Just a question for the tuning guys.......

With the C3's bodyshape / aerodynamics - even given enough power, will it be comfortable at around 150mph for long periods - hundred miles or more in one go ??

And if the answer is yes - what engine drivetrain would you suggest to be reliable to do that week in week out ?

One of the reasons I ask this is..........

http://www.circuit-days.co.uk/cannon.php?page_id=15

 

not sure why youd need 150 mph for extended periods of time....
Have covered 800 miles in a days driving at UK motorway speeds without too much hassle and lots of coffee!!

Yes some of the cars that take part are monsters but you also get Lada's and Trabants etc taking part just for the fun of it.

Seems like a fun drive though!

 

I have a later c3 with a different front end, but I have heard that the earlier c3s feel like the front end wants to come off the ground at that speed without a spoiler. God bless, Sensei

 

All I can say is I did 150 across the Buckman with top/windows down in my '72 here, some 5-6 years ago.....the car had far more ***** than I did.....

the front end seemed fine to me, but then again my car is a hotrod, so comparo to something totally stock may not be valid....

GENE

 

I don't run at 150 but I do run at a 132 I know a funny number but that is what the GPS is reading and I do it consitantly for as long as the road remains free of cars and the car just idles along.
I am running alot of motor so pulling that speed is not problem.
I did have alot of handling problems in the beginning, the car really felt unsure but now with a better suspension, good shocks and no bump steer for those times you crest a hill and almost become air born and it only takes once to loose it and kill you.
My biggest concern now it blowing a tire even though I run a better Zee rated 18 inch tires, that and tickets.
Set up right, enough motor and you can run at those speeds.

 

Forgot I did a few runs back to back with and without the heavy rear sway bar and I definitely feel the rear bar makes a big big improvement.

 

All it would take is a reliable motor, stiff suspension, front air dam, Z-rated or better tires, and final gearing in the 2.40 - 2.90 range. Oh, don't forget the big set of nuts

I figure out that with 4.11 rear end and .70 overdrive that @ 175 mph could be done at a leasurely 6500 rpm.

For extended high speed driving. I would suggest a steering change. My Vette has to quick of steering. At high speed it's hard to hold a line and that is with new everything in the steering and suspension with Poly bushings everywhere.

There used to be a guy on this forum from Spain I think. He had installed a 502 ci 500 hp motor and some kind of OD manual tranny. He drove all over at 150 mph

One thing is, I feel safer in my Vette doing 150 than being on a Super Bike doing 200 mph

 

I've done 140 for 60 miles at a time.

 

I used to drag race a 1968 L88 and had a trap speed of 131 back in 1975---I was aproached by a guy that said he was a GM engineer and had worked on Corvette aerodynamics and he cautioned me that in some tests the hood would lift off at 130mph I went home and put straps on the hood.

 

Any well prepared BBC with the correct gear and suspension should do that kinda speed all day long if you are so inclined. A OD sure would be nice. If you have a 4spd a 3.36 rear would do the trick nicely and give you plently of pull when you need to blow the porsche boys away.

 

The problem with the shape of the C3 body is that the front end splits the air about a foot off the ground (roughly bumper height on the chrome-bumper cars). The #1 trick to aero stability is to make the air go OVER the top of the car. All the air dam does on these early vettes is a) force some of the air up into the radiator for cooling and b) try and force the rest of the air AROUND the front end rather than UNDER it which causes lift, drag, and hence INSTABILITY. Without seeing it tuft-tested in a wind tunnel I would still think that the last iteration of the C3 (1982) would do better in this regard than any of the others. Look at almost any modern race car and you'll see what I mean- the furthest-forward part of the body is also that which is closest to the ground. The second issue with a C3 Vette is the flexi-flyer frame coupled with very spooky rearend geometry giving you toe-steer every time you hit a decent-sized bump. Occasional trips into 150mph territory are OK for C3's for short periods of time IMHO if you've got the HP to do it but I would think such a car would be very fatiguing to drive that way for long periods of time, and fatigue affects concentration- which is EVERYTHING when driving at speeds fast enough to kill yourself. Be careful.

 

I've gone 165 mph with my blue/white '68 before (with plenty left)... Car still felt pretty good at that speed. However, I had upgraded suspension when I had the car up to 165 mph..

 

Just as a minor addendum, the question should not be ..."CAN my C3 go 150 mph?" but rather "SHOULD I go 150 mph for long periods in my C3?". The [qualified] answer to that one should be "only if you put a fully triangulated 8-point cage in it which severely limits frame flex, stiffen the rear suspension grossly to limit high-speed toe-steer, and modify the front bodywork to effectively reduce lift". If you were gonna do this type of event with a Corvette a C4 would actually be a better platform to start with since the frame is much stiffer AND the basic body shape (particularly the nose) doesn't inherently want to fly at those speeds. In spite of the C4's nondescript, antiseptic sterility, it was designed as a whole to be a safe car at high speeds. Some C3's weren't much more than frighteningly unstable 500-hp fiberglass-bodied pickup trucks. Clint Eastwood comes to mind....

 

Ibtl

 

Another well thought out reply.
NCCC and SCCA cars were prepared with rear wings to effectively balance the car on the road.

 

WOW are C3's really that bad...............

 

Well they are pretty

 

That might very well be true for an improperly maintained, rusty car. A C3 with a solid frame and some suspension improvements (like poly bushings) is going to behave much better than that. A C3 set up according to the Chevy Power Manual chassis recommendations should be just fine, as long as you make some bodywork modifications to keep the nose down.

 

I drove my stock 79 with a larger chin air dam fast. all it needed was the front lowered with one inch shorter 550 pound front springs with smaller diameter tires.

To really make it run better i removed the front end and replaced it with a 81 twin turbo race car front end. It took another 150 pounds off the car and better earodynamics.

This body shape does really good at speed. A couple of C-5 open road race friends told me that it really puts out the rear turbulance and they have to really run right behind me or stay clear. In the rain at high speed it's just a great big fog behind me.


straight back pipes help you go faster!

 

I seem to recall reading about the privateers running 'de-tuned' L88's at Le Mans in the very early 70's having front end 'lightness' issues even with front air dam and rear spoiler. This was at speeds approaching 200 mph (their words not mine)