Safe rev limit on a 392 crate?

rob frink · #1 (**permalink**) 04-23-2004, 03:30 PM

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MidOHasp · #2 (**permalink**) 04-23-2004, 05:08 PM

You say your 392 is a crate motor. what are the guts? Sometimes "safe" and "makes sense" are different numbers.

My 408 is all forged guts, basically bulletproof, could probably spin up to 7K without any issues, but it's got a hydraulic roller cam with hydraulic lifters and starts to float much past 6K. Bigger valve springs could get me up a little higher, but not a whole lot.

Just curious what is comprising your 392. If it's a hydraulic roller cam, there's really not much reason to take it past 6300-6500.

I just put the 6300 chip in mine after some test miles at 6K. Sounds VERY nice running up to 6300. At 6K it had more to go. At 6300 I don't think it really has much more to go....perhaps another 200 RPM but I'm not so sure. I will test it and see if it is floating.

Just my $0.02

RedBarchetta · #3 (**permalink**) 04-23-2004, 05:13 PM

I run basically the same combination and have a 6,000 rpm chip.
I've driven high winding small blocks before, and though I've never punched a hole into one, I've learned that going much beyond 6K doesn't add back much. And if you're not running a scattershield, forget about it!

What you really need to do is determine if your camshaft and intake manifold combo can effectively support much rpm above 6K. It may sound great and all, but you might be running out of "flow" by then and an overly rich/lean condition could actually be hurting you more than helping.

My two cents.....

-Deano

rob frink · #4 (**permalink**) 04-23-2004, 05:31 PM

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OneFastRide · #5 (**permalink**) 04-23-2004, 11:34 PM

If you have a hydraulic roller cam 7000 rpm is way too high. Most street 392 crates are set up to make power at relatively low rpms (Ford's SVO 392 Crate peaks out @ 5800). If you have one of these, w10273382681027338268inding your motor much past 6000 rpm won't produce anything but a shorter engine life.
Steve

G.R. · #6 (**permalink**) 04-23-2004, 11:38 PM

Rob, had a 392 crate in my SPF, a solid build by a local engine builder, engine dynoed at aprox 425hp, delivered with a 7k chip in the MSD, after some consultation with the Olthoffs, after about 100 mi, I changed it out on their advice very quickly to a 6K chip. Better to phase out at rpm than blow an engine which depending on the build could easily happen.

rob frink · #7 (**permalink**) 04-24-2004, 04:46 PM

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MidOHasp · #8 (**permalink**) 04-24-2004, 05:04 PM

Rob, if for whatever reason you feel like it's still pulling hard at 6K, you can always throw in the 6200 chip. I have some video of me smoking a burnout in a lineup after a car show and it's really hard to burn out my car in 1st...I'm just immediately at the rev limiter. A comment on the video got me thinking. As it bounced off the limiter, a guy in the background says "loaded up!"

And it did sound like that. There was clearly further to go. I put on the 6300 chip, and literally...that's how much further it had to go. When it hits the limiter at 6300 there is no doubt that there isn't a whole lot of power yet to be had. Dual plane intake, hydraulic cam/lifters...just no sense in it.

Play around, have fun, but recognize your motor's limits. Not necessarily it's "blow up" limits...but its power limits. Only thing you gain revving it up way past the power peak is wear and tear. But it is nice to hone in within 100 RPM of the ideal full throttle shift point. And when they start spinning north of 6 grand, they do sound NICE!!

Enjoy!!

JP

uncltodd · #9 (**permalink**) 05-03-2004, 11:35 AM

Rob, just finished fine-tuning the specs on my TBD BDR powertrain... (starts with a Keith-Craft 351W short block)

One thing I insisted on that made Boudy howl and curse-

I will have a 5500 RPM rev limiter.

My policy right now is... if that little buttrocket is in motion, I am in it!

...But I may not be driving...

Cheap insurance, I think.

Just my 2 cents' worth

UT