Crate vortec 350, 390hp question

[tdc917]

If you could start with a 6.0L but you really aren't going to find one of those cheap unless it needs a complete rebuild. Even then a LQ4 is only 300 hp and 360 TQ. When you start adding more cam to it, the already weak low-midrange torque only becomes even more noticeably gutless.

I have a LQ4 with ported/milled 5.3 heads, a 220/224 cam, headers and a trailblazer SS intake in a 1987 G20 van backed to a 4L80E and 3.73 gears. Once it gets into the 3,000+ rpm range it moves pretty good and continues to make good power up to about 6,500 rpm. In the lower RPM range it is a pig. Its no better on gas than the 350 in my Express van and actually worse with a trailer behind it.

Yes, I agree a 6.0 is going to be a much more expensive starting point because they’re all the craze right now. I was talking about the 4.8/5.3 platform. Sure they definitely like to rev, but he’s coming from a 305. You also took an already rev happy engine and moved the power curve up even more with the your mods, and are comparing it to a truck with 5.13 gears. It’s not really apples to apples.

I’ve had several 6.0s in work trucks and have never had a major repair. I have a 2012 6.0 now with 180k hauling right at capacity with a CAT 259 skidsteer around every single day for the past several years with no hiccups. Zero. One set of plugs, a front end rebuild, and fluid changes, and it does fine. It takes a little throttle to get moving and doesn’t pass many gas stations, but my 3/4 ton 350 Suburban doesn’t even like OD on flat ground at 65 with a 20 foot bass boat behind it. And in 122k miles it’s needed intake gaskets, injectors, a distributor, took the heads off for a valve job and found both to be badly cracked with zero instances of overheating since my dad bought it new, consumes a ton of oil, etc. I love the 400 platform, that’s why I’m here- but I don’t think that the stock small block does anything better than the newer platform engine-wise.

 

[L31MaxExpress]

Yes, I agree a 6.0 is going to be a much more expensive starting point because they’re all the craze right now. I was talking about the 4.8/5.3 platform. Sure they definitely like to rev, but he’s coming from a 305. You also took an already rev happy engine and moved the power curve up even more with the your mods, and are comparing it to a truck with 5.13 gears. It’s not really apples to apples.

I’ve had several 6.0s in work trucks and have never had a major repair. I have a 2012 6.0 now with 180k hauling right at capacity with a CAT 259 skidsteer around every single day for the past several years with no hiccups. Zero. One set of plugs, a front end rebuild, and fluid changes, and it does fine. It takes a little throttle to get moving and doesn’t pass many gas stations, but my 3/4 ton 350 Suburban doesn’t even like OD on flat ground at 65 with a 20 foot bass boat behind it. And in 122k miles it’s needed intake gaskets, injectors, a distributor, took the heads off for a valve job and found both to be badly cracked with zero instances of overheating since my dad bought it new, consumes a ton of oil, etc. I love the 400 platform, that’s why I’m here- but I don’t think that the stock small block does anything better than the newer platform engine-wise.

I actually made BOTH of the engines alot more rev happy. Comparing 5.13 gears pulling along in OD to towing in 3rd with 3.73s is almost a mute point once rolling at speed. My current tire size also makes those 5.13s more like 4.56s when you compare the LT265/75R16 tire I am running to a stock size LT245/75R16 you find on a 1-ton Express van from the factory which incedentally usually come with 4.10 gears with a 4.8 or 6.0L and only 3.73s with a 5.7.

I had intake gaskets cause an engine failure at 57K and sitting for a year caused the poppet setup to gum up. I have also had the cracked head routine as well as warped a set of Etec's and both of those were non engine related overheats. One of those stupid GM 4 hose port heater diverters split apart on a 15 year old van. The other overheat was a plastic radiator drain plug that split in half. Both of those things are POS designs. 4.8s and 5.3s also have cracked head issues to the point I will not touch 706 castech heads. I pulled a set of 862s this weekend at the wrecking yard to put on a 5.3 I have sitting in my shop with cracked 706s. 6.0Ls have cam bearing issues and often main bearing issues. LS engines also often burn 1 qt every 1,500 miles or less and GM considered that normal. They also have a nasty habit of spinning lifters in those plastic trays and wiping the cam. Not to mention the piston slap that makes them sound like a diesel on a cold morning. The knock sensors are also a bad problem especially the rear one. I had a small leak in my front timing cover seal and only had to add 1 quart on a 2,200 mile trip. I have a Comp cast aluminum timing cover on order to hopefully fix that. My distributor was also replaced with a Rockauto aluminum piece even though it is only used for cam synch now and no longer has a cap or rotor on it.

I put a cheap set of 200cc intake runner aluminum heads on my 350 to as an alternative to cast iron vortecs. I eventually plan to build a 400+ cube small block out of a Dart block. I just had a set of those 200cc Aluminum heads ported by Lloyd Elliot as well. For a cheap head they flow like crazy. I am in the process of putting those on the 350 to see what I can get out of what alot of guys consider a boat anchor of an engine.

I put the Etecs on a 305 Vortec after milling them flat and with a little cam it pulls like a freight train in a 1980 Camaro.

As for your oil burning 350. Try one of the dummy PCV valves you can get aftermarket for a 2002 5.3. It has the guts removed and metered orifice hole drilled into it. It practically stopped my oil consumption on a lower mileage 350 and keeps my intake much cleaner inside.

 

[mrvsfriend]

A little backgrounds and to address the ls swap, from everything ive read its a better motor to build from, turbocharge, etc. From what ive seen locally i can buy a used 5.3 for about 500, then i have to figure out wiring, mounts, routing hoses, tune, headers, exhaust. Apples to apples the 5.3 has a few more hp, but has a few ftlbs less torque, in stock form theres not much of a gain for me. I have an nv3500 manual trans, so i think the flywheel would need to be changed as well.

I want reliability more than i want hp, and willing to spend a few buck for some power gains. I`m eyeing crate motors because i recently bought a "running" 350 vortec that i was planning on installing in the truck, i spent a lot of time cleaning the engine with plans to rebuild and found a tiny crack in both heads and really worn valves, and a small scuff on the crank... at this point im just going to buy a crate motor, figure the exhaust, and whatever minor tuning needs to be done. Im a novice when it comes to making the thing actually run at the end of the day, less wiring and problem solving is better.

 

[L31MaxExpress]

If you alr

A little backgrounds and to address the ls swap, from everything ive read its a better motor to build from, turbocharge, etc. From what ive seen locally i can buy a used 5.3 for about 500, then i have to figure out wiring, mounts, routing hoses, tune, headers, exhaust. Apples to apples the 5.3 has a few more hp, but has a few ftlbs less torque, in stock form theres not much of a gain for me. I have an nv3500 manual trans, so i think the flywheel would need to be changed as well.

I want reliability more than i want hp, and willing to spend a few buck for some power gains. I`m eyeing crate motors because i recently bought a "running" 350 vortec that i was planning on installing in the truck, i spent a lot of time cleaning the engine with plans to rebuild and found a tiny crack in both heads and really worn valves, and a small scuff on the crank... at this point im just going to buy a crate motor, figure the exhaust, and whatever minor tuning needs to be done. Im a novice when it comes to making the thing actually run at the end of the day, less wiring and problem solving is better.

If you already have a good 350 block it could probably be made to run very easily. Have a machine shop check it over, clean it, possibly hone it(doubt it needs bored), install cam bearings, polish the crank (small scuff may not hurt a thing at all) or turn it .010/.010 and build a nice short block. You could do a stock rebuild on the bottem end, add a small cam and put Etec 170 heads on it for less than that crate engine and end up with more power and alot better heads.

 

[mrvsfriend]

What kind of fuel economy do you get with those heads?

 

[L31MaxExpress]

What kind of fuel economy do you get with those heads?

If you are talking about the Etec 170s the fuel economy is every bit as good as stock as long as you keep your foot out of it. Even on the mild stock cam they would give you another 20-25 hp. I bet a 395' marine cam, 1.6 rockers and Etec 170 heads could still do very well on fuel and hit the 360 hp range. The 200cc heads hit my fuel economy a bit but I also swapped to a bigger cam and 1.7 rockers at the same time and raised my shift speeds at WOT from 5,150 to 6,200. I also like to put my foot into it and GO! My stock engine pulled about 210 gms/sec of airflow at about 4,800 rpm. The current setup pulls 380 gm/sec @ 6,000. The additional fuel requirement at WOT hits my MPG pretty hard when I get into the pedal alot.

 

[L31MaxExpress]

FWIW,
210 gms/sec is about 370 cfm

380 gms/sec is about 670 cfm

You can see the drastic airflow and fuel flow difference from the HP gain.

 

[RDF1]

Stock 5.3 and turbo it.....
BWS366 turbo and let it cruise.
Would tow about like a diesel and still get good mileage empty.

Sent from my HiDiNg PlAcE

 

[tdc917]

I actually made BOTH of the engines alot more rev happy. Comparing 5.13 gears pulling along in OD to towing in 3rd with 3.73s is almost a mute point once rolling at speed. My current tire size also makes those 5.13s more like 4.56s when you compare the LT265/75R16 tire I am running to a stock size LT245/75R16 you find on a 1-ton Express van from the factory which incedentally usually come with 4.10 gears with a 4.8 or 6.0L and only 3.73s with a 5.7.

I had intake gaskets cause an engine failure at 57K and sitting for a year caused the poppet setup to gum up. I have also had the cracked head routine as well as warped a set of Etec's and both of those were non engine related overheats. One of those stupid GM 4 hose port heater diverters split apart on a 15 year old van. The other overheat was a plastic radiator drain plug that split in half. Both of those things are POS designs. 4.8s and 5.3s also have cracked head issues to the point I will not touch 706 castech heads. I pulled a set of 862s this weekend at the wrecking yard to put on a 5.3 I have sitting in my shop with cracked 706s. 6.0Ls have cam bearing issues and often main bearing issues. LS engines also often burn 1 qt every 1,500 miles or less and GM considered that normal. They also have a nasty habit of spinning lifters in those plastic trays and wiping the cam. Not to mention the piston slap that makes them sound like a diesel on a cold morning. The knock sensors are also a bad problem especially the rear one. I had a small leak in my front timing cover seal and only had to add 1 quart on a 2,200 mile trip. I have a Comp cast aluminum timing cover on order to hopefully fix that. My distributor was also replaced with a Rockauto aluminum piece even though it is only used for cam synch now and no longer has a cap or rotor on it.

I put a cheap set of 200cc intake runner aluminum heads on my 350 to as an alternative to cast iron vortecs. I eventually plan to build a 400+ cube small block out of a Dart block. I just had a set of those 200cc Aluminum heads ported by Lloyd Elliot as well. For a cheap head they flow like crazy. I am in the process of putting those on the 350 to see what I can get out of what alot of guys consider a boat anchor of an engine.

I put the Etecs on a 305 Vortec after milling them flat and with a little cam it pulls like a freight train in a 1980 Camaro.

As for your oil burning 350. Try one of the dummy PCV valves you can get aftermarket for a 2002 5.3. It has the guts removed and metered orifice hole drilled into it. It practically stopped my oil consumption on a lower mileage 350 and keeps my intake much cleaner inside.

I guess it’s a preference thing. The L31 is inherently better down low, but after years of working out of 6.0s, I’ve really grown to appreciate them for what they are. I’ve always been a BBC guy, so I’m all about the down low. But I’ve found that a 6.0 with 4.10s is more than adequate for my needs, which are greater than most who are just driving them back and forth to work everyday. I ride mine hard and put them up wet since my first one in 2003, and they’ve always been loyal. I even did the Duramax thing for awhile and came back. Far more expensive up front, they cost at least twice as much to operate, and are of no practical use to justify the costs to anyone not towing >15k. But that’s a whole different argument.

And if the trans went out tomorrow I could pull the engine, throw rings and bearings in it, put it in a street car and throw 20lbs of boost at it all day long, and go buy a new truck dirt cheap. The versatility is unmatched. If the heads are cracked, you can find a good set of 799s for $300 all day long. You won’t find 062s for under $700 because good used ones simply don’t exist. Unless you buy cheap eBay remans and send your cores back. You want to run a cam in a 6.0 and not pay $150 for springs and retainers that may or may not work or try to hack up your valve guide bosses with a die grinder, go ahead. Those are the kinds of things that deter people from even bothering with the L31. I have a lot of respect small block builds because nobody bothers with them anymore. For me, it just doesn’t make sense. You’ll make much more power per dollar spent with a big block build in NA applications, and with an LS based iron block in boosted applications.

 

[Supercharged111]

Lots of stuff I missed here, but I would NEVER swap a 5.3 for a 5.7 unless I wanted to boost that garbage to hell and back. Even still I'd throw an easy 10# at my 350. A 6.0 stock for stock barely matches a 5.7 down low, it's not until you wind them out that the 6.0 wins and guess what? A wound out 5.3 in my experience does not beat a wound out 5.7. If it does, it ain't by much. Less motor is less motor especially when there's a trailer out back. It's my opinion that the 5.7 is more restricted from the factory than a 5.3.