SBC or BBC in my Suburban ? ? ?

[Uncle Fester]

Hey all,
Well, I am trying to gather parts for a new motor, as my current engine has 150K on it, and I can not deceide should I keep the 350ci sbc or upgrade to a 454ci bbc. I am planning on about 400hp-425hp and 450ish torque. These numbers can be made fairly easily with either engine.
My other plans for the truck are as follows: SM465 transmission / NP205 transferrcase, upgrade to a Dana 60 front/ 14 bff rear with 4.56 gears and a locker in the rear, use 37" or 38" tires, 2" EZ-Ride lift kit with the fender trimming I have already done. Planned usage is a daily driver and weekend trail explorer, mostly on "green" or "Blue" rated trails in the Colorado / Wyoming regions, as well as doing the "OUTLAW TRAIL", as described in the last few issues of OFFROAD magazine, and other such trails.
I want to keep the truck as strong, and reliable, as possable, so I want to go with trail proven parts...no new fancey stuff that MIGHT break on the trail. Any other changes you might recomend will be welcomed and considered... Thanks in advance to all who reply.

 

[diesel4me]

BIG truck,BIG block!..

I'd go with a 454 myself..I've swapped them in place of 350's and 400 SB motors,and was impressed with the difference in torque and HP,and at NO added expense as far as fuel costs!..in fact,one 74 C10 I had with a 454 got better gas mileage than my 79 C10 did with a 305 ,beat it by 2 mpg!..and NO comparison when hauling heavy loads or towing..

A small block has to work a lot harder to lug 6000+ lbs of truck around..a big block will pull it easier, and wear less as a result..--you can use higher gears and not have a "dog"...and you cant beat the "bling" factor of a BBC either!...

 

[k30bb468]

There is no
replacement
for
Displacement

BIGBLOCK​

 

[blazinzuk]

Go for the big block your sub is heavy and the added torque will be nice. On the plus side you don't have to put as much money into the 454 to get those numbers. Those numbers on a small block is a pretty nice small block. So as far as reliability goes I think the big block wins because it can be build milder with a lower compresion ratio.

 

[longbedder]

Definitely a big block.

 

[barneybasher1010]

There is no​

replacement
for
Displacement​

BIGBLOCK​

X100

 

[Uncle Fester]

Well, lets see if I understand you all right,

GO BIG or stay home....


Does that about cover it?!?!? LOL

I guess I will go big block, as you guys have made some good arguments, lower compresion ratio, same or better torque/hp with milder build = better reliability/longer life of engine.

 

[Ned Kelly]

I guess I will go big block, as you guys have made some good arguments, lower compresion ratio, same or better torque/hp with milder build = better reliability/longer life of engine.

Your 100% right on all of the above. I went from a 350 to 454 and fuel mileage is about the same - power is ALOT better. My setup is 454/th400/205/4.11/39.5" tires. I can't imagine having a 350 now. You won't regret a 454. Some fellows I know built up 350's, 383's, and 400's for their trucks. All were well done builds, some were pricey. In the long run they thought they should have just gone with a 454. My BBC is stock except for a RV torque cam - and it is wonderful. I don't think I've ever heard anyone regretting going to 454 (unless they could have had a 502 ).

 

[GMCJason]

My setup is 454/th400/205/4.11/39.5" tires.

How well does this work for the low speed stuff? Your tire size seems pretty large for the 4.11s, especially with the relatively high 1st gear in the TH400 and the same for the 205s low range. I'm in a similar situation to Uncle Fester thinking (knowing) the 350 doesn't cut it for the Burb and am planning on a BBC. I'm concerned about 4.10s with 37-39.5" tires and am interested in how your set up works.

 

[Ned Kelly]

Good question. Not much rock in my area. Mostly lots of mud and snow. Performs excellent in these environments. If I did rock, I would NEED a doubler for sure. Cruises highway ok at about 2500 rpm, best fuel economy I find is about 2300rpm @ around 55mph (roughly).

My D60 is open and haven't broke anything. Locked 14ff rear. Gotta be careful when there is alot of ice on the highway, rear sometimes wants to drift out on you - but it's not too bad.

 

[Uncle Fester]

Good question. Not much rock in my area. Mostly lots of mud and snow. Performs excellent in these environments. If I did rock, I would NEED a doubler for sure. Cruises highway ok at about 2500 rpm, best fuel economy I find is about 2300rpm @ around 55mph (roughly).

My D60 is open and haven't broke anything. Locked 14ff rear. Gotta be careful when there is alot of ice on the highway, rear sometimes wants to drift out on you - but it's not too bad.

Thanks for the input, I really apriciate it alot! I also plan on a Dana-60 (open) front and a locked 14bff in the rear for my truck...someday, but I will be going 4.56 gears and 37" or 38" tires, I currently have 35" mud rovers and 3.73s...

 

[Ned Kelly]

If you do go with a 454/TH400/NP205/4.11's/39.5' (or 38") combo, and do rock, the LoMax might be a worthwhile mod.
http://www.jbconversions.com/pages/products/lomax205/index.html

With my drivetrain combo, I usually wheel in 4low to keep the tranny cool.
I do run a big trans cooler and my trans never overheats and usually hovers around 100F even under heavy, continous load in the summer.
http://www.txchange.com/heatchrt.htm

My truck has only overheated once, due to faulty thermostat. I run a stock HD rad (Moline Brand I'm 99% sure) that is a normal GM OEM issue size and therefore is a normal part number.

Off road I stay mostly in 1st and 2nd (mostly 2nd) and my truck pulls hard in heavy mud and deep snow. I find 2nd nearly perfect for everything once I get moving. I rarely use 3rd in 4Low.

On the road I use 4H (ice and light snow) or 4L (snow storms) and use all gears - 1-2-3. I just leave it in drive most of the time.

I was contemplating the LoMax conversion, but since I find my combo perfect for my needs 95% of the time, I'm going to leave it (only because I'm putting that money towards my other 4x4 ..... if I didn't have the other project I would most likely do the LoMax).

You'll love having a 454.