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Old 10-04-2014, 01:34 PM   #11 (permalink)
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RX 7 road load

While the Mazda is lighter and smaller,the Pontiac had a lower Cd.The CdAs of the two cars might be closer than you think.
The weight difference won't mean anything on the open road.
If you're going for HWY mpg you're gonna have to do something to the back of the RX-7.It's contour is too aggressive and prone to attached longitudinal vortices.

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Old 10-04-2014, 03:15 PM   #12 (permalink)
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I rebuilt an RX2 many years ago. I am not so keen on automatics, though. I thought rx7s had a low CD, or maybe that's the next generation body.
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Old 10-06-2014, 08:00 AM   #13 (permalink)
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cosmick- The sig isn't about that, it's about the infinite mpg you can get with a manual while the engine is off.
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Quote:
Originally Posted by sheepdog44 View Post
Transmission type Efficiency
Manual neutral engine off.100% @MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%

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Old 10-06-2014, 08:44 AM   #14 (permalink)
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Quote:
Originally Posted by aerohead View Post
While the Mazda is lighter and smaller,the Pontiac had a lower Cd.The CdAs of the two cars might be closer than you think.
The weight difference won't mean anything on the open road.
If you're going for HWY mpg you're gonna have to do something to the back of the RX-7.It's contour is too aggressive and prone to attached longitudinal vortices.
Agreed, good dialog like yours is appreciated, and cD isn't difficult to improve, as my S-10 has proved to me. Much the same way the 5"-tall rear spoiler actually helps the '70-'81 Camaro / Firebird, even though it adds downforce, and the 2" rear spoiler on the '82-'92 Camaro is nothing but drag reduction, functionally (style is a matter of opinion) there are similar examples of spoilers reducing drag on late model cars ranging from Tauruses to Porsches.
So here I'm attaching an image that shows the rear spoiler I'm hunting for.



Even so, The plan is baseline the car, then try the airdam, then remove the airdam and try the spoiler, then try both together.
I'm not finding much for side skirts, but undercar airflow looks like something I might help with a belly tray.
I don't believe the Pontiac is all that good, it is the worst MPG in its class, even with its so-called ecotec engine, which may be a moniker getting slapped on several different families of 4 cylinders, and that pic looks nothing like wind tunnel test results I've found for similar cars.
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Old 10-06-2014, 08:50 AM   #15 (permalink)
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Quote:
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cosmick- The sig isn't about that, it's about the infinite mpg you can get with a manual while the engine is off.
Oh. So like turning it off when coasting down a mountain?
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Old 10-06-2014, 09:21 AM   #16 (permalink)
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Engine braking's better then, but yeah. If inertia and/or gravity will do the job without using gasoline...
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Originally Posted by sheepdog44 View Post
Transmission type Efficiency
Manual neutral engine off.100% @MPG <----- Fun Fact.
Manual 1:1 gear ratio .......98%
CVT belt ............................88%
Automatic .........................86%

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Old 10-06-2014, 05:12 PM   #17 (permalink)
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RX-7 aero

*The Mazda suffers too much slope.The centerline flow may be attached due to downwash but its accompanied by high drag vortices

*'relaxing' the roofline helps

*When you hit the Koenig/Kamm aft-body contour you can be separation and vorticity free

*The hashed lines behind the RX-7 indicate the volume of space which is compromised by it's body design,leading to Cd 0.38 instead of Cd 0.10 as with

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Old 10-07-2014, 05:05 PM   #18 (permalink)
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There's something worth pondering, thanks!
Just pulled an L36 from a '96 Camaro, brought it home. Going after the trans tomorrow morning. Also scored a 28-spline 2-series Auburn, for under $ 50. Then got the new rotors, now that I've had them in my hands I think I can make them work.
The gears arrived, I expected 39:17, got 48:21, so that's 2.2857:1, but should always be loading 2 teeth at a time, on both the ring and on the pinion.
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Old 10-08-2014, 03:24 PM   #19 (permalink)
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Got the transmission.
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Old 10-08-2014, 03:30 PM   #20 (permalink)
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Great looking car! That spoiler is sweet is well. I'll be following.

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