Top speed question
Melting Slicks
Joined: Dec 2004
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From: Gurley (Keel Mtn, Sweet Home) Alabama
All I got is "Fast", ...and "Faster"
I've had my CE LT4 to 154 on the track at Talladega and I can tell you it had plenty more to give. Verified speed with portable Garmin GPS.
Started to run up on the others on the track so had to back off. Was enough though to put a smile on my face.
I've had my CE LT4 to 154 on the track at Talladega and I can tell you it had plenty more to give. Verified speed with portable Garmin GPS.
Started to run up on the others on the track so had to back off. Was enough though to put a smile on my face.
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Le Mans Master
Joined: Feb 2000
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From: Epping NH
I don't think I've ever seen that mention in the C4 forum, not sure I agree. That's one sure way to **** off a lot of Corvette owners...Z rated means the tire can support a maximum speed of more than 149 mph, but I don't recall seeing any Z-rated tire list a top maximum speed.
Last edited by bac22; May 15, 2018 at 03:42 PM.
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Verdad Gallardo
Racer
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As as a comparison, I know Z rated tires were an option but not standard on the auto equipped V8 f bodies in the 90’s. So the ones that came equipped with H rated tires (130) were limited to around 125-130 top speed. You can tell one of those cars because the auto gear selector doesn’t have a 1 option either. It’s the same transmission, just locked out of manually selecting first gear.
Drifting
Joined: Jul 2004
Posts: 1,356
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From: MA
There is no speed limiter on the LT4 or LT1 cars, at least the manual transmissions.
Top speed for the LT4 in the magazines were around 164 to 168 MPH in 1996. I have seen 160MPH on my GS when it was new and all stock. Top speed is done in 5th gear. 6th gear is double overdrive for gas mileage and top speed is not achieveable in that gear.
Top speed for the LT4 in the magazines were around 164 to 168 MPH in 1996. I have seen 160MPH on my GS when it was new and all stock. Top speed is done in 5th gear. 6th gear is double overdrive for gas mileage and top speed is not achieveable in that gear.
Le Mans Master
Joined: Sep 2013
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From: near the thumb in the mitten
Honestly I never paid attention to the extra codes.
275/40 zr 17. ZR over149 mph
Load rating 93W up to 168 mph 93Y 186 mph.
It's a liability thing; there were wheels and tire brands( Michelin mostly ) that only came with certain suspension options. Dealers were told not to swap the wheels and tires from car to car, because the buyer of the base car wanted Michelin tires as part of the deal. The buyer of the car with the performance suspension that is on base tires (because of the swap) could have a very bad day driving 149 with 112 speed rated tires.
A tuner can disable engine and mph speed limiters.
275/40 zr 17. ZR over149 mph
Load rating 93W up to 168 mph 93Y 186 mph.
It's a liability thing; there were wheels and tire brands( Michelin mostly ) that only came with certain suspension options. Dealers were told not to swap the wheels and tires from car to car, because the buyer of the base car wanted Michelin tires as part of the deal. The buyer of the car with the performance suspension that is on base tires (because of the swap) could have a very bad day driving 149 with 112 speed rated tires.
A tuner can disable engine and mph speed limiters.
Le Mans Master
Joined: Aug 2017
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From: New Jersey
I had the 84 around 135 and it would have kept going if I had another gear...
160s seems about right given horsepower and drag. I believe zr-1s were able to run into the 180s iirc. You need a lot of power to overcome drag alone at those speeds so...
160s seems about right given horsepower and drag. I believe zr-1s were able to run into the 180s iirc. You need a lot of power to overcome drag alone at those speeds so...
Race Director
Joined: Oct 2005
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From: Rolla Missouri
2021 C4 of the Year - Unmodified Finalist
St. Jude Donor '10 thru '25
Le Mans Master
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From: St. Charles MO
FWIW, I just looked at the stock calibration for my 1996 LT4 and the fuel cutoff speed in it is 255mph - essentially there is no limit on top speed for that car. The OE tires by that time were Z rated, either "more than 149mph" or 186mph. So there was no need for a limiter. I know some cars have definitely been speed limited over the years due to tire ratings, but this one definitely wasn't. Motor Trend got a top speed for a 96 GS of 168mph, and that car is a bit draggier than a base car due to the wider tires and flares. So I figure 170-172mph for a base, stock LT4 car. That seems to jibe with old posts on this topic. I'd think low 160s is right for an LT1 automatic.
I wonder if some earlier C4s have a limit? The earlier C4s had V-rated tires, for 149mph. I think that's the realistic actual top speed capability for an L98 C4. I don't think they could muster more than that in stock condition.
I wonder if some earlier C4s have a limit? The earlier C4s had V-rated tires, for 149mph. I think that's the realistic actual top speed capability for an L98 C4. I don't think they could muster more than that in stock condition.
Last edited by MatthewMiller; May 15, 2018 at 11:03 PM.
Le Mans Master
Joined: Feb 2000
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From: Epping NH
Interesting question, I suppose, but I would be highly surprised if any C4 was speed limited, I don't think it was a thing to do back in the 80's and 90's especially on a sports car.
I do know my 2016 Colorado pick-up is speed limited to 95MPH because of the OEM tires, I seem to recall reading that C7's are speed limited to 190MPH.
I do know my 2016 Colorado pick-up is speed limited to 95MPH because of the OEM tires, I seem to recall reading that C7's are speed limited to 190MPH.
Last edited by bac22; May 16, 2018 at 09:38 AM.
Team Owner
Joined: Oct 2004
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From: altered state
St. Jude Donor '05
Not worth worrying about. It takes forever to get there and everything better be perfect on your car trying. Had a coyote run across the road at 158 in my Z followed bya strong crosswind. No more top speed crap for me, you have 0 control at that speed, youre along for the ride.
Le Mans Master
Joined: Aug 2015
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From: St. Charles MO
It was definitely a thing to do, because the function is clearly there in the PCM. But it does not appear to have been done on C4s.
Team Owner
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From: Lacey WA RVN 68-69
NCM Sinkhole Donor
I remember that the early LT1 cars had an RPM limit in the computer. The LT1 in my old '92 roadster had a limit of 5850 RPM. At that point the engine would start to cut out. Can't remember if that was actually a fuel cutoff or if the ECM pulled timing at that RPM.
Top speed in the 6-speed LT1 cars occurred in 5th gear. The engine didn't have the power to overcome aerodynamic forces like wind resistance in 6th gear. I think the C5's are the same in terms of what gear provides top speed.
Top speed in the 6-speed LT1 cars occurred in 5th gear. The engine didn't have the power to overcome aerodynamic forces like wind resistance in 6th gear. I think the C5's are the same in terms of what gear provides top speed.