Ultra Slow

Here is the results of 4 different runs on a well lit 8 mile stretch of road at 4am. Two ZR1s, both with K&N and cat back... Nothing else. Both very comprable in real HP.. One has 4:10's and the other the 3:45's


Yea, just got in... 5am... Are we hardcore or what! It was fun and I tried my damndest to get the car to go any faster. A ZR1 with the 4:10's gets to rev limiter/red line in 5th pretty quick. That speed is right at 175 on the GPS. The other 3 mph were achieved by pulling 6th gear a bit over about a mile where it would actually slow down and speed up 1 or 2 mph. I saw 180 for a brief second, but it was not long enough for the unit to capture and 178 was it for the record.

8388's 3:45 geared car was another story. Both cars have pretty much the same things done.. Air filter and cat back. I am sure they dyno within 10 HP of each other as most ZR1s with the same thing do. We raced a bit while we were doing this and the 4:09 car was just a bit quicker in some areas and others not... Like having to shift into 6th while the other car is walking away still in 5th. The 3:45 geared car could pull red line in 5th, 7200 RPM and about 189 MPH... He only got to 181 as there was a curve he was not used to, but I know for a fact a stock ZR1 with air filter and mufflers will hit 189 in 5th as I have done it with two others I have already owned and his car is completely capable too. There is no way a ZR1 with 3:45s will ever pull 6th at all, even with quite a bit more power over stock. I figure if you are dynoing about 450/450, you might get the 3:45 car to slowly accelerate in 6th, kind of like my 4:10 geared car, but its about usless. I also guess with 450/450, you could pull the 6th a bit easier with the 4:10's with that power and definatly hit 200MPH.... On the other hand, I think you could take either one of the ZR1s and put 3.23 gears in them and red line 5th... not as quick... but get darn close if not 200MPH without any motor work.

Moral of the story.... If you are not using your ZR1 for only 1/4 mile, and only with sticky tires.... Dont EVER change the gears... 4:10's suck and just slow you down in many areas, mainly in the area that the ZR1 was designed for... Top Speed! My gears are coming out....




[Modified by Ultra Slow, 5:21 AM 1/17/2002]

xsmph

I would think in a race from 50 to 175 mph the 4.10 car should get there quicker.... Does it?

USAZR1

I'm really beginning to wonder about you guys. 200mph with 4.10's? A good 415" probably couldn't manage that feat with those gears. 4.10 gears suck? 99.9% of us could care less about top speed so in the real world,they work just fine,thank you.
Driving 180+mph at night,on uncontrolled public roads,is nothing you need to be encouraging others to do. Sorry,you guys that do this cannot justify it in any shape or form so please don't try to do so.

C56spd

Ultra Slow,

Interesting info, thanks for sharing. I would hate for anthing to happen to anyone at those speeds - especially our ZR1 brothers - be safe!

What do you think a 368 (~425-440rwhp) would do with 4:10 gears in 6th? I have not found a road around here to find out officially, and I don't think I would if I did. :blueangel:

USAZR1

David,next time you're at DRM,ask Doug how fast one of their stout DRM-600(385")cars went with a 409 gear.(hint:it was less than 190). People like Rick Doria,John Lingenfelter,etc that do top speed testing often will tell you that a ZF's 6th gear is useless for top speed running,,regardless of rear gearing.

RatRacer

200mph is a barrier that requires an exponential amount of additional horsepower to punch through. Even 190mph takes about 450rwhp to achieve with ZR-1 aero's.

If there was one place on the street that was relatively safe to make high speeds run like Matt's crew does, it's their local highway. It is a super wide 8 lane freeway that is straight as an arrow for miles and smooth as silk. At 4am I imagine there is no traffic and you don't have to worry about animals because the highway is depressed. It's still hairy with multiple cars.

They have tried to get me out there but I prefer a 10 second race to buzzing along at 180mph for miles. Duration equals risk in my book.


[Modified by Cam Potter, 9:41 AM 1/17/2002]

8388

Actually my Z had started pulling ultra around 150 or so. Although from a dead stop(with sticky tires) he would have the advantage. My car has the 3.45 gears and on my second pass, I under estimated my take off point and wound up hitting a curve at 181 and backed off, my car has been sitting in my garage for almost a full year with the exception of one trip to the fox/hound for a gathering and not having checked my tire pressure in a while I didn't feel too comfortable in the curves, but there was alittle more rpm left and still pulling when I let out.
We plan on doing it again once the weather gets better again, and I've had a chance to go thru the car. As far as the 409 gears goes, if your not into what we do (top end) then those gears along with sticky tires would be the way to go, Ultra did try on several occations and 178 was his best and can't see much more top end with those gears, he's forced to go into 6th way too early.


[Modified by 8388, 10:10 AM 1/17/2002]

USAZR1

My thoughts are not on whether it can be done(or where),but whether you should. Have I done these things,too? Yep. Was it smart for me to do it? Nope.
FWIW,Rick Doria has made the comment many times that it takes approximately 450rwhp to push a C4 to 200mph. A good running ZR-1 w/stock displacement LT5 is capable of 190mph,running a 3.07 gear. You just need a lot of road to do it. The Pony Express 100 has one section of road that is almost arrow straight for 13 miles.

scorp508

What about a 3.73 gearing, any thoughts into testing that?

USAZR1

Julio(xsmph) could probably give some input on that. He's been running 3.92's for awhile. Any comments,Julio?

91mongoose

Has anyone ever regeared 6th in a ZF? I'm sure it would be very expensive, etc. but I'm curious what would result. It seems like a .65 - .70 ratio on 6th would allow you to pull a little in 6th, especially if you had more horse power while at the same time keeping the RPM @ 60MPH a little below 2K.

scorp508

What would that make 5th? Isn't 5th something like .75 right now?

xsmph

Julio(xsmph) could probably give some input on that. He's been running 3.92's for awhile. Any comments,Julio?
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I definetly don't understand here, and maybe some of you Top End Kings, with stcok cars, can clarify.
How exactly is it that you race top end? Do you just cruise next to each other and see who can run out of gear first? Does one of you wait for the ohter to stop pulling and then you pull.....
I run top end Type racing... however The reason I call it top end is not Because I take my car to its top speed, but because I start from a 70-80 mph roll.
I'm geared with a 3.92 gear so I can get tp 180 mph (if I need to) as fast as I can possibly can. I don't understand how a 3.45 gear ZR-1 can pull a 4.09 gear Zr-1 after 150 mph , when both cars are in fith gear...
Even if the 3.45 car is still in fourth at 150, once in fifth it will slow down more than the 4.09 car...

To me it does not make a difference if your stock 400 hp car can do 200 mph
If I race you, by the time I hit 140 I'm 10 cars ahead.. what is the point???
At least that is the type of Top end I do.. And it only lasts for a few seconds.. do you guys race for miles... What kind of racing is that??





[Modified by xsmph, 1:35 PM 1/17/2002]

8388

A Richmond 6 speed would come the closest with 5th 1 to 1 and 6th with .68.

W i l l

91Mongoose,
Rick Doria asked one time if anyone wanted to go in with him on having new gears made. He was planning to regear a ZF 6 speed on his ORR car. I don't know what the new ratios are. The ZF S6 40 comes in some European cars with different (I believe) gearing. You may ask Kurt White about selection and availability.

My take on the whole matter is that 5th is enough overdrive and is close enough to the direct drive (4th) not to bog the motor on the 4 to 5 shift. I can do anything I want with 1st to 5th gears and the rearend gear selection. Sixth gear is just there for when I want better gas mileage (which is almost never!).

8388

Julio, when two competitive cars get together, the race for the top end goes until one starts pulling the other to the point where its obvious that the other can't pass, this sometimes takes 170 + mph if the two cars in question are capable of those speeds. These races can start anywhere from a dead stop all the way up to where ever the two drivers want to take off from.

I know that our type of racing is not that popular all over, but we're basically doing what the ZR-1 was engineered to do. In answer to your question about how a 3.45 car can pull a 4.09 geared car, my only explanation would be that the 4.09 geared car must shift more often, and as you know every time you shift your loosing time and speed untill the car starts pulling again after the shift. Other than that I don't know.

929rr

Well, I personally feel that you should give these guys some credit, at least they are telling you what your car is truly capable of, rather than what the magazines say. You may not have the skills to push your car that hard, or may be scared to do so, or maybe just want the ZR1 for the status. That's what these cars are made to do, and at least you know factual first hand information about what a ZR1 will do.
I guess we can't please everyone, but really though how many people here on the forum do these things with their cars? Everyone likes to talk, but this is black and white proof.
:cheers:

Ultra Slow

No.. 4:10's are a mistake all the way around in my book. The way I look at it is the ZR1 was neve designed for a 1/4 mile car. There are 1000 better solutions, like a 67 nova, 69, camaro, cheap alcohol dragster,etc. You can buy a cheep car and go quick. The fast is the ZR1 is know for what..... GOING FAST.... If there are those that think this is crazy, well you just have not experienced life. I wont get into the lecture about whether or not this is right or wrong, but I can say I do not recommend this to someone who does not have at least 50 hours of driving skils above 150MPH. I am no mario andretti, but I have been around the block a couple of times. The point I was making is the fact that putting 4:10s in a ZR1 is spending money to take away the cars inherant ability to go 190 MPH. I dont put slicks on mine and go and side step the clutch at the 1/8 mile track.. Been there done that, not in one of these....

I dont think 4:10's help any ZR1 beyond a drag race and only with drag tires, no matter what the power..... In fact a 3:23, or even a 3:08 would be the gear for a 500HP machine as you would pull 5th without a problem and go WAY fast without having to pull your torque against a .50 ratio and possible blow the transmission apart at hight speeds. .50, as clint said, was never meant to pull... A car with 600FT LBS can do it even on 3:45s, but it would be better at a .75 with a 3:08, or even the most desired top speed OD ratio of .68, that is in the Z51 cars with 4+3's and the richmond 6 speed. It is also the ratio the Sledgehammer ran.

I guess again the factory knew what they were doing when they put 3:45s in the car, anyone second guessing is just going against a proven thing. The right thing to do would to re-gear 6th... .68 would be the best, but I have no clue if anyone could do this, and I could just see putting some aftermarket part in a ZF... Boom...


This is an honest test I wanted to do to finally prove what these 4:10's do... Hurt the car.... Not try and get others to do crazy things like go 190 MPH, but to really know, not speculate. I wish I could say they made me go faster and kick but on cars with less done, but they dont... They are a step backwards and this is not the first time this has been proven.. I also proved it in 1/4 mile races years ago with GSC vs GSC.... 3:45s killed the 4:09 car.




[Modified by Ultra Slow, 2:50 PM 1/17/2002]

xsmph

obvious that the other can't pass, this sometimes takes 170 + mph if the two cars in question
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I guess that is obvious in cars that can stay side by side that long.. don't see too much of that down here.. our races are not so evenly matched.. Usually one car destroys the otherone... quickly...

Anyway the argument on the amount of shifts is not valid if you take the 409. gear car to its top speed (175 or so), by that time the 345 car will have to shift to fith gear.
It has been my experience that gears do make you accelerate quicker. Granted Over do it and you slow down (Zr-1 with 4.56 is too much).
But a 6spd. Car with 7200 rpms and 3.45 gears does not make too much sense.
It just takes for ever to pull those gears.. and 5th has NO punch.
The only way I can see a 3.45 gear pull on a 4.10 is if The 3.45 is in second gear, and the 4.10 is in third.. but Like I've said before... at 5000 rpms in any gear those 4.10's have a punch!

IF not let's just put 3.07 gears and pull 1st gear to the moon, will that make the Zr-1 faster??
I don't think so..

8388

Sorry Julio, but I have to disagree with the your shifting senario, We've been proving this here in dallas over and over again, the more gears the better your launch from a dead stop with sticky tires, other than that they hurt you. We've proven that with other cars we've owned where the only change was the gear.