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Can a C3 compete with a C6 Z06? Video added 8/10/12

44K views 205 replies 32 participants last post by  phantomjock 
#1 ·
Can a C3 compete with a C6 Z06? That was the question some one ask a year or so ago. And if yes at what cost.

So I set out to find out. Including the cost of the car I set myself a budget of 30K and I am well below that figure.

Here is what I have so far.



1971 Corvette coupe
383 ci sbc
Eagle rotating Assembly
KB 18cc dished pistons
Comp forced induction cam
MSD 6AL ignition
MSD boost timing control
Edelbrock 750 CFM carb.
Holly 144 blower
AFR heads
Oil cooler
Long tube headers
3" collectors
2.5" exhaust



NV3500 5 speed trans.
3.08 rear end
C5 rims and tires.



Front suspension VB&P
Rack and pinion steering with hydro boost
Dual mount 8 pt. adj. transverse spiring
1.125" anti sway bar
Tubular off set A arms
QA1 single adj. shocks
Ploy Bushings
C5 rotors and calipers
Hawk pads



Rear suspension VB&P
Dual mount 8 pt. adj. transverse spiring
No sway bar
Off set trailing arms
Adj. smart struts
QA1 single adj. shocks
Ploy Bushings
Rear brake bias adj. valve
C3 calipers and rotors
Hawk pads



Holly 14 lb. 95 GPH fuel pump
fuel pressure regulator.



Hand built Cold air cowl induction hood.
Aux. elect. fan
HEI distributor



Custom built Dash
Sparco seat
5 pt harness.



Roll Cage. Coming as soon as I complete my TIG welding class.:D


 
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#6 ·
Well, there's a couple things a C6Z has that most C3s don't.

1) A ton of tire width, and wider track, under flared fenders. It's been my experience that tires are 90% of the "secret" to good lap times. How much tire can you get under your fenders?

2) Horsepower (500+). Rare in most C3s, but attainable.

3) Light weight. With some parts stripping or a bunch of light material substitution a C3 can get well below the weight a C6. Light weight in a C3 helps compensate for smaller tires or sub-500 power levels.

4) Weight distribution. I'm not impressed with the weight distribution of a C3 (particularly L/R), and I have to believe that a C6 was designed with more focus on where the weight was placed.

There's a hundred additional minor items, but the above stuff seems to be the major contributors IMO.

I hope I'm right, or otherwise I've wasted a lot of time and effort tweaking a hundred things on my car.
 
#7 ·
IMHO and only that:

i think there's only so far that you can take the C3 with bolt-ons. i'd guess the rear "trailing arm" suspension geometry is a serious limiting factor, being used since 1963, replaced in 1984 by the much-more capable multi-link IRS in the C4, now a favorite with hot rod chassis mfr's. although I still think the C3 iron differential housing can take more abuse than a Dana 44. Metalurgy has come a long way since, though.

Greenwood fixed the rear suspension shortcomings with some serious welding, fabrication & redesign on his 1970's era legendary racers, and those probably represent the epitome of C3 suspension technology.

Dick Guldstrand offers a weld-in 5-link conversion for the C3 which probably gets you in the ballpark.

otherwise you're comparing 50-year old technology with the current state-of-the-art. it's a serious handicap.

it would be interesting to see what a Greenwood racecar (w/ alum BBC, Kinsler, etc) could do at the Nurburgring for a lap time. did it ever run there?

please don't get me wrong on this, I myself own 2 C3's, so I'm not slamming C3's. and my GF owns a C4 (i get to soup it up :D) but even on a good day, I know my 540 BBC with all kinds of suspension hop-ups, lightening tricks, probably couldn't hold a candle to an idiot-driven C6 Z06, which, when the price for used 2008 Z06 drops low enough, that's my plan. it'll be a while, but in the meantime, i'm definitely enjoying the hell out of my 540BB C3.
 
#8 ·
Active Handling and Traction Control in the Z06 REALLY help make that an exceptional track car.

You have done a lot to that car, and it should be a super blast to drive on or off the track, but I think you need more tire contact area, and more brake mass to be competitive on the track with the Z06.
 
#13 ·
I guess every one miss my Three long posts on the build of this car over the last couple of years. I,ll dig out some of the pics and post them here.

I under stand the advantage of all the current state-of-the-art technology. I drove a C6 Z06 on and off the track for 40K miles. And at the Bondurant school.

But like most of you out there I don't have a ton of money, and about 3 years ago I came so close to putting my Z06 in to a wall at the track in Topeka Ks. And at $1200 for a front fender, $900 for a hood, $1500 for a windshield, and if the aluminum frame got bent... Well I thought there has to be a cheaper way to race.

As far as the traction control and active handling goes, it is a great safety factor and teaching tool. If you can drive with out activating it you are making your fastest laps. When it comes on it stops you in your tracks.

I do miss anti lock brakes, Its easier to come in to a corner braking late with your foot full on the brake all you need to think about is steering input, and not feathering the brake.

I love reading your posts both pro and con, It makes me stop and think about what to do next. Just like my first time on the track with it I found it was useless with out rear brake bias control, only a $30 item...



The old track car.



The C3 interior under stand this is still a work in progress.



One of the motor.



The Rack and front and rear spring.





The brakes and A arms.



This car is street legal, the suspension can be adj. for track or street. And it is as smooth power wise to drive as the Z06. It has great street manners.
 
#18 ·
Thanks

Looks really good. What seat is that? Can you let us know how it fits, comfort, seating position, mounting, etc.

One thing you might consider as a low cost upgrade is the tall Howe upper ball joints. For $150, they apparently improve steering geometry ( lots of info on the web for c3's).
Its a Sparco Pro2000, It took a few modifications to get it to fit in the C3. I am 5'9" @ 165# and I use a shoe horn to get in and out. I have the tilt steering column and a small 14" flat dish wheel. And leave the top off most of the time.

So since you have driven both how does it compare on the track? Either way I think you are the winner because you built this one.:thumbsup:
I am still dialing the chassis in and working bugs out, like the the rear brake bias control. So time will tell. Acceleration wise it will white knuckle you just like the Z06.:laughing:

I think your C3 is drop dead gorgeous. Awesome job. I think it competes with a C6 Z06 right there.
Thanks

Well we are off to Mid America Motorplex, Pacific Junction, IA Friday. To give it some more track time. Hope to make it the whole week end with out breaking it this time.:rolling:
 
#15 ·
Looks really good. What seat is that? Can you let us know how it fits, comfort, seating position, mounting, etc.

One thing you might consider as a low cost upgrade is the tall Howe upper ball joints. For $150, they apparently improve steering geometry ( lots of info on the web for c3's).
 
#17 ·
I think your C3 is drop dead gorgeous. Awesome job. I think it competes with a C6 Z06 right there.
 
#25 ·
Because I am an SCCA driving instructor I get to drive and ride in various fast cars. I always wondered about how good the late z-06's were. I was very dissapointed.

At only 505 hp or even the modded ones at mid 500 hp I found myself to always be having my foot on the floor and hoping for more. The power to weight ratio was much less than my 434 c-3. So they are really down power wise and kind of boring to drive. I guess that I expected more

The major depression about the z-06 is poor brakes. You would think that the factory would have improved cooling to the point where you didn't have to add all kinds of air ducting................ to keep them from over heating in just a few laps

Now the modded trailer queen z-06's with big slicks are a whole different animal. lightened with brakes and more power. The suspension............... right down the line makes them faster than yesteryear racer C-3 with equal power to weight and the same size slicks.
 
#27 ·
So tell how your lap times compare between the two? I imagin that a blow 383 and n/a 427 must put out the same amount of power.

I personally was never a fan of the cross leaf. I never thought the spring rate was high enough, but to each his own:thumbsup:
 
#30 ·
Hope to get some good time this week end. Jumping in a track ready Z06, and setting up your own suspension I find is two completely different things...:rolling:

There is a fast prepped Z06 running in the TTU class so I have some one to judge times against, and he is fast.

He runs slicks, and I am still running street tires, hope to have a set of Hoosiers before next season.
 
#28 ·
I think I totally agree with the look and feel of what you have built and it's a bigger victory than even beating a modern Z06. It's hand built and unique...not something that can be bought off of a show room floor.

I think, however, that you probably can get very close and without much more work. I like the idea of the side to side weight distribution and it's something I have thought of before. The driver's side is probably far heavier than the passenger side. Brake system, driver, and battery.

Obviously the brake system needs to stay where it is, but the battery can move over. On top of that, there might be a way to lighten the driver's side to compensate for the weight of the driver and brakes...striving for a near 50 / 50 distribution.

A big step, if you ever get the bug, would be a tube frame chassis. Lighter, stiffer, and set up for actual C6 suspension. That would be a treat.
 
#31 ·
I know what you are saying. I am going to move my battery to the right side, and balance the weight. I need to rig a scales to measure the corner weight.

I am right around 3100 lbs now and want to stay there to keep the same power to weight ratio as the Z06's are running.
 
#37 ·
The only track I have ever ran ccw was Bondurant. But as you said before the entire set up is track specific. Most tracks can be ran cw or ccw and most I have been on have close to equal amounts of right and left turns. But most have sweeping combined turns that could benefit from right or left weight distribution, depending if you are running cw or ccw. All I have attended were posted in advance which gives time to move your weight.

Two things I am looking at longer centered battery cables so I can move the battery from right to left. Also an easily removable passenger seat.
 
#36 ·
I think its all about the what ifs...and the fun in the build that really counts. If you meet your goal then its a bonus!I just like to see the projects and the creativity in the builds I have similar goals and hope to come close but really just think its cool to improve old iron to even compete with new tech. The guessing is all part of the fun for me.
iburke ,gkull,those rides are LOOKIN GOOD!:thumbsup:
 
#38 ·
I agree Show, I don't race to win, I enjoy building the cars more.(Don't get me wrong, I like winning as much as the next guy.:laughing:)

I have found the you must know how to drive a car to be able to build a good one, but you don't have to know how to build a car to drive a good one...
 
#47 ·
Well we are off to Mid America Motortiplex in Iowa for the week end. I see there are 3 track prepped C6 Z06's registered so I will have a lot to compare my slow times to...:rolling::rolling:

Be back Monday...
 
#50 ·
OK the results are in.

I will not make any direct comparisons at this time as all my results are from a week end on the track with full track prepped cars. C6 Z06's, C5 Z06's, Supercharged Lotus's, and one very very very fast supercharged Honda S2000. Most running Hoosier Radial R6 slicks, coil overs, most with cam and head packages.

I was running Goodyear Eagle F1 GS-D3, I had trouble with the secondary of my carb disconnected(it was running way super lean lean for some reason.). So I was eventually running a 375 CFM carb. (pay attention every one out there that thinks you need an 1100 CFM carb.


I had one C5 Z06 driver came and ask what I had under the hood, because he was running over me in the corners but could not keep up in the straight aways.

I would say at this point if I were running a HPDE with stock Z06's and street tires, I would have no trouble staying with them.

Next season when I can get racing rubber on it, and my carb working correctly. I also think I need to replace the 3.08 rear to a 3.36 or 3.55 gear.

At that time I feel I will be able to run in the TTU class with respectable time.


On a lighter note this being the first TTR (unlimited class) to run at this NASA event and being the only TTR car to enter.

I took first place in the R class time trials, And I now hold the NASA TTR Track record at the Mid American Motorplex in Pacific Junction, IA.

As my good buddy John Force would say,"It was not fast, and it was not pretty, But a Win is a win"... And I now hold top place points for NASA CENTRAL TTR class for the year...:rolling::rolling::rolling:
 
#51 ·
glad you had a good weekend and things ran relatively smoothly. Like you said, a win is a win! :laughing:

What class were the other guys running?

How does the car feel in the corners? Are you running a square tire package, or are the rears wider? Do you get some push running no rear bar? What did you have the shocks set to?
 
#54 ·
I am trying to get it to push, still running over steer. Running C5 sizes. 245/17 front 275/18 rears Shocks are set +2 front 0 rear. (thats a 12 position dial - to + cw, counting 6 clicks cw or centered as 0.)


Most vettes run TTU some TTS...

Time Trial R (TTR) = “unlimited” wt/hp ratio
Time Trial U (TTU) = “adjusted” wt/hp ratio equal to, or greater than, 5.50:1
Time Trial S (TTS) = “adjusted” wt/hp ratio equal to, or greater than, 8.70:1
 
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