To make a long story short I had to drive my C4 to work last week. The job site was 60 miles from my house and off a relatively new freeway. I had taken the drive the day before in a truck and noticed very little traffic. So the next day as we are leaving for the drive home I decided to get down on my modified L98. I did not have my foot to the floor. I was going between 3800-4000 rpms. I hit 140mph with so much left it made me wonder how fast the car can actually go ? I suspect the car is capable of 160mph. My max RPM's with this cam is 5300. I realize when getting into this zone there are so many variables. Road conditions aside I wonder if the car can go past the 160mph mark ? Before I modified the car it stopped accelerating at 144mph. I remember the tach peaking at 4400rpm. It would not go any further. Pedal to the floor. The other draw back is it takes several miles to get to the car's top end. I am afraid unless I get onto the Bonneville Salt Flats or some place like that I will never see what the car's maximum speed is. All I am able to do is hit short bursts at the risk of getting arrested. I don't need to hear all kinds of criticism about speeding. I don't make a habit of it. However this opportunity presented itself and I took it. I might add I was on a very long turn in the freeway not a straight away. At 140mph the car stuck to the road like a dream. My friend has a 1985 with a stock LS motor in it. We went to the monthly Corvette meeting last month and the on ramp from one freeway to the next has a 45mph turn. He punched it and I followed since it was early in the morning with no traffic. We were hugging the turn at 95mph. Very easy. I am so impressed with how the C4 hugs the road. Not bad for a couple old cars. By the way to anyone who lives in the Phoenix area the new freeway I was talking about is the 303 Loop. Exit the I-17 go west and it is wide open very little traffic.

 

Considering that a stock '88 is supposed to top out at around 150mph, I don't see any reason why your modified one won't eventually top 160. But as you alluded to, how much does that really matter. I don't know about you but if I could snap my fingers & magically accomplish it, I'd gladly trade 20mph of top speed on my stock LT-1 for 2 seconds off my 70-120mph time, or 2 seconds off my 0-100 time, or 2 seconds off my.............well you get where I'm coming from, I'm sure.

 

 

Reminds me of when I was in the shop that rebuilt my motor going over the details before dropping it off. I was talking to the owners kid not knowing it at the time. An older guy stood up looked at me and said, I will take as much of your money as you want. The reality check was well intended and well received.

 

What is your gearing?

My prior modded '88 would pull through 5,800rpm. With stock 2.59s and A4 top speed in 3rd would have been 162mph. Had it pulled enough to 6,000rpm top speed would have been 168mph.

 

I'm not sure what your response meant so let me instead clarify mine in another way. I can understand why anyone would want to find out what the top speed of any car is. But having said that, in the US, I just don't see the difference, the significance, the importance or the advantage in having a car that will do 160 versus 140.................if said car takes an eternity to accelerate from 140 to 160. What do I mean by eternity? Imo if you can't continue accelerating at a rate of at least 1 mph every 2 seconds then there's no point in it. I'm guessing that your car can do that from 140 to 150, but I'm guessing perhaps not beyond that.

 

There's a new stretch of Highway 20 in northwest Iowa that's about 30 miles long I'm guessing. It's the latest addition to the four lane project and it's SMOOOOOOTH. Many times I've been tempted to just open the car up and have a serious joyride as it's one of the very few roads around here on which I'd even consider doing such a thing...however...the troopers of the Iowa State Patrol take their jobs seriously (as they should) and the fear of losing my license and therefore my job is the only thing preventing me from seeing just how fast mine will go. Like the old saying goes "there's never a cop around when you want one" but for some reason they have the habit of popping up when you least expect them

astepup said that

 

Hi there
My 85 when she was "stock standard as from the factory" some 16 years ago did 150 mph on a closed airfield, there were plenty of rpm left. (The wind resistance and horsepower came to some sort of an agreement at that speed).

That was with stock air filter TPI an auto trans and 3.07 rear and 255 50 16 tires.

A ZR1 (c4) will do 190 mph and that is with 400 hp, compare that to the 230 hp a standard 85 has.

Callaway got to 254 mph in 1988 and it took 898 hp to get to that speed, wind resistance is a bitch.

 

At the risk of drawing the ire of the ZR-1 crowd let me say this.......... but if a later model C4 ZR-1 does indeed do 190 then I'm confident that the last 20 mph leading up to 190 will take longer than cooking the microwaveable sweet & sour chicken I'm about to do in a moment. Please feel free to "try" to prove me wrong.
So other than bragging rights, I just don't see what the hoopla is about. I'd be more impressed if it was shown that it was the fastest car from 0-150 or 0-160 or something like that.

 

take it to the Drag strip that's how you find out how fast it will go fast. My 95 will hit 107 in 12.8 seconds, now that's fast for a C4 with bolt on's.

 

I have the 700R4 and I have been told it's 2:59. I have yet to confirm this as I get conflicting information. My Comp Cam produces power up to 5300 so going past that point would be pointless, right ? Since I have yet to run the car up past 150mph I have not reached a point where the engine is pulling as hard as it can. My engine produces over 300 horsepower which is why I expect it to be able to top 160mph. The gears should allow it.

 

Buddy doing a quarter mile in under 13 seconds is BAD ***. Is your 95 an auto ?

 

I hear constantly and the proof is quite obvious that going beyond 150mph takes incredible horsepower. I am assuming this is because of the wind. The C4 body has the lines for speeds over 185mph which in my book is WOW. I would like to get past 160mph someday in my C4. However time will tell if my set up is capable of that top speed ? One of the things I find so remarkable about the ZR-1 is the fact the LT-5 can run for hours on end at 7000 rpm. I too agree that 0-150 time is awesome. I wrote a thread months ago titled the fastest car I was ever in. My friend Chris cam by house and picked me up in his 600 rwhp C4 and that thing blew my mind. A 10 second car all day everyday. I just love Corvette's !

 

It's got nothing to do with 150mph. It's not some magic number. It's also not wind, it's aerodynamic drag. I don't remember the exact formula but it's something like needing 8 times the hp for every doubling of your speed, So for example in order to increase your speed from 80 to 160, thereby doubling it............ it will take 8 times the horsepower that you were using at 80mph to move your car along at 160. So if you don't have enough, you're not getting to 160.
That is why I previously said IF the stock C4 ZR-1 can get to 190, because I doubt it can regardless of how long you hold the pedal to the floor. Close, but not quite I'm guesstimating.

You're referring to Chris who had the heavily modified black '96? The one he has since sold?

 

In theory, 8 times the HP is in the ballpark...

By your formula...if it takes 230hp to reach 150mph, the Same Vehicle will need 1840hp to reach 300mph!...

Although in Reality, Aerodynamics, Suspension, Tire Friction and Weight play a Huge role in reaching top speed.

Super Car engines produce well, over 1000hp to reach speeds over 260mph with the top speed record of 270.49mph set by the Hennessey Venom GT with 1244hp!





.

 

Yes, of course the Venom got to 300 with only 1244hp. The Venom didn't need 230hp to reach 150mph. It needed less. Why? I'm guessing it's lighter & had much much better aerodynamics than a C4. A Corvette or a car of the Corvettes weight & aerodynamic characteristics would need ballbark 1840. Like I said I was giving a ballpark estimate & didn't know the exact formula. I'm guessing there must be all kinds of permutations for altitude, temperature etc that need to be thrown in there.

 

In comparison, it took 2000hp to get Don Garlit's Dragster to 303mph in 4.72 seconds!...

 

My poor choice of words buddy.I get anxious to respond since I read the Forum on my phone. I'm not so eager to wrap up my responses using a key board versus on my cell phone. I wasn't saying that wind outside some how caused a car to have drag. I thought you would have caught that when I refered to the lines of the car. I was under the impression a Mustang for example could never reach speeds of 180mph and beyond due to it's aerodynamics. It does have a back seat ! But the Ford GT which is sleek can reach top speeds like a ZR-1. Yes ? The quarter mile I haven't heard this coming into play so much. I can't say I looked into whether or not a C4 ZR-1 has ever reached 190 ? I read that it was tested doing 180 for a couple hours ? I assume a BIG race track like the Indy track.
Yes I am talking about Chris. That is one cool dude. I enjoy spending time with him when I get the chance. He lived in Chandler for a awhile which is next to Gilbert AZ and where I live. He told me a guy from Nebraska flew into Skyharbor with his son and drove that awesome car home from AZ. He said the guy called and told him they returned safe and sound. I am afraid the temptation would be unbearable taking a road trip in that car ! Truely the most awesome C4 I have ever seen. Sure the LT-5 is respectable in every way but it's production numbers make it something I would avoid.

 

Yes with a 2800 Stall

 

You are VERY lucky, the sheriff patrols the 303 regularly for speeders. VERY regularly. They get rich off them, and there is a lot of places to hide.