"SBC's" vs the 4.7L, Toyota V-8

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Aug 2, 2002
Apologies to all my fellow mechanical engineers at GM ....

I actually gave some thought to this bias in wear rates instead of shooting my mouth off.... There are three main reasons why Fe levels are significantly higher in the 5.7L,GM Vortec engines:

1) They use a fully lubricated timing chain and gears and not a timing belt and cogs that run completely dry. I suspect this GM chain generates lots of the iron wear you see....Do an oil analysis after a timing chain swap and I bet iron levels are through the roof!

2) The valvetrain uses a roller, pushrod and rocker arm between the cam lobes and the valve lifters - these are all ferrous materials that wear....The cam lobes on the DOHC toyo engine push directly down on the valve lifters, ie there are simply less wearing parts with this type of design ....

3) The GM engine has 20% more displacement, which translates into more "swept" cylinder wall area and more iron wear.

Thanks for this post Ted! I always felt that even though the GM V8s showed higher iron in the UOAs, that they were still very durable motors, as the testimonials from actual owners getting long lives out of them are pretty much proof that these things go a while.

I still think it's possible to have a relatively low iron number though, I've had as low as 5ppm of iron in a 3300 mile sample in my LT1 V8.

My next two UOAs should show a lot less iron than my last one, due to the weather being warmer.
Not too many mention chains and iron (we do talk alot about rotating impact wear in push rods and cams....)....good points for changing the ol' break in oil on wet timing chained cars a bit early.
Lots of engines use timing chains and don't have high iron...Nissan, BMW, I really thought the Toy V8 did but maybe not.
They are about the only ones still building OHV engines though!
Has anyone looked to compare the SBC numbers with a typical small block Ford or Chrysler? That should help ( or not? ) support Teds observations. We have lots of SBC UOA's but few on other brands with similar designs...
Could this be why newer Saab turbo engines typically exhibit high iron? I know my older Saab N/A engine showed relatively low iron on its first-ever UOA, but it seems like all the newer turbo UOAs show iron thru the roof.

Is there an oil choice which might mitigate this characteristic?

Thanks for the insight, Ted!

Yeah, but the Toyota has a bunch more cams located higher up in the engine. Wouldn't that create more Fe wear, especially on startup?
It also has twice as many valves/valvesprings/.......

On some DOHC engines, there are also gears or chains that drive one cam off of the other. Anyone have a parts blow up of the 4.7L?

I think we should quit looking for excuses for certain automakers engines.

My only question is, why bother comparing the SBC to the 4.7?
The 5.7 shouldn't even be able to compare to the 4.7.
How about the smaller GM V8's?

Anyone have a UOA on a blueprinted and upgraded SBC to compare to a stock one? Makes me wonder if its an oil PSI issue, a parts supplier issue, or poor balancing and clearance selection(let alone tolerance levels).

I can't wait 'til Toyota comes out with and engine in the 340-360 CID range.
Isn't Toyota coming out with a 5.4L eight for the next gen trucks? Probably for the bigger trucks i.e. Tundra, LX, GX, 4Runner, etc.
We have UOA of blue printed Gen II blocks. I belive SBC350Gearhead has a nicely blueprinted SBC. I suspect that this engine has been blue printed. It has been my experince that the GEN II's once blue printed and built with top notch parts wear excellent! The only GEN III blocks we have seen blue printed have been built well beyound the normaly power density we would see on an OEM engine and they are being auto-x'ed or drag raced?

THe Gen III engine has a lot of potential!! I think that in the end material selection and treatment like heat treatment, moly, nitride coating etc.... are just as important as design.

I am hopeing that the new high content 3.6 will adress some of my concerns about the Gen III.
I've said it before, but I'll say it again: I honestly think when comparing different engines, the differences in the UOA's between them mean very little in terms of how long one engine may last versus another.

As pointed out above, there is more than one way to skin a cat. One may produce higher wear metals than the other, but so long as the engines are designed on a similar target for durability, that wouldn't matter.

A classic example is the Jeep 4.0 inline six. Very commonly produces iron wear that most people cringe at, yet we all agree they will pretty much last forever so long as any oil is used at all!

I see wear metals as being a pretty engine specific comparison. Things like vicosity retention, TBN, etc, seem less dependant.

Originally posted by MNgopher:
I've said it before, but I'll say it again: I honestly think when comparing different engines, the differences in the UOA's between them mean very little in terms of how long one engine may last versus another.

This is exactly what I've been saying all along. I never disagreed with the fact that Toyotas are very well built and very long lasting engines.

What I disagreed with was the assumption that GM V8s didn't last long because their UOAs typically show higher wear metals. My point is that on the road you do see a huge number of high mileage GM V8s.
Iron or not. I'll take an LT1 or LS1 over pretty much any other V-8 any day. They make gobs of power and torque, they are relatively inexpensive to maintain, relatively easy to work on, there are tons of parts available to modify these motors AND they last a good long time.

Send all your unwanted LT1 and LS1 motors to me please
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