is in the efficient area of its map, and EGTs rise very slowly from there on up. I can go charging up a hill with 7000 lbs in tow at nearly 70 mph and keep it under 1000F easily. Overall I like this turbo better for towing than the stocker. I'm not running too heavy on the fuel though . . . DDP stage II and a #10 plate in the middle with 3GSK.



Vaughn

 

[JEstes]

While we are on the topic of cams, who makes a good one?

 

[GiesJ]

I have no experience with any of these but would like Helix from F1 someday:

http://www.f1diesel.com/helix.html

http://www.piersdiesel.com/DodgeCamshaft.htm

http://www.scheiddiesel.com/trkpull.htm

 

[2broke2smoke]

[QUOTE I just wished that I was smart enough to figure out the "improved intercooler" formula and if upgrading to a better one would be good dollar per degree F decision.



Jim[/QUOTE]



same here brother ... i must just be one of the lucky ones but the new HTBG i've got spools almost exactly the same as my HY did down low and much better up high ...



may just be the perfect combo at my 400ish rwhp ...



intercooler seems like the perfect place to cool things down some more ...



although i can't get it above 1150 at all empty i'd like to maximize effeciency, without a cam change, for the next time i do tow heavy

 

[RustyJC]

To get back on the original poster's topic, my 1450 maximum pre-turbo EGT while towing only rears its head during acceleration onto the freeway or pulling a long grade - that's when I have to watch the pyrometer.



At a 65-70 MPH cruise when towing, my EGTs are typically in the 700 to 800 degF range - maybe 50 degF higher than stock injectors under the same conditions. That's probably due to the sloppy atomization of the extrude-honed DD2 injectors.



Rusty