Some Performance Questions.

[Tongan310]

Hey guys.

I've done of lot of looking around and googling. The more I read the more I can't seem to find an answer that makes sense to me because one place says good the other says not so good. So here it is:

I'm looking to get some more power out of my 97 c3500 with the 454. Questions is more related on what to stay away from and what actually works.

So about the truck. EVERYTHING ON IT, IS STOCK (Yeah I still got the stock Stereo with tape player..) except has K&N drop in air filter (stock air box) 103k miles.

So the list of things I want to do are:

Exhaust (The whole thing headers included but can't seem to find ones that don't have fitment problems (headers) in the reviews. I also know I have to match my tubing size or I will kill some of my low end)

Intake (better manifold? or CAI that actually works? I happen to like the sound of "noisy" intakes when you hit the gas..)

Cams? (I don't wanna kill my towing rather I would like to help produce more torque)

Chip (Seems like Hyperchip is the best bet, My old superchips chip won't work on this but will on the 98...)

Electric Fan setup (Summit has a few that look good are they worth it?)

Also anything else that can free up some power or help a little on MPG (not really concerned as long as I don't loose MPG).

 

[df2x4]

Personally I'd forget everything on your list, and get a real tune from someone like Black Bear Performance. Made a bigger difference than anything else I've done to either of my trucks.

The only thing on your list that's actually going to help anything (noticeably) is exhaust.

EDIT - And go back to a factory paper filter in your intake. That K&N isn't doing you any favors.

 

[RichLo]

I would stay with the e-fans, exhaust, and get a good tune specific for your truck (Like Black Bear or others). Then maybe spend the extra that you would have on intake and cam on beefing up the transmission and/or re-gear the axles.

 

[Tongan310]

Sounds good. Do you guys have any recommendations on header/exhaust combos? Sound isn't a problem for me as I'm used to driving a Mustang with no mufflers daily..

 

[RichLo]

Long tubes with thick flanges and heavy guage tubes into an H-pipe and 2.5" duals with the mufflers of your choice.

 

[Tom P]

Long tubes are great but I have a 2000 K3500 7.4L and I'm having a heckuva time finding any long tube headers that wont cost more than what I paid for the truck. Summit, jegs, etc... mostly only have shorties which tend to be a direct replacement (you know, direct in a perfect world). And they will flow better but you're still looking at shelling out $600+ for something with a 3/8" flange that wont rust after six months. The 7.4L vortec manifolds aren't a horrible design if you compare them to similar era engines. With a port and polish you might be surprised at the gains you might see. Plus they are plug and play, and once you bolt them on, you can forget about them! They aren't going to leak or crack or fry your starter or blow out gaskets.

Depending on emissions restrictions in your area, you might consider getting some "high flow" catalytic converters. The P/O of my truck replaced my cats with test pipes and with leaky injectors my truck smells like a 1967 396 with an 800cfm rochester. From what I can tell the muffler is the biggest choke on the exhaust. It has 2.25" or 2.5" duals all the way to the muffler and then they choke it down to a single 2.5" tail pipe. Unless you plan on running 500+ horsepower, you don't need to worry about too much more than just replacing your muffler and tail pipe with something less restrictive. Running an x pipe with true dual exhaust will pay dividends for sure.

I have a K/N filter with a stock air box right now and I'm probably going to have to toss it. It was cleaned and re-oiled very poorly and I'm hoping it hasnt screwed up my MAF. Go with a dry media air filter if anything.

Tunes are always great, however I haven't done much research into them.

Think about doing the Injector Upgrade. Your truck doesn't have a ton of miles on it but it is 20 years old now. A set of bosch 4 holes should wake it up nicely. Plus if you do get the tune done, the shop can adjust with your new injectors in the mix (wont really get you more power but the truck will start and run smoother and may even increase your mileage). My replacements are on order, but I'm ready to do the job as soon as they show up.

One other thing to consider is dropping in a 180 degree thermostat if you will be towing. Tricks your computer into dumping a little extra fuel in to warm it up, but also helps prevent overheating while towing.

 

[df2x4]

One other thing to consider is dropping in a 180 degree thermostat if you will be towing. Tricks your computer into dumping a little extra fuel in to warm it up, but also helps prevent overheating while towing.

FWIW, I've been told by multiple people I trust (Justin at Black Bear Performance being one of them) that these Vortec trucks really don't like anything better than the factory 195 degree thermostats. I'm sure something a little colder won't hurt anything, but I've been advised that there's absolutely no benefit to it for us.

EDIT - To expand a little... A thermostat that opens at a lower temp than factory won't trick the computer into doing anything, the computer still gets the coolant temp reading from the sensor in the block. All the cooler thermostat will do is let coolant flow sooner than normal and potentially cause the computer to take longer to switch over to closed loop operation. Technically more fuel could make it into the engine in this scenario, but only because the computer is operating in open loop for longer than usual. I've also read that these computers actually go into closed loop before the coolant temp ever hits 175 degrees, so it might not have any effect on open/closed loop operation at all to be honest. Never seen that first hand, maybe someone else can verify.

I am very sleep deprived and rambling, apologies to anyone who made it this far. Carry on!

 

[Tongan310]

I have to agree with those prices on headers are expensive. My old 99 350 cost me about 300 for headers. I was thinking of maybe seeing what a shop here would cost me to make some. Based off past experience it be about the same just wouldn't be "pretty" which is least of my concerns.

I live in Arizona rust is not an issue as I'm in the valley but heat definitely affects everything here.

For that thermostat advice I wonder if that would be beneficial for me as the summers here are 110+. I noticed you guys are north where its quite cold so might be different. I'll contact Black bear and ask seems everyone on this forms seem to use them or just like them.

From the input I probably going to do a tune and exhaust for now. Some tow/air bags and leave her be. Rest is cosmetic/ electrical. Getting told by a lot of people local area that own this truck that messing with it might give me power but at the a big cost of gas mileage.

 

[df2x4]

Sounds like a solid plan to me. A tune and a new exhaust system will wake the truck up very nicely!

 

[Christian Steffen]

Getting told by a lot of people local area that own this truck that messing with it might give me power but at the a big cost of gas mileage.

I disagree, having it tuned and installing better exhaust will only help mileage when you drive it in a sensible manner. If you constantly use all of the newly available power, then your mileage will definitely decrease.