Overfill Corvette if racing?!

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I am thinking about acknowledging my midlife crisis and buying a Corvette. I downloaded a 2008 owners manual and noticed this:

Except Z06: Be sure to check the oil level often during racing or other competitive driving and keep the level at or near 1 quart (1 L) above the upper mark that shows the proper operating range on the engine oil dipstick. After the competitive driving, remove excess oil so that the level on the dipstick is not above the upper mark that shows the proper operating range.
 
Same for Honda S2000, many S2000 owners race their car and they overfill the crankcase by 1/2 quarts or a little more, from 5.2 quarts to 5.7-6.0 quarts.
 
I find this advice a bit unexpected. I would expect overfilling to be more problematic on the track where greater G-forces will slosh the oil around more compared to street driving. If you may add an extra quart for track use without ill effects, why not do the same for street use?

hotwheels
 
Oh...you just wait until someone lose their bearings because of overfilling---crankshaft starts churning the overfilled oil inside the pan, which the oil pickup tube picks up the air bubbles and then send them all over the oil passage, and into the crank bearings where the load is great...then wipe the crank bearings off....

The proper way to do this (racing) is to get custom oil pan with extra baffles built to overcome excessive turning related sloshing, and not just by adding a quart over the full mark into your oil pan.

Q.
 
The over filling is recommended because at high rpm, ,the heads are going to fill with oil,,and the sump level will sink.

This is why the R35 GT-R has electric pumps on the cylinder heads to suck oil out and return it to the sump. Gravity can't keep up with the oil pump's production.

This is very common in engines of all types.
 
Originally Posted By: splinter
^ Instructions are to 'overfill' the circuit's remote reservoir as the Z06 and its variants are so-called dry sump equipped.


The instructions are for non-Z06 cars. They're wet sump.
 
Originally Posted By: typ901
I am thinking about acknowledging my midlife crisis and buying a Corvette. I downloaded a 2008 owners manual and noticed this:

Except Z06: Be sure to check the oil level often during racing or other competitive driving and keep the level at or near 1 quart (1 L) above the upper mark that shows the proper operating range on the engine oil dipstick. After the competitive driving, remove excess oil so that the level on the dipstick is not above the upper mark that shows the proper operating range.


Yep. It's been SOP for guys tracking their LS-equipped cars to overfill the sump. I've been doing this on my Camaro for 10 years, but have found that at 1 quart over full, the oil carries over into the PCV system, and I get a big belch of oil smoke out the exhaust on the next startup. So I just overfill by 1/2 quart, and check/top-up the oil before every session. But I never have followed the instruction to pump out the excess oil for street use. It burns down the excess eventually.
 
Originally Posted By: A_Harman
Originally Posted By: typ901
I am thinking about acknowledging my midlife crisis and buying a Corvette. I downloaded a 2008 owners manual and noticed this:

Except Z06: Be sure to check the oil level often during racing or other competitive driving and keep the level at or near 1 quart (1 L) above the upper mark that shows the proper operating range on the engine oil dipstick. After the competitive driving, remove excess oil so that the level on the dipstick is not above the upper mark that shows the proper operating range.


Yep. It's been SOP for guys tracking their LS-equipped cars to overfill the sump. I've been doing this on my Camaro for 10 years, but have found that at 1 quart over full, the oil carries over into the PCV system, and I get a big belch of oil smoke out the exhaust on the next startup. So I just overfill by 1/2 quart, and check/top-up the oil before every session. But I never have followed the instruction to pump out the excess oil for street use. It burns down the excess eventually.

I basically do the same thing in all of my LS engines. I overfill by 3/4s of quart, it's good for them, never had a problem.
 
But... but what if I drive my car on the street as if it were on the track?!
grin.gif
 
Originally Posted By: A_Harman
Originally Posted By: splinter
Indeed. And M1 15W-50 recommended when beating on 'em!


http://www.chevrolet.com/content/dam/Che...ackPREP_v23.pdf



I love this instruction:
Limit the vehicle load to the driver only, with no other cargo and inflate the tires to 26 psi (180 kPa); drive at a maximum speed of 174 mph (280km/h)

Hey, I would if I could. Mine only does 168. I need to work on that.
Find a few miles of down hill road!!
sick.gif
 
I began overfilling at road courses over 40 years ago on the advice of the old timers there.

Conversely we always used to underfill at the strip!

Most higher performing cars that are truly track ready have extensive baffling in the pan to address this. I do not have to do a thing to the 6.1, it comes ready to race...
 
C5 Corvettes (1997-2004) have software which limits speed if you drive too fast in a continuous circle (skid pad), so oil won't build up in sump/heads and starve the engine!

They do have baffles to prevent this in normal driving, but the testing and design was extensive, they thought of everything possible!

The book "All Corvettes are Red", details the design and development of the C5, a great read if you are interested.
 
Last edited:
Originally Posted By: SteveSRT8
I began overfilling at road courses over 40 years ago on the advice of the old timers there.

Conversely we always used to underfill at the strip!

Most higher performing cars that are truly track ready have extensive baffling in the pan to address this. I do not have to do a thing to the 6.1, it comes ready to race...


See my post above, not to be critical, but your SRT8 is not capable of the road handling performance of a Late model Corvette. The overfilling is due to oil not draining from heads when kept at high rpms and applies to all cars/engines, except those with dry sumps. Corvettes have baffles in their oil pans for normal road racing and are capable of pulling over 1g on skid pads!
 
Originally Posted By: Quest
Oh...you just wait until someone lose their bearings because of overfilling---crankshaft starts churning the overfilled oil inside the pan, which the oil pickup tube picks up the air bubbles and then send them all over the oil passage, and into the crank bearings where the load is great...then wipe the crank bearings off....

Q.


Overfilling by one quart will do no damage. The Mfg. have the scenario already accounted for when an absent minded owners puts in too much oil. If you've ever had an egine apart and look at the distance between the crank and the oil level you know what I mean
 
I'm sorry blue but the logic simply doesn't make sense.

So, you are saying that GM sez overfilling 1qt (or 1Litre) poses no harm but you must(?) drain it out after racing; then ordinary "full" mark must be 1 quart low and that's considered normal?

In other words: GM designed that engine/oil pan to be underfilled as normal?

Given that logic: why not ordinary owners simply "overfill" it by close to 1qt above "full" mark and consider that the regular normal?

*confused*

Q.
 
Originally Posted By: Quest
I'm sorry blue but the logic simply doesn't make sense.

So, you are saying that GM sez overfilling 1qt (or 1Litre) poses no harm but you must(?) drain it out after racing; then ordinary "full" mark must be 1 quart low and that's considered normal?

In other words: GM designed that engine/oil pan to be underfilled as normal?

Given that logic: why not ordinary owners simply "overfill" it by close to 1qt above "full" mark and consider that the regular normal?

*confused*

Q.

I suppose they found that the heads are going to have a quart or more of oil in them under typical track usage(high rpm), so its possible to starve the oil pump in some cases with the normal amount of oil. But when idling around on the street, there's no oil in the heads and the extra quart may get into the crank and foam the oil?
 
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