You're not using the proper perspective... 80hp loss at the drive train is tremendous if you're talking about a 160hp (50% loss)

But if we're talking 425hp, then 80hp is only 19%... pretty typical for your average drivetrain...

 

yeah, i guess. it just seems like soooo much horsepower to lose.

 

Check out the Greedy TT-350Z video on my site:
http://nissancar.tripod.com

The site is bandwidth limited, so please be patient.

 

Actually, the age old theory of % loss isnt correct. There was a discussion about this on the S2000 boards, I thought about it and it makes sense.

Amount of power loss IS NOT a %. If a person would try to spin the transmission by hand, would 85% of that power be put down to the ground? NO. Therefore, there is a certain amount of power needed to spin the tranny itself. So then why do factory high powered rear wheel drive cars generally lose more power? B/c they have beefier internals to their transmission to handle the power, which takes more power to move than your average car. However, on top of that, there is probably some more power that gets lost due to inertia and friction, but compared to the power that is lost to spinning the tranny, this number should be relatively small. When you make more power, the loss due to inertia and friction should increase, but not more than a few percentage points. So I think that this % loss figure was something mocked up by companies to inflate crank horsepower numbers from wheel horsepower numbers.

 

We had this same discussion on the Lan Evo boards as well. However, I do not think that it is a straight percentage either. It is a mix of a percentage of drivetrain loss AND a number as well.
Lets do some computations here for a second with the power set out by the 350Z.

287HP/274TQ at the crank
224.7HP/219TQ at the wheels (just guesstimating using #s I have from a dyno on the net)

This equates to a 55TQ decrease (or 20% loss). Peak HP drops by 52.3 (a 18% loss), (HP loss should be disregarded when talking about transmission losses because it is just a function of TQ).

Anyways, if what you say is correct about this, the losses should be equal everywhere along this dyno. So lemme take 2 points from this dyno graph.

At peak torque RPM, the engine supposedly makes 274TQ. Now, with transmission losses, that would be around 219TQ (55TQ loss or 20%). At peak HP (6200 RPM), the engine supposedly is making 243TQ. On the graph, it says that the engine is making only 193TQ (a 50TQ loss or 20.5%). So, the percentage theory doesn't seem to work completely, yet the set power loss doesn't either.


BTW, if these #s are in fact the correct whp for a stock Z, I'm disappointed. 20% loss in a RWD car is extremely high, some AWD vehicles, like the EVO, get around this percentage.

 

224 hp is the lowest dyno I've ever seen for a 350z. Most people in this forum have posted 235-240 at the wheels after a substantial break-in period.

I would say that friction is NOT the primary reason for power loss. Remember that all the components of the drivetrain have mass, which is going to resist changes in rotation speed.

Though I wonder if a dyno attempts to keep a constant RPM while measuring power at the wheels? I have to admit I'm ignorant about them. Anybody know how these things work?

 

Yeah, that is what I am wondering as well. There is no perfect dyno and who knows if they are working precisely/efficiently.

 

Though I wonder if a dyno attempts to keep a constant RPM while measuring power at the wheels? I have to admit I'm ignorant about them. Anybody know how these things work? [/B][/QUOTE]

A typical chassis dyno determines the power output of a vehicle by measuring the manner in which it accelerates a pre weighted drum. The drum is usually mounted in the floor horizontally and the drive wheel(s) are positioned so that they remain positioned on the drum during a simulated acceleration run. (see big straps from the vehicles chassis to anchor points in the floor) A gear, closest to a 1to1 final drive ratio should be used, probably 5th gear in the 6mtZ, and full throttle acceleration from just above idle until redline to yield a plot of output datapoints at various rpms.

 

Ok I don't understand all the % and ratio's, What I need to know is this if I spend the money on This twin turbo kit can I kill a mustang

 

you should be able to kill a Mustang now... a GT at least.

a Bullitt will depend on the drivers...

a Mach I will likely leave you by a few car lengths

a Cobra should destroy you.

So you should be asking... "Will I be able to kill a Cobra if I spend the money???"

 

A Mach 1 will take a Z with the TT set up?

Someone explain the math please.

 

......Nothing to explain--he's talking Zs in STOCK form

 

Where is the relese date???

 

The car looks great!

 

Ah.

Thanks for clearin' that up.

 

What is the estimated price range?

Any ideas?

 

It's going to depend on what's all included in the actual kit but I expect the kit to be in the 5-8 grand price range.

 

I would only want to run 7PSI of boost to the stock 350Z motor. If you want more power you should switch to forged pistons and polish and shot peen the stock connecting rods. . That should be good for 400-500 HP if the turbos can pump out the PSI to get it there.

The stock motor has too high of compression to be a good turbo motor, my RB26 has 8.5 to 1 compression that is why it can push 600HP on the stock bottom end.

www.rb26dett.freeservers.com