RC45

Title says it all.

What bit of the stock GM dry sump system for the LS7 is the weak link?

The sump, the pump, the tank?

I know they can all be upgraded, but I am interested in what bit/bits MUST be upgraded.

I am looking to do a combo stock/ARE dry sump setup for the LS7 in my C5 Z07.

JoesC5

Nothing you listed has failed on my 09 Z06, so I don't see any of them being a weak link.

smbstyle

from what i have read, it appears most people upgrade the tank itself so it is a higher capacity. I know ARE has a full stage III setup that pretty much replaces pretty much all the OEM dry sump components. all depends how far you want to go.

RC45

I am hoping to address any future oil starvation issues on track. I am 580rwhp, sticky DOT R tyres, coilovers, full front and rear ground effects - enough hardware to drum up oil starving cornering G's I hear.

I was thinking of an Accusump setup - but wanted to get feedback on what the weak link int he LS7 dry sump setup is first.

Stock LS7 pan and tank and ARE pump or ARE sump and pump and stock tank? Just thinking out loud.

If money where no object then an ARE Stage III would already be installed

Painrace

It depends on how you drive the car. If you are fast, you need the ARE tank, extra pump, Katech replacement oil pump, ARE pan and larger lines. We also relocated and increased the size od my oil filter. I tracked my C6Z twice with the stock system and saw oil pressure and volume was an issue.

Jim

Michael_D

The suction line origin point on the pan......

FrankTank

I thought this was more of an issue on earlier year Z's? 06-08

GM upgraded the system in 09 correct? Is the system still not up to par in the newer models?

Unreal

Not for a full track car.

JoesC5

My Z06 is a 09 with the larger 10.5 qt reservoir. I've driven it through the 1100' radius curves at Talladega at 140-145 MPH and didn't have a problem. That's a pretty long sweeping left hand curve at high speed which everyone reports is the problem. In fact I saw plenty of wet sump C5's and C6's doing the same corners with no oiling problems. I didn't see a single engine failure the two times I've been on that track.

BEZ06 has a video of his 2006 Z06 with the 8 qt reservoir, driving around the 1,000' radius left hand turns at Daytona at 145-150 MPH and he didn't blow up(at least while he was taping his run), that I know of.

Bill Dearborn

The G Loading on the banked tracks may not be the same as on a flat track where the G forces are more lateral. From what I have read on the forum the people who have increased the reservoir capacity by installing the LPE modified tank haven't had any issues. It seems the issue is the amount of oil in the system Vs the amount of time the car is in a high lateral G turn. The problem with all LS engines from the beginning has been long high G left hand turns where all of the oil gets pumped up in the engine and the engine basically runs out of oil. According to All Corvettes are Red during testing of the C5 there were multiple engine failures due to oil starvation and the that is why the 97s came with the winged pan. On the wet sump engines GM has always recommended running a quart over if running on a track. So it seems it is a storage capacity issue for LS engines that happen to see a certain type of operation. You don't hear of any starvation problems from people who run on road courses where there are long right hand high lateral G turns.

Bill

40YRW8

My quick opinion is tha the the real weakness of the stock system is the scavenge side of the pump doesn't have enough capacity to keep up with demand from the pressure pump. If the pan had zero volumn, then running 20 or so percent greater scavenge volume over pressue volumn would not be an issue. However, I think that since a lot of the oil gets forced away from the scavenge pickup it gets behind the "Power Curve" of the sysetm and it pumps less actual oil than the pressure side and the volume of the tank goes down. A couple of extra quarts in the new tanks doesn't solve the problem but buys you a little more time until the g load relaxes and allows the built up oil volumn in the pan to slosh back to the pickup. I think that if the car continued to sustain the g load for a longer amount of time, such as running in a true circle, the problem would return. More scavenge volumn would help with the problem and so would a two (or multiple) stage scavenge pump with a pickup on the other side of the pan. That is why race type dry sumps have one pressure stage but 3, 4 or sometimes 5 scavenge stages. Anyway, if the two extra quarts of oil solve the problem with the stock cars, anything else is just insurance or, if weight and cost are a major factor, overkill.
Gary

JoesC5

My understanding is that because of external body design criteria, the C5 had to have the engine placed low in the chassis to allow for a very low cowl. In order to have the shallow oil pan hold enough oil(6 qts) they had to spread the pan out(thus the wings), because they couldn't go with a normal depth oil pan(ground clearance). When they designed the LS2 engine, they still had the ground clearance problems but found they could get rid of the winged oil pan from the C5 and decrease the oil capacity.

While the dry sump pan of the Z06/GS/ZR1 has the same depth oil pan as the wet sump oil pan, the actual sump itself is very small, so a little oil in it has some depth to keep the pickup covered as much as possible and it helps keep the oil from climbing the walls during the high g turns. The small sump keeps the oil at the mouth of the pickup. As long as the oil is draining back into the sump, the reservoir will stay full and the engine will have plenty of oil supply for the second stage oil pump.

With the 10.5 qt reservoir, and the Z06 oil pump pumping at 27 gals/min, it would take 23 seconds to drain the reservoir dry. That's if no oil was being pumped from the engines oil pan sump by the first stage oil pump back to the reservoir. But we both know, that the oil pan sump is being continuously emptied and the reservoir being replenished with oil, so the 23 seconds is expanded by quite a bit.

At Talledega, it takes ~8 seconds to complete turns 1 & 2 or 3 & 4 at 150 MPH. That's calculated based on 180 degrees at a 1,100' radius and driving 220 ft per second(150 MPH)

RC45

So would an '09 or newer stock LS3/7/9 dry sump setup be able to get the task done?

Bill Dearborn

Again a high speed banked corner isn't as much lateral load as vertical load. On a flat surface the speed may be lower but the lateral Gs may be higher since a Z06 with R compound tires can pull a consistent 1.3 lateral Gs. Jim Schefter writes on page 342 of All Corvettes are Red the development team found out the C5 LS engine couldn't pass a standard skid pad test done by the car mags. Oil would pump into the heads and the oil pressure would drop. They had to increase oil capacity but the hood height limited the depth of the pan so they added the winged pan which still didn't stop the starvation until they added some baffles in the pan. As I said before the problem seems to be endemic to all LS engines and they are still trying to perfect a solution to a problem they discovered in 1996. Schefter even finishes one paragraph stating this wouldn't affect real world drivers unless they drove on a racetrack.

Bill

FrankTank

Joe and Bill, very interesting discussion.

I do LOVE me some Talladega, I go to the fall race almost every year. I gotta make it down when the vette event happens again sometime.

I am very interested in the point about a high bank turns, vs flat turns and the G's

JoesC5

Driving on the Texas motor Speedway(24 degree turns at 750' radius), I feel more lateral g's compared to Talladega. At Talladega, I feel more vertical g's at lower speeds(100 MPH) but as I get close to 145 MPH, I can feel the lateral g's increasing.

The reason you can hit a higher speed on the high banked turns is that the radius measurement becomes 3 dimensional, causing the effective radius to increase vs measuring it 2 dimensional, as on a flat track. I tried to see what my g meter was reading on the HUD last time out at Talladega, coming out of turn 2 at WOT, but the glare on the windshield washed out the HUD( plus I didn't want to spend to much time trying to read the HUD at that speed).

But I know what you're saying about the banked turns vs flat turns.

I'm going to Daytona in December and maybe I can get a HUD g reading there. BEZ06 was running his stock 8 qt 06 Z06 around the turns at Daytona at 150MPH without any problems

Another thing is that, on the ZR1, the oil pump is rated at 33 GPM(vs 27 on the Z06) because of the piston squirters. Combine that with the new cup tires available for 2012, and the car should be able pull higher g's. Apparently GM isn't worried about running the reservoir dry during high g, sweeping left hand turns on the 2012 ZR1.

Of course, if one builds their car way beyond the design limits that GM placed on the car, all bets are off.

track junkie

Correction it would take 5.8 seconds to drain the reservoir dry with the 10.5 qt reservoir or 4.4 seconds with the 8 qt reservoir.

JoesC5

You are correct. I forgot to convert the 10.5 qts to 2.5 gal before doing the math. But as I said, the first stage pump is still sucking the oil pan sump dry and replenishing the reservoir during that time. I find it hard to belive that the oil pickup would be sucking nothing except air for more then 5.8 seconds going around a curve.

wstrysko

Will a accusump system on the LS7 help with pre lube to protect the valve
guides that get worn out on these engines ?