More HP or lower gears?

[TheBeast80]

Hey, so I have a little extra cash in my pocket and I want to do some mods to my truck. I have an 82 three-quarter ton with 9 inches of lift and 39 1/2 inch Iroks. It has a crate 350 making 350 hp but I only have 410 gears right now. I am thinking of either getting some aluminum cylinder heads put on to get the horsepower up to 400 or swapping out the gears to 488. I'm also going to do a disc brake swap for the rear end for better stopping.

 

[MadOgre]

Th400 ?

 

[TheBeast80]

700r4 that has been rebuilt to make it stronger

 

[MadOgre]

I say do the gears then. You sure 4.56s wont suffice? Or are you planning on bigger tires yet ?

 

[Green79Scottsdale]

Always go gears first, imo. Most effective way to overcome mechanical disadvantages as opposed to simply throwing more power at it. I would agree with 4.88's also. Only moving one ratio on the chart seems like a waste of $$$.

 

[SkinnyG]

4.88's with a 700R4 would have you turning 1890rpm at 65mph. If it were me, I'd go even deeper, and try to get cruising rpm around 2100-2200 - more grunt to push through the air way up there. But that's just me.

 

[MadOgre]

Ya you guys are right

 

[TheBeast80]

Thanks guys, I think I will go with at least 4.88 gears. Right now it kicks in and out of overdrive because the RPMs or two so I might as well use that gear if I have it right

 

[Joe383]

I would go 4.88 gears. I use to do mud drags and had a lot of friends that also raced and we all ended up running 4.88s a few friends tried deeper gears but the pinions get too small and would snap so I will not go lower than 4.88s. We were all running a lot of HP (Most of us had modified big blocks) with high stalls and trans breaks though. I might be putting a modified 700R4 in my truck too with a 350 HP small block. Going to do 4.56 gears if I keep the 35s on it. You running an aftermarket stall converter? I would do the gears first and motor mods later. What heads are on the truck now? After my last build I am a fan of the vortecs. I want to try the fast burn heads next or the edelbrock E200 heads.

 

[TheBeast80]

It is a crate 350 making 350 hp, I'm not sure what heads, but I was planning some Summit Freedom series that are 185cc.

 

[Joe383]

I would find out what heads you have before you replace them cuz you might have some good heads in which you might want to replace something else like the cam. Can you upload a pic of the front of the heads? The pattern can some times be used to identify the heads. If say you have a ZZ4 350 I would replace the cam first for example cuz although the heads are small the cam is not the best. It takes a pretty good cam to make 350 HP with stock heads. Your looking at something with around 230* duration @0.050 and just doing a head swap on a motor with such cam would be pretty easy to hit 400 HP with but I would use a 200CC head.

 

[TheBeast80]

Ok, I will take a look. Since I didn't put the engine in the truck I'm not sure exactly what it has. The camp is pretty lumpy when I'm idling

 

[MikeB]

Change the gears first, because the only thing that will get you substantially more torque to pull the 4.10 gears and the tall tires is more cubic inches.

The parts required to build a 400 hp 350 will give up some low RPM torque, which I don't think you can afford with your truck's current gearing.

However, good heads (with 170-180 cc intake runners) and a mild roller cam can give your 350 the best of both worlds.

 

[MadOgre]

X2.

 

[77 K20]

New gears will also be a great time for you to add some lockers/limited slips to the truck. Amazing what a difference they make vs. open diffs.