Looking for more torque

[Batass]

Id like some more low end torque in my truck. I had an old blazer with the 4.3 and it felt like it had more low end but less top. The truck is completely stock. I want more power right off idle, I dont like to push it. Can this be done without stroking it? I plan on changing the muffler, but keeping the stock pipes. Generally stock headers produce more torque than aftermarket up to 2k rpms. The throttle blade diffuser may help, I'll look at that tomorrow

[killian96ss]

The throttle blade diffuser may help, I'll look at that tomorrow

One of my favorite mods, and the best for off idle power and throttle response.

You don't need to buy a new throttle blade, just modify your stock one.

Intake and exhaust mods also make a noticeable difference in power.

The best power mod would be custom PCM tuning, but you don't want to do that unless your warranty has expired.

These trucks lack low end torque.

This is why GM uses such a high stall torque converter with the newer 4.3's (1800-2200 rpm stall vs. the normal 1400-1600 rpm stall).

Steve

[a2b]

get a cam and heads

[Batass]

If I were to do that much work and spend that much money, I'd just drop in two more cylinders

[killian96ss]

If I were to do that much work and spend that much money, I'd just drop in two more cylinders

A new 400 horse LS2 in a CC would be sweet.

Steve

[Batass]

Actually I think a stroked tpi motor would be excellent.

[2kwik4u]

GT35R with Sy/Ty manifolds will get you full boost (~15lbs) and about 400ft-lbs as early as 2500rpm. That enough torque?

[Jigg]

The March Pulleys are supposed to be a pretty good mod for low end power. I'm installing a set tomorrow... i'll let you know

[killian96ss]

The March Pulleys are supposed to be a pretty good mod for low end power. I'm installing a set tomorrow... i'll let you know

There are 2 down sides to the under drive pulleys.

#1, They slow down your water pump, so if you ever have overheating problems in the summer months then this would be a bad idea.

#2, They slow down your power steering pump, which in some cases causes hard steering or PS pump noises.

Other than that expect about a 4-8 hp gain.

Steve

[Jigg]

hmmm... the water pump doesn't bother me... i've never had overheating problems.

The power steering pump though... that might not be good with my 33's. I sometimes have a hard time turning them at slow speeds (like in the parking lot). I think i need to replace it anyways.

[killian96ss]

The power steering pump though... that might not be good with my 33's. I sometimes have a hard time turning them at slow speeds (like in the parking lot). I think i need to replace it anyways.

You might not have any problems, but some do.

The temps get high where I live in the summer, so I have stayed away from the pulleys for now.

Maybe a high flow water pump and e-fans would be the answer?

I had the March pulleys on my SS for a while, but then I removed them due to hard steering which sucks during auto-X events and road courses.

I know HenryJ was experimenting with PS pump pressure upgrades so maybe you could bump up the pressure if you run into any PS pump problems with the pulleys.

He is also running 33's so you might want to ask him about his upgrades.

Steve

[2kwik4u]

I'll second the pullies as well. I've got them on the Xtreme (ASP, not March). They were the best bang for the buck mod to date. I'd STRONGLY suggest you get aluminum pullies, and not steel. Underdriving is only about 25% of the gains from what I've read. The other 75% of the gains come from reducing rotating mass. For reference the pulley on the front of the 2.2 stock is a steel one that weighs ~2lbs. The ASP aluminum one is ~.75lbs.

I'll be putting aluminum pullies on my ZR5 at some point or another. Not sure how soon or when though, as I never get anything done when I plan to!

[killian96ss]

Underdriving is only about 25% of the gains from what I've read. The other 75% of the gains come from reducing rotating mass.

Where did you get this information?

For reference the pulley on the front of the 2.2 stock is a steel one that weighs ~2lbs. The ASP aluminum one is ~.75lbs.

You are claiming that a reduction of 1.25 pounds on the crank pulley is worth 75% of the usual "claimed " 10-15 hp increase.

A weight reduction of 1.25 pounds on a crank pulley will make very little extra horsepower, however it will increase the throttle response due to less rotating mass.

Slowing down the accessories does make more horsepower because you are reducing parasitic horsepower loss.

I've used March aluminum underdrive pulleys on 2 of my vehicles with very little change in power output (1968 Impala drag car & 1996 Impala SS road race car).

One thing I noticed on both vehicles is that the aluminum deteriorates (gets chewed up) if anything gets between the pulleys and the belt like little rocks, dirt, etc.

The pulleys I had were on street cars so I can only imagine the contamination problems with an off-road vehicle.

I would rather chew up belts than pulleys, so IF I ever use underdrive pulleys again they will definitely be steel.

One other thing that isn't mentioned very often is that if you do want to run underdrive pulleys make sure you also get a new underdriven (smaller) alternator pulley or you will almost certainly have charging problems at idle.

Can you tell I'm not a big fan of underdrive pulleys.

Steve

[HenryJ]

I will be a second vote for passing on the under drive pulleys.

The problems have been outlined above.

The alternator speed is already borderline. Actually it preforms a little better with a 2mm smaller pulley. If you add the smaller pulley included with the underdrive pulleys , you will have no where to go to speed it up a little more.

Running the waterpump and power steering slower is not an option. We need the available rpm.

Those that are seeing big gains, I would bet they are running the stock fan. I bet that an efan would offer the same gains without the negative effects on other systems. Well, other than a need to upgrade the charging system.

For the composition, Steel, hands down. Aluminum on the crank pulley will not last and will squeal all the time once it breaks in. You might get away with aluminum on some of the other pulleys. Those are done for "looks" on a show rig though. On a street car for looks, that works. I still use a steel crank pulley though. For a truck, no way would I use aluminum. The abrasives it is subject to will prematurely wear them out.

[Batass]

GT35R with Sy/Ty manifolds will get you full boost (~15lbs) and about 400ft-lbs as early as 2500rpm. That enough torque?

Yes that is.....Does it come as a kit?Cost?

[Batass]

The throttle blade diffuser may help, I'll look at that tomorrow

One of my favorite mods, and the best for off idle power and throttle response.

You don't need to buy a new throttle blade, just modify your stock one.

Intake and exhaust mods also make a noticeable difference in power.

The best power mod would be custom PCM tuning, but you don't want to do that unless your warranty has expired.

These trucks lack low end torque.

This is why GM uses such a high stall torque converter with the newer 4.3's (1800-2200 rpm stall vs. the normal 1400-1600 rpm stall).

Steve

I cut it out today, and it did help much.

[Torskdoc]

Took my blade out today. Real Easy.

The difference in performance is very noticable from about 900 to 4000. Offline part throttle pickup is much improved. Feels like 1/3 throttle now is more responsive than 1/2 throttle before. Also noticed that at 55 on an incline on Rt. 100 that would drop the TCC out about 1/2 way up the incline (this is with Cruise on holding anywhere from 55-60, depending on what I set it at 2 miles down the road)now it holds the TCC IN and it chugs along like nothings happening.

Also noticed when I come off a sweeping cloverleaf entrance ramp from 100 to I-97 and hit resume at 35 (leveling off @ 60) it used to drop all the way down to 2nd by the time it hit 43-45. Now it drops to 3rd and the pickup is quite satisfactory.

It holds speed on cruise better now and I notice that I don't have to use as much throttle either cruising down the road or coming off the line.

The one thing I DID notice is that the blade was sticking (felt it thru the pedal) when closed. T-15 driver and a 1/2 turn offset the blade enough to get rid of the stickiness. The ECM adjusted automatically (had my scan tool hooked up. NO perceptible change in idle rpm.

Combined with the OPEN AIR BOX (I just cut the front off the bottom 1/2 and fashioned a transition plate to the radiator support.) It feels like I gained 5-7 hp. Mostly down in the Low MId range of the Torque band (900-3500) I didn't feel too much difference from 3500 to 5000. It won't squall the tires (3.42, G-80, and 255/70R-15) But I'm not looking for that. It does respond off the line a lot better.

EGR is NOT Affected as the 02 DOES NOT have one. I know there has been some issues as to when GM finally took them out. Buddy of mine has an 01 S-10 with EGR, my '02 CC is WITHOUT. And the trucks are only 4 months apart from the assembly line. Go Figure

So If I can keep my foot out of the firewall, we'll see if the mpg comes up some.

Larry

[bwenny247]

i used the aluminum March underdrive pulleys and had no complaints. i might have just been lucky though???

33X12.50 mud terrains, never had a problem with power steering
didn't notice any problems with charging, but i didn't have extra accessories to draw away the charge
no squeking after 1 year, ~12000 miles
no belts chewed up...and i did my fair share of offroading

3.42 gears and i could turn over the 33's on dry pavement, had a lot of other supporting mods though

thought i'd share my personal experience