more torque from 4.0 ohv?

[MikeRWK]

Just wondering whats mods i can do to get more torque, i was thinking headers, Catless, 2.5" Exhaust to cherry bomb turbo muffler, coldair/snorkel, half-shafted or bigger tb (wouldnt a bigger one gain more topend than down low?), comp cams 410 (is there better?), maybe some roller rockers? and can u use sohc pistons to raise cr? Also the snorkel on the trudck use the stock rubber intake hose between the filter and tb, whst size abs pipe do you recommend i replace it with?

 

[rhauf]

Just wondering whats mods i can do to get more torque, i was thinking headers, Catless, 2.5" Exhaust to cherry bomb turbo muffler, coldair/snorkel, half-shafted or bigger tb (wouldnt a bigger one gain more topend than down low?), comp cams 410 (is there better?), maybe some roller rockers? and can u use sohc pistons to raise cr?

axle gears are quite literally a torque multiplier. a lower gear ratio (higher numerically) will prevail more torque to the wheels in exact relation to the increase in gear reduction.

in other words, if you've got 3.08:1 gears, and you go to 4.56:1 you'll increase you're torque by about 30 or 40%

in general, stock cams are mild grinds (very little overlap, low lift) and that's exactly what you want for torque. so a cam change would probably be a bad idea. exhaust upgrades are always fun, but i wouldn't expect any major gains from it. roller rockers are not necessary unless you have a ton of lift, a lot of spring pressure or some other reason to have them... increasing the size of throttle body, and other intake ducting will help with top end, but wont gain anything in low rpm torque (could possibly even reduce torque due to lower air velocity, and a larger TB will be less accurate at low air speeds, i.e. low rpm, than a smaller one) you're engine is an OHV, correct?

my vote is for gears!

 

[MikeRWK]

Its got 3.73s atm, how are they for mudding? i dont have the truck yet since buddys gtn the rad fixed before we trade.

 

[rhauf]

well it depends on you're tire size..

in low range, my '93 with a 4.0 OHV, 3.73 gears, and 31" tires screams in the mud. you'll proably want to lock it in first or second gear so the trans doesn't keep shifting.. it should do great.

you might consider lockers though

 

[MikeRWK]

i got the same size tires, yeah i'll remeber to put in in low gear, is there any shift kits for those trannys?

 

[rhauf]

Yeah, there's shift kits for all transmissions... get one (a mild one) and you'll increase you're transmission life greatly. a transmission cooler is also a good idea, especially for mudding and other high load applications. the most important thing for the transmission though, is in mud it will rev up, shift up, bog down, shift down... over and over again, and it'll do it without you even noticing, and that *will* destroy the transmission, i've seen it happen that way. so always lock it in first or second gear for mudding (first = first only, and second = second only, so you have no shifting at all)

 

[Mbrooks420]

Going catless will gain you nothing. It might actually hurt the torque, as some backpressure helps low end power. Don't go too big on the pipe either.

 

[Spdrcer34]

One of the intake spacers that I make will help make more torque....

I made 257 ft/lbs at the rear wheels, at 2800 rpm, and one of the pieces in the build was my intake spacer.

It goes between the Upper and Lower intake. NOT between the upper intake and the Throttle Body.

Ryan

 

[MikeRWK]

i dunno about spacers but wouldnt shortening the intake runners give me more tq?

 

[rhauf]

Going catless will gain you nothing. It might actually hurt the torque, as some backpressure helps low end power. Don't go too big on the pipe either.

myth.

the less exhaust gas left in the cylinder when the intake stroke begins, the more room there is for fresh air/fuel to come into the cylinder for the next cycle.

back-pressure is the enemy of exhaust exiting the cylinder, this is the reason headers are tuned for exhaust scavenging, not plugged up for backpressure.

 

[MikeRWK]

what size pipe do you recommend? 2.25"?

 

[rhauf]

well i like quiet exhaust so i'd probably go with a single 2.25.. that would be a fine size for a stock (or stockish) 4.0 high flow cats and a good muffler would be a good idea too (remember a physically bigger muffler will flow better while muffling more than a smaller, similar style muffler)

but you mentioned something about cherry bombs earlier, which actually sound pretty good on a 4.0... that would be fine too, if you want it to have a bit of a deep tone to it then go with 2.5" i think if you went to 3" it would sound crappy.

if you have headers, you'll want to match the pipe to the collector size of the headers, at least for the first couple feet of pipe after the header. this helps with that exhaust scavenging stuff.

exhaust is all preference.. decide how you want it to sound, then build a suitably flowing (and suitably priced) exhaust system to suit.

 

[MikeRWK]

well i was thinking of headers>2.25pipe>Cherrybomb turbo, i want a setup that will give tq, all im after is tq here.

 

[rhauf]

are you going dual exhaust? if you're going single make sure the pipe right after the headers matches the collector size of the headers

 

[MikeRWK]

going single, not a fan of duals on a V6 and the skyline taught me one big pipe can sound nice
The collector on the pacesetter headers is 3" how much 3" pipe should i run and should i step down to 2.5 or 2.25?

 

[rhauf]

if the collector is 3" then run 3" as far as the muffler(s) or Y connection etc... behind the muffler run whatever size you like, the *only* reason to run smaller exhaust behind the muffler is to make the muffler work better (sound quieter)

I'd probably run 2.5" out from the muffler just for good measure.. it'll sound nice that way. but if you want it a little quieter run 2.25, it wont sacrifice any horsepower, but it'll take the drone out of the exhaust system.

how are you planning on bringing the exhaust together? Y pipe before the cats?

 

[MikeRWK]

going catless and making a y pipe and im not running any pipe past the muffler

 

[rhauf]

Going catless will gain you nothing. It might actually hurt the torque, as some backpressure helps low end power. Don't go too big on the pipe either.

going catless and making a y pipe and im not running any pipe past the muffler

catless and no tailpipe.. it's going to drone like crazy... i bet you're next mod after that will be a tail pipe.

sorry, i'm just not a big fan of turndowns... IMO they sound like crap, drone like crazy, and result in fumes inside the vehicle.

 

[MikeRWK]

ok maybe a side exit pipe before the back wheel, i was thinkin headers<dual 3" in single out cherry bomb vortex<rear pipe

 

[rhauf]

ok maybe a side exit pipe before the back wheel, i was thinkin headers<dual 3" in single out cherry bomb vortex<rear pipe

perfect. done deal, do it. let us know the results.