350 or 454?

[shane.griffin.79]

Hello Everyone, The other day I took my 1986 GMC 2500 TO the shop to have the 350 rebuilt. He presented me an option to help get around the smog testing and that was to put in the big 454. The question I have is is it worth it? I am going to be doing the upgrading on the suspension as well. The reason I am considering this is I will be towing a fifthwheel 2004 jayco egale 33ft4in long, gross weight 12500 and I dont want to struggle to bad hauling it every couple of months but if your from Cali you know this Dang heat can get crazy and will want to install ac whats the worst I should be looking at cost wise?

Shane

[Captkaos]

What trans is currently in it?  What gears?  How far are you towing it?  Is there lots of hills?
The 454 is going to get pretty much the same mileage towing or not, as in about tops of 12mpg, the 350 could see 15-17mpg, but not while towing... 
The 454 is going to have an easier time pulling, keep in mind if there is a TH350 trans you will need to change it for the 454 in my opinion.

[LTZ C20]

Not to rain on your parade, but I California,  you can not change the engine from the original size that it was when built. As your saying, the guy you took it to said to increase the engine size, if the truck came from factory with a 350, then only a 350 can go back in. Increasing the engine size and suspension as you say will not eliminate you from smog testing. The only way that you can do that legally,  is if the truck was originally, from the factory, a diesel. Then you can change the engine, if it was gas, then you cant. There are stiff fines and penalties for that kinda thing. Unless there's new laws and rules I don't know about. Hate to see a site member get in big trouble.

[shane.griffin.79]

Thanks for the info LTZ C20 and your not raining on my parade that was just what I was told from the shop.  I did call a smog referee and also talk to a tech who verified each other basically.  As per Cali if the truck was first registered here in Cali more than likely it's going to have to be smoged in some form but there are differences between light duty truck and heavy duty and it's not much.  If your truck for that year came with 3 engine configurations then you can upgrade to either the same year rebuilt engine or a newer version of those engines and be ok .... an example of that would be (a common one) going from my 86 350 to a GM 6.0.[/b]  Does it make sense?    As LTZ C20 stated you can go from diesel to gas but not the other way around.  The other main thing is this Go by the year your truck was made and how it was configured.  For me as I just found out even upgrading to the 454 I have to have a air pump and egr but for the 454 there was no catalytic converters(did I spell that right?) so you know your going to have to play with the exhaust a bit.   If there is any questions please contact me. 

Shane

[LTZ C20]

Looks like you have some more homework to do before you make a decision on what you can go ahead and do.

[Dr_Snooz]

You're pulling a pretty heavy trailer. I'm not an expert on 350s by any means, but it just seems like that would be too small. If you ever pull that 5th wheel over the Grapevine, or up any steep mountain grades, I'd expect you to be taking a few breaks along the way.

Of course, you'll still be making pitstops with the 454, but they will be for gas. LOL. Seriously though, for hauling a heavy 5th wheel, I wouldn't want a 350.

FWIW, I have an '86, 454 and no cats. As I understand it, the lack of cats has more to do with the GVWR than the engine size. At the time, a GVWR of 8600# or above was classified as a heavy duty truck and exempt from the cat requirement. If you simply put a 454 in a truck with a lower GVWR, I don't think it will work. It's definitely something to check before spending the money. Of course, I doubt any smog ref is going to go looking all those details up, so maybe you can slide it by them. I don't know.

Good luck with the build.

[shane.griffin.79]

Thanks for the post Dr_Snooz for that info and it is classified as a heavy duty Truck.  I notice on this and another forum I have been on reccommend that I upgrade to a 6.0/4l80e combo.  Is it enough to do what I want such as towing a fifthwheel 2004 jayco egale 33ft4in long, gross weight 12500 and I dont want to struggle to bad hauling it every couple of months.  What about a newer 454 efi trans whole nine?  Thanks for all the advice guys appreciate it.  If you can approx cost for the two and what am I looking for? miles, vin code etc... Thanks


Shane

[Jason S]

For a point of perspective; I've got a 2005 Chevrolet 2500 with the 6.0L/NV4500 5-spd and 4.10 gears - pulling a trailer with a tractor (similar weight, but less wind resistance) there is enough engine to get the load moving and maintain highway speeds. However, the torque seems to be more on the upper end of the rpm band- so on long uphill grades I may have to grab 3rd gear and take the grade at 45-55 mph (depending on the grade).

[LTZ C20]

The 90s TBI 454 or 496 big Blocks would be good. Those also came with a 4L80 I believe.  Like stated tho, changi BG engines won't increase your GVW. It it's already legally a heavy duty, then do your homework, figure out exactly what your allowed to do then make a decision.

[Irish_Alley]

my 91 v3500 with a 350 4l80e/205 is a 9.2k gvwr. yesterday i went and rescued a friend that was supposed to be hauling a trailer to go pick up a couple pieces of furniture. well he broke down so i took the trailer and this trailer dogged my truck bad part is its only a landscaping trailer but had one bog ramp on it that was catching the wind. went up a bridge and it was all i could do to stay at 55. had it floored and it wouldnt go any faster.
 
after i dropped his trailer off i went back and picked his truck up with another trailer me and my other buddy made just for hauling trucks. it has ramps but we dont have them sticking up in the air and most time stay in the back of a truck. i think that truck trailer with the truck on it was easier to haul than the empty landscaping trailer.

that 350 is coming out asap and a cummins will be going in her place

[Jason S]

Here's another thought...

A 383 (or 400) with a modern head design and modern cam might also be a good compromise.

Physically it would appear to be the correct engine, it could have loads more torque than a 350. It would just be a matter of it getting by the smog sniffer.

[LTZ C20]

There ya go, more options.