Is the LS Right for my Project?

[Psyekl]

Originally Posted by kipps

There's some question how well the LS platform would handle staying in boost for hours on end. Cooling would definitely need to be up to snuff.

My experience with turbos has been with race applications only, and I hadn't considered the issue of long-term durability as far as cooling is concerned.

The concept I considered was for quick-spooling, low-boost to keep it reliable. I was thinking of the smaller displacement for economy purposes during normal travel, but saw that they are also capable of impressive power when pushed. I'm not too sure I'd want to invest in being the Guinea Pig to test the viability of it over a long haul, however.

The diesel pusher concept is tempting, but unfortunately I don't have access to the fabrication facilities that I once used to enjoy.

[clay68c10]

I’d be tempted to get it running and use it for a bit. Let it tell you what it needs. And also if it’s really as useful as you want it to be for your purposes.
If the frame rail dimensions are the same width as newer donors, then that’s convenient.

[Overdriven]

Okay so I think I understand where you want to go but I might be missing something with how you can get there. On one hand you say you don’t have fabrication facilities yet it seems like some of what you are thinking of requires some fabrication. While fancy stuff like cnc plasma is nice, there’s a lot you can do with a grinder, a bunch of cutoff wheels and a welder. And with today’s mail order you can get steel in shapes and sizes where you can minimize the amount of cutting. It’ll still take longer than cnc plasma but with some planning you’ll get there with similar results.

Do you want to replace the trans? You could get a big bump in power and some efficiency gains just by going with something like a modern 383 crate engine with vortec heads and fuel injection. The only thing you’d need to change would be the flywheel and damper due to internal vs external balance of the engine. Actually going LS swap with the original trans would require only a flywheel change, besides the obvious engine mounts.

Turbo LS. The big unknown for heavy, high load applications is can the engine make 200+hp more than stock for prolonged periods of time. I think the pistons are the biggest concern. People already open up the ring gaps to help the stock LS pistons live with high boost levels and cylinder temps. Add an oil cooler and a good intercooler with good airflow across it and I think the stock LS pistons will live under prolonged high load with low boost. Could always talk with a piston mfg to find out how best to setup one of their off the shelf forgings for this kind of use too.

[Overdriven]

Speaking of turbo LS in heavy vehicles, go to YouTube and search “turbo LS Winnebago”. A channel called Fuelinjectionsucks built one with a 6.0L, 4l80e and GT45 clone turbo. The GT45 normally doesn’t spool up very fast but in this heavy vehicle it spools much faster because turbos like load on them. On the highway it seems like the turbo is always right there without much lag if any. I don’t know what kind of rpms or speeds they’re doing but you can get a pretty good idea. In the review Regularcars did on their YouTube channel the owner claimed 10-12mpg on the highway. They also use Methanol injection as supplemental fuel and probably also for cooling the intake charge to help on long grades as it is in boost when climbing grades. The owner mentions long grades being a concern and limits boost to about 10lbs, so far this guinea pig has survived...

I’m not advocating for LS turbo here just providing a similar project someone has done because it was mentioned. I would advocate for 6.0 4l80e nonturbo though.

[gmc684x4]

My vote is turbo 6.7 Cummins with a 6 speed great torque fun to drive and pull dam near anything

[Psyekl]

More excellent info and advice.

I am aware that I'm not going to be able to avoid fabrication, I was just hoping to keep it to a minimum. Though I no longer have my own CNC, there are many companies that offer custom CNC fabrication as long as I provide the required design files (CAD design is a service I provided for our shop). The internet makes so many things readily available!

I'm away from home for the next couple of weeks so I'll have time to dwell on the plan, but all of the combined advice has me seriously considering sticking with the existing engine/transmission, or at least an inexpensive 1st-gen 350 upgrade (w/ transmission and rear end) to use in the interim. In the meantime I can look for a diesel truck to provide a donor while setting aside the finances to cover the more extensive fabrication that will be required.

I'm still going to consider alternatives if anyone has other suggestions to provide.

[suburban99]

Back in the day I worked for a department store up here in BC doing heavy goods delivery. We had a few 1968 GMC's with the 2 speed rear end. The trucks all had 24' boxes and power tailgates. We loaded those trucks with furniture and headed out. We have some pretty steep terrain here in Vancouver area, North Vancouver and Up towards whistler. Those trucks were geared well and although they slowed on the hills they went to work everyday.. i would build your RV as is and see what it is like. You can always swap out the engine later as the cab tilts to allow access..