Mr. Gizmo

Not really zr-1 specific. But I think the c4 has the least aero drag of any generation of corvette. The 375hp zr-1 would punch through the air at better then 180mph and averaged 175 mph in the 24 hour endurance run with throttle stops at 75 percent — only mod was removal of cats.

The c7z06 with nearly 300 more hp and 300 ft lbs of torque can barely achieve 190mph with stage 1 aero. With stage 3 aero it barely hits 180 and takes forever to get there.

What do you all think top speed would be in. C4zr-1 with a 650 horse lt4? I think a twin turbo zr-1 with a turbo’ed lt5 went 212mph.

Crabs

LT5, slightly modded, naturally aspirated, 227.74 at Bonnyville.
See the thread, "My Bonnyville Project Update" by Dave's Obsession in this forum

World record for C4 I believe was the Calloway SledgeHammer, ran 254.

'Crabs
'90ZR1 #792

Zrxmax

If memory serves me correctly it takes about 527 crank hp to achieve 200 mph with a C4. As I also recall the drag coefficient is ..34.which is the same as a 1994 400 Lexus... yes... the one with 4 doors.

Anyway, the drag ( mostly low pressure vacuum behind the car ) rise by the square... so... to go another 20 mph faster would require another 110 to 125 additional hp.

So, how fast would a 650 hp ZR-1 C4 go? I would say about 220 mph. One more memory from a Corvette mag somewhere in my collection.

A Lingenfelter 415 powered ZR-1 went 217 mph in a shootout against other high powered sports cars sometime in the early to mid 90s.

What Dave's Obession is doing on the Salt Flats is an entirely different experiment into what it takes to go fast. The salt robs cars in ways pavement or concrete racing surfaces never will.

If Dave's ZR-1 was running on smooth pavement I think the results might be better by 5 to 10 mph than they are on the salt.

Mr. Gizmo

The c4 is an awesome design. 650 crank hp gets you a lot farther in a c4 then it does a c7.

Zrxmax

Add to that the C6 ZR-1 which I would love to have with 638 hp. From the reports I have heard about top speed for that car is around 205 mph.

I am sure if we were to venture over to the ZR-1 C6 section the top speed will be there for all to see.

Dominic Sorresso

In fairness, I think that was a narrow body but not an LT-5.
Pete’s stock displacement LT-5 did 154 in the half mile from standing start.

EvanZR1

I did 152MPH in the 1/2 and 176MPH in the standing Mile with Pete's 391 build. This was with a conservative tune making 494RWHP. By comparison, my '13 GS with a blower making 672RWHP did 157MPH in the 1/2 and 186MPH in the Mile. To me this backs up that the C4 gets more speed with less power than an equivalent C6/C7.

Dominic Sorresso

Pete was nearly equaling what the C6 ZRs were doing. Al and Kevin did 160 with their 441s which was good enough to be the only NA cars to be in the top 25.

Tom400CFI

There are other 'Vettes that have a lower Cd, but the C4 has a smaller frontal area; it's a smaller, lower car. Total actual drag is lowest for the C4, I believe. Super Chevy did a good article on this a while back, but the pics that were graphs of all the gens seems to be gone now.

GOOD READ

Daves obsession

I run a 1990 ZR1 with a 372 cubic inch LT5, naturally aspirated I am putting over 600 to the rear wheels, best speed is 230 on the salt, with a 4800 # car at density altitude of 8400' on a track that has only 10 % of the traction that is found on pavement. Early on I ran 180 at the texas mile with 550 hp at the rear, with the ZF tranny and a 4500# car. Today with the Jerico tranny, more Hp with and cutting some weight, the car would make over 200 in a mile with no problem.

My racing buddy Rick Harden runs a 1994 C4 at top speed on the salt with twin turbos and a massive big block has run 294 on the salt.

Mr. Gizmo

Whats up with these c7’zo6’s. 650 hp/ 550 to 580 hp at the wheels. And they can barely creep up to 185 at 3500 lbs. I guess it’s all in the aerodynamics

EvanZR1

C7Z has a crap load of drag, especially the Z07 and level III aero package cars. Plus they have significantly more frontal area than a C4, and a lot of that is open to direct air through the radiator/coolers. C7 was never intended to be a top speed car.

Daves obsession

The later model vettes were focused on the minimum production of 500 cars used for GT Racing designs that require massive ducted air for brake cooling, top speed was never in the plan.

zrc3john

Interesting....I thought top speed on a C7Z06 was over 200 MPH..... I know it peters out up top stock...I'm guessing with a few tweaks to the supercharger it would hit over 200 MPH...

Mr. Gizmo

Stage 1 aero cars with the poverty front splitter might go 190-195. It takes years to get there. Stage 3 aero cars might get to 180-185.

The c7z is good for 1 or 2 hero runs while it’s luke warm. Once they get up to operating temperature even on the street they Peter out. Shhh! Don’t let the guys on the c7z forum see I said this.

emmvette

@Daves obsession , For a large cubic inch ZR-1 to go fast in the standing mile; what are the next couple steps one can take to improve the top end for an otherwise stock ZR-1? My car is a driver so I'm not interested in gutting it to reduce weight. I'm still at stock height with the stock rear end. Will lowering it be the biggest bang for the buck to reduce the frontal area? Any other interesting things you've learned and are willing to share for us non-salt drivers? Last year I ran 171 and would really like to go a bit faster. I threatened to save a 100# pounds by making my daughter sit out a run, but decided the fun we have together is worth lots more than an extra mph :-)

zrc3john

Put blue painters tape around space in headlights....You can also put it on the day time running lights....Put a cover over front license plate area to make it flush ( the one with the corvette lettering )....

Daves obsession

Underhood air is a really big effect on a C4, at 175mph you are pushing a lot of air on the fire wall. Put a fine mesh screen blocking the area that feeds the radiator. Buy a used set of gill plates and cut the gills out, take a 3.5 by 3.5 sheet to aluminum curve the front and pan from the front crash bars back.

all of the above will get you 10 mph. You welcome

Dave

emmvette

Thanks, Dave, for the suggestions. To make sure I'm understanding you correctly, I would cut the gills out to allow more air to flow out and not get "blocked" up at the firewall, right?

The mesh screen to just to cut down on the amount of air incoming into the engine bay.

Then the 3.5"x 3.5" aluminum goes horizontally in front of the oil pan? Or am I misunderstanding that one?

Daves obsession

Yes, yes, yes you are panning the front. If you use a O2 cylinder laid down on the sheet of 1/8 Aluminum and roll bend a 45 degree angle it will fit to the two front sliders. You will have to drill a hole in the sliders to bolt the the plan to.