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-   -   How were C4s so quick (https://www.corvetteforum.com/forums/c4-tech-performance/4690796-how-were-c4s-so-quick.html)

LemonC4 11-28-2022 01:00 AM

How were C4s so quick
 
I understand compared to now they’re pretty slow or maybe average but the thing is these things from 85-89 made like 240hp? I also recently found out the corvettes weighed quite a bit like 3200 pounds it confused me how these pulled mid 5s in the 0-60 range.

vetteLT193 11-28-2022 03:47 PM

Horsepower isn't measurable, it is calculated based on torque. L98's had plenty of torque, 345 with only 245HP. It is simply because they were low revving engines. When I went from a l98 to an LT1 I was getting better 1/4 mile times but it took the while track to catch up to my buddies in L98 cars. I think the L98 is a GREAT street engine. The LT4 is when GM finally got the power right where torque was high across the page AND they can Rev high to make more HP.

This is also why diesels don't make much HP. My truck has nearly 1000 torque, but hp is in the 400's.


bjankuski 11-28-2022 04:02 PM


Originally Posted by vetteLT193 (Post 1605963126)
Horsepower isn't measurable, it is calculated based on torque. L98's had plenty of torque, 345 with only 245HP. It is simply because they were low revving engines. When I went from a l98 to an LT1 I was getting better 1/4 mile times but it took the while track to catch up to my buddies in L98 cars. I think the L98 is a GREAT street engine. The LT4 is when GM finally got the power right where torque was high across the page AND they can Rev high to make more HP.

This is also why diesels don't make much HP. My truck has nearly 1000 torque, but hp is in the 400's.

I want to clarify the response above because it may be confusing the issue. HP produced under the RPM band where the engine is used determines how much work can be done or how fast the car will be, not torque.

(Torque x RPM)/5252 = HP

The higher the HP under the band where the car is used will give the most acceleration (Torque by itself means nothing) HP tells you how much work can be done. An L98 makes it HP from 2500 to 4500 RPM (Which means it does have good torque in that same RPM band) but the average HP in that RPM band determines how well the car will accelerate.


s346k 11-28-2022 05:44 PM

the cars certainly lacked power in all regards back in the day. yet they still performed much better than expected.

look at the car minus the power train. chassis was light years ahead of its time, the car is low, somewhat narrow & shaped like a door stop, the engine sits low and behind the front tire, it has a factory 5 link rear suspension, very short driveshaft... is any of this clearing things up? the cars are factory race cars with all of the right ingredients. the only thing they need to compete with & beat a car 35 years newer is a remotely similar power number and updated tire.

Kevova 11-28-2022 09:13 PM

Chevrolet used the gear ratios to allow 0-60 without having to shift to 2nd.

ex-x-fire 11-28-2022 10:05 PM


Originally Posted by Kevova (Post 1605964476)
Chevrolet used the gear ratios to allow 0-60 without having to shift to 2nd.

What? Maybe with the 2.56 axle but no way with the 3.07s.

bjankuski 11-29-2022 07:07 AM


Originally Posted by ex-x-fire (Post 1605964694)
What? Maybe with the 2.56 axle but no way with the 3.07s.

None of the C4 vettes will hit 60 mph in first gear, at 4500 rpm with an auto and 2.59 gears you are at 43 mph.

ex-x-fire 11-29-2022 07:26 AM

Don't tell me, tell Kevova.

dizwiz24 11-29-2022 08:02 AM

Welcome to the new member !

MatthewMiller 11-29-2022 08:20 AM

Yeah, it's not about "torque," it's about power (which damn sure can be directly measured) and traction. The C4 was light with a good-hooking rear suspension and big (for the time) sticky tires, and the automatics generally came with a torque converter that was relatively loose and allowed a good launch. But a 0-60 in the mid 5s isn't all the quick/fast in today's world. The C8 does it in about 2.8s.

LemonC4 11-29-2022 09:10 AM

This got a bit more attention then I was expecting but my confusion has been resolved still surprised they weighed in at like 3200 pounds!

JD'S WHITE 93 11-29-2022 08:15 PM


Originally Posted by MatthewMiller (Post 1605965507)
Yeah, it's not about "torque," it's about power (which damn sure can be directly measured) and traction. The C4 was light with a good-hooking rear suspension and big (for the time) sticky tires, and the automatics generally came with a torque converter that was relatively loose and allowed a good launch. But a 0-60 in the mid 5s isn't all the quick/fast in today's world. The C8 does it in about 2.8s.

The C8 does it, exactly… sport mode double click apply brake mash the gas and the car does everything.
The car is really quick and it’s boring, I got tired of mine and sold it. Launch control and an automatic trans 🤢

Desert Rider 11-29-2022 08:20 PM

Yes- what's the point?

MatthewMiller 11-29-2022 08:31 PM


Originally Posted by JD'S WHITE 93 (Post 1605968254)
The C8 does it, exactly… sport mode double click apply brake mash the gas and the car does everything.
The car is really quick and it’s boring, I got tired of mine and sold it. Launch control and an automatic trans 🤢

I'm not sure how this helps answer the OP's question.

JD'S WHITE 93 11-29-2022 09:04 PM


Originally Posted by MatthewMiller (Post 1605968327)
I'm not sure how this helps answer the OP's question.


I don’t think he asked what a C8 runs 0-60 either. I was replying to YOU.

MatthewMiller 11-29-2022 09:56 PM


Originally Posted by JD'S WHITE 93 (Post 1605968448)
I don’t think he asked what a C8 runs 0-60 either. I was replying to YOU.

He asked why C4s are so quick from 0-60mph. Part of my reply to him is that they aren't especially quick for their weight or power: they run like we would expect a 240hp RWD car weighing 3200lb and with close to 50/50 weight bias and fat/sticky tires would. A quick perusal of Motor Trend's list of 0-60 times will point out that a ton of cars with similar weight/power are similarly quick, including a legion of FWD four-bangers. I should have led with that, but my point with the C8 is that quick cars these days do the deed in half the time. It's irrelevant whether you think they are exciting/interesting or not.

JasonAndrew 11-29-2022 10:11 PM


Originally Posted by Kevova (Post 1605964476)
Chevrolet used the gear ratios to allow 0-60 without having to shift to 2nd.

I'd say 3rd, 60 in first gear?

MatthewMiller 11-29-2022 10:36 PM


Originally Posted by JasonAndrew (Post 1605968689)
I'd say 3rd, 60 in first gear?

It depends on the year/engine/transmission/axle. I'm sure no 2-valve (L98/LT1/LT4) C4 could run 60mph in first. A 96 LT4 (came with the ZF6 manual trans only and 3.45 axle ratio) was good for 53mph in 1st at its 6400rpm redline. A 93+ LT1 (5500rpm redline) with base 2.59 axle and A4 with 3.06 1st gear could also hit 53mph in 1st gear. I think those were the highest 1st-gear top speeds for any 2-valve C4. The ZR1 with the ZF6 and rear gear but a 7100rpm redline (I think?) gets really, really close: 58.45mph in 1st gear.

All of that's academic, though, because if you really wanted to get the best 0-60 time you wouldn't gear the car this tall at all. You'd probably aim to nearly max out 2nd gear just over 60mph in order to maximize average power over the speed interval.

jdjenk 11-29-2022 10:40 PM


Originally Posted by MatthewMiller (Post 1605968761)
It depends on the year/engine/transmission/axle. I'm sure no 2-valve (L98/LT1/LT4) C4 could run 60mph in first. A 96 LT4 (came with the ZF6 manual trans only and 3.45 axle ratio) was good for 53mph in 1st at its 6400rpm redline. A 93+ LT1 (5500rpm redline) with base 2.59 axle and A4 with 3.06 1st gear could also hit 53mph in 1st gear. I think those were the highest 1st-gear top speeds for any 2-valve C4. The ZR1 with the ZF6 and rear gear but a 7100rpm redline (I think?) gets really, really close: 58.45mph in 1st gear.

All of that's academic, though, because if you really wanted to get the best 0-60 time you wouldn't gear the car this tall at all. You'd probably aim to nearly max out 2nd gear just over 60mph in order to maximize average power over the speed interval.

Which for the record, is pretty damn close to what the 4+3 cars are geared at.

I'm hitting 60 right around 4500 rpm in 2nd when the motor is starting to run out of air.

Technically yeah, you can go a little faster by extending out in to the RPM band, but its really out of air not much above 60.

MatthewMiller 11-29-2022 11:17 PM


Originally Posted by jdjenk (Post 1605968770)
Which for the record, is pretty damn close to what the 4+3 cars are geared at.

I'm hitting 60 right around 4500 rpm in 2nd when the motor is starting to run out of air.

Technically yeah, you can go a little faster by extending out in to the RPM band, but its really out of air not much above 60.

Oh, that's interesting. I wasn't thinking about the much lower powerband on the TPI cars. So yeah, given the engine's characteristics they are probably geared just about perfectly for 0-60 times.


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