5.7 v8?
 

Anyone have any experience with the 5.7L V8? I'm just wondering what kind of an engine they are...both strengh wise, longevity and mileage? I'm assuming it has just as bad (if not worse) mileage then a 4.3?

Actually the 350 CI can have better MPG then a 4.3. The 4.3 is just a 5.7 with two cylinders cut off.

If you take two full size blazers (everything being equal except for the engine), the 5.7 should perform better and actually get better MPG.

assuming we're talking about a newer LT1 engine, I've actually heard pretty good things about the mileage. No worse than the 4.3. Strength wise they're bullet proof heard of alot of people running 100shots on DD's.
very good engine from what Ive always heard, unfortunately this is all based on hearsay I have no personal experience to relay

Thanks guys. I'm just curious...the specific engine I'm talking about is in a 97 burban. I've heard they can get better mileage then a 4.3, so I was just curious. I was looking online and the figures were in and around 12-16mpg.

If it is the lt1 version of the 350 then it will be really good.
Our high school drivers ed car was an old police intercepter (caprice classic), I believe like a 94/95.... It had the LT1 with SOOOOO many miles, and that thing would still burn out, turn it on to pass.... they sold it and some guy bought the motor and rebuilt for the track....

a 1997 5.7 is a good motor to drop into just about anything, depending on what it is out of it could be an lt1, or an ordinary (vortec) motor. the lt1 has issues with an optispark that is quite expensive to replace, but get good mpg, and has about 275 rwhp. The other problem with an lt1, aftermarket performance heads are expensive, due to the reverse cooling, but the camshafts are plentiful. The only difference with the camshafts is that the dowel that the timing gear uses to time the shaft is longer than the traditional 350. One other thing, the lt1 motors were only available in the Camaros and i believe the b-body car platforms. They never came in any of the pickup or suv models

The motor out of your suburban won't be an LT1, but it will make good power. The 350 chevy has been around for many many many years and has been used in very many applications. I would call it the most popular V8 engine in existence. The LT1 is a variation of the original 350 with revisions such as a front mount optical distributor and reverse flow cooling. An Fbody lt1 made about 275 horsepower in stock form. The corvette Lt1 made 300 horsepower. The corvette Lt4 which was basically a modified Lt1 made about 330 horsepower I believe, but i'm not 100% sure. I'm not sure on power numbers for your truck 350 either, but I would guess around 240. I know the older TBI 350s made 210 horsepower, and yours would be an improvement over that. Which when you look at it isn't really a great improvement over a 4.3. But they accept modifications better than a 4.3, and can run 300 crankshaft horsepower very easily. The aftermarket for a 350 is huge, while for the 4.3 it is very limited in comparison.

Fuel mileage will be similar to the 4.3...it mostly depends on how you drive it. I wouldn't make the change to get better fuel mileage because you may be disappointed. Your truck should get between 18-20 mpg driving it nicely with the 4.3. If you can't get close to that, theres other problems. I'm getting 16-17 mpg with the 4x4 driving through all the snow we've been having

Wow...an encyclopedia of comments lol. Thanks all.
I wouldn't mainly be making the switch (if I ever did) for mileage. I dream of having a full sized, so that would be the main reason. I'm a big fan of the burban's. I'm only getting 11mpg in my Blazer right now, but I found out my o2 sensor is bad. I have another one on order, so that should help my fuel economy woes. I didn't expect better MPG's as going to a bigger engine for better mpg's is sort of an oxymoron lol.

91chevywt is correct Alex, it won't be a LT1 in that 'Burb.

regarding fuel mileage, again, it all comes down to our own driving habits. but i can tell you for a fact that my '90 (gas) 'Burb got better fuel mileage than my '98 Blazer.

if i drove my Blazer like i did my 5.7 powered 'Burb, i sure as hell would be getting a lot worse mileage than the 13-14 MPG that i'm getting now. driving that 350 hard, i was getting 13-14 MPG. but if i drove like an old white guy (or any long hauls on the highway) i could get 20 MPG no problem.

i don't care what anyone says about these 4.3's, the newer ones aren't as good as the 1st gen ones-and i had quite a few of those.

not sure what the cost of diesel is out there Alex (it's currently around $0.96/L here), but you if you can find your Sierra or a 4th gen 'Burb with the 6.5 in it, it's worth the little bit extra to get it. i'm actually surprised @ how many 4th gen 'Burbs were bought with the diesel option, compared to my 3rd gen 'Burb.

just another avenue of thought for you to be looking/thinking about.

Thanks for the info Chris. I really don't expect a large mpg out of the 5.7 I was just researching to see how people who have owned one compare it to the 4.3. The results are right on par with what I was thinking.
I'm hopefully going soon to check out the burb. I highly doubt I'm going to trade. Mostly because its older, and I'm unsure of the current condition of it. I would only ever consider trading it if it was in mint condition. Anyway...still a BIG maybe, and lots of research to do on my end.

With a 5.7 in a 'Burb vs a 4.3 in a Blazer, you need to keep in mind the HP:weight relationship. Sure the 'Burb weighs more and it has 2 extra cylinders, but that extra power makes up for the added weight and then some, making it easier for that truck to move itself than a Blazer and it's 4.3. Hence why I seriously don't get why 2nd gen Blazers weren't offered with a 4.8 or 5.3 as an option. For the extra power and slightly extra weight of the bigger engine, you'd get such better fuel economy.

no problem for the info Alex.

i also forgot to sing the praises of the 350. (kinda sounded like i'm pro-diesel in the last post :))

i had the engine in my gas 'Burb get washed out (ie. flooded) by some ass-hat in a Hino. hugh rain storm in August, 5 or 6 years ago, and i was going down this side road on the way home. it was flooded, but only to the bottom of the doors (it was a 2WD, so only 18 inches or so deep), but this tool comes into the water, and when it starts to push on his truck (creating a wall) he guns it, sending a wave over my hood, sucking water into the engine.

dragged it home on my trailer. let the exhaust drain out, pulled the plugs (4 cylinders were full), turned it over by hand (pumping out the water). couple of squirts of oil in each cylinder before putting the plugs back in, changed the oil, and she fired right up. drove that truck for another 80,000km (year & a half or so), never had an issue with the engine. EVER!

Yeah I've heard really good things about the 350, which is one of the big reasons I'd switch. I'm not really happy overall with the performance or the overall daily use of the 4.3. I know mine has a few things wrong with it, but overall I don't think it's that great of an engine.
I still have yet to see said burb, so there is a LOT up in the air.

The 350 will last about as long as you want it to as long as you take decent care of it. The original 305 in my 86 Monte SS was still running great with 287,000 miles on it- and I drove it pretty hard- got it when I was 17 :).

I definitely agree that my '93 with 180K+, had a little more "UMPH" than my '99 with only 28k, unfortunately I haven't driven the 99 enough to get a good idea of the gas mileage.

Phil you have a good point about the power to weight. I'll have to continue my research...I'm curious to see what the power to weight is on one of those compared to a little blazer.

If you're going to go through the trouble of putting in an LT1 why not just go for an LS1? Even though you said it's not an LT1 to begin with...

I'm not swapping engines...it's a project that would take wayyy too much money and something I'm just not interested in in the least bit. The Blazer is too small a truck for me, and I've always had plans and hopes to go full sized. There's no point in pouring that kind of cash into something I never planned on keeping for my life. My question was about the 5.7 because I'm looking at trading my Blazer for a Suburban.

whoa!i never realized you were kickin' the Blazer to the curbs Alex, i just thought you were lookin' @ getting a bigger DD.

i thought you were gonna keep the Blazer as a weekend warrior.

all those mods..............*sigh*

if its 95+ it gets decent mileage
96 is when they started vortec 350s
my dad had 95 z71 that got 12-14 on the highway
newer models are quite a bit better

If you want gas mileage and power go for something with a 5.3L in it.

^^^ definately! but that engine was never available in '97 (the year of the 'Burb he's looking @).

I get about 24mpg in in my S15jimmy with the TBI350

hey Alex, it seems like you need to get back on this thread and clarify what it was you were inquiring about, 'cause people seem to think you're looking @ an engine swap. guess a few posters haven't read your question. :icon_shrug:

it's been a bit, have you decided on that 'Burb yet? or at least gone to look @ it?

I'M NOT DOING AN ENGINE SWAP PEOPLE!!

lol...there is that enough clarification?

And Chris, I went to look at the burb last night. To my suprise it was a GMC suburban. I thought it was a chev. It was around 11pm though, so I didn't get a real good look at it. I went back today and I don't think I'm going to trade. It's the style I love, and it's fully loaded with leather and whatnot but it's just not worth what my Blazer is. As much as I want to go full sized it would be a poor deal for me. The body was in decent shape, but the rockers were starting to go (as is on my truck) and the paint was pretty faded. The interior would have been a piece of work too. It was VERY dirty. Not that that bothered me though. I enjoy detailing vehicles, so a challenge like that I welcomed. It also had a few cracks in the bumper. Overall it was a nice truck, but it had a few rust spots and overall not nearly the kind of condition that I would have hoped for.
Besides the major things, little things like not having a sun roof (a MUST have for me now lol), not having tinted windows, being 5 years older then my current truck. I'm going to make the smart choice and hold out for a full sized in better condition. Hell, maybe even a newer one when I can afford it someday.
In the mean time I need some work done to my Blazer. I have a bad random misfire now. I need a new distributor cap and rotor (luckily not a new distributor though). While I'm at that I'm going to do plugs and wires. I also need a thermostat and O2 sensor. Along with that I noticed the other day as I washed me truck the rust has finally cracked the paint along the rockers on the drivers side. This means I may be looking at some minor body work this year, and to cover that up I've decided I'll probably go 2 tone (I know, terrible right?) with black roll on bed liner below that line on the side of the truck. I think it might turn out ok though since my truck kind of has a blue/black theme going. Should be a good spring/summer for work on the truck :)

Yeah, thats my bad, I didn't read it right. I thought he was doing an engine swap..... 97 only had a 5.0 305 and a 5.7 350....

lol, yeah, i think that'll cover it Alex. :icon_razz:

nice that it's a GMC, those grill & HL's are much better looking IMO-especially on my era of 'Burb. :icon_wink:

:icon_really: seriously? your rockers are going? i know you guys tend to have a little more salt thrown on the roads than we do here in Ontario, but the only (visable) rust is happening on my back bumper (around the plastic cover below the licence plate).

mind you, i noticed last year that the front cab mounts are going the way they did on my '92 (ie; starting to rot through the floor).

you're right not to bother trading rides though. but i seriously thought you were just looking @ buying it for another vehicle, not to replace your Blazer. you're right, something better will come along, that's how i came across my current 'Burb.

hang tuff, it'll happen.

So... when are you gonna start the engine swap?

:icon_wink::icon_wink::icon_wink::icon_wink::icon_ wink:

thats because of the power to weight ratio
it takes hardly anything to get that 350 to move the jimmy
as the burb, which ways 1000+ pounds more, but more stress on the engine
but anyway, i wouldnt worry about gas mileage too much if its a 97

Damn, if I had known you needed a t-stat I would've mailed you mine for free if you wanted it. I just had to pull out my Hypertech 180* after only like 150 miles because my Hypertech Programmer said to go back to a stock rated one for their tuning.

Anywho, hold out for a better deal and just try to get more time out of the Blazer. Besides, your truck has inspired my build so much, its going to be a sad day when you get rid of it.

Chris, I was going to swap since I can't afford a full on 2nd vehicle right now, so my plan was to go full sized for now and whenever I can afford 2 vehicles buy a Blazer and make it my weekend/trail Blazer. I've changed my mind though and doing the complete opposite of that. Keep my Blazer and buy a full size as my DD whenever funds will allow it.
As for my rockers, yes mine are rotted right out. It's right behind the doors in front of the rear wheels. Keep in mind I live right on the ocean, so on top of the salt from the roads we also have the salt spray from the ocean and the endless fog. I'll try and get a pic sometime of my rust.

And Phil, thanks for the comments! I don't think Il'l be getting rid of my Blazer anytime soon. I'd like to keep it forever and make it my 2nd vehicle someday. I'm not worried about the t-stat. It's a $8 part, and right now it's not a big big priority for me lol. Thanks for the offer though!