Can a stock 1989 corvette run with a stock 1969 L71, 427ci, 435hp corvette in the long run on the highway?

 

No, but it would get better gas mileage.

 

who cares, just drive em and have fun...

 

Only if the highway was in the mountains with a lot of tight curves, if it's a straight shot I can tell you from having driven a 427 435hp C3, it's not even close, the C4 would lose sight of the L71 after a few minutes. However, as was previously noted, the C4 would pass the C3 when it has to stop for gas!

 

In theory, depending on the gearing of the 69, the 89 may outrun it on the top-end since it doesn't run of out RPM like the 69 would. Granted, this would be more than a few miles down the road, but the C4 should top at 150-155 where the C3 tops at 135, from what I've read up about the old trannys.

Basically, it's the L71 revving itself out vs. the L98 choking itself. A stock motor, L71, will only take 6500-7k RPM so long, but the L98 can chug along at 5k for a while until it catches up.

 

The C4 should walk away from the 1969 L-71 in a top speed contest.

http://www.uniquecarsandparts.com.au...ifications.htm

 

Overall (clipboard and lab coat) performance wise, stock to stock, the C4 would do well; much better on a road course, for sure, top-end too, and wouldn't be totally embarrassed in the quarter either. In comparision, the C4 is immensely more refined - especially in the handling department than a BB C3; a car you can just take a long cruise in and enjoy the ride, and definitely straighten out a few on-ramps along the way!

Now, as for "grin factor", ain't nuttin like lighting the fire of a BBC and feeling the whole chassis shudder with anticipation! With the 4.xx rear end on the C3, and all that torque available, the C3 w/ it's BBC is going to be a hoot to drive on the street, and be a heckofa head turner as well. On the street the BB C3 would be in it's element, and nuttin' gonna touch it there, IMO. And, THAT is part (if not most) of the fun and charm of the C3s (especially w/ side pipes and a cam): Rude, crude, and social unacceptable (some say), and every moment is pure joy!

P.

 

I'd have to humbly disagree. That C3 would walk all over the 89 in acceleration, and possibly top end if it has the 3.08's in the rear. That motor just pulls and pulls until it blows itself apart!

The stats listed above were probably done with the F70, 8" tires. Yeah, with those tires, the C4 would give it fits, but put some equivalent tires of the C4 on it and it's game over. F70's + that much low-end torque = an interesting and hair raising 1/4 mile.

Just don't try to brake and turn!!

 

Completely stock I don't think the C3 will run 150mph and you would be out of your FN mind to try it with a COMPLETELY STOCK one, have you seen the tires they came with or ever driven a bias ply tired car ?

 

My point exactly. Those F70's were and still are not safe and cannot handle that motor. The C3 could get there with the right optioned rear, just don't try with the F70's. Also, who would want to try since those cars are getting more valuable!!

 

Yes they could do 150, even with stock tires. Here's a quote from the book "Corvette: An American Classic" written in 1978 anout the '71 LS6: "Price of the car was now up above $7000, but in return a customer got a vehicle which would cruise at 140 with ease, and had a top speed of 152 mph....."

And 435HP cars had more power.

 

My very first memory of riding in a Corvette was a 1969 big block.
I was 16 years old at the time, and my best friends mom had a brand new one sitting in the driveway.
As dumb as it sounds now, she let him drive it (he was only 16 also) and we went for a ride.

How we survived that ride, I'll never know. Looking back at it now, the only thing I can remember his him shifting through the gears (4 speed).
He mashed the throttle and from that point on, the only time I could see the road was when he pushed the clutch in the shift.
Somebody was looking out for us that day, as we should have been wrapped around a pole in the Las Vegas desert.

 

"And the winner is....(may I have the envelope, please.....)"

"C4."




I think an L98 C4 could exceed 152mph, if not by much.
If it's in real sharp tune/condition.


Larry
____________
not easily impressed....

 

But that was with 3.36 geaing. Put in a set of 3.08 gears and the car could exceed 160.

There were stock C4s that were faster, but the L98 wasn't one of them. The LT1 was on par (perhaps) and the LT4 and surely the ZR-1s had higher top ends. But just remember, the L98, which was the base engine or one of the least powerful C4 engines is being compared to the top dog C3 engines (like the L71 or the LS6) - and that itself speaks volumes for the advancements from C3 to C4.

 

exact gearing (of either car) was unspecified.

I guess the true answer is: it depends.

Larry
___________
not easily impressed....

 

Interesting point U make. Um-yeah...but we're talking "mods" now, and mods are mods and stock comparisons go out the window with mods. I don't know if the L71s in the C3 ever came with 3.07s in the rear. But, if it did, I'm guessing it would have to be a special order item. (referring to the factory build sheet posted above).

Yeah, you are so right. "Power under the curve" or more correctly, "torque under the curve" over a wider rpm range has really surprised a lot of higher (but peaky) hp engines at the track. One of my favorite examples is the LTx engines, especially the LT1. It has 90% of full torque just off idle and is virtually flat to redline. That means it pulls all the way across the entire rpm range - and will bury many a bigger hp but "peaky" engine in the quarter. For example, the LT1 makes 300 hp, compared to the L71's "435", yet the LTx will give the ol C3 L71 fits at the 1/4 track. HP sells cars, but physics wins races. I'll take the flater torque curve (and a couple extra gears) any day!

I'm with you, regarding the advancement of technology and our Vettes. It is interesting to step back and look at all the 55 MY (no '83s production excepted) and trace the thought process of our passion, the Corvette. And, it is flat amazing what technology has been able to do to recover from the removal of lead from the gasoline. (I remember reading some articles back in the day saying "bye-bye" to high performance. Ha! )

All this to say you make an astute observation, my friend!

P.

 

But don't forget, they rated horsepower different between the two engines. Gross vs Net

Not sure how the "real" horsepower difference between the two would be.

 

According to what I am reading a 69 L71 will do 0to 60 in 6.6 seconds. I know a 90 l98 was 0 to 60 in 5.7 according to the press release. There is nothing like EFI for responsiveness.

 

Applying the 15% "rule" (for manual transmissions) the adjusted L71 peak hp would be about 370ish. That makes it the comparision a little more palatable!

P.

 

Paul, The 3.08 rear end was a regular production option that could be ordered with any early C3 Corvette. It is not a "mod" and I am comparing stock to stock. Off hand, a 2.73 may also have been available but I need to check my sources for that one.

As for calculating the "net" HP working from gross numbers, be careful. The 15% is not likely to work very well considering that the gross numbers were undercalled - that 435HP (gross) number was restricted to appease the insurance companies. In reality the number was probably closer to 465. Note that the 66 Corvette was arbitrarily reduced in HP from 450HP to 425HP without changing anything because GM thought there would be problems with insurance companies.


Of course this number now needs to be translated to net HP to get a valid comparison. Given that I have both a 95Z and a 67 435HP car, I can say that the two cars feel very similar from a power perspective. I would suspect that the 67 probably puts out somewhere around 390HP. This seems consistent in the comparitive acceleration times between the two cars. Note that 1971 was the only year that GM published both gross and net for the same engines. That year, the LS6 big block with the significantly lower compression was rated at 425HP gross and 325HP net. The drop in compression had a large effect on the dirrerence between gross and net - but the car did keep much of its torque.