What cam for Tahoe?

[Uraijit]

I have a 2001 Chevy Tahoe, that I'm quite fond of It's got the 5.3L LM7 engine.

It does a decent job of towing my boat around, and for the most part, I hardly notice it's back there. However, when I'm towing through the canyons, my poor tranny can't make up its mind what gear it wants to be in, on the really steep inclines.

Being reved up to 5000+ RPM to climb a hill, while pulling a load is just KILLING my fuel efficiency; and I don't like what it means for the engine either.

Anyway, I've been contemplating putting in a cam for a bit more torque for a while now. It's not quite as hot off the line as I like. I'm not looking to turn it into a street racer or anything, but a nice solid pick-up in bottom end for in-town driving and towing would be just lovely. I'd like to maintain a nice smooth idle. I don't mind sacrificing a little bit of fuel economy/power for freeway driving, since I don't really do much of that anyway.

Basically, I'd just like a noticeable increase in torque, without sacrificing driveability. And without sacrificing mega bucks!

I'm hoping to spend <$250. I was looking at some of Comp Cams' offerings for my application, and they start at about $450!

According to factory specs, this engine currently puts out about 285HP, and about 335 FT LB of torque. Not bad numbers, but I don't know exactly WHERE it's making those numbers. I'm not feeling it down low (which is where I do most of my driving.

Can anybody suggest a moderately priced cam to liven up my engine? I heard that Summit used to carry a <$200 plain white box variety that really woke it up--I can't seem to locate it though. Maybe I just don't know where to look; maybe it never existed.

Can I just figure out a profile, and just throw in any old LS1 cam, or is there something special to the LM7?

I know there are plenty of cam Gurus in here, so whadda ya say? Is my price range a pipe dream? I just can't justify $450 for a cam. Maybe I'm just spoiled by the plentiful classic SBC cams, which can be had all day long for $125...

Maybe I should just re-gear?

Thanks in advance for the input.

 

[TilliamWe]

Re: What cam for Tahoe?

I have a 2001 Chevy Tahoe, that I'm quite fond of It's got the 5.3L LM7 engine.



According to factory specs, this engine currently puts out about 285HP, and about 335 FT LB of torque. Not bad numbers, but I don't know exactly WHERE it's making those numbers. I'm not feeling it down low (which is where I do most of my driving.

HP is at about 5200 and torque is about 4400.

http://www.gm.com/experience/technology/gmpowertrain/engines/vortec/vortec_engine.jsp
This link is for 2009 model year engines, but you'll get the point. Click "Product Information" and "Truck engines" and them a list comes up. The chart you want is labelled "SS" on the line to the right of the enignes listed.

I'd call Summit on the phone and tell them what you are trying to do.

 

[MikDee]

Re: What cam for Tahoe?

You might be better off if you just re-gear. It looks like your hp & torque, comes in at a pretty high rpm. What kind of gearing is in there now?

 

[Uraijit]

Re: What cam for Tahoe?

Don't honestly know what gearing is in it now. Educated guess would be that it's a 3.73, but I'd have to look at the tags...

The problem with a re-gear, is that I don't WANT to be revving the engine higher. I'd rather just bring the torque down lower in the powerband. Easier on fuel, and easier on the engine that way.

And since it's 4WD, a re-gear is also going to be a pretty costly option. Specially when I have to recalc the speedo

 

[Wingnutt]

Re: What cam for Tahoe?

You have found the Achilles heel of today's V-8...low end torque. This is due to the emissions and mileage requirements mandated by the Feds. Fortunately, that little 5.3 loves to rev, so a re-gear won't hurt the engine as much as you might think. As for fuel mileage, a less powerful engine will require more throttle to make the same power at a given load and speed as a more powerful (or larger) engine will, and it needs more RPMs to do it. So IMHO, it's six of one and a half dozen of another.

A custom tune, a cam swap, cold air intake and exhaust work can give you a little more low end torque, but these engines were designed to produce their torque higher in the RPM range. For a little more than the price of the things listed above, you can go the supercharger route. You can find complete kits for around $5k. Instant horsepressure when you need it and reasonable fuel mileage when you don't.

 

[MikDee]

Re: What cam for Tahoe?

I agree with Wingnutt about the modern smaller higher revving economy V8's.
If re-gearing is out of the question cost wise, maybe you could go to wider, lower profile tires. It looks like you have either 70, or 75, series 16" tires, if you went to a 65, or 60, series, it would make a big difference in low end grunt. As far as a cam, I don't know what's available for the 5.3V8?

I used to have an online rear end gear ratio calculator, that gave you what ratio you had by changing tire sizes,,, but it disappeared recently

I do know with my S-10 if I went from the stock tire size, to a 2" smaller in diameter tire, it went from a 3:08 to a 3:42 rear

 

[TilliamWe]

Re: What cam for Tahoe?

Urajit, open you glove box and look at the codes on the sticker in there. GU6 is a 3.42, GT4 is a 3.73, and GT5 is a 4.10. I'll bet it's a 3.73, also.

 

[MikDee]

Re: What cam for Tahoe?

Urajit, open you glove box and look at the codes on the sticker in there. GU6 is a 3.42, GT4 is a 3.73, and GT5 is a 4.10. I'll bet it's a 3.73, also.

Yes, I know this works with the Chevy S-10's, didn't know if it worked on the bigger trucks?

 

[TilliamWe]

Re: What cam for Tahoe?

Those codes are common to all GM products. They've been the same for years!

 

[Uraijit]

Re: What cam for Tahoe?

So the consensus is that a cam is out?

 

[speedwrench]

Re: What cam for Tahoe?

Up graded to 6.0 2500 this week after 160K towing with 2001 Tahoe 1500 5.7. What a difference.

Just changing the cam in EFI engines is not simple. The ECU (computer) would have to be changed out to a programmable one, and you would have to experiment with the programming until you find what the engine wants to take advantage of the upgrade. Then if you change anything else (Exhaust, air cleaner, ect.) it starts over again. And you may not ever get the Check engine light to go out. And there are other issues that go with it.

The most economical route is go with smaller diameter tires. Recalibration speedometer is minor issue. Next would be gear change.

My 8 years, 160K miles towing 5000K+ with 5.3 experience is:
1. Do tow in 3d and in tow/haul mode all the time.
2. Don't leave on cruse in the hills.
3. Don't worry if it slows down pulling a hill.
4. Enjoy the scenery

Yea, Yea, I know, your brother in law changed the cam in his and horsepower went up to 400+ and gas mileage is 20+ towing. Glad it worked out for him.http://forums.iboats.com/images/icons/icon10.gif


Dave