0-60mph any tips?

[BigBrakeFuelie]

Hey fellas I was going to try to guage my 0-60 acceleration and see how much if any improvement I got since I beefed up my engine.I have a TH350 Auto tranny with a 3.08 rear.My engine is in the 250-285hp. range.What sort of times should I expect?What would be good for this car.
Should I start out in 3rd. gear or in a lower gear on my console?What RPM`s should I take off at?Some technique tips would be appreciated before I give it a run.

 

[Vette/Berlina-coupe]

BerlinaBob here: -as has been eluded to elsewhere on this C3-site, if'in you are looking for an up-to-date 0-60 time with an automatic, --the only practical route via an "its got it all" TH-700R4 with enough low-gear to climb the side-of-a-wall, -in combination with a 30%-overdrive! Do yourself a favor pal, -that TH-350 is just for those wanting to get from A to B without concern for acceleration and fuel-economy.

 

[JHL]

If you just stick it in drive and accellerate hard the auto box will change up reasonably quickly and not allow the most from the engine. If you can, start in first and manually shift to second. For a 0-60 sprint in a car with a 3.08 it will only take two gears.

Try a few different take off routines to see which is best. With a standard converter you might be able to hold it on the brake and bring the revs upto about 1200 -1500rpm. Take your foot off the brake and stamp on the gas. At the track I give it all it`s got AND THEN SOME off the line usally around the 4000rpm mark and work with the clutch to limit wheelspin but you can`t do this in your auto so if you are getting excessive wheelspin or starting to slide just ease off the gas a slight touch to get the traction back and then get on the gas again ASAP.

I would have thought with the weight of a Vette and your sort of horsepower & gearing it should be around the 7.0 second mark to 60.

Have fun trying, you could try and borrow a G-Tech. I have used one before and it was reasonable accurate against the timing ticket.

J.

 

[Evolution1980]

BBF,

Since you are in an automatic, starting in 3 isn't going to change anything up to 60mph. Manually selecting 1 or 2 in the shift gate only allows you to hold that gear regardless of RPM. But they are same gears the car uses if you were to just leave it in 3, just that it shift automatically.

60mph stock was about 7.5 seconds with the L48 190hp engine. If you've bumped it up about 100hp, you can likely expect to get into 6 seconds somewhere. To get your best manual shifts, it helps to know the powerband of your engine since the mods. Finding your peak torque is key for a 0-60 run. Use my engine as an example: I generate the most torque at 3250 rpms. So, in order to keep my car in that power band, I'll shift out of first gear around 3600 RPMs. That way when 2nd gear hits, I'm right back into my peak torque again.

As you're nearing the upper ranges of the 3K band, you should just about be clearing 60mph, give or take... so you see that 3rd gear isn't even used.

NOTE: When you have high RPMs at a slower speed, don't come off the throttle then shift into a higher gear. You'll SLAM that transmission which really beats up the entire driveline. Example: Dont turn 4500 RPMs in first, then let off the throttle and shift into 2nd gear as the RPMs are falling. BAD BAD BAD...
If I get into that situation, I'll either accelerate slightly again then upshift, or throw the car into neutral, wait a second, then drop it into 3rd. (Jst my experience...)

 

[BigBrakeFuelie]

Here`s a ?? If I were to put it in neutral and rev to about 2200-2500 rpms then bang it in drive would that be risky on the tranny.Stress cracks?I would only do it a few times at the most.

 

[JHL]

If I were to put it in neutral and rev to about 2200-2500 rpms then bang it in drive would that be risky on the tranny

I wouldn`t try that you might end up wearing transmission parts.

J.

 

[BigBrakeFuelie]

JHL-Your right it`s probably not worth it.I think I know the best way to try it.The two footed brake/Gas techique is the only way I`ll get a good strong time.I`m gonna give it a try and let you guys know how it turned out.

Thanks
BBF.

 

[Evolution1980]

Here`s a ?? If I were to put it in neutral and rev to about 2200-2500 rpms then bang it in drive would that be risky on the tranny.Stress cracks?I would only do it a few times at the most.

I would only do it a few times at the most.
..yeah, that's right. Because any more than that and you'll likely be picking up pieces of your drivetrain from all over the street...
BAD BAD BAD...It's called a "neutral drop", and it's not something you want to do, even once...

 

[BigBrakeFuelie]

I just did a few runs yesterday to see what kind of performance I have.I pulled about 5 runs.My best time was 7.9 seconds to 60mph.I also pulled a couple of 8.3`s. I was a little dissapointed until I checked my Chevrolet High Performance book for some comparisions.I was trying to guage where my car should be.The 1968 Corvette with the base engine of 300 gross HP. and auto tranny pulled a 8.4 for Car and Driver.I just need to tinker a little more with this bad boy to get the performance I want.The 700R4 is where I`m going fellas!

 

[BigBrakeFuelie]

I just checked the 1980 Corvette site and they had two test from CD and RT.Car and Driver pulled a 7.6 with a 190 hp.engine in a 4 speed manuel.Road and Track pulled a 9.2 ouch!With the same car basically.

 

[MoeJr]

7.5-8.0 Secs is what a stock 80 Corvette L48 Auto should do. At your current power level I wiould expect 0-60 to be about 6-6.5 secs and 1/4 mile at 14.3-14.8.

 

[BigBrakeFuelie]

Moe Jr.- Yeah I want to at least break into the 6 second range before I`ll be satified.The engine has the power but I don`t feel like it`s getting to the wheels like I want it to.

 

[JHL]

MoeJr is right on the mark, in it`s original incarnation with a mild Crane cam and a few bit`s and `pieces my car had just over 200rwhp which was propably about 250 or so in the engine and ran a best of 14.8 in the quarter. I would expect an auto with a standard converter to be a shade slower.

I had an 80 L48 4 spd a few years ago which had nothing other than a mild Comp cam and a bit of work to the quadrajet. It never bettered mid 15`s at the track.

J.