SouthernSon

So true! That was the procedure plus the rear end lube change. To track such a highly strung vehicle is not the cheapest route to go! Sometimes 'just good enough' ain't 'good enough'.

My student's vehicle mentioned above was shuddering pretty darn badly and it was a GS, IIRC.

d16dcoe45

You are trying to rationalize reasons for your top of the line Corvette having a transmission that is NOT the best that GM offers! You are trying to reduce your anxiety by stating reasons why the A10 "cannot be better".

The A10 from what I gather is am amazing bit of kit!

The A10 was a joint GM/Ford design and is used (with slight programming differences) in the Mustang, F150, Camaro and I am sure a host of others. From what I understand (and that isn't much!) the A10 is one of the BEST passenger car TC automatics in the world right now--at least on the level of the ZF A8 in the Hellcat and other cars. From people who have driven the A10 ZL1 Camaro on the track they say it is TELEPATHIC and better than the M6! The ZL1 1LE Camaro was only available with the M6 at first, but due to demand you can now get the A10 in the ZL1 1LE.

The A10 is not available is C7 Corvettes simply because it won't fit with out expensive tunnel redesigns, NOT because the A8 is superior. It is NOT!

Racingswh

What were your lap times at MO?

SouthernSon

That A10 transmission does, indeed, sound like the cat's meow! Nice to see GM/Ford not sitting on their laurels. This article on the A8 suggests there were some areas of special attention to the A8 in the ZR1, too.

http://gmauthority.com/blog/gm/gm-transmissions/m5u/

SouthernSon

Whoa! Stop! HOLD ON. That is not what I am doing. You stated that it is better. I simply asked how? The only thing I see as different in performance from your links is better gas mileage and a more aggressive first gear ratio. Do you really think I give a rat's poo-tooty for either one of those supposed advantages?? The ZR1 breaks the rear 335's at will most anywhere on track and I really never gave gas mileage a thought. I simply paid the gas guzzler tax and picked up my little ZR1. Now, if you have any further insight as to why you consider the A10 a 'better' transmission, then have at it. Let's hear it.

d16dcoe45

Wow. Truly astounding. Your superego is trying to protect your ego by rationalizing. The A10 is a superior transmission for performance than the A8. It is irrelevant whether you believe me or not. It doesn't change the facts.

Good luck with your A8.

d16dcoe45

Car & Driver review of C7 ZR1 A8:

"The blower is unmistakable, though, in the way the ZR1 marries the instant response of a naturally aspirated engine with the fat torque band of forced induction. It’s a forgiving personality that will yank hard in any gear at any speed, which is that much more useful because the ZR1’s lazy eight-speed automatic wouldn’t earn a passing grade in a minivan. You can count a whole Mississippi between pulling a shift paddle and powering toward the horizon on the next gear. Another reason to opt for the seven-speed manual."

Chevy Press Room on ZL1 1LE w/A10:

"During development, Chevy engineers pushed the limits of the automatic transmission to be more than one half second faster than the standard manual on General Motors’ 2.9-mile Milford Road Course. In fact, on longer tracks like the Nürburgring where you can take advantage of the lightning-quick shifts and all 10 gears, drivers can expect to shave off several seconds from their previous lap times with the six-speed manual ZL1 1LE.

“This transmission is optimized for speed,” said Camaro Chief Engineer Mark Dickens. “With unique Track Mode calibrations and 10 gears, you are always in the perfect gear when rolling on or off the throttle. You may not be a professional race car driver, but now you can shift like one.”"

I have no dog in this fight and personally don't know much, but if given a choice I know which trans I would take. And it wouldn't be the A8.

SouthernSon

Well, according to those facts I suppose there is absolutely no need for any other transmission in the world. However, those articles are dealing with the camaro and its powerplant as well as the other particulars of its drivetrain. But in the real world, a particular vehicle depends upon many factors for optimal performance. So I suppose the ZR1 will just have to rely on the little A8 with its few special touches (refer to my link above) unique to the ZR1 while it continues to set road course records (refer to my link above) for a production car. And if you read all the particulars of the A8 in the ZR1 you will learn (maybe) what the rest of us know. Fro me, paddle shifting is only fun on the street in Tour mode. For the track, the ZR1 programming left in automatic while in Track mode is faster than PDK/DCT (refer to my link above). As for the A10, I am sure we will see it in other vehicles considering the need for corporate fuel averages and the 1st gear ratio will be great for heavier vehicles such as trucks.

Hib Halverson

GM's 10L90 automatic is, indeed, one of the best automatic transmissions in the world, but Camaros and full-sized trucks aside, and with respect to the C7 ZR1, if the car is driven in track mode, left in drive with PTM in five, the A8 is quickest in the hands of talented drivers. Proof of that is Jim Mero's choice back in early '18 of an A8 for the test session at VIR which resulted in the ZR1 being quicker than a Ford GT and setting a lap record that, as far as I know, has stood for over a year now. The A8 was, also, Mero's choice for GMs unsuccessful attempt at running an sub-7 second lap at Nurburgring–he was close at 7.04 and would have gone under 7 had GM been allowed to pre-warm tires as it has done in the past. Being that Mr. Mero had his choice of transmissions and has run hundreds of laps at both tracks as well as at the MRC at the Grounds in Milford and at several other tracks were GM tested speaks volumes about which transmission is quickest. Significant advantages of the A8 are: 1) the shift programing in track mode with PTM 3-5, 2) six track gears instead of five, 3) enables the driver to concentrate on brake and throttle.

As for ZR1s running hot, GM ran a lot of laps at racetracks in the summer–pretty sure that one of the tests was on the big track at Willow Springs, (high-desert outside of Rosamond, California), in the summer. The usual test was fast lapping for a tank of fuel. I'm told there were no problems with overheating.

Yet, some posting here claim this is a problem. That has me wondering about the gasoline people are using when tracking. GM's Track Preparation guide says that a minimum of 93-octane fuel is required and best performance in a race track duty cycle comes with 100-octane unleaded fuel. I have run some "fuel tests" with 1878. My testing so far has all been done at sea level and with IATs of from 68-75°F. I found that, with 91-oct fuel, which is all I can get out west where I live, the E99 is pulling a lot of spark with knock retard and that at least 5° KR and sometimes as much as 8° is present almost continuously from before peak torque to the rev limiter. Then, I started mixing 91-oct with 100-oct. Rocket Brand Unleaded racing gasoline. Mixing it 2:1 which is about 94-oct, the KR was mitigated but not eliminated. I got a big hit of KR around peak torque and then went down by small steps to zero. When I increased the mix of91-oct:100-oct to 1:1, which is about 95.5-oct, I was able to run from 1800-RPM to the 6600-RPM rev limiter with zero KR. , but, again, that's with really good air. That it takes 95.5-oct fuel to run KR-free in really good air, my guess is that in warm weather, that's where you need 100-oct. fuel.

The point of all this is that when the LT5 is running long periods of time at WOT in cool weather, if you're not using at least 95.5-96-oct gas, the engine is going to be running with retarded spark and that will make the engine run hotter than normal. The factory 40/60 coolant mix doesn't help, either. Now, let's start doing sustained hot laps in warm/hot weather. In that case if you're not using 100-oct unleaded, your engine likely getting KR and is running hotter.

What about octane boosters? The only octane boosters which actually work use MMT as their active ingredient. You have to be very careful with MMT because in most cases of MMT-based boosters, the MMT can cause problems with cat converters, O2 sensors, spark plug life and hard metallic deposits on piston tops, valve heads and chamber walls. There is one octane booster which has just come on the market, Driven Racing Oil's "Defender+Booster Fuel Additive" with uses a brand new and quite interesting formulation which has a lot of detergents in it to solve the metallic deposit problem with cats, O2s, plugs, pistons, valves and combustion chamber walls.

The downside of most of these boosters is that my testing seems to indicate that they are not capable of improving the octane rating of a 91-oct unleaded to 95.5-96 much less 100-oct. The one test I have not run, yet, would be to see if an octane booster used with 93-oct gas can get that fuel to 95.5-oct. To conduct such a test would be a bit of work. First I'd have to "make" some 93 by mixing 3.5:1 91 and 100 then run the booster at the manufacturer's recommended "treat rate" then go makes some runs to see if I can run detonation free. I have a couple of bottles left of Defender+Booster Fuel Additive and I have one more five-gallon can of Rockett Brand 100 so maybe I'll try that.

Aside from the octane and knock retard issue, another reason some ZR1 A8s might run hot when lapping on warm/hot days is how the engines are driven. If you are the type of driver who manually shifts and likes to have the engine always at the high-end of the RPM range, then it is likely that your engine is going to run hotter. Reality is that, with the LT5, sometimes the quick way around a track is not with the RPM in the very high end of the range. The car might be quicker when some segments of a lap are run with the engine down around peak torque and not up near peak power.

Lastly, on cooling, if you are a track rat with a ZR1/A8 and your car doesn't see temperatures below 25°F when parked or stored in the winter, reduce your coolant mix. 40/60 or 50/50 mixes of coolant suck for cooling compared to low/no antifreeze coolants. Since I live in Southern California and seldom if ever park or store any of my Corvettes where it gets down to 25, I run a 15/85 mix of Dexcool and water along with one bottle of either Driven Racing Oil "CSP" or Red Line "Water Wetter". That tends to reduce peak ECTs. If you do that keep in mind that you MUST use one of those two additives because they restore the corrosion inhibiters, lubricants and anti-foam additives you loose when you reduce Dexcool from 40 or 50% to 15% and...you must change the coolant every 2yrs/24,000 miles whichever comes first.

d16dcoe45

Whatever you say. Good luck.

SouthernSon

Thanks for the above post, Hib. I have access to the 100 octane but the last I bought was 10.5 gallons for $100. With the availability of the 93 around here I will try for the 96 blend of the two. Really good information!

Hib Halverson

96 will work as long as it's not hot out.
Starting with 93, to get 96 you need to mix 93-oct and 100-oct in a 4:3 ratio. If you go 1:1 you'll have a little extra at 96 ½.

Heres a link to a 93-oct blending chart.

ZR-1DUDE

I wonder if some 100LL would hurt it...

D.

SouthernSon

100ll has four times the lead of old leaded 87 gasoliune. Yes, it would destroy the cats.

ZR-1DUDE

Just checking to see if anybody is actually reading this stuff. The ole IO-520s drinks it.

D.

d16dcoe45

There is alot of misinformation on 100LL (100/130). It probably would reduce effectiveness of the O2 sensors and cats but apparently it takes a while to do that.

Many people who have ACTUALLY run it have had great results.

Some info worth reading:
https://www.google.com/amp/s/www.yel...=1721610&amp=1

d16dcoe45

Where are you getting your information stating 100/130 avgas has "four times the lead of old leaded 87 gasoline"?

From what I gathered, current 100/130 Avgas is permitted have 2.12 grams per gallon, while the old automotive leaded pump fuels had up to 2.2 grams per gallon.

SouthernSon

Good stuff for the Mooney IO-360, too.

SouthernSon

More information about the other problems associated with running avgas in earth bound engines:

https://www.fuelexpert.co.za/canirunavgas.php

Just don't do it.

If you want to see what little lead globules actually look like stop by the nearest airport with an A/I on duty and ask to see used fine wire plugs. With a few sets of old plugs you may be able to salvage enough lead to cast a few bullets.

Hib Halverson

DO NOT use AVGAS LL100 in a ZR1.

It will destroy your cats. It creates hard lead deposits in spark plugs, piston tops, valve heads and chamber walls and it will void your warranty.

As for AVGAS 100/130, with the exception of Hawaii and Utah, it is not available in the U.S.

If you insist on AVGAS, try to find 91/96UL which is unleaded, but still has other problems using AVGAS in automotive engines such as slow burn times intended for engines with much larger cylinder displacement and lower operating speeds.