Holley TBI on LMCtruck website

[Paul Greathouse]

Ok, what do you guys think about this TBI that Holley has? Could it be the answer to our 95' and older power/MPG needs?

http://www.lmctruck.com/ICATALOG/CSD/full.aspx?Page=84

Has anyone ever heard of or used one of these? Seems like I can remember in another thread where it was mentioned that someone was boring out TBI's for more power. Looks like Holley is trying it too.

And what about the underdrive belt pulleys just below it. Can anyone explain that one? Do these fall under the too good to be true catagory?

Allow me to be cynical for a moment. Lets see, 25% more HP with the Holley TBI and another 20% from the underdrive pulleys, that should bring my 95' Tahoe up to 290 horses. But if its even half true, my 95' would be up there in vortec territory.

 

[General Stalin]

First off, you should never really judge power gains based on what the company advertizes. read real reviews and testimonials. I mean hell, the AIRAID POWERAID TBI spacer claims to give you "tremendous gains" and advertizes 20 HP increases. That is complete bull because they do practically nothing.

I don't really see how that throttle body would give you better mileage. More flow means that it uses more fuel. Now, it WILL give you more power, that I can say. I am actually building my own 355 to put in my truck and I am going with a Holley 670 CFM TBI setup. The stock TBI unit I believe is only 500 CFM, so there is some bottleneck in that department. If you did happen to see an increase in fuel mileage after installing the bigger throttle body, I personally don't think it would be very much of a gain.

Underdrive pulleys are pretty decent at freeing up some horses by simply reducing the drag on your engine that the pulley system takes. It gives you smaller and lighter pulleys that don't take as much power from your crank to turn, but I'm not honestly too sure how much of an effect they have on your accesories. I would imagine that installing underdrive pulleys might make things work less than optimal (like your AC compressor). I could be wrong, though.

You mentioned getting a crate engine in the other thread. If you have the dough to buy up a crate motor, then that is the best route. The crate motors are made of reliable parts that all go together and compliment eachother so that you don't have to pick and choose the parts that are best. Crate motors are not really for mileage, though, more for performance.

 

[Paul Greathouse]

Yea, I know they are just for performance but when you pair the higher HP crate motor with higher gears you get performance with decent MPG. At least we did with the motor we had in the 93' Z71. If I recall correctly it was bored .60 over. The guy that owned it before my son was a transmission mechanic and had built the transmission himself. It shifted nice and hard with the modifications he had made.

I hated to see my son trade it on the 02' Z71 he has now but you can't impress the ladies in an old truck. At least thats what he thinks.

The truck got 15mpg city/hwy combined with a 17 year old driving it. That's impressive to me and the only thing I can credit that to is the 3:44 gears. It had 265/75/16 buckshot mudders on it, with a 3" body lift.

Do you know if 3:44 gears are available for a 95' 4WD? Everthing I am seeing on the 95's is 3:73. I wouldn't even be considering the higher gears if gas wan't so high now. Well at least its down to $3.85/gal here "wu ho". The most I've paid so far is $3.98.

Let me know how you like the Holley TBI when you get your motor built.

 

[Mike97]

I hated to see my son trade it on the 02' Z71 he has now but you can't impress the ladies in an old truck. At least thats what he thinks.

To some ladies, an 02 is an old truck, lol.

The truck got 15mpg city/hwy combined with a 17 year old driving it. That's impressive to me and the only thing I can credit that to is the 3:44 gears. It had 265/75/16 buckshot mudders on it, with a 3" body lift.

265's are stock sized tires, and shouldn't affect fuel mileage. The lift also shouldn't make your mileage any worse. But for a 17 year old driver to get 15 mpg, that's the amazing part. My son used to have an 82 El Camino with a 5.0 liter V8, and he was lucky to get 10 mpg with it when he was 17. He loved to hear those secondaries open up in that old quadra-puke carb, lol.

Do you know if 3:44 gears are available for a 95' 4WD? Everthing I am seeing on the 95's is 3:73. I wouldn't even be considering the higher gears if gas wan't so high now. Well at least its down to $3.85/gal here "wu ho". The most I've paid so far is $3.98.

It's been quite a while since I've seen gas for under $4/gallon. The most I paid was $4.27. You should count yourself fortunate.

I was looking into getting that Holley TBI setup for my 94 K1500, but decided against it for now. It's still in the back of my mind though. I hope someone here can give us a comparison.

 

[General Stalin]

265's are stock sized tires, and shouldn't affect fuel mileage. The lift also shouldn't make your mileage any worse.

Well, if they are mudding tires, then they aren't meant for road driving 24/7. Heavy tread and thick sidewalls make foir a pretty heavy tire, and increased friction on the road. That would definitely affect mileage. Also, a lift very much so effects mileage. If you change the way the weight is carried on your vehicle, it will have an affect on milage. The body lift lifted the center of gravity on his vehicle, which makes for more weight transfer and body roll when turning.

The tires will make more of a difference than the lift.

 

[Mike97]

Well, if they are mudding tires, then they aren't meant for road driving 24/7. Heavy tread and thick sidewalls make foir a pretty heavy tire, and increased friction on the road. That would definitely affect mileage. Also, a lift very much so effects mileage. If you change the way the weight is carried on your vehicle, it will have an affect on milage. The body lift lifted the center of gravity on his vehicle, which makes for more weight transfer and body roll when turning.

The tires will make more of a difference than the lift.

Depends on the tread, but the tire size he mentioned means that the outer circumference of the tire will be the same. Maybe if the tire is extremely heavy, it will add some weight, but won't make a noticable difference in fuel economy. The lift, if it makes any difference, would be from increased wind resistance. Not because of where the center of gravity is. Unless you are taking corners like a ferrari.

I agree that tires will make a difference, but only if you are going up in width or circumference. Or if the weight of them is dramatically more than stock.