Setting RPM redline
 

So I got my engine running earlier this year and have a couple hundred miles on it. It’s running pretty good. I still want to get it properly tuned with a good timing curve and knowing what my air fuel ratio is and I would like to know what it’s putting out on a dyno.

Once that’s done, I’d like to set a proper redline but am unsure what that should be.

This is a stroked 400 (461) it’s a forged crank (4.25” stroke) forged rods and forged pistons. Roller cam
.541/.544 lift 230/236 duration @.050, 112 LSA.
6x-4 heads mild porting, stock intake and stock Qjet. Compression ratio is about 9.3:1

Using an MSD RTR dist with blaster 2 coil. Currently set rev limiter to 4,500 rpm.

What would be a safe max rpm be?

Thanks!


Sent from my iPhone using Tapatalk

5200 for now.Tom

2 kind of red lines,
One being physical depends on stroke and exactly which pistons and rods along with valve train information mainly springs valve weights and so on

Second when the engine quits making power no sense on winding it further that will come from the dyno

With info provided so far the cam will be the limiter close to Tom's number

The build quality of your motor will take far more rpm then point where the HP level it can produce has well nosed over!

With this comment I am assuming that your valve springs are good to 6000 rpm.

I don’t think you will find much of a change if you shift ar 5200 or 5500 for street usage, at the track if you do such with good traction things may be different though.

The main thing is that when you do shift you want the rpm to drop right back into the middle of the torque band, and this rpm range you will find out from the chassis dyno run’s ,big for now figure 4000.

We're with Tom S on this - 5200 until you dyno and know exactly where your peaks are.
 

Shifting a little low has always seemed like a better idea than shifting a little high.

Unless this is an all-out race car.....

Our mostly-stock SD455 TA ran its' fastest 1/4 mile time when we let it shift at about 46-4700RPMs. It still feels like it's pulling up to about 5,500, but runs the fastest times when we just leave the shifter in 'D'.

Have fun!

Setting RPM redline
 

Great replies. Thanks all! The cam was from Comp and I used the recommended springs for that cam. I’m not sure of the open and seat pressures right now.

Also, the bottom end fasteners are all ARP. The mains (2 bolt) are ARP studs and the rod bolts are ARP bolts.

This is a street car although I would love to take it to the track to see what she’ll do.

Turns out I sure do like full throttle driving! It pulls like a freight train!


Sent from my iPhone using Tapatalk

Assuming standard parts these days like eagle rods, speedpro/ross/dss pistons etc. your engine will tolerate more RPM than it will be able to produce power to, as steve25 eludes to.

If it was me and my car, I'd probably set the chip to 5700rpm and shift between 5200-5500 depending on where the power peak is.

Agree with above. Your bottom end parts will go 6500 to 7000. Your heads and cam will choke around 5600 or less. 5600 would be my "chip" and redline at 5400.

The engine in my sons car is a stock crank 455 .060 with a cam a lot like yours I have the limiter set at 6100 and have him shifting at 5500 for now his first time in a fast car 14 passes in as of now. I have no doubt the engine is making power past 6000

With those heads, 5200 RPM max shift point. Probably run better shifted lower. Cam is sorta like a roller RAIV cam.
You could spin it to 6500RPM but its done long before that.

Your giving away et shifting that setup at 5200

Anyway back to the original question with your combination assembled correctly it will last a long long time at 6000 or less.

x2
Hitting the limiter should be rare.

To the OP, keep in mind that 455s set up for super stock racing in the 1/4 mile run far bigger roller cams then you are and they are shifted between 5800 and 6000.

You’II gain nothing but noise and bigger fuel bill’s by shifting your motor above 5500!

In general with a 3.23 rear gear 4500 rpm with the trans in high gear will be about 120 mph.

You'll know exactly where to shift it when you get it on the dyno.

Or go to the track and play with shift points and see what works best.

Agree 100%

when it noses over.......shift 500 rpm BEFORE that/////5200 ...7200...who cares the cam is the BRAIN and will dictate WHERE it makes power

The induction can affect even more than the cam IMO.Tom

X3 ON THAT POST.

Most who actually have run on the Drag Strip over the years are only concerned
about finding the best rpm that gives them the quickest ET. MPH is for bragging
if you are racing. Races are won by how consistently you ET.
BUT YOUR CAR IS NOT A RACE CAR. Stick to around 5200 rpm for now.
What carb do you have on the engine?

Tom V.

Thanks, Tom. It’s a pretty stock ‘68 QuadraJet with stock fuel pump.


Sent from my iPhone using Tapatalk