Has anyone modified a vortec big block? I have a crew cab that is a dog, but I can't seem to find much in the way of performance parts. I also can't seem to find any web sites where the vortec's are discussed. Are they dogs that can't be fixed, or I am just not finding the right places?

TIA

 

Anybody??? I know it is OT, surely someone here can help...

 

Ok, so now you got me on my soap box :-) So sorry in advance for my rambling .... and long post.

I am a veteran of 5 big block duallies from a Q-jet, BG/Holley, TBI and two Vortecs. I still have a '76 GMC with a purpose built internally balanced 454 tow motor with a comp hyd roller, ported 049 oval ports, and a custom exhaust with x-pipe, backed up with HD NV4500 5 speed. This is my "reference vehicle." Forget that it gets 7-8mpg, it will tow anything any speed. With that said, I compare the performance of my other 454's to that truck.

I had a '94 454 ... horrible ... wouldn't out pull a fat kid on a bicycle .... next subject. I then had a '96 Vortec 454, 5 speed that was a good performer with only a programmer & cat-back dual exhaust. Then I traded it in on a '99 spec'd the same way. Well, my '99 was a dog from the factory, and lost about 2 mpg straight across the board. I have been told GM started a "torque management" program in '97-'98 that reduced the power output in certain situations to protect their parts from idiots (and reduce their warranty claims). I would have to agree there is some type of this reduction programmed into our Vortecs as the performance and mileage was significantly reduced between my 96 and 99 models. From the factory, the 99 just wouldn't go. It pulled better with 3/4 throttle in 5th (OD) than if you dropped a gear and put it on the mat which is not typical of a 454.

Now on to your question. No, they aren't dogs that can't be fixed ...it's more like they were fixed (neutered) at the factory, but they can be unfixed. First, upgrade your intake to atleast a high flow filter or intake system. Make sure you get cool air, don't buy any intake that will suck in air that has come through the radiator, its a costly mistake. And save your money, a brand name MAS is a waste. Next, upgrade your ignition with a MSD 6a box (or equivalent), a good coil and some iriduim plugs. Don't run Bosch platinums in this motor, it doesn't like them. Next and very importantly, spend the bucks on a good exhaust. Headers (Gale banks makes a nice set), high flow cats and a good cat back with a tru x-pipe is what you need. Finally, you need to have your PCM reprogrammed. Forget the handheld units, go with a custom tune (somebody like Nelson) or even a dyno-tune after you do your ignition, intake and exhaust mods, and make sure they take out all the factory limiters and torque management. It's not cheap, as what I've outlined is about $2,500, but it is well worth the results. Your 454 will run like it should when you get all this done. My 99 now runs pretty good.

I'll quit rambling now, but if you have any more questions, let me know, I'll be glad to help.

 

I installed a Whipplecharger on mine (95 454 ) added headers and exhaust with a cat. It helped greatly. MPG was about the same , pulling a 28 ft. enclosed it did a great job.At the time the charger kit was 3400 complete. The kit was an easy install.

 

Yeah, I have heard lots of good things about Whipples and know two people who have run them with no problems. Unfortunately, Whipple has dropped the 454's from their production when they changed to their new compressor. Everybody's onto the diesels now & there's just no love for the fat motors

 

Thanks guys. I was very interested in the Whipple, but was waiting for them to come out with an intercooler, since the last thing I wanted to do was add heat to my engine when I drive in 115+ degree heat. I guess I waited too long. Oh well, I'll just have to make power the old-fashoned way...

So, Retro - would there be any value in just getting my PCM re-programmed? I hate to go with headers as I like the quietness of the stock setup. From what I can see, it looks like the manifolds would flow pretty well, and the pipes are like 3" diameter through the cats, and into the muffler. Would a cat-back system work as well?

As for the air intake, I have the stock, large-filter, setup and I can't imagine that it restricts flow. The surface area of the filter looks to be huge, and the air is drawn in from between the inner and outer fenders - thus it should be as cold as it gets.

How about new heads - has anybody tried an aluminum head with larger ports? When I pulled my exhaust manifolds off, their ports were substantially larger than those in the heads. It seems like larger ports would add more flow - but might hurt the torque??

How about a different cam? Any potential there, or is the payback not worth the expense??

I appreciate your feedback, and am just trying to clarify there issues before jumping in... I seems like there are very few aftermarket performance parts available for the '97 - '99 engines, maybe the volume produced was too small, so I guess my options are limited. Anyway, let me know what you think, and I will be off to the trusty parts store...

Kelly

 

Rimcrew:
I have done mods to my two vortec 454's in stages, so I've felt the incremental increases. So here goes:

1) Yes, If you only reprogram your PCM, you will notice an improvement, especially when you stick your foot all the way down.

2) Yes, the factory exhaust system is good for factory; however, it can definately be greatly improved. For exhaust manifolds, the vortec 454's do well, but compared to headers, they are costing you about 30-35hp right were you need it most in the 2500-4,000rpm range. The dual cats do flow well, don't mess with them, but the muffler is holding you back. On my '96, the first thing I did was cut off the exhaust behind the cats & dual it out. There was a noticable improvement. As for the noise level, I now have dual 3" turbos & a Dr. Gas true x-pipe with dual 3" exhaust (no big tips or "echo chambers") out the rear sides. It is not loud at all, infact, everybody give me a hard time about it sounding stock. Yes a good cat back will work well.

3) Yes the factory intake is ok, just add a K&N filter or the like.

4) The factory heads flow plenty well for the application. You'll never see the high side of 5,000rpm. The aluminum heads will definately outflow the factory ones with a big cam, but with the stock cam or close to it, the aftermarket aluminum heads won't benefit you at all.

5) I have never changed out a cam in a Vortec. With my exhaust, intake, ignition and PCM mods, my factory cam long block will buz to 5,000 rpms like a small block. And you don't need to go much past that with an external non balanced big block ... bad things can happen.

If I had a totally stock vortec 454, the mods I would do first are:
Cat back exhaust
PCM reprogram
K&N Filter
MSD ignition & coil
Iridium plugs

These are all easy mods. Later you can add the headers, they are a pain, but worth it when the budget allows.

Hope this helps.

Stace

 

Stace,

I appreciate you taking the time to answer each of my concerns. I will listen to your voice of experience, and make the changes you have listed, in the order listed. If I'm happy without the headers, I will pass. If not, I guess I will bite the bullet and put them on too.

Thanks again!

Kelly