Doc_speeder

iTrader: (1)

To start with: I DON'T WANT A DIESEL. I LIKE THEM. I'VE DRIVEN THEM. I HAVE FRIENDS AND FAMILY WITH THEM. I DON'T WANT ONE!!!!! PLEASE DON'T SUGGEST ONE!!!!!



So with that out of the way: I DD my old Silverado 2500 LQ4. It's old and my kids are getting too big for the EC. So I'm looking for a 2008+ 2500HD CC to replace it. I tow fairly heavy (7500 lbs) at altitude over some gnarly passes, but not really often. My current truck does it ok so I don't really NEED more power. Current mods in my old truck are ported 706 heads, headers, intake, 210/218 cam and a decent tune.

But here's a plan I'm working on:

2008+ 2500HD CC LY6, with small boost. Like 5-6 psi or so.

Many turbo+towing discussions are aimed at keeping the truck out of boost while towing, but my whole purpose of this build would be to improve towing and bring in some serious torque (400 lb-ft or more if possible) by 2800-3000 rpm to give it more "diesel like" ability on the long climbs but retain the feel and sound of a gasser while just daily driving.

So now some questions:

1) I've heard that EGT's can be in issue while towing in boost. I get that, but when you search it seems like it's a second/third/fourth hand repeated story. It seems like very few people have actually monitored EGT's on a gasser turbo while towing.

With low boost, properly sized turbo/exhaust and a good tune, I wonder if high EGT is REALLY a serious issue??? If so, would a good water injection system bring it under control?

2) Can you run boost with VVT? I know VVT is pretty easy to eliminate, but I'd keep it if possible for this truck.

3) Is there any advantage to a remote-mount turbo, or even a box-mount turbo rather than a front-mount for this type of build?

4) Ford does this with significantly more boost with the Ecoboost motors. What kind of black magic do they use to control EGT? I know the DI helps with this. Anything else besides careful tuning?


I'm not an idiot and I have no expectation that I could climb big grades at WOT at 5500 rpm for 10 minutes at a time with my foot on the rug. But if I could maintain my speed while climbing them at 3000 rpm in 4th gear with the 6L90 instead of 4500 rpm in 2nd gear with my 4L80 like I do now, I'd have met my target.

I figure I could build this for about $5-7K on top of the truck purchase, which around here still puts me $3-5K less that a comparable Duramax truck. I'm not doing this for cost reasons, but obviously that is a component I need to consider.

I guess I just like being the odd guy that doesn't always push the easy button.

Anything else I'm really missing? Anybody have any useful towing+boost experiences to share?

Atomic

iTrader: (42)

I would do a roots blower if I were you. Much better suited to this task than a turbo while maintaining a much higher level of reliability with much lower maintenance. I have had both; a roots blower and a turbo, so I speak from experience.

LS1TRUCKGUY

iTrader: (7)

i agree with atomic on this. i have towed 5000lbs with my turbo truck up a few decent grades a couple of times without issue, but i have not monitored EGTs. but the roots blower is much more simple, and will provide the low rpm boost you are looking for.

Doc_speeder

iTrader: (1)

hmmmm. I think this forum is broken, it's not giving me the answer I want to hear...lol

Thanks for the input guys. I realize that a roots blower is likely perfect for my application. That's probably why I don't want one.

This afternoon I did some more dreaming. Seems like a bed mounted turbo in a small toolbox right behind the cab with a totally stand alone oiling system would be cool. True cold air intake, and run the long charge pipe through a big intercooler. Should really work at keeping intake temps and EGT in check as well as general underhood temps.

Maybe I'm crazy. Maybe I should just plan on a twin screw and call it a day...

timmay208

iTrader: (4)

bed mounted turbo is not a good option IMO, thats asking for more lag

i towed with my turbo 5.3 and had no issues with a s472 charger. I didnt monitor egts but as long as your air/fuel is good and timing is right you shouldnt need to worry about it

Turbo09

I have had no issues towing 4hrs each way to mud bog events with a 10,000lb + trailer, that was through some northern Ontario Hill climbs and lots of stop and go as well. I have no blower experience but I have towed with n/a gas GM trucks my whole life, and this turbo made the drive much faster and allot more fun!
Like you mentioned I never monitored egt's or anything really, just the temp of my 4l60e, and even with the stock cooler and 8psi at the time, the truck never missed a beat.

smokeshow

iTrader: (16)

I can appreciate custom projects. I've been known to do a few myself. If you don't want to run a roots blower, don't run one. If you want it to run 'like' a diesel without being a diesel, you'll need to mimic some diesel towing truck characteristics. Big radiator, big intercooler, small turbo. Keep the stock cam. And run a large turbine housing and turbine to keep EGTs in check if you're worried about it. Running small on the compressor and maintaining the small cam will keep spool time reasonable despite having a big hot side.

Doc_speeder

iTrader: (1)

Perfect!!! Thanks for the solid advice.

So I found a S475 with 75mm compressor and 88mm turbine 1.32 AR. Too big? Maybe with a smaller AR?

Or another BW turbo #177101T with 75mm compressor, 77mm turbine 1.10 AR?

As I see it lag is not really an issue as I will constantly be under some type of load. Instant response is not as important as the rpm needed to ultimately make boost. As long as it will start making boost around 2300-2500 rpm or so with a good load on it and maybe full boost by 3250-3500.

timmay208

iTrader: (4)

imo that is to big id say if you do a s475 do a 1.0 housing. my s472 was a .90 and 83mm turbine and it worked great

lag with towing is a issue imo. id stay away from the 1.32ar

smokeshow

iTrader: (16)

^^ He is right. Lag can be an issue while towing as well. Turbo 'load' is also a function of rpm, and that huge hotside may not even spool under 2500rpm at all. I would definitely go smaller than the s475. I ran a s465 on a 6.0 for a while and it was like a blower. I might try an s468 with the 1.10ar housing and 83mm turbine to keep compressor speed down a bit.