The AccessPORT records 0-60mph times.....I just need to find a place to do it now LOL. If I could rip off under 5.5 seconds I'd be happy. Back when I was NA the best I could muster was around 6.8 seconds with a TERRIBLE launch.

 

I fluked a 5.85 with a perfect takeoff when I was NA one day but typically got around 6.3 - 6.4 with a decent launch .

If anyone wants to compare NA to FI open up this one on the same screen and it will be pretty obvious .

0-100mph is about 15.3 . Over 3 seconds slower than the turbo .



http://www.youtube.com/watch?v=NzlvS...e=channel_page


On another point - the 0-110mph time (176kph) for the turbo vid. appears to be about 13.2 which indicates a 1/4 mile time of < 13s being very achievable

 

Nice comparison!

 

Good job, Bret. I still need to hit the drag strip since installing the turbo.

I haven't found a spot I can rip a 0-60mph run yet. I can't do on-ramps since I obviously need to floor it from a standstill

 

Can't you pull to the shoulder and wait until traffic clears?

 

^+1/

 

Thats what i do lol , or just do it at 3 am when theres almost nobody around ;p. 300whp at 13 seconds sounds about right.

 

in my neighborhood there are multiple "slow children" signs. I do my 0-60 tests around there. I figure it's the safest spot since I don't have to worry about them darting into the road.

 

I thought it was cuz slow children are easier to hit ?

 

ROFL Hahahahahaha!!! Priceless

 

Yeah, my car always accelerates faster in school zones, don't know about you guys..

 

My car always seems to go fast when running over babies....I thought all 8's did this?

 

I would have to agree.

 

Well wait a minute... you can't do 0-60 times while running over babies then, because not all RX-8 owners will have enough babies to run over. It's not a fair test. Maybe if you just run over like 1 baby (under each wheel) to launch or something?

 

hahaha loved the babies stuff

but would that mean I need 4 babies?

 

I'm curious, what's the reason for this? Wouldn't either/or be about the same at altitude? They're both compressors. And why do they use superchargers in aviation in that case?

 

LMAO!

 

I was just watching how insanely fast the rev's were climbing, didnt even pay attention to the speedo lol.
Quite possibly the best thing I have read all day.

 

Superchargers are effected by altitude because the compressors speed is fixed to the engines rpm, meaning the compressor will never speed up more than the engine will allow it to.

A turbocharger, on the other hand, is not fixed to engine RPM, instead the compressor speed is varied by engine load.

So, for example, say you have two compressors, a supercharger and a turbocharger, both set to boost at 10psi. At sea level, there is ambient air pressure (14.7psi) of pressure available to each compressor, so each compressor is producing 10psi + 14.7psi from the ambient air pressure at sea level which equals 24.7psi total pressure.

Now you run the both compressors at altitude, say 5,000 ft, and due to the elevation the ambient air pressure has now dropped to 11psi. This means per each square inch of air there is actually less air available (air is less dense at higher elevations).

The turbochargers wastegate is set to hit 10psi, so it won't open until 10psi (I know it will crack the door before 10psi, I'm making this simple) so in order for the turbos compressor hit 10psi, the compressor wheel must spin faster (for example it will now spin to 120,000 rpm instead of 100,000 rpm where it made 10psi at seal level). So the turbo will still hit 10psi of boost.

The supercharger can not do this because it's compressors speed is fixed to engine rpm since it is belt driven off the engine main pulley. So the compressor will spin to the same speed it did at sea level, which was good enough to compress 14.7psi of ambient air pressure, but now at 11psi of ambient high pressure in elevation the superchargers compressor can only compress the less dense air to say 6.5psi (rough estimate).

Of course you can dial this out on a supercharger by installing a smaller belt pulley, but you can only go so small really...ideally every setup runs better at sea level but turbos always hit the same boost regardless of altitude, making them ideal for higher elevation areas. The only difference is with less dense air the boost threshold is slightly increased.

Hope that explains it.

 

Thank you! That does make sense

 

Good explanation Chicken . But could you elaborate on the above please

 

if my mechanic, Tito from Alamo Rotary can do it in his 3-rotor rx8, with the STOCK rx8 tranny.. YOU CAN..

 

With less dense air available to the turbochargers compressor it takes slightly longer for the turbo to make the same boost since the compressor has to spin faster.

With a ball bearing turbo the difference is small, but still there. I noticed this personally when I moved from Phoenix, Az (about 1200ft above sea level) to north of Denver, CO (where I'm at it's 4980ft, but I travel to places to 5800ft and even 6200ft elevation) so with the drastic increase in elevation and thus pressure drop, I have noticed slightly slower spool from my snail, even tho it's dual ball bearing. I was able to dial most of it out with the boost controller, however.

 

I wanna know how a car pulls, not times I wish we could and the industrie would start rating cars acceleration as g force

for example a drag car doing 3.5sec 300mph 1/4 miles runs is about 5.3g's

 

Why not just do the calculation yourself?

Force = Mass * Acceleration . That is basic physics, from there you just have to translate the answer into units of gravity.

Of course, this will give you an average of the force the car is exerting, since it will have to be over a certain amount of time. Not to mention the car is going to pull differently at 2k rpm than it is 4k rpm, or 6k, or 6k, etc etc...

If they were to rate a cars acceleration in G force measurements, it would NOT give you any idea of actual performance. It would tell you the amount of force the car is exerting at a specific time, or over a specific period of time. Not to mention that you would need to know more about the car to even begin to comprehend whether the performance was good or not. Look at our cars handling specs, I believe it pulls something like .53G on a skidpad, not overly impressive. If you could keep the handling performance the same and increase the mass of the car, it would improve this figure, but you arent actually improving the performance...