TrendSetter

I currently have a NA S10 with a LS3 headed LS2, 0411 pcm w/efilive, t56 magnum transmission, 3.73 rear.

i want to get rid of the ls3 top end.

So on to the question at hand. I intend to convert the truck to turbo.
I have a set of 317s for the LS2 I can use, and I also am buying a L33 block.

Here are my options that I would like everyone's thoughts on.
goals are: good low end torque, this truck is 100% street driven, 30+ mpg(aim for the stars, land on the moon)

1) LS2 with 317 heads, single 76

2) buy a JY 5.3 and swap in the aluminum block, 72mm turbo

3) buy a JY 4.8 and swap in the aluminum block, 72mm turbo

4) ?? any suggestions?

I have read around a lot and I haven't been able to decide one way or another on the fuel economy issue. From the torque perspective its obviously a no brainer to go with the LS2, but I don't want to give up more than a couple mpg.

Old Geezer

iTrader: (3)

"U say terrible mileage". What is it?
Starting w/ a tune on what you have now, comes to mind.
Fuel mileage being the target, change the rear gear, and the tune.

"0411 pcm w/efilive"... Post your tune file and some data logs/

I see little economic value to spending several thousand to save a few hundred, over the long haul..

TrendSetter

...........

1CAMWNDR

iTrader: (21)

No, there is something wrong there. The 6.2 engine in the full size trucks get that mpg or better with a worse gear ratio and much more weight.

How are you instantly calculating mpg? What do you get when you calculate it the old fashioned way my resetting the trip meter and seeing how many gallons you have to put in it to fill it up?

I do not see going to a turbo any size motor gaining you a lot of mpg over the properly running and tuned set up you have now.

TrendSetter

8888888888888888888888888

1CAMWNDR

iTrader: (21)

Valve lift isn't gonna change the overlap area of the cam. You need less duration, and or more LSA.

I think it might be cheaper and wiser to swap to some 317 heads and LS2 intake now and see how it performs normally aspirated. I THINK the 317 heads will like that small cam a lot better than the LS3s.

Then if you are still not happy, then see about turbo.

But either way, get a pro tune. At least a starting place.

Where in Florida are you located?

TrendSetter

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1CAMWNDR

iTrader: (21)

5.3. Thicker cylinder walls than the 6.0, and cheaper. Of course a 4.8 has the smaller crank and longer rods........Any of them will work well if set up properly with the right cam and turbo.

There is no aluminum block 4.8 I don't think. You would have to get an aluminum 5.3 block and install the 4.8 crank and rods. Not worth the effort to me. Just get an aluminum 5.3 and go.

TrendSetter

I actually have been trying to find a L33 for a while to no avail. I did manage to find a bare block that I am waiting for shipment on, so I can buy a complete 5.3 or 4.8 and move everything over to the L33 block to make whatever will work best.

Does the 4.8 give up very much in regards to off boost torque for highway cruising? Right now my S10 cruises 75-85mph in the 1800-2000 rpm range
would it be a measurable increase in fuel economy ?

87silverbullet

iTrader: (11)

I agree with everyone here. Something is definately wrong. My wife's 2008 Denail with 3.73 gears and a 6.2 get better fuel economy than you. I'm not saying you don't know what you are doing but there are too many guys with the same setup you have and getting decent gas mileage. You might want to get with a professional tuner to look at your tune. Post this in the PCM section too to see if some guys there can help such as James Short or LSX power tuning.

There is a guy here with an LS2 vette with the 1st cam you posted and he has LS3 heads on the car. With a stock converter the car still managed an 11.40. He put a converter in the car and ran a best of 10.53 on the motor. I don't remember his economy or driveability being that bad either.

TrendSetter

--------------------------

HRHohio

Keep your foot out of it! Hahaha

No seriously, it may be just too much valve overlap. With high valve overlap on your cam, you may be blowing unburnt fuel/air out which improves flow, but at the expense of fuel economy. Same cam with a higher LSA will give you fuel economy gains and still maintain performance. Something with closer to 115 LSA on the stated duration cam vs say 112 LSA. What's he LSA on the cam you have in it now. I'd say have Martin at Tick give you some input on a cam that would meet your needs.

TrendSetter

566666666666666666

87silverbullet

iTrader: (11)

No matter what, something is still wrong. My 6 speed manual ls2 corvette that was bone stock got 28.6 mpg on the highway and a buddy of mine with the same car as mine with a 228/232 cam and Dart heads got 32.3 mpg doing the same speed with the cruise on. We drove a total of 392 highway miles to get that average. With his car being more efficient in the tune, cylinder head, and cam is the reason why I think he got better economy than me. I would figure you would be somewhere in there between those 2 numbers.

TrendSetter

im fat

1CAMWNDR

iTrader: (21)

If you are wanting between 25 and 30 mpg drop the turbo idea right now.

I am telling you, there is something wrong. Switch the heads and intake and see if you still like the power and see if the mpg improves. Look at the tune. Talk to a pro shop about your combo and tune.

A turbo 5.3 WILL give you the power you are after; but it is not gonna be a 30mpg truck.

87silverbullet

iTrader: (11)

Still, you shouldn't be losing 10-12 mpg's because of some heads.

Plus look at a g8 GT, 6.0 with rect port heads ~25 mpg's ---heavier and has an auto.

My ls2 with a 6 speed and a better aerodynamic car 28 mpg's

Same cubes different heads.

Forcefed86

iTrader: (4)

Why not?

Not sure where everyone is getting their MPG ratings from?

http://www.fueleconomy.gov/feg/noframes/32414.shtml

2013 2WD 5.3 silverado 15/21

Drop 1000lbs off the total weight and add a low enough gear I think he could get close.

On e85 my 5.3 with 317 heads and zr1 cam is netting just under 22mpg with a power glide and 3.10 gears. (29” tire) at 50mph. That’s at 8.6:1 compression.

Throw a 10:1 L33 with stock cam in an S10,2.73 gear, 28” tire, manual trans with OD, and it would be close IMO.

Adding a turbo isn’t going to make much of a difference on the MPG.

dirthead racing

My lq4 bottom ended LS3 top end chevelle is getting over 20mpg on average with it running fat(14:1) and a 3500 stall(with lockup). That's less CR........with 4.10's and 18" wheels......something isn't right man.

Car/engine specs
70 Chevelle, 4L80e, 3500 stall, 02 LQ4 short block, LS3 heads/intake/injectors, Patriot extreme springs, EPS 222/230 on 112, Edelbrock 90mm TB, 85mm maf, Walbro 255

1CAMWNDR

iTrader: (21)

If he does go turbo 5.3 he will have to keep his foot out of it to get 20-25 mpg. What would the point of going turbo be? He needs to just find out the problem, be it tune or that head/cam combo. Fix that first, and see where he is. Unless he has buckets of money to throw around and doesn't want to fix what is wrong.