Dyno proof of NO GAIN when using...............

[WESTCOAST JASON]

I could not resist seeing if those 'tornado' style inserts made a difference on the dyno for Vipers. Using a set of them on the shop car, I made back to back runs two different times, with and without the 'vortex creators' placed in the smooth tubes. They don't work.

Then, I figured I would try more things. The following was surprising. Using the stock air box (with rain mod and 3" back half) and K&N's netted me 540RWHP and 562 peak torque. (the norm for this particular car) I then removed the airbox and ran with the tubes only. I lost a solid 10 horsepower on the pull without the box. Then for fun, I removed the tubes (ran with nothing on the TB's) and the power dropped to 522! I knew the factory box was a good design, but booting it cost this car 18RWHP. Amazing.

Looking around I found some 3" fuel line (yes, 3" clear fuel line used for fill necks on sandrails) I made myself two 24" long 'smooth' tubes. I ran these without the box on the 'end' of them. The horsepower was even worse, but the torque went up! (not as high as the 562 baseline, but higher than it did without any tubes)

Just to run another baseline and be sure external factors were no affecting this I put the car back to normal and did another pull. 537/564. Back to normal even though the car is more heat soaked than when I started.

At this point I got tired and came home and wrote this but I am so interested in how this works and why, that I will do a more scientific test sometime soon.

For those few that run conical K&N's on the end of the throttle bodies, maybe you should get some dyno time on that mod, I am curious if this affects all Vipers regardless of mods.....

 

[Bad_Byte]

I'm guessing its the Venturi effect increasing the volume of air.

venturi effect is when wind increases velocity due to contricted flow

 

[SingleMalt]

Nice work, Jason! Glad you're getting some use out of the new dyno! Be sure to keep some secrets for the shop

I could not resist seeing if those 'tornado' style inserts made a difference on the dyno for Vipers. Using a set of them on the shop car, I made back to back runs two different times, with and without the 'vortex creators' placed in the smooth tubes. They don't work.

Then, I figured I would try more things. The following was surprising. Using the stock air box (with rain mod and 3" back half) and K&N's netted me 540RWHP and 562 peak torque. (the norm for this particular car) I then removed the airbox and ran with the tubes only. I lost a solid 10 horsepower on the pull without the box. Then for fun, I removed the tubes (ran with nothing on the TB's) and the power dropped to 522! I knew the factory box was a good design, but booting it cost this car 18RWHP. Amazing.

Looking around I found some 3" fuel line (yes, 3" clear fuel line used for fill necks on sandrails) I made myself two 24" long 'smooth' tubes. I ran these without the box on the 'end' of them. The horsepower was even worse, but the torque went up! (not as high as the 562 baseline, but higher than it did without any tubes)

Just to run another baseline and be sure external factors were no affecting this I put the car back to normal and did another pull. 537/564. Back to normal even though the car is more heat soaked than when I started.

At this point I got tired and came home and wrote this but I am so interested in how this works and why, that I will do a more scientific test sometime soon.

For those few that run conical K&N's on the end of the throttle bodies, maybe you should get some dyno time on that mod, I am curious if this affects all Vipers regardless of mods.....

 

[Craig 201 MPH]

you shoulda had vipair installed or whatever the heck that thing's called.

 

[SingleMalt]

Hehehehe.. Maybe he already has!!!








Or not...

 

[SNKEBIT]

that's why I did the stepped-tube design on my tubes.
Venturi effect.....

 

[GR8_ASP]

I think what you were seeing was the effect of a non-ideal entry. That is the initial entry with just tubes or just the throttle bodies is abrupt. If you installed a smoother entry (more like a parabolic funnel) the divergent flow at the entry would be eliminated and flow would increase. If you look inside the air box you will see the transition is smoothed. An ideal entry at the throttle body should make the highest power for those tests. If the K&N's have an internal feature to smooth the flow then they should work just fine (except for the underhood heat aspect which I will leave to the Vipair thread )

 

[Dave's Big Brakes]

Hey Mikey, glad you came up for some air. Are you going to do Dyno Days?

 

[SingleMalt]

Howdy Dave! Well, I sincerely hope to, but we're coming down to the wire here; I've got three developers working full-time on it and need to finish up by the first of next year... We've got customers signed up already (better than none ). I'll let you know within a week.

Jason: Sorry about the thread hijack.

Mike

Hey Mikey, glad you came up for some air. Are you going to do Dyno Days?

 

[Brad Manhattan Beach]

Jason:

You have way too much time on your hands...

 

[FE 065]

I think what you were seeing was the effect of a non-ideal entry. That is the initial entry with just tubes or just the throttle bodies is abrupt. If you installed a smoother entry (more like a parabolic funnel) the divergent flow at the entry would be eliminated and flow would increase. If you look inside the air box you will see the transition is smoothed. An ideal entry at the throttle body should make the highest power for those tests. If the K&N's have an internal feature to smooth the flow then they should work just fine (except for the underhood heat aspect which I will leave to the Vipair thread )

Increasing the tube length from about 8" to 24" didn't help the HP either.

Ron's right on the air entry point. With just a cut tube end for entry, the air is shearing as it meets the tube end. Flow bench operators always add a bit of rolled up clay to the port face before doing serious flow testing to get maximum air flow.

In a velocity stack they'd call that a 'full round' style stack with the the flare curving almost completely around behind itself as it turns away from the mouth.

 

[MaxedGTS]

Interesting results

 

[Paul Hawker]

Jason.
I believe I will have a new K&N system for SRT-10 to bring by for your dyno days this weekend.
They have redesigned the stock airbox, removing the helmholz resonator, and smoothing out the flow.
Will be interesting to see what kind of improvements they are able to achieve.

 

[joe117]

The question of, "how good is the stock airbox", comes up all the time.

I wonder if there would be any way to get some DC guy, who was in on the design of the airbox, to give some details as to the testing that went into it?

I would think DC would be glad to have someone talk about it, perhaps an article for the VCA quarterly.

 

[FE 065]

I'd bet there wasn't much max HP testing done. There isn't alot of room under there for many variations in design.

Probably just some minimum filter area calculations.


At Norwalk last summer a tuner from TX was complaining that the engine guys get whatever space is left after the body guys get done doing what they want to do .(at DC)

 

[Russ M]

This is nothing new, I spent a day on the dyno testing cold air pipes for the viper vs the factory air box.

All results were the same the factory box is supperior to anything else I could imagine.

Now through a Vipair into the mix and you have the beginings of a 30 page long thread.

 

[joe117]

"Probably just some minimum filter area calculations."

Well, you might be right. They might have just thrown something together that would fit into the space available with filters that would let it get enough air.

The only thing is, it seems funny that it would work better than no box at all if it was just made to fit and nothing more.

I wonder how we could find out.

 

[Paul Hawker]

The K&N guys also commented that the Viper stock airbox was well designed. They were doubtful that they could improve on it. After quite a few designs the came up with an improved Y intake. It uses the stock box, and only changes the filters, and the internal plumbing.