Top Speed

[Scarrzz]

I was thinking about the transmission.

(excerpt from Radz28's info)

Tremec 6-Speed Manual TR6060 (MG9)
Gear ratios:
First: 2.66
Second: 1.78
Third: 1.30
Fourth: 1.00
Fifth: 0.80
Sixth: 0.63
Reverse: 2.90
Final drive ratio: 3.73

Is the published 180 MPH for the manual the result you get from combining fifth gear with the tires that come on it and the engine making 6200 rpms... or is the 180 an artificial limit?

Could it be that this is where friction equals available horsepower, in which case a couple of easy mods would up the top speed?

I could do the math if I knew what equation to solve, but I'm not too proud to ask.

[jayman]

Well look at the trans ratios for the CTS-V since it has the same gears in the rear end as the ZL1 and the manual is listed at 191 for top speed. If they are the same gear ratios in the trans then I'm betting the camaro is drag limited to 184 or whatever they tagged it at. Sorry I dont have the caddy ratios on hand.

Cad CTS-V2 automatic versus manual trans data (as of 05-16-2010):

Manual trans (M6): Tremec TR6060 6 speed manual,
fully synchronized with single overdrive (MG9):
Gear ratios (:1) 1st: 2.66, 2nd: 1.78, 3rd: 1.30, 4th: 1.00,
5th: 0.80, 6th: 0.63, final: 3.73, reverse: 2.90

Found them. Looks to me like the ZL1 is drag limited.

[Scarrzz]

Originally Posted by jayman

Found them. Looks to me like the ZL1 is drag limited.

Different direction that I was thinking, but you came up with the right answer, I'll take it.

That would mean a bump in HP gets me faster than the stock speed of 186 on my Hayabusa. That was my goal.

I'll take the better control that comes from that downforce along with the drag it creates. Aerodynamic drag can be compensated for.


Edit: ... but as I'm thinking about it, there is more friction involved in turning an auto transmission than a manual, and the auto is rated for 184 while the manual is rated for only 180. This seems contradictory to me if the limits are from aero drag.

Hmmm...


Post Edit edit: "only 180"

[IOMZL1]

Originally Posted by Scarrzz

I'll take the better control that comes from that downforce along with the drag it creates. Aerodynamic drag can be compensated for.

Yes. Consider ‘stable’ or ‘usable’ top speed vs. ‘theoretical’ or ‘ideal’ top speed. You may be able to go 200 in another car but a gust of wind will cause you to crash vs. you can go 184 in the ZL1 and feel more planted and secure. This is why they have wings on IndyCars – sure, they slow the cars down in theory but in reality the cars can take the turns faster for it and are more stable on the straights. I’ll probably never see 184 but it is good to know however fast I do go I’ll feel ‘stuck’. I’d take this over a slightly higher top speed 'statistic' any day.

[jayman]

True. The auto in the caddy is limited to around 180 because of the output shaft on the trans. But I didn't realize the auto in the ZL1 is faster than the manual. Doesn't make much sense unless the auto has slightly different gears that give it a slight mechanical advantage. I would guess that the hennessey or lingenfelter 700+hp package will get you to nearly 200 mph.

[Scarrzz]

.

Like Maxwell House, I drink it to the last drop.

At least on occasion.

[hognutz]

well top speed at redline in 5th is 176. then you jump down to .63 gear maybe it will do another 4mph then???? or maybe 180 is a round number and top speed is in 5th at redline.

I assume you could get around this though with gearing change. I have a feeling the torque is there if the gearing was right. maybe not though .75 5th would have given the car 195mph top end theoretically but maybe it would not pull there.

I have only had my Z06 over 180mph in three years and it was very brief so I am not that concerned. Even brand new bikes are electronically limited to 185mph so without tuning that is all you get.

[Scarrzz]

Originally Posted by hognutz

well top speed at redline in 5th is 176. then you jump down to .63 gear maybe it will do another 4mph then???? or maybe 180 is a round number and top speed is in 5th at redline.

I assume you could get around this though with gearing change. I have a feeling the torque is there if the gearing was right. maybe not though .75 5th would have given the car 190mph top end theoretically but maybe it would not pull there.

I have only had my Z06 over 180mph in two years and it was very brief so I am not that concerned. Even brand new bikes are electronically limited to 185mph so without tuning that is all you get.

A timing retard eliminator takes care of that really quickly. That would be fun to run my bike beside your Z06 at speed.

Sometimes I wish we could tell street stories. You see there was this Rustang...[ziiiiip.]

[MrDew]

Below is what i wrote in another thread...

Top speed on the manual is in 6th gear and it is drag limited. Therefore a boost in HP should also increase your top speed!
--> You would sit at 5750rpm in 6th when going 200mph... (or at 7300 in 5th if you want to live risky and raise the limiter)

Originally Posted by MrDew

I went off the gears / tires provided in the order guide and came up with the following "theoretical" top speeds for each gear. The 6th gear is definitely limited by aerodynamics but it might pull higher than 5th...

mph:
1st 51.1
2nd 76.3
3rd 104.5
4th 135.9
5th 169.9
6th 215.7

kmh:
1st 82.2
2nd 122.9
3rd 168.2
4th 218.7
5th 273.4
6th 347.2


Definitely needs a ton more hp to reach the limiter in 6th but it should be a great gas saving gear with only 1470rpm at 75mph...

[Scarrzz]

Originally Posted by MrDew

Below is what i wrote in another thread...

Top speed on the manual is in 6th gear and it is drag limited. Therefore a boost in HP should also increase your top speed!
--> You would sit at 5750rpm in 6th when going 200mph... (or at 7300 in 5th if you want to live risky and raise the limiter)

That is exactly what I wanted to know, and I'm quite pleased that for every power mod, there will be an increase in top speed.

Therefore after every power mod, there will have to be verification top speed runs.

BWAHaHaHa...


I love my ZL1, love before first sight.

[htron50]

I had heard, YA HEARD, that with the Suede package you get more DRAG? Dunno? Hmmmmm Guess I go with leather. Higher top speed!

[MrDew]

Anybody know the Cv value of the ZL1 (or the SS for that matter)?
I'm wondering how much drag it actually generates at speed... One could make some conclusions as to how much more power is needed to hit 300km or 200mph.

Not sure if my train of thought is right but i beleive it's somewhere around 80-90 ft.lb?
(I am most likely way off with that)

[Deki]

Originally Posted by MrDew

Anybody know the Cv value of the ZL1 (or the SS for that matter)?
I'm wondering how much drag it actually generates at speed... One could make some conclusions as to how much more power is needed to hit 300km or 200mph.

Not sure if my train of thought is right but i beleive it's somewhere around 80-90 ft.lb?
(I am most likely way off with that)

300kmh is 186mph

[MrDew]

Originally Posted by Deki

300kmh is 186mph

i know, i looked at the 200mph mark that was stated so proudly by the guys in oval blue...