generally how long to chevy v8 small blocks last?

[k3werra]

From what ive read the nissan L6 engines last around 200k - 250k with a rebuild in between. how long to chevy small block engines last (w/ regular maintence and moderate use of the power)? how long before a rebuild is needed? im not asking specifics just generally

[HICKL]

I got about 4000 miles out of my last one. Of course dropping that bolt into the intake may have taken it's toll.

 

Sorry, couldn't help it.

 

Good luck getting that kind of answer on a performance based site. I expect to get at least 100,000 out of a daily driver without needing a rebuild. As long as you don't do anything foolish, should be able to get a few re-builds out of any 350 block.

[grumpyvette]

that depends mostly on the level of horsepower and the quality of the parts and assembly care, and your driving style,if its nearly stock and regular maininance is done correctly and frequently (filters,& oil changes) and you keep the rpms reasonable ,youll easiy get 100k-150k before a refresh becomes necessary (rings & bearings & gaskets)

boost the hp significantly , but use decent parts and youll still get 80K-130K, (I know several 383s Ive built have over 100K currently and are still fine, (with only the standard,oil,filter,& sparkplug changes)

the secret is getting good quality forged parts correctly clearanced, installed and ballanced and keeping the oil and filters clean and frequently changed,and the heat the engine sees reasonable (IE oil temps kept under 240F and over 215F and coolant temps under 220f and over 190F) and not running the rpms into rpm levels where valve control or heat levels up to where detonation becomes an issue.

most guys will have few problems simply because your generally not useing a sports type car as your main and only transportation and most guys don,t put excessive mileage on the (TOY) they built, my 3 corvettes for example seldom see more than 10k-15k a year in drive time (each) and I drive constantly, but I generally use the parts truck for a good deal of the little trips.

btw Ive got 80K on my main current toy(1985 ,383 vette)and its showing no wear/problems, but its been dissassembled and re-assembled several times durring major parts testing

[COZY Z COLE]

I have 20,000 on mine in 5 years and my engine builder said I'd be dead before it would need a rebuild...

 

 

 

LARRY

[dr_hunt]

Engine life is inversely proportional to HP level. Lower the HP the longer it'll last. Twice the HP, half the life. If you don't believe that try using NOS on a regular basis. Another example is pro stock engines. 3 races with 3 qualifying runs and potentially 3 or 4 round runs and it's time for a rebuild!!

[Guest Gr8White]

Another big factor, and one of the biggest IMHO is rod/stroke ratio with your combination. Stroker motors are great, but you have to really keep this in mind when building a combination you want to last. I have most of my experience with the Ford 5.0/5.8 liter, and am just now getting into the LS-X Chevrolet motors, but the physics are the same and the math doesn't lie. You can easily cut the life of a motor by 50 or even 75% with a poor rod/stroke ratio. For instance, (and please pardon me for using a Ford small block as my basis for comparison) a typical small block 302 can last 100-150K if properly cared for. Stuff a large 3.4" stroker crank into the block for 347 C.I. will mean an engine life of 10-20K tops. The higher (numerically) the rod/stroke ratio is, the longer the engine will potentially last. The only good example from GM that I know of (I'm sure there are countless examples) is the 403 Olds. My folks had one in a 1977 Delta 88. The car was in the shop with only 30K miles on the odometer with the rods knocking. Doing the research, I found that these had notoriously poor rod/stroke ratios. I believe these were the motors in the 6.6 T/A's of the late 70's but I could be wrong.....Is the extra torque worth the tradeoff? You decide...

[dr_hunt]

Another big factor, and one of the biggest IMHO is rod/stroke ratio with your combination. Stroker motors are great, but you have to really keep this in mind when building a combination you want to last. I have most of my experience with the Ford 5.0/5.8 liter, and am just now getting into the LS-X Chevrolet motors, but the physics are the same and the math doesn't lie. You can easily cut the life of a motor by 50 or even 75% with a poor rod/stroke ratio. For instance, (and please pardon me for using a Ford small block as my basis for comparison) a typical small block 302 can last 100-150K if properly cared for. Stuff a large 3.4" stroker crank into the block for 347 C.I. will mean an engine life of 10-20K tops. The higher (numerically) the rod/stroke ratio is, the longer the engine will potentially last. The only good example from GM that I know of (I'm sure there are countless examples) is the 403 Olds. My folks had one in a 1977 Delta 88. The car was in the shop with only 30K miles on the odometer with the rods knocking. Doing the research, I found that these had notoriously poor rod/stroke ratios. I believe these were the motors in the 6.6 T/A's of the late 70's but I could be wrong.....Is the extra torque worth the tradeoff? You decide...

 

Oldsmobile 403's, like most Oldsmobile engines used 6 inch rods. That coupled with the 3.385" stroke puts the rod/stroke ratio at 1.77 which is pretty darn good when compared to a 350 chevy at 1.63.

 

IMO it's the rod to stroke ratio is but a small part of the overall picture and has nothing at all to do with the rod bearings failing at 20 or 30K miles.

[k3werra]

why is it that they dont last as long as the old nissan engines? i would think the new crate chevy v8 engines would last just as long if not longer than the older engines. bc of new technology and such...

[bodie]

with proper maintaince ive seen stock/slighty moded sbc last over 200k.

its not really hard for a sbc as longas your not too extrame on the motor and dont run it hot.

[Guest Gr8White]

Oldsmobile 403's, like most Oldsmobile engines used 6 inch rods. That coupled with the 3.385" stroke puts the rod/stroke ratio at 1.77 which is pretty darn good when compared to a 350 chevy at 1.63.

 

IMO it's the rod to stroke ratio is but a small part of the overall picture and has nothing at all to do with the rod bearings failing at 20 or 30K miles.

 

Hi Doc,

I respect your opinion since you already know more about GM engines than I probably will ever know. I am under the impression that this ratio is important, although I am talking about small block Fords- and the question wasn't about small block Fords. This is a bit off point but I would be interested in your opinion on the 347 CI Ford, which sports a 1.58 rod/stroke ratio. Every engine builder I know will warn you of the longevity of this combo due to the rod/stroke ratio. Do you not agree with this?

 

Back to the point, I would be interested in everyone's opinion on RPM range and engine longevity. I know that RPM is a factor due to the higher stresses, but I have always wondered if this was more of a factor due to the actual RPM the engine is turning or due to the fact that the motor is making more power at high RPM's given the same C.I. displacement....I guess my question is- Do you go with more cubes and less RPM or less cubes and more RPM to achieve the same result, and which will last longer?

[dr_hunt]

Hi Doc,

I respect your opinion since you already know more about GM engines than I probably will ever know. I am under the impression that this ratio is important, although I am talking about small block Fords- and the question wasn't about small block Fords. This is a bit off point but I would be interested in your opinion on the 347 CI Ford, which sports a 1.58 rod/stroke ratio. Every engine builder I know will warn you of the longevity of this combo due to the rod/stroke ratio. Do you not agree with this?

 

Back to the point, I would be interested in everyone's opinion on RPM range and engine longevity. I know that RPM is a factor due to the higher stresses, but I have always wondered if this was more of a factor due to the actual RPM the engine is turning or due to the fact that the motor is making more power at high RPM's given the same C.I. displacement....I guess my question is- Do you go with more cubes and less RPM or less cubes and more RPM to achieve the same result, and which will last longer?

 

IMO sb fords weak point is the 2 bolt block and the well documented history of block failure at about 500HP. Probably not a good example. Side thrust causes more wear on the cylinder wall and piston skirts, granted that, but it's not the deciding factor. Heck all the 302's I've ever taken apart had cracked piston skirts (those with cast pistons anyway)

 

Well IMO rod/stroke ratio is more important in higher HP and rpm applications than in stock form, mainly due to rpm limitations of the cam and valve train. Basically if your not going to turn over 5K rpm then it's insignificant IMO. Oldsmobile rods are like most, weak bolts. Pontiac rods (400 455) are complete junk if stock. Most stock rods have their limits goes without saying. Peak stress on the rod is at exhaust TDC and it actually pulls the rod bolts apart. This is why turbo motors do so well with the increased HP output, as the piston sees some resistance during that phase of the exhaust since the intake is open and the piston sees some pressure or resistance IMO.

 

Higher rpm will never last as long as lower rpm, period end of story.

 

Basically the internal stresses are exponential with engine rpm as a rule of thumb for the v8 and the stress at 6K is double that of 5k and 7k is double that at 6K. Obviously piston speed is a big factor and IMO is the limiting factor for the most part. That being said, that is the basic rule for cubic inches, tq and rpm. More cubes, means more tq and less rpm so you don't have to spin it to get the tq and hp that you would a smaller engine.

 

But the discussion is basically null unless you have budget constraints since the aftermarket has provided the everyday guy with options and parts that directly affect durability, like rods, cranks, blocks, pistons, heads, valves, springs, etc, etc. If we are talking about stock parts (OEM) being used to generate 500HP then yes, it's more of a factor, if not, then your basically pissing in the wind cause we would be comparing apples to watermelons.

[280zwitha383]

From what ive read the nissan L6 engines last around 200k - 250k with a rebuild in between.

 

Rebuild in between?! Shoot. SBC will last just as long as (almost) anything if you treat them right.

[280z-racer]

unless there is damage due to other issues an L6 should last 200-250k without a rebuild. same goes for an sbc. somethings to think about though especially in the gen3 sbc's. the wristpins in the 6.0's are weak from the factory so premature enging failure is possible. GM put out a fix for that. 5.3's and 4.8's had valvetrain issues which could damage them and also cause premature engine failure. 4.3 v6's which are based off of the small block had some crankshaft issues in the mid-late 90's which will cause engine failure. aside from these basic issues sbc's should last a very long time.

[Teekass]

how long to chevy small block engines last

 

The higher the horsepower, the shorter the fuse.

 

I know his question was already answered, but I've always like that saying.

[mark]

My stock 93 lt-1 lasted untill 2006. It spent the last 10 or so years in my Z doing weekend duty and track days. Regular oil and filter changes.

 

Now it's a 383 pulling the same duty. I expect it will last at least as long as the 350 did.

 

the life of a 350 with out oil pressure is about 5 seconds. Unfortunantly, I learn best from experience.

[Michael]

I bought a 454 out of a Chevy Suburban with something like 130K miles. I did a cam swap, and got maybe 20 miles out of the engine before wiping the cam.

 

Years later I rebuilt the engine with some pretty high-quality parts, but the cam sprocket bolts (not the 3 that hold the cam timing gear to the camshaft, but the rosette of 6 which hold the 2-piece adjustable timing gear together) worked loose, dug into the aluminum timing cover and scattered aluminum shavings all over the engine’s oil path - after 43 miles of driving.

 

Engines fail early because owners are incompetent, complacent or just plain unlucky. While there are the occasional bad apples, a blanket statement that “Brand X engines fail much more readily than Brand Y engines†is, in my opinion, pointless.

 

That said, if I kept the original L6 in my Z it might still have been running…

[A. G. Olphart]

There seems to be some validity in thinking Datsun L6 goes a long ways, and SBC may not. Strictly personal opinion, but I think the average Japanese block is harder, so it doesn't wear as quickly.

 

GM has a history of building stuff to sell, and seemingly provided better quality where they felt it was needed/justified. (For example, the Gen I "10/20" blocks, with their higher nickel/tin or tin/nickel... I forget which number represented what content).

 

A friendly machinist might be able to confirm/deny or expand on this.

 

Don't have any idea how the current stuff may last.

 

 

<>

[Guest Gr8White]

Engines fail early because owners are incompetent, complacent or just plain unlucky.

 

Hmm, so top fuelers are incompetent and complacent since their engines only last 1 pass?

 

Then again, I guess "early" in this case would be the 330' marker!

[BRAAP]

When comparing the Domestic V-8’s to pretty much any import, whether it be the Datsun L-series, or Toyota, Mazda, Honda etc, the metallurgy used Japanese engines was, for a better word, better suited for long engine life compared to the domestics. I’ve torn down many L-series with well over 200,000 miles and the cross hatch from the factory hone operation is still present, at least in 80% of the bore, and no ridge at the top. Some domestic V-8’s and at 100,000 miles a huge ridge at the top. Not all of that is due to metallurgy. A huge influence on engine wear is maintenance such as tune ups, air filter and oil maintenance and also owner/driver habits, such as revving the engine immediately after initial start up. EFI has played a HUGE role in engine wear and the ability for oil changes to go past 5000 miles with NO ill effect. Complete combustion with no misfires makes for a very happy long lived engine, no matter what part of the world it was manufactured. The piston rings and cylinders, valves etc will live a long happy life. Throw on a carb that is out of tune, an ignition system that is not up to snuff, now you have fuel wash, diluted oil, rings that don’t seal completely due to misfires, etc. engine wear just increased dramatically. Also, firing up the engine and revving it up immediately after start up adds considerable wear to the bearings, rings and cylinder walls.

As for the domestics and metallurgy, a person can acquire over the OE parts counter, blocks, cranks, rods etc that utilize similar and even tougher metallurgy than the imports used. This is through the performance parts divisions of those domestic manufacture such as Chevrolet, Ford and Chrysler. Even the Aftermarket has addressed this as well.

 

Any how, engine life is a two part equation. First part being metallurgy, the second part being proper maintenance and care, even if the engine is driven hard, as long as proper tune ups are kept up, air filter and oil maintenance is kept up, the engine will last a long time. It has already been covered that when an engine is modified to work harder, i.e. produce more Horse Power, the lifespan is shortened, depending on how far this taken of course.

[randy 77zt]

i changed out a tbi 350 chevy in a 3/4 ton truck with 500,000+ miles on it.truck had a fold down repo rig in the bed and was on the road 12+ hours a day.truck had oil changed once a month.my 96 e 150 van has 177,000 and runs strong -uses 1 quart per 5,000 miles.between efi systems and better oil a car that has oil changes should last 200,000.its usually the auto trans that goes first