NV4500, SBC, 4:10 and MPG - The 1947 - Present Chevrolet & GMC Truck Message Board Network

Aruba1 · 03-12-2015, 03:23 PM

Currently I have a 1972 C20 with a 1989 C3500 front end and a 4:10 rear end. The tires are 225/70/19.5 (dually). The motor is a 383 SBC bored over 30 with a holley carb. It has a low cam (not sure of the numbers), stock manifold and dual muffler.

Now I am running a TH350 but my plan is to do a lot of heavy towing. The tranny is excellent shape now so I want to go ahead and install a NV4500 gearbox before I mess it up. What sort of mileage will I be seeing with this gearbox? I am no longer a pedal to the metal person

.

Thanks for your help.

**steelhorse** · 03-12-2015, 03:37 PM

I am thinking 8-12 mpg.

**LockDoc** · 03-12-2015, 03:41 PM

-
I'm thinking a little more than that. What ever you get it will be easier on the engine....

LockDoc

Longhorn 70 · 03-12-2015, 04:23 PM

First the with TH350 you'll have around a 20% loss in drive train. Second TH350 is 1:1 final drive.

NV4500 has 15-17% loss so you get a small gain. NV4500 also has 1:.73 final drive as well as a deeper first gear. Take off whilst pulling should be more effortless. Cruising down the freeway with the overdrive should give you the ability to have better economy by working the engine less.

You may have to find how it "likes" to be driven to get the best performance.

Aruba1 · 03-12-2015, 08:19 PM

WOW, I was hoping for 16-20 mpg, lol. Thanks, I will be going this route anyways so it can be easier to pull the weight. :-)

hugger6933 · 03-12-2015, 08:36 PM

A 20MPG 3/4 ton? We can all dream. The overdrive is def gonna help but not that much, But your drive train will seem to be in less strain all the time. Jim

**special-K** · 03-13-2015, 09:56 AM

My '72 K2500 350/TH350 4.10 235/85-16s truck gets 12.5 mpg. The '72 K/20 I had with SBC400/4spd 4.10 315/75-16 truck got the same. I am sure the NV4500 will get you a good bit better than that with a well tuned motor

03-12-2015, 03:23 PM	#1
Aruba1 Registered User Join Date: Apr 2014 Location: Birmingham, AL Posts: 560	NV4500, SBC, 4:10 and MPG Currently I have a 1972 C20 with a 1989 C3500 front end and a 4:10 rear end. The tires are 225/70/19.5 (dually). The motor is a 383 SBC bored over 30 with a holley carb. It has a low cam (not sure of the numbers), stock manifold and dual muffler. Now I am running a TH350 but my plan is to do a lot of heavy towing. The tranny is excellent shape now so I want to go ahead and install a NV4500 gearbox before I mess it up. What sort of mileage will I be seeing with this gearbox? I am no longer a pedal to the metal person . Thanks for your help.

03-12-2015, 03:37 PM	#2
steelhorse Senior Member Join Date: Apr 2008 Location: Franklinton NC Posts: 1,309	Re: NV4500, SBC, 4:10 and MPG I am thinking 8-12 mpg.

03-12-2015, 03:41 PM	#3
LockDoc The Older Generation Join Date: Aug 2006 Location: Montezuma, Iowa Posts: 25,771	Re: NV4500, SBC, 4:10 and MPG - I'm thinking a little more than that. What ever you get it will be easier on the engine.... LockDoc __________________ Leon Locksmith, Specializing In Antique Trucks, Automobiles, & Motorcycles (My Dually Pickup Project Thread) http://67-72chevytrucks.com/vboard/s...d.php?t=829820 -

03-12-2015, 04:23 PM	#4
Longhorn 70 Registered User Join Date: Dec 2012 Location: Chandler AZ Posts: 1,149	Re: NV4500, SBC, 4:10 and MPG First the with TH350 you'll have around a 20% loss in drive train. Second TH350 is 1:1 final drive. NV4500 has 15-17% loss so you get a small gain. NV4500 also has 1:.73 final drive as well as a deeper first gear. Take off whilst pulling should be more effortless. Cruising down the freeway with the overdrive should give you the ability to have better economy by working the engine less. You may have to find how it "likes" to be driven to get the best performance. __________________ 1970 Longhorn, Front Disc, 350/4 bolt, 882 heads, HEI, Edelbrock, 700R4, HO-52/4.11. 1996 Corvette, Collector Roadster, LT4, 396, 450RWHP, 6sp, 4.11/Dana44/posi 5 point roll bar And let us not grow weary of doing good, for in due season we will reap, if we do not give up. Gal 6:9

03-12-2015, 08:19 PM	#5
Aruba1 Registered User Join Date: Apr 2014 Location: Birmingham, AL Posts: 560	Re: NV4500, SBC, 4:10 and MPG WOW, I was hoping for 16-20 mpg, lol. Thanks, I will be going this route anyways so it can be easier to pull the weight. :-)

03-12-2015, 08:36 PM	#6
hugger6933 Registered User Join Date: Oct 2008 Location: Marianna Arkansas Posts: 7,280	Re: NV4500, SBC, 4:10 and MPG A 20MPG 3/4 ton? We can all dream. The overdrive is def gonna help but not that much, But your drive train will seem to be in less strain all the time. Jim

03-13-2015, 09:56 AM	#7
special-K Special Order Join Date: Nov 2004 Location: Mt Airy, MD Posts: 85,851	Re: NV4500, SBC, 4:10 and MPG My '72 K2500 350/TH350 4.10 235/85-16s truck gets 12.5 mpg. The '72 K/20 I had with SBC400/4spd 4.10 315/75-16 truck got the same. I am sure the NV4500 will get you a good bit better than that with a well tuned motor __________________ "BUILDING A BETTER WAY TO SERVE THE USA"......67/72......"The New Breed" GMC '67 C1500 Wideside Super Custom SWB: 327/M22/3.42 posi.........."The '67" (project) GMC '72 K2500 Wideside Sierra Custom Camper: 350/TH350/4.10 Power-Lok..."The '72" (rolling) Tim "Don't call me a redneck. I'm a rough cut country gentleman" R.I.P. ~ East Side Low Life ~ El Jay ~ 72BLUZ ~ Fasteddie69 ~ Ron586 ~ 67ChevyRedneck ~ Grumpy Old Man ~



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