westsiderc51@yahoo.com

Currently in my shop I have an 2003 C3500 4x4 duelly 6.0L...Big terd!!! Owner asked me if I could swap his 6.0L with an 8.1L?

Can it be done without changing the trans? Just want to know if any of you out there have done this swap or know of anyone who has? Need some advice on this one!

Thanks...

2002C5COUPE

iTrader: (3)

8.1L are big gas guzzling turds too. Do a search. One guy posted dyno results of <300 hp and pretty unimpressive tq #s on a 8.1l, with minor bolt on mods .

Wide Open

Yes it can be done without chaning the trans. The 8.1 Suburban uses the 4L80E.
I haven't done it myself nor do I know anyone who has.

The question will be is the money and time spent to install an 8.1 worth it when a 6.0 can be modified to make more power than the stock 8.1 for less money.

mcfarlnd

iTrader: (15)

wouldnt it make more sense and be cheaper (gas and parts) to just go FI.

mds2004

Slap a Magnacharger on there and get a custom dyno tune for it. If its still not beefy enough for you, theres still a lot more you can do. This is cheaper than swapping in a 8.1L too.

GMC_DUDE

What it boils down to is that the 8.1 is older technology, based on the old BBC design. Much has been learned since then, and these improvements have found their way into the GenIII engines (e.g. the 6.0). Although an 8.1 could be fit into the vehicle, and some performance mods are available, it would be both cheaper and more effective to enhance the existing 6.0. There are many ways to do this. Check out the different categories here in PT.NET and it will give you an idea of what can be done. Good Luck!!!

nonnieselman

iTrader: (10)

What about trading that truck in on a Duramax.... problem solved.....

Sorry... i know im not any help...

OH and welcome to the Forum!!!!!!

moes04silverado

iTrader: (2)

Im very surpised that the 3500 dullay didnt come with the 8.1L.... Thats a big truck for a small block...

If you did do the swap I would suggest a Allison Trans - cant beat them...

Manic Mechanic

iTrader: (3)

That was probably me, or easily could have been. I pulled my filter out for a cleaning and cleaned the MAF about a month later and found a ton of power. The airbox was coated inside with evidence of when I had drove it through flood waters a few months earlyer. It reached all the way to the bottom of the cone filter. In any case the truck runs a hella lot stronger but I don't know what it truely makes again.

As for the engine fitting the trans, GM did it every time the built a Suburban or Avalanche with the 8.1. See what they use for engine mounts etc.

Also the 8.1 is a major redesign on the BBC and very similar to the LS small blocks, completely the opposite of what was posted prior. But they were optimised for low RPM torque, not high end horse power. 450 lbs./ft. stock.

The are very limited in factory trim by the camshaft and torque managment. But if you're swapping engines a few upgrades to the engine should be a cake walk. There's power to be had in cubic inches. See www.Raylarengine.com.

Mileage will blow dead rats no matter what you do.

Vernon

2006 8.1

I really like my 8.1. So much so, that I sold my dmax and got another 8.1. For what I do, they are more fun to drive and they pull more than I even need. However, I have heard of guys putting in Marine injectors (more flow) and a marine cam, (much more of everything) and a tune, and really had a stout machine. The stock cams in these are very mild. They do this for longevity. The swap should be pretty straight forward. Engine mounts, wirinig and computer. They will bolt to a 4L80E, but on a dually, it may tear it up. If you are buying from a wreck, see what the allison would cost with it. Would a lot more hassle, but might be worth it in the long run.