michael bush

Good morning all,
I have a gen4 4.8 I put together with 862 heads/studded with bronze trunnions and howards valve springs. Also did a 225/236 .525 110lsa cam. The plan was/is to turbocharge with a s366 all going into my Lifted 2006 Envoy Denali XL. The new plan is to install it into my 2006 Envoy Denali short version I just picked up. It has the LH6 in it now, runs great, but I don't have the money at the moment to do a DOD delete, converter, headers, and gears. This stupid thing only has 3.42's in it, and it is difficult to find 3.73's or 4.10's in good shape, as these front diffs usually are bad when you find them.

Anyways...I put that same cam in a 2005 2500HD with longtubes, 4.10's, and couldn't believe how soft is was on the bottom end. It killed the bottom end power, came on real strong up top though. It wouldn't brake torque, it was a total pig just flooring it from a dead stop. The other issue is I was running out of injector at 5800rpm, so I set the cutoff there. I never thought I would need injectors for a "smallish" cam upgrade like that, but I am fairly new to actually modifying FI stuff.

Here is my problem/options.... I have a 4.8 that's ready to rip with a potentially oversized cam in a heavier SUV, that would probably be fine once I am able to add the turbo. I am shooting for around 500hp. How bad is the performance going to be NA though? I keep thinking about that 6.0 and knowing this is a lil 4.8, I feel like it's going to be a complete turd. Soooo I either have the money to buy a good converter for the 4.8 swap, (as the cheapest quote I got was about $780 for a 2600 stall), and not upgrade the injectors yet
-------or------
I can do the DOD delete in the 5.3 that is currently in there, but I 'll have to stick with a baby cam upgrade, as I won't have the money to do the DOD delete AND a good converter AND gears AND injectors. I guess I could pull the 3.73's from the long envoy and swap into the short one (sigh). What's the biggest cam I can run with stock 2006 5.3 LH6 injectors and a stock converter with crap 3.42 gearing? Whats the next step up cam I could run with a plan in the future of better converter and gears? At that point am I better off just swapping in the 4.8? I could possibly swing a set of headers, but they are around $600 minimum for these envoy/trailblazers. Either way, with stock manifolds or headers, it will not have converters, and more than likely a dual 2.5" into 3" exhaust.

If i do just a cam swap/DOD delete in the 5.3, I'm gonna be honest it would be nice if it had a lil lope to it. I am NOT a cam genius. I understand the numbers to a degree, but I start to get lost in all the 112+3 and all that. This cam I have been using sounds amazing, and I thought the 110 would keep the power down, good for a truck. It must be the higher duration that is hurting the bottom end.

The other possibly worse option is to buy the good converter, install the 4.8, and deal with it until I can get the turbo system installed, which realistically won't be until this winter.

Lastly, this is a 4600lb envoy with 285/45/20 tires, lifted a little, and a 4l60e. I have a complete build kit for the trans, that I will do this winter and swap in (maybe a good time for a converter upgrade). I am not looking to beat on it, but just looking for something that gets out of it's own way, sounds awesome, get's groceries, and can make 10 hr trips reliably as a vacation vehicle.

Thank you everyone for ANY solid input.

RB04Av

I think you already know the answer. Even already put it in your post. Us either repeating it, or pretending to put on rose colored glasses and lying to you, isn't going to change the outcome.

With the small motor, terrible gears, and stock converter, about the biggest cam that I would use, would be one of those 206/212 "truck torque" cams.

Not sure about "sounds awesome". Any cam that does that will directly oppose your other goals.

shakenfake

The performance is going to be horrible. Absolutely astonishingly bad. You would 100% need a converter.

I'd sell everything and start over. If that isn't an option then I probably would just not do anything until you have the funds to do what you want. The AFM isn't going to crap its pants tomorrow.

michael bush

Hahahaha I was hoping you guys would tell me exactly opposite...RBO4Av thank you for confirming, I was looking at the truck torque cams, seems like a lot of money for not much power difference. I'm wondering if the small LS's for light duty truck use would just benifit from some forced induction and leave it at that. Cost per useable ponies, in a truck or SUV seems like trying to "build" one of these smaller engines just isn't worth sinking the money into, other than a turbo setup.

shakenfake I'm gonna keep the lil guy, and use it in my G body Olds with a 4 speed and 4.10's (already have all that). Figure being able to wind it up with that, and 4.10's with a 26" tire, it oughta do perty good there... I have had bad experiences with the AFM stuff, so I wanted to get it out as soon as possible, but your advice is pretty undeniable..
Thank ya guys

_zebra

iTrader: (5)

225/236 110° is a big LS cam and meant for top-end performance in a lighter vehicle. no surprise it sucked ***** in a 6.0 HD truck. it'd be even worse in a 4.8 with almost the same weight. it also would suck for turbo efficiency because it's got a lot of overlap & would push pressurized air:fuel right out the exhaust valve.

start by talking with Comp Cams, TX Speed, BTR, and the like about your goals & how you actually use the truck. they'll provide you with a realistic grind recommendation to meet that (and it'll likely be something in the low 200s duration).

michael bush

So for now....I am leaving the 5.3 in it, unmodified. Do all the normal synthetic fluid changes, filters, all that jazz, tune out the DOD and maybe TM and rear o2's, etc. . I'm even gonna leave the stock exhaust on it, although I may remove the cats and rearmost muffler.

Anyways, this fall I think I will get the 4.8 in it, but swap in this cam

• TSP "CHOPacabra" Truck Cam Specs: 214/222 .550/.550 108 LSA 106 ICL

and do a supercharger, a converter, and swap gears. That will give me time to be able to purchase all these things also, as that's alot of coin that I don't currently have right now. But that should get me to a pretty reliable 500 ft lb mark.

What do you guys think about this plan? That cam shows it doesn't require a converter, but it would only help. I've been doing a ton of reading, and it's so suprising that guys are DD'ing trucks with 3200-3600 stalls in them. I would have never dreamed of doing that in a truck or SUV that needs to actually do truck or SUV things, but I guess I've been out of the game too long. Too used to big blocks and diesels I guess.

michael bush

Zebra I know there is alot of overlap, but in my head that is gonna help spool the turbo a little sooner, that's alot of heat and pressure going right into the turbine. Richard Holdner did some pretty wild cam testing and ALL of his results showed the cam is not quite as big of a deal as previously thought. I built a twin turbo 468 BBC years ago and used Megasquirt to tune. It had a massive cam in it, I don't remember exactly, but the lift was in the .700 range, heads were around 340cc. Anyways, everybody said you HAVE to use a turbo cam, and it was most def not a turbo cam. It ran amazing, never had it dyno'd, so I don't have any real numbers. It was in a 4wd 96 extended cab shortbed chevy, and would break the tires loose at freeway speeds. I get the turbo's can overcome alot of other engine "inefficiencies", but I just don't know how much I buy into "you have to use a turbo cam with a turbo". I think alot of it is marketing, emissions, and maybe controllable driveability for less-experienced drivers. JMO though.

But your right, I should talk with someone, there are just so many options and I am NOT a good cam guy obviously, lol

shakenfake

That cam also sucks for a 4.8 lmao


Why would you swap in a 4.8, who wants to go down in displacement? Not sure why that is a thing here.

michael bush

What am I missing? Aside from the .550, the rest of it is "small-ish". The advertised rpm range is 1200-6500, but just by the specs I would say more like 2000and up. But with a gear change to 3.73 or 4.10, a 29" tire, a converter, and a supercharger helping that should be plenty of bottom end help until 2000-2500. Plus this isn't exactly smog compression. Also the 108 lsa should move the powerband even lower.. I did a old 109 lsa cam in a 327 and it had loads of 2000 up power into midrange. 2.02 heads gassed out around 6400 so it was a great match.
Even the converter and gearing alone should be a huge improvement. I figured the drop in what.... 25hp from a 4.8 to a 5.3, could easily be made up by a converter alone. The thing for using the smaller motor is to keep the larger engines for my more performance higher hp planned vehicles. This envoy is just a fun SUV, not a racer.
I'm lost in these small cubic inch engines I suppose. Only looking for 400-500 ft lbs, shouldn't be this difficult, lol. I guess it is only 292 cubic inches though....

How about this one, but maybe with a little more lift?

Camshaft, BTR, Stage 2 Truck V2, No Springs Required, 212 int./218 exh. Duration, 0.480 in./0.480 in. Lift, 111 LSA, 3-Bolt, 4.8L, 5.3L, 6.0L,

shakenfake

400-500 ft lbs NA or boosted?

My point is that there is 0 point in going to a 4.8. I have no idea why you would do that other than "Oh it is already out of the car and easier to swap"
The Chopacabra cam is just a buzz word fad cam. Let me see if I can dig up the thread where I did quite a few cam comparisons. I would check it out: https://www.performancetrucks.net/fo...advice-561178/

Yes the cam is "small-ish" but you don't have cubes to eat up some of the cam, add that to a 4600 lb vehicle you still are going to hate life.

The 212/218 cam is getting better but I would maybe go a touch smaller. Something like a 20x/21x. If you are going to put in a converter then 212/218. A 5.3 and a 212/218 is perfect though.


I am pretty conservative when it comes to cam choices. You won't regret doing a too small cam but you will regret doing a too big cam, as you have discovered.