I had a 97 Cobra that I spun to 8500rpm all day and every day for 60K miles and the
valves
did not float. I believe that limit is more like 9200rpm, not 7400rpm. I had to spin
it this high
because the motor was all stock except the runners were removed.
Brad P
Joe Stewart wrote:
> Bill,
>
> I agree with 99% of what you said except the DOHC above 7500rpms will experience
>valve float with the stock springs. Turning any DOHC past 7400rpms without the proper
>valvetrain components could result is a quick failure.
>
> 96 Vobra #6741
> Joe Stewart
> [EMAIL PROTECTED]
>
> >>> Bill Kaiser/APEX Motorsports <[EMAIL PROTECTED]> 11/24/99 10:57AM >>>
> >Why ATI??? the answer is obvious. I have many
> >friends with vortech, about 90% of them have their
> >head gaskets blown.
> --Actually, that's mostly improper tuning and/or too much boost for the
> engine setup. The _only_ Vorteched DOHC that we've worked on that had any
> problems at all was one that was making 490 rwhp and was being _heavily_
> opentracked in Texas in high heat. And that wasn't a head gasket failure,
> it was a piston failure.
> Stock 5.0s are another story, though. Because of their inferiority,
> strength-wise, to the DOHC, they have a tendency to blow head gaskets,
> break cranks, etc. if not properly set up. To be able to handle a lot of
> boost in a DOHC, you simply need to change the rods and pistons. To handle
> the same amount of power (500+ rwhp) in a 5.0, you'd likely need a strong
> (A4) block, o-ringed heads, large fuel system, and a lot of tuning. The
> DOHC is a perfect candidate for supercharging (or turbocharging) because of
> its 32 valves and the ability to spin to 7k rpm. Put in the better rods
> and pistons and an upgraded fuel system, though, and it'll spin to 8k+ rpm
> with proper tuning.
>
> Bill Kaiser
> APEX Motorsports, Santa Clara, CA
> www.apexmotorsports.net
> 4.6, 5.0, and 5.8 Liter Late Model Mustang Performance Specialists
> (408) 562-1000, Hours: Tues-Fri 8am-5pm, Sat 8am-4pm
> Griggs Racing Products, Official Vortech Supercharger Distributor, Ford
> Motorsport, Edelbrock, Baer Racing, Bassani exhausts, Hawk brake pads, and
> more
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