So you're saying you think you have a 58x reluctor wheel with a 24x PCM and it's just hard to start?? I don't see any way the car would even run. I quite sure your problem lies elsewhere. I have seen warped reluctor wheels cause the problem you're describing.

 

sooo... LS2 or LS3?

 

If you wouldn't mind, could you tell us more about how many HPDE events you ran & with what mods (tires, oil cooler, sumps, what wt oil, qt over, programming, etc)? I thought the LS6 & trans were pretty stout as long as the car was near stock trim & the temps kept under control.

It always seems as if it's #7 that goes--I had my timing pulled back a bit in the PCM because of that very reason. I ran it to 282 F oil once this last year and I just sent out the oil for analysis, we'll see what it tells us.

 

If you are going to go road racing I would look for an after-market forged LS-3. It just makes more sense in the long-run and you can get the correct reluctor installed.

My brother is going to stuff a forged LS-3 416 into his 2001 vette. If you spin the wrenches yourself you can probably get something for around $8K, which is not too bad.

I know if my motor ever goes I am going to look into the LS3 also.

 

Road racing as track days? LS2 for sure. If you do the LS3 you will also need a bigger radiator, and oil cooler/ accu-sump combo, which are not a bad idea anyway.

LS3s run very very hot.

 

If you wouldn't mind, could you tell us more about how many HPDE events you ran & with what mods (tires, oil cooler, sumps, what wt oil, qt over, programming, etc)? I thought the LS6 & trans were pretty stout as long as the car was near stock trim & the temps kept under control.

It always seems as if it's #7 that goes--I had my timing pulled back a bit in the PCM because of that very reason. I ran it to 282 F oil once this last year and I just sent out the oil for analysis, we'll see what it tells us.

I tracked this car since 2003. I bought it new in 2002. I ran it completely stock for 2 years. I ran 2003-2004 about 4-6 events a year. Mostly Pocono and Watkins. Once I got to the advanced group I started some mods. LG Long tube, high flow cats, cam, dual comp springs all with a tune, CAI Callaway. Suspension was Hotchkis sway front back and Bilstein Sport shocks. #7 piston is known to be a problem and this year it let loose and exploded. With the setup I had I ran from 2005-2008 about 45 HPDE events so I am not disappointed. The tranny swap was a choice due to a grinding that started at Watkins this year which I did find the pilot bearing in the clutch was most likely the culprit that I thought was a syncro issue. Due to the time/labor I decided to bite the bullet and swap that out since eventually the tranny does become an issue for track cars (not in all cases). I have run Nitto Extreme II, but I prefer Hoosier R-Compound. I also run Hoosier Rains. Both Nitto and Hoosiers are great. The old motor I ran Mobil-1 10/40 and Redline High Temp ATF and High temp gear oil with GM additivie for rear-end. In the new LS3 I run Lubrication Engineer Oil LE 10-50 with Synergyn oil additive. The oil is the recommendation from the engine builder that builds and has built motors for circle track cars and formerly for Ricky Hendrick Motor sports and he told me to use this! New motor: without oil cooler temps on the street running 253 now with EOC 190. Accusump was an insurance to avoid starvation with the fast tracks like Pocono, VIR, Watkins etc.. the reluctor wheel issue is still there I believe the ealier post may be a solution for this problem. Other than starting the car runs great. Motor is detuned some I did send oil out to Blackstone at 1500 miles all is good and "normal". I am sending it out after Road Atlanta this week.

 

#7 goes do to poor oiling in and around that cylinder - An accu-sump and oil cooler do the job

#8 goes do to poor block cooling or guys just running coolant temps for too high and too long.

High coolant temps (above 210*) and high oil temps ( above 250*) are not good things.

Keep the radiator clean of any debris. I blow the radiator clean be fore each track weekend

 

Well if you are willing to get a 427 then buy a Warhawk block its a bit more but no kaboom.

 

I go back to the beginning and ask what are you using the car for? Planning your engine upgrade starts with a budget. I am pleased with the performance and life of the original LS6 motor. I did some top end work to strengthen the weak areas. Did oil changes before every HPDE event. Every year tranny and rear-end fluids got changed. Clutch fluid changed (not the turkey baster method I added a remote bleeder). All this is overkill for a street car. I believe with this type of maintnance you can get a lot out of the LS6 if you want to have a great HPDE track car. If money was no object there are a lot of choices out there for a motor. However I am not sure if there is such a thing as "bullet proof" motor.


Chevrolet Corvette 427 Blocks - The Great Cylinder-Block Debate
Race-Designed C5-R Or Economical LS7: Two Choices For Building A 427 Street Engine


writer: Barry Kluczyk
photographer: Barry Kluczyk




Between 1999 and 2005, the Corvette C5-R racing program annihilated the competition in the American Le Mans Series. The team collected 45 wins in 66 starts-a win ratio of about 70 percent. It will certainly go down in history as the most auspicious racing program in the Corvette's history.

Much of the credit for those continuous wins can be ascribed to the fortitude of the powerful C5-R 7.0L racing engine. The C5-R was based on GM's Gen III small-block V-8 but featured numerous enhancements designed to provide the strength needed for daylong endurance races. It was also designed as a structural member of the Corvette C5-R race car's chassis.



The LS7 block is based on the same casting as other Gen IV engines, including those with the cylinder-deactivating Active Fuel Management (AFM) feature. The cast towers of the LS7 are carryovers from Gen IV engines with AFM, but because the engine isn't equipped with it, the towers aren't machined.
After some internal prodding by far-thinking employees and external begging from some deep-pocketed enthusiasts, GM Racing released the C5-R cylinder block for civilian use through the GM Performance Parts (GMPP) network. Weekend racers and street enthusiasts rejoiced-and winced. The retail price for a C5-R was (and is) more than $6,000. That's just the cylinder case, mind you-not a whole engine. Granted, for the money, one receives a race-prepped block with some serious hardware. To date, about 500 C5-R blocks have been purchased outside of the Corvette racing program.

A paradigm shift in affordable big-inch LS engines has taken place with GMPP's release of the LS7 cylinder block (PN 17802854). Like the C5-R, the LS7 block is an aluminum block that enables the construction of a 427ci engine. The LS7's production manufacturing, however, means it costs substantially less than the C5-R block. In fact, at around $3,200, the LS7 block costs about half as much.

This is huge. It opens up a new world of engine-building possibilities for those who have trouble rationalizing a $6,000 charge on the American Express card.



The C5-R block doesn't have AFM provisions.
The High Cost of Racing
Invariably, the question is begged ... if the LS7 is half the price of the C5-R block, is it only half as strong or half as good? Not at all, according to GM Racing's Bob Cross. "The C5-R block was originally designed only for competition use, so it features a lot of exotic production treatments and racing hardware," he says. "This block was never intended to be offered to the public, and its cost reflects the processes involved in its manufacture."

In other words, the cost disparity between the C5-R and LS7 has less to do with what the LS7 lacks than what goes into manufacturing the C5-R.



The LS7 block's rear bulkhead has a cast-in reminder of its intended displacement.
"Keep in mind, the LS7 was designed to support up to 650 hp," says Cross. "The C5-R was designed for 750 normally aspirated horsepower, but it also had to integrate within the chassis as a structural member and last for 24 hours of all-out competition."

Admittedly, those are performance parameters most private enthusiasts won't push-making the LS7 look even more like a value. One of the caveats of jumping onto the LS7 bandwagon is the current absence of an over-the-counter controller from GM for the engine. But just as engine builders have adapted stand-alone systems for their C5-R-based engines, so too will they find a workaround for LS7-based buildups. FAST, for example, recently introduced an adapter that allows the factory LS7 MAF to clip onto the LS2 wiring harness, making the swap that much easier.



The large hole at the rear of the Gen III-based C5-R block is a boss for the camshaft-position sensor. The LS7 block is based on the Gen IV design, which also includes the LS2. Gen IV engines have a front sensor mounted in the timing cover.
Side By Side
There are obvious differences between the LS7 and C5-R blocks. Production differences include details such as varied external ribbing-the C5-R has increased ribbing because the engine was designed as a structural member of the race-car chassis-and conventional (LS7) versus screw-in (C5-R) galley plugs. The major differences are the ones that account for much of the price disparity between the two blocks.

To begin, the C5-R block is cast with a very specific recipe of 356M aluminum. Once cast, it is heat-treated and hipped. Hipping, a reference to hot isostatic pressure, is a procedure in which the block undergoes a multistep treating process that pressurizes, heats, and cools it to ensure strength and all but eliminate porosity. Approximately 20 percent of the C5-R block castings that undergo this expensive (several hundred dollars per block) and time-consuming process are rejected. The production LS7 block doesn't receive this treatment, but it also wasn't designed for professional endurance.

 

Thanks for the info! We'd all do well to get that much time out of that motor. Did you have oil coolers or accusump on the LS6? How long--just after the mods for advanced? You mention accusump but that's after you mention the LS3 replacement. What at VIR would cause starvation? I can see Pocono is an issue because of the NASCAR banking.

This is great stuff for everyone to learn about.

 

I did not have an oil cooler or accusump on the LS6. Oil temps would get to 290, but from everything I was reading and folks I talked to this was not a problem. The interesting thing is the motor blew on my cool down lap at CMP. The air temps were 75 degrees and it was raining and I was running on my Hoosier rain tires. CMP is not a really fast track but when the motor is going to go I guess it does not matter how fast you are running. I had no warning either the car that day was really fast and running well. Lesson learned: should have put an accsump on the LS6 and likely the oil cooler as well. A little insurance does not hurt! VIR is a fast track especially in areas like coming around the "oak tree" the hill is steep and you are hard on throttle coming out of that turn. VIR is where the new ZR1 was tested.

 

Exactly. 260 is MAX for oil temps. Over that you need an oil cooler and an accu-sump.

CMPs T7 ( Hope, Faith and Charity) turns are more then fast enough to cause oil starvation.

any one who tells you that the engine can take more has never run hard enough

YES the oil can take those heat ranges, but the engine cant, especially on high speed sweeping corners.

as far as engine blocks. for a street 427 the LS7 is perfect. for a race engine the C5R block or for the budget minded a resleaved LS2 block 402/ 403 is perfect. The iron sleeve makes for one very stout engine. or 383 or 408 iron block. These will make some great HP race motors.

What a lot of ppl dont understand or want to understand is high performance engines need to be rebuilt every so many races or hours of use. Not miles but hours of use.

Unless your running a chevy create motor, plan on some engine rebuilds and major inspections each winter.

I normally run 8 to 15 weekends a year. past year excluded. My LS6 motor runs about 400 rwhp and 400 rwtq. I pull the heads off each winter, check the valves and replace the springs.

have about 22,000 hard 3000 to redline track miles. The best mod I have done was the oil cooler accu-sump combo and tranmission cooler

 

^^Already have the bigger radiator and oil cooler. Putting on an accusump would not be too hard.

 

Go to David Farmer's website for tips on accusump installation!

 

Good Deal. I know one guy who went though 3 create LS3s this year alone road racing

Finally GM changed the LS3 valves to the C5Z06 style valves and voila no more problems.

He says the LS3s run very very hot compared to the LS6s

 

Thanks again for the feedback. Amazing that the LS6 held up to 55 events (110 days) without coolers! Obviously it's better to have the cooler but for those of us who run on stock tires and only run 1-3 events per year, I just don't think it's worth the expense.

It sounds like if you keep it down to 260 oil you are good. I almost always do except for the one event in the 90 deg July heat. Short shifting works. Guess I have to watch it coming out of oak tree--should help to keep the throttle & rpm down.

 

Oak Tree is a 3rd gear corner. If your in 2nd you going to slow around the corner.

Only time 2nd gear is need on VIR is if your in traffic other wise VIR is a 3rd and 4th gear track.

Even some of the faster guys who have tried 2nd in Oak Tree and T4 were not any faster then just staying in 3rd gear and using that great low end tq the vettes have.

 

The LS3 is one hell of an engine sounds like a good idea to me. Give the guys at Mast Motorsports a call. They are doing some great things with those engines. Im sure they can help you out in some way. Ask to talk to Shaun and tell them Ryan sent you.
866-551-4916

 

When you consider the abuse my LS6 motor took along with driving the car on the street I was not disappointed. I would like to see how many other cars can take the abuse and have 43000 miles on it before it they have problems. Thanks for all the comments and feedback especially AU N GEL. I am at Road Atlanta right now and I will be on track 8:30 AM Saturday! Wish me luck!