Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

[cjforumadmin]

http://www.bangshift.com/blog/Screaming-Dyno-Video-660hp-At-Nearly-9000-RPM.html

[Birdman]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

Sweet music!

Each time the throttle is leaned into for a power-pull, after a few seconds a fine mist appears above the injector stacks. Is this fuel misting out of the injectors? If so, wouldn't that be cause for concern? Might the injectors need to be leaned-out a bit at higher revs? JW...

[TheSilverBuick]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

Sweet music!

Each time the throttle is leaned into for a power-pull, after a few seconds a fine mist appears above the injector stacks. Is this fuel misting out of the injectors? If so, wouldn't that be cause for concern? Might the injectors need to be leaned-out a bit at higher revs? JW...

Function of the injectors being open 85+% of the time and the intake valves only being open 25% of the time?

[dieselgeek]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

That fuel you see is because of a phenomenon called "standoff"


We get that on aggressively-cammed N/A engines, especially Individual Runner engines. It makes carb tuning a real PITA, EFI tuning is also a pain because no matter how much fuel you throw at the engine during the standoff, it's only going to take in what it wants.

There are lots of engines that DON'T show this phenomenon, where the injectors are open longer than the intake valve.


As I understand it, it's a result of the backwards-moving pressure wave created when the intake valve opens while the piston is still on it's way up during the exhaust stroke...

I recently observed one N/A engine whose intake valve came off the seat at 50* BTDC on the exhaust stroke. At lower RPMs, there's nearly as much being pushed OUT the intake, as drawn in. Standoff was huge at lower RPMs in the pull.


Good induction tuning guys are able to set up an intake/exhaust/cam/heads combo that puts the reversion point somewhere well outside the usable powerband.

[TheSilverBuick]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

Interesting. Makes sense.

[Tazracing]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

That fuel you see is because of a phenomenon called "standoff"


We get that on aggressively-cammed N/A engines, especially Individual Runner engines. It makes carb tuning a real PITA, EFI tuning is also a pain because no matter how much fuel you throw at the engine during the standoff, it's only going to take in what it wants.

There are lots of engines that DON'T show this phenomenon, where the injectors are open longer than the intake valve.


As I understand it, it's a result of the backwards-moving pressure wave created when the intake valve opens while the piston is still on it's way up during the exhaust stroke...

I recently observed one N/A engine whose intake valve came off the seat at 50* BTDC on the exhaust stroke. At lower RPMs, there's nearly as much being pushed OUT the intake, as drawn in. Standoff was huge at lower RPMs in the pull.


Good induction tuning guys are able to set up an intake/exhaust/cam/heads combo that puts the reversion point somewhere well outside the usable powerband.

so at that point the injectors are just water hose..

[dieselgeek]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

so at that point the injectors are just water hose..

uh, no, they are only for fuel. not water.

[Barry_R]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

An example of one of mine. No standoff problem. An occassional "poof" as we chased the tuneup. And check out the sparks - the puleeys were too big & touched under load - they get replaced with pretty billet stuff on the car.

It's an FE Ford. Anybody notice anything that looks kinda "different"?

http://www.youtube.com/watch?v=QR1E92NUsTU

[Matt Cramer]

Re: Screaming Dyno Video: 660hp At Nearly 9,000-RPM!

It's an FE Ford. Anybody notice anything that looks kinda "different"?

Distributor is below the valve covers and horizontal?