sbc vs. lsx

T5MalibuWagon

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Sep 27, 2004
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Ok guys let me start of by saying that this is a little off topic because the car in reference is a 2600lbs 1967 Rambler American and while most want all out performance Im after economy also as this is my daily driver. Ive finally realized that what I want is 300-350hp, 22-25mpg, and an engine that weighs less than the I6 (550lbs) thats in there now. I had been thinking about a 4.8 or 5.3 with a rpm intake and carb set up for a while because it seemed to fit my wants, but I just read an article about a mild sbc with afr's that seemed really nice also and has got me thinking. The only thing they never test in the mags is economy, and at $4 a gallon its a must for me. Ive read around and it seems there are lots of claims to 20+mpg's in bigger cars without overdrives using 283's and 327's.


The thing that Ive been wondering for awhile now is a carbed lsx any more efficient than a comparable cubic inch sbc with a good set of heads? What are some advantages to going with a lsx over a sbc? What would it take to get my goal out of a 4.8l or 5.3l vs. a 283 or 327ci sbc, both being carbed?
 
A

Anonymous

Guest
This just my own experience. I have a 2000 chevy Suburban
4x4 and i get 19mpg in the city and 22mpg on the highway it has a 5.3 vortec , i don't know what the gross tonnage is but it is heavy and i believe the motor is rated at 290 hp not bad but i read with a simple cam change and some exhaust work it would bring it up to 390 with no effect on gas milage. stay away from the 5.7 vortec crappy gas milage
good luck
al
 

T5MalibuWagon

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ROOSTER007 said:
This just my own experience. I have a 2000 chevy Suburban
4x4 and i get 19mpg in the city and 22mpg on the highway it has a 5.3 vortec , i don't know what the gross tonnage is but it is heavy and i believe the motor is rated at 290 hp not bad but i read with a simple cam change and some exhaust work it would bring it up to 390 with no effect on gas milage. stay away from the 5.7 vortec crappy gas milage
good luck
al

Yeah, thats great mileage but its also efi overdrive and I havent been around any efi overdrive sbc's for comparison. Also I dont really want a efi engine in this car. I know that there are gains with it but I really like the simplicity of a carb.
 

t72ss402

Amateur Racer
Aug 12, 2007
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Springfield, MO
Well when you retrofit either engine go with an overdrive. the fuel injection really isn't that hard to put in and you can play with the computer to gain even more horsepower and MPG. And if you go with a carb setup just go mild.
 

T5MalibuWagon

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Sep 27, 2004
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t72ss402 said:
Well when you retrofit either engine go with an overdrive. the fuel injection really isn't that hard to put in and you can play with the computer to gain even more horsepower and MPG. And if you go with a carb setup just go mild.

I plan to get a manual overdrive but if I go with the sbc I might put a 4 speed behind it for awhile. t56's seem to be as cheap as any good 5 speed so Ive been lookin at them, hopefully I can find a smoke in deal on one soon. If I do end up with a t56 I will more than likely have to change gears, or rears, because Ive got 3.35's now and with a .5 odd it would put me at 1500rpm at 65MPH.

I dont know a lot about efi but I understand that its not very hard to install. Ive just had efi cars leave me stranded and run like crap for unknown reasons. They are terrible to trouble shoot and everything seems to be ten times the price of what it cost to fix a carbed engine. To many little black boxes in there for me to ever understand whats going on. Besides that Im still learning about carbs, no need to skip the basics. Everyone I talk to says go efi but on this car I really just dont want it. I thought 300-350 hp was mild?
 

StreetBu

MalibuRacing Junkie
Mar 21, 2004
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Upstate NY
Here's my .02, I have a mild sbc in my Malibu now. I know what I'm doing as far as bulding an engine, etc, BUT when it comes to tuning-idk my butt from hole in the ground. My car gets the worst mileage. About 4mpg. It's only about a 300hp engine, think I finally have the timing down correctly, now time to work on the carb. Gotta rebuild it, then tear it back apart to change jets, rods(quadrajet) etc. If I had it do all over again, I would go efi-plug and play. They really arent complicated, plus you can get a little black box to replace the pcm on lsx engines from several manufacturers, has like 5 wires to hook up and your done. Hit the key and it starts and runs perfect. No screwing around. Yes more expensive to get up and going, but well worth it-PLus you can sell off some of your old stuff and make some back!
 

Horsepwraddict

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Mar 3, 2007
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Princeton MA
A guy over on LS1tech with an s10 has a Carbed 6.0/th350/ford 8.8" and he told me he got 18mpg on the way to the track. Not bad for a 3 speed. I beleive his brother is on here with the maroon LSX malibu wagon. Maybe he can chime in.
 

Doober

Moderator
Jun 2, 2003
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Catalina, AZ
www.cardomain.com
I'd go with the LS motor hands down if you're between that and building an SBC. You'll be close to 300hp easy with a stock 5.3, but you'll also probably spend more $ on the swap overall since the LS is a fairly new animal compared to a Gen 1 SBC.
 

T5MalibuWagon

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Sep 27, 2004
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StreetBu said:
Here's my .02, I have a mild sbc in my Malibu now. I know what I'm doing as far as bulding an engine, etc, BUT when it comes to tuning-idk my butt from hole in the ground. My car gets the worst mileage. About 4mpg. It's only about a 300hp engine, think I finally have the timing down correctly, now time to work on the carb. Gotta rebuild it, then tear it back apart to change jets, rods(quadrajet) etc. If I had it do all over again, I would go efi-plug and play. They really arent complicated, plus you can get a little black box to replace the pcm on lsx engines from several manufacturers, has like 5 wires to hook up and your done. Hit the key and it starts and runs perfect. No screwing around. Yes more expensive to get up and going, but well worth it-PLus you can sell off some of your old stuff and make some back!

Well we now have a baseline for the worst mileage possible :p

Once again, I dont want efi. I know how easy it is and how great everyone thinks it is but its just not for me on this car. I have 4 cars one of witch is a 98 pickup that has efi, a/c, pb, ps, and an 5 speed with overdrive. When I want something like that I jump in it, when I want something that doesnt have all the b.s. I hop in the rambler, and when I want something to work on I go out and play with my malibu, lol. The last car is up for sale so I dont do anything with it. I like the rambler because of its simplicity, not in spite of it.
 

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