427 engine (part 2) - RHS block - Page 54

shakedown067 · 10-08-2010, 11:01 AM

LMAO. Yeah, she's pricey, and really meant for all out racing. The ZR1 trans is under $4000, I thought it was in the neighborhood of something stupid like 18K. By what you are planning to use it for, the C6Z trans should be right up your alley...if you are able to go that route. The ZR1 trans would be better suited if you planned on hitting any road racing tracks regularly.

Gannet · 10-08-2010, 12:29 PM

Quote:

Originally Posted by shakedown067

I haven't personally driven a ZR1, but the "main" difference is that the ZR1 doesn't have an overdrive, it's all pull, all the time.

Actually, the biggest difference with the ZR1 box for an FI car is that it has a very tall first gear: 2.29 vs. 2.66 in the standard MN6 (vs 2.97 in the MN12). The idea is to help it hook up. The ODs are lower as well, so no, for you Rich, I guess this one wouldn't be a good choice.

Ratio comparison:
MN12 (C5Z/Z51)
2.97 2.07 1.43 1:00 0.84 0.56

MN6 (std 6spd)
2.66 1.78 1.3 1:00 0.74 0.5

ZR1
2.29 1.61 1.21 1:00 0.81 0.67

Looking at it another way, here are the percent drops between gears:
MN12
30.3% 30.9% 30.1% 16.0% 33.3%

MN6
33.1% 27.0% 23.1% 26.0% 32.4%

ZR1
29.7% 24.8% 17.4% 19.0% 17.3%

You can see that the "point" of the MN12 was not to give "more gear", as commonly supposed, but to give almost exactly even drops between gears for those doing autox/HPDE. That makes downshifting on-course much easier for non-expert drivers.

The MN6 has a "standard" spread from 1-4, making it the best for drag racing (given a proper rear gear ratio).

The ZR1 gearset looks like it's basically a "Nurburgring" set. It has tall lower gears to keep wheelspin down, and then upper gears pretty evenly spaced for when you're going really, really fast. The ZR1 gearset is clearly for a high-powered car; it "throws away" torque multiplication in 1-3, assuming you'll have enough. 5-6 are now "running" gears, not gas-mileage overdrives. I like both ideas, so that's the one for me (when I can).

As to my car, the engine has been done for a long time, but there's quite a bit of detail work to be done to the car. The old saying is that the last 10% takes half the time, and that seems to have applied in my case. The good news is, we're probably at 95%, so we're gettin' there.

shakedown067 · 10-08-2010, 12:41 PM

Well put Gannet. I guess the ZR1 would be considered more of a close-ratio gear box, correct? Certainly makes since for the taller first gear when trying to put down that kind of power. Great info.

**Rich Z** · 10-11-2010, 04:07 PM

Well, it appears there is a clicking noise coming from the differential when Aaron took the car for a test drive. I decided to just go ahead and have both the transmission and differential shipped up to RPM Transmissions and be done with it. Just go ahead and get what I had originally intended (and paid Chris for). Only difference is that I want the C6 Z06 gear ratio in that transmission.

Aaron said the car had good power during the test drive but was definitely slipping in the higher gears. I figure it is a likely combination of the clutch disks not being broken in yet (Fidanza states the carbon organic ones take 500 miles) and possibly the power level under boost (Aaron said he was showing around 5.5 lbs) is exceeding the rating of those clutch disks. In any event, Chris told me that the new higher rated disks should be shipping out today.

In any event, everything from the clutch back is going to have to be pulled out again. And there will be the delay of getting the trans and diff shipped to and from RPM. So of course, tuning is done for the duration, since the WOT stage can't be done anyway with the clutch slippage.

Aaron said the rocker arms were hitting the valve covers on the passenger side as well, and the cover was leaking. It appears to be another oil leak coming from one of the standoffs for the coil packs, but he needs to look at that closer.

Oh yeah, he said it appears that the engine is burning a bit of oil, but I'm hoping that's just normal ring break-in.

Well, the GOOD news is that I haven't died from a heart attack or brain embolism yet....

85vette · 10-11-2010, 04:56 PM

I'm sorry Rich, but it appears that Murphy has been kicking your a$$ for the longest time. Do you have any hair left on your head? Don't start drinking!

**Rich Z** · 10-12-2010, 06:24 PM

Quote:

Originally Posted by 85vette

I'm sorry Rich, but it appears that Murphy has been kicking your a$$ for the longest time. Do you have any hair left on your head? Don't start drinking!

Actually, I'm thinking drinking might be a hobby I need to take up now.

One good thing about this time of year, however, is that the squirrels are much more active and I can take out my frustrations on them by putting crosshairs on them. Of course, Connie isn't too keen on my putting some rounds through the bird feeder.....

But the birds are actually cheering me on, so all is not lost...

gmjunkie · 10-13-2010, 06:25 AM

Quote:

Originally Posted by Rich Z

Actually, I'm thinking drinking might be a hobby I need to take up now.

One good thing about this time of year, however, is that the squirrels are much more active and I can take out my frustrations on them by putting crosshairs on them. Of course, Connie isn't too keen on my putting some rounds through the bird feeder.....

But the birds are actually cheering me on, so all is not lost...

Fall is the best time for moms Old Fashioned Squirrel and Dumpling recipe!

fletcher4u · 10-13-2010, 08:39 AM

At least its not Chris and dumplings.

donzee · 10-13-2010, 09:20 AM

Quote:

Originally Posted by Rich Z

Actually, I'm thinking drinking might be a hobby I need to take up now.

One good thing about this time of year, however, is that the squirrels are much more active and I can take out my frustrations on them by putting crosshairs on them. Of course, Connie isn't too keen on my putting some rounds through the bird feeder.....

But the birds are actually cheering me on, so all is not lost...

Thats funny, Ive culled mine to the point most of them are genius , s now.

**Rich Z** · 10-14-2010, 09:54 AM

The latest words from Aaron yesterday are that he thinks he has the oil leak from the valve cover licked. Pulled out the carbon fiber driveshaft and noted that there is 30 thousandths play in the input shaft that he doesn't like and believes the shaft itself is bent.

He also noted that the clutch disks are not making full contact on the pressure plates, but is not sure what is going on with that.

He also recommended that I have him remove the solid motor mounts and put stock ones back in, otherwise the vibration from the engine will make the car uncomfortable to drive.

The transmission and differential are pulled out and ready to be shipped to RPM Transmission in Indiana.

Oh yeah, he found bolts missing holding the bell housing in place....