Camaro XV

[PTAddict]

Originally Posted by Track Junky

I'm probably going to step out on a real thin limb here but I dont see the purpose of running coolers for rear diff, power steering, and trans when you may run 25 minutes a session at most?

I'm running a NA LS7 with a lot less HP than Mark - about 600 - and I certainly can't drive my car as close to the limit as he does his But I still find PS and trans cooling to be essential for Summer track days, I think partly because temps never return to baseline between sessions. By the 2nd or 3rd sesssion, both steering and shifting went to hell by 10 minutes in without coolers. My diff temps are marginal - 260 - 280 with synthetic fluid - and I haven't added a diff cooler yet.

[Track Junky]

Originally Posted by PTAddict

I'm running a NA LS7 with a lot less HP than Mark - about 600 - and I certainly can't drive my car as close to the limit as he does his But I still find PS and trans cooling to be essential for Summer track days, I think partly because temps never return to baseline between sessions. By the 2nd or 3rd sesssion, both steering and shifting went to hell by 10 minutes in without coolers. My diff temps are marginal - 260 - 280 with synthetic fluid - and I haven't added a diff cooler yet.

I'm running an NA 427 620/560 to the crank and my KRC aluminum PS pump has treated me well so far since 2002. My trans is spec'd for Royal Purple by the builder and I change fluids after every track day and the oil still looks good. Trans in car since 2006. No cooler for rear diff either and car is used strictly for time trials on road courses. Same Eaton carrier since 2004.
This is why I asked the question.

[PTAddict]

Originally Posted by Track Junky

I'm running an NA 427 620/560 to the crank and my KRC aluminum PS pump has treated me well so far since 2002. My trans is spec'd for Royal Purple by the builder and I change fluids after every track day and the oil still looks good. Trans in car since 2006. No cooler for rear diff either and car is used strictly for time trials on road courses. Same Eaton carrier since 2004.
This is why I asked the question.

Yeah, I think the experiences on this can be quite variable. For instance, I think the T56 trans in 1st or 2nd gen is likely to be more vulnerable to overheating issues, due to the very tight fit in the tunnel and the close proximity of exhaust routing for optimal ground clearance. I've built two 1st gens and one 2nd gen with a T56, and all of them would develop sticky shifting issues as the day went on with multiple track sessions - and I tried, by my count, at least 5 different synthetic trans fluids trying to cure the problem.

I'd note that late model Z06 vettes and SS or ZL1 Camaros have trans coolers standard, and that probably influences my perspective as well. As an engineer myself, I tend to think the decisions of engineers to add extra cost/extra weight items to a production vehicle are based on rational considerations.

On the PS front, things again are quite variable. On my 2nd gen, with an older stock style PS pump and recirculating ball box, never had a problem with no cooler. On my '69, using DSE pump and rack, I've had fluid boilover even with a cooler.

Overall, after many track outings that have ended early for one obscure failure or another, I am much more in the "over-engineer from the beginning" camp. Different strokes

[Track Junky]

Originally Posted by PTAddict

Yeah, I think the experiences on this can be quite variable. For instance, I think the T56 trans in 1st or 2nd gen is likely to be more vulnerable to overheating issues, due to the very tight fit in the tunnel and the close proximity of exhaust routing for optimal ground clearance. I've built two 1st gens and one 2nd gen with a T56, and all of them would develop sticky shifting issues as the day went on with multiple track sessions - and I tried, by my count, at least 5 different synthetic trans fluids trying to cure the problem.

I'd note that late model Z06 vettes and SS or ZL1 Camaros have trans coolers standard, and that probably influences my perspective as well. As an engineer myself, I tend to think the decisions of engineers to add extra cost/extra weight items to a production vehicle are based on rational considerations.

On the PS front, things again are quite variable. On my 2nd gen, with an older stock style PS pump and recirculating ball box, never had a problem with no cooler. On my '69, using DSE pump and rack, I've had fluid boilover even with a cooler.

Overall, after many track outings that have ended early for one obscure failure or another, I am much more in the "over-engineer from the beginning" camp. Different strokes

I hear you...most guys build for the street so different strokes for sure.
With Mark trying to incorporate a street/track combination there are definitely more challenges to be met. Especially when laying down that kind of power.

[Stuart Adams]

Seeing the engineering and the product Mark produces I think after 15 camaro's of learning and testing each, I'd be doing what he sais. Cool stuff.

[garickman]

Good Point!

[kwhizz]

When you are making Stielow power.......Just think about the pressure transferred between the teeth on the pinion and the ring gear under full throttle......tremendous pressure equals Lots "O" Heat........and that go's for everything else in the system...........

Ken

[Vince@Meanstreets]

Originally Posted by Track Junky

I'm running an NA 427 620/560 to the crank and my KRC aluminum PS pump has treated me well so far since 2002. My trans is spec'd for Royal Purple by the builder and I change fluids after every track day and the oil still looks good. Trans in car since 2006. No cooler for rear diff either and car is used strictly for time trials on road courses. Same Eaton carrier since 2004.
This is why I asked the question.

says the guy that "boiled" the top off of his power steering pump on a track day.

[CarlC]

Originally Posted by Vince@MSperfab

says the guy that "boiled" the top off of his power steering pump on a track day.

Been there, done that.

Mark, are you running thermostats on the drivetrain coolers (differential + transmission) combined with differential gear oil squirters?

Any concerns with EHL film thickness on the engine bearings running 1000+ piston horsepower?

[mikels]

Originally Posted by CarlC

Any concerns with EHL film thickness on the engine bearings running 1000+ piston horsepower?

First Thomson 427SC engine was built and run way back in 2008. This was for his Pontiac Solstice and utilized LSX block, LS7 heads and Harrop 2300SC. Engine made 990+ crank HP with an aggressive cam, and dropped to 850 crank HP with milder cam as installed in car. After over 100 dyno pulls and 5000+ miles installed in car, engine was disassembled and all parts blueprinted / inspected for wear. All looked great. Keep in mind this was never used for road-race or extended high duty cycle use, so powertrain cooling was never an issue.

At same time this was ongoing, Thomson was developing a twin-turbo LSX generating 2000+ HP. Original engine was 440 CID and dyno testing reveled that after few pulls, crank bearings were distressed, and had they not been coated bearings, a bearing failure would have been likely. Issue was traced to crank deflection under load, so stroke was shortened (increased overlap of throws and mains) to increase strength. Engine then completed 150 full power pulls on dyno (2058 HP average) and subsequently disassembled. All bearings looked like new.

Fast-forward to today:

Based on these and countless other engine builds, testing and further development, Thomson 427SC engines have proven themselves robust even under extreme racing type usage (Mark's cars being one of the most aggressive test beds used). We continually refine and improve package based on knowledge gained over each build and test data. This includes not only hardware selection, but assembly clearances, powertrain cooling requirements and calibration refinement.

Mark has said on many occasions that not only are the Thomson 427SC engines the most powerful he has ever utilized in his builds, they have also been the most reliable and driveable as well. And hard to dispute the results.

Not sure if this directly answers your question as we lack the technology to measure oil film thickness, but empirical data based on many, many engines supports where we are today (with headroom to grow ).