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Topic: Proper RPM at highway speed

in Forum: C3 Engines


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Proper RPM at highway speed

Posted: 5/5/06 10:30am Message 11 of 19
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Redwingvette
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Waterford, MI - USA
Joined: 9/13/2002
Posts: 1754
Vette(s): 1973 Red coupe
I took my motor out and replaced it with pedals. Now I get great gas milage but I can't take it on the highway anymore. Here is a picture with my granddaughter driving it http://www.cardomain.com/member_pages/show_image.pl?bg=CCCCC C&image=http://memimage.cardomain.net/member_images/1/we b/565000-565999/565523_84_full.jpg


Brian - NCM Lifetime Member

73 coupe L48, Flat-top pistons, Performer RPM Heads, Crane Cam and roller rockers, Holley 650 vac sec. Performer intake,
3.55 gear BTO 200-4R trans,
Leather seats, Seatbelt Plus 3point seatbelts, Pioneer CD player
Magnaflow Exhuast System

Dewitt radiator and dual electric fans
Borgeson Steering box
 


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Proper RPM at highway speed

Posted: 5/5/06 10:31am Message 12 of 19
VETTERBOB
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DUNEDIN, FL - USA
Joined: 10/22/2004
Posts: 833
Vette(s): 1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp

put a hefty amount of $$ in the trip budget for fuel and drive the hell out of her.  i log 3000 rpm at 65mph. I did`nt buy for econony. enjoy it.!




Proper RPM at highway speed

Posted: 5/5/06 10:33am Message 13 of 19
VETTERBOB
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DUNEDIN, FL - USA
Joined: 10/22/2004
Posts: 833
Vette(s): 1969 COUPE CORTEZ SILVER, BRIGHT BLUE INTERIOR 383 cu. in. 512 HP. Hooker headers w/ side pipes PS PS AC AM FM STEREO. 68,000.MILES C5 5oth Anniversary Coupe , auto.350hp

By the way ... with the new 383 and 3:55`s  , side exhaust. I don`t monitor miles per gal. I monitor miles per minute. LOL




Proper RPM at highway speed

Posted: 5/5/06 4:03pm Message 14 of 19
rearn2go72
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Bladenboro, NC - USA
Joined: 1/22/2006
Posts: 1058
Vette(s): 1972 conv., sunfire yellow, blk interior, blk vinyl and convertible top. Off frame restoration with American Speed 383 stroker engine producing 500hp plus a 200hp NOS system. MSD ignition. Hooker super competition headers with chambered exhaust.
Speaking of MPG, I filled my car up with aviation fuel about a month ago, checked the milage and  got just a little over 7 MPG. On 93 octane and adding the 104 octane booster I was getting 9 MPG. Should there be that much difference in the fuel usage or was those "take-off and landing" the difference?


Proper RPM at highway speed

Posted: 5/5/06 4:28pm Message 15 of 19
Eddie 70
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Kingston, TN - USA
Joined: 7/5/2003
Posts: 900
Vette(s): 1970 Vert Both Tops Kiesler 5 Speed Steeroids Rack and Pinion Stayfast Convertible Top
I agree with Ken also. The only way to drop the revs is to change the gear ratios somewhere. Adding OD will give you the biggest drop. You can change the rear gears for some 3.08 and that will help some. You could go with taller tires also and that would help also.

What I did was add a Keisler tranny to mine. Now when I am in OD, I can cruise around 80 MPH at approximately 2000 RPMS. I have 3.36 rear gears and 255/60/15 tires. Hope this helps some.



Proper RPM at highway speed

Posted: 5/5/06 6:20pm Message 16 of 19
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Adam Wartell
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C3VR Founder
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Eagleville, PA - USA
Joined: 11/1/2001
Posts: 18411
Vette(s): Used to own a 1979 Corvette now owned by JB79

[QUOTE=Eddie 70]...What I did was add a Keisler tranny to mine. Now when I am in OD, I can cruise around 80 MPH at approximately 2000 RPMS. I have 3.36 rear gears and 255/60/15 tires. Hope this helps some.
[/QUOTE]

What kind of City/Hwy MPG are you getting with this set up?

Thanks!




-Adam Wartell
NCM Lifetime Member #1222
Founder: C3 Vette Registry 
C4 Vette Registry, C6 Vette Registry

My first Vette, now owned by JB79:

Proper RPM at highway speed

Posted: 5/5/06 7:25pm Message 17 of 19
2 cruzn
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Poquoson, VA - USA
Joined: 11/20/2004
Posts: 1023
Vette(s): 73 Conv, Blue-Green/White Top - 454, M21 - Dark Saddle Leather, Power Windows, A/C, Tilt/Tele, AM/FM St. (orig. and sounds like it too).#2 -- 2007 Coupe,3 LT package, Z51 option, Victory Red, Ebony Int. Clear Top.
My question is... how much will it cost to get this additional MPG.. ?especially if it's not a daily driver... cost even more if you have to pay to have the work done.. is it worth it? How many years/miles/gallons will it take to pay back?


Lifetime Member #86

USN 1966-1970
WestPac 67-68 Tet I&II

Featured in Corvette Enthusiast Aug 2007 "Shark Attack"
Blue Green *** 454,4 Spd, Dark Saddle Leather, A/C, AM-FM St. (orig), PW, Tilt -Tele Wheel"



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Proper RPM at highway speed

Posted: 5/5/06 8:04pm Message 18 of 19
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dwright
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Victor, NY - USA
Joined: 7/12/2004
Posts: 6841
Vette(s): 2004 Commemorative Edition Coupe, Auto w/HUD. 13K miles in 2015. Sold 1982 Red Coupe
[QUOTE=2 cruzn] My question is... how much will it cost to get this additional MPG.. ?especially if it's not a daily driver... cost even more if you have to pay to have the work done.. is it worth it? How many years/miles/gallons will it take to pay back?[/QUOTE]

That really is the question. What is the ROI?
How high will the cost of gas have to go and how many years will you keep the Vette before you break even?

One other benefit of the lower RPM at highway speeds is less wear on the engine.
And possibly less noise in the cockpit.

It's your choice.



 
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Proper RPM at highway speed

Posted: 5/7/06 8:01am Message 19 of 19
Autom8r
Former Member
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Old Hickory, TN - USA
Joined: 5/26/2003
Posts: 599
Vette(s): 1978 L-82 Silver Anniversary hotrod. /////////////
With the stock 1978 L-82 and TH350 trans through 3:55 rear gears I was turning 3500 RPM @ 75 MPH and getting 15-16 MPG highway.

After I dropped in the ZZ-4 crate motor hooked up to a 700-R4 OD trans and lockup converter, I am turning 2350 RPM @ 75 MPH and getting 20 MPG hwy and have an extra 135 HP to play with...

R.O.I.????? I'll recover the cost incurred sometime around 2043 in saved fuel costs.

I'm happy!

Dave


in Forum: C3 Engines


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