What size throttle bodys are the stage guys running?

[DonWG]

Originally Posted by bison

I wonder how much air is lost in the overlap period though?

That is where a computer simulator comes in. That can be taken into account.

[DonWG]

Originally Posted by bison

Those are really small valves in those heads.

The central theme of my project was to see how much power I could squeeze from these heads using the valve sizes they came from the manufacturer with. The whole idea was to see if camshaft and manifolding design could make up for the imagined shortcomings of these heads. Add to that the smaller displacement I'm using compared to most everyone else and it's turned into quite a challenge. Every aspect of the engine design has come about with the heads being the central consideration. There are actually many tricks that can be used to make a relatively small port and valve head act as if it was bigger. Air speed through the intake port was a big factor in the configuration of the engine.

If max hp had been the target, it would have been max displacement and stage II heads. But then, everyone else has done, or is doing that already.

I'm trying to show the small guy that you don't need to have the killer heads to make respectable hp. And to do that you need to pay very good attention to the efficiencies of every support system on the engine.

[DonWG]

Of course, when you're making more hp than the chassis can handle, any hp loss that you might be having due to a support system is not very important.

[Dusty Bradford]

I understand what your talking about Don. I'm saying boost pressure changes everything. A 90mm TB will flow a certain amount at 5# and flow alot more at 30#. Picking a TB size by a flow rate is only part of it. You would need to know what pressure it was flowed at. Just like flowing heads. The standard is 28 inches of h2o. Put 40 inches on it and watch the flow skyrocket. The only way a turbo car will pick up 30hp from a TB swap is if the TB was originally undersized. I remember when Kenne Bell was advertising 30hp from a 70mm TB. How many people swapped from the stocker to the KB 70 and never gained anything....I know it was a bunch.

I do agree a TB must be sized properly for the set-up but Ted A has proven how far a 80mm will go. 8.40's at 30# of boost with plenty left. If his TB is smaller than his charge tubing he could possibly see a gain from a larger unit.

[DonWG]

Originally Posted by Dusty Bradford

I understand what your talking about Don. I'm saying boost pressure changes everything. A 90mm TB will flow a certain amount at 5# and flow alot more at 30#. Picking a TB size by a flow rate is only part of it. You would need to know what pressure it was flowed at. Just like flowing heads. The standard is 28 inches of h2o. Put 40 inches on it and watch the flow skyrocket. The only way a turbo car will pick up 30hp from a TB swap is if the TB was originally undersized. I remember when Kenne Bell was advertising 30hp from a 70mm TB. How many people swapped from the stocker to the KB 70 and never gained anything....I know it was a bunch.

I do agree a TB must be sized properly for the set-up but Ted A has proven how far a 80mm will go. 8.40's at 30# of boost with plenty left. If his TB is smaller than his charge tubing he could possibly see a gain from a larger unit.

Every system of the engine must be looked at as a package. If you make a change, such as the KB example you brought up, you must look at the rest of the systems in place to determine if there might be an improvement or not.

Yes, more pressure will increase flow through a given tube size. To a point. The big question becomes, how much more pressure does it take to flow a target cfm through a tube compared to a tube that has a little bigger ID? When a certain air speed has been reached regardless of the pressure, more pressure will have to be used to increase the flow, until a max air speed has been reached where any flow increase becomes very small no matter how much pressure you use. It's called approaching max mach number. Efficiency drops rapidly in the range of .6 - .8 mach number. Maximum efficiency is in the range of .3 to .5 mach number with no tuning effects (pressure pulse tuning).

Again, flow in feet/second becomes very important. If you have to increase the pressure to move the target cfm through a given tube, you are unnecessarily heating air and reducing density.

[DonWG]

Originally Posted by Dusty Bradford

The only way a turbo car will pick up 30hp from a TB swap is if the TB was originally undersized.

The main point I'm trying to make here is, you'll never know if the TB and tubing sizes are undersized if you don't bother to do the math.

[DonWG]

Why would you do so much research to make sure you have the killer intercooler, just to be forced to run a higher boost and unnecessarily heat the intake air further to flow the target cfm because your tubing is too small. That to me doesn't make any sense.

[Dusty Bradford]

I thought we were talking TB's here

Charge tubing sizing is the first thing to look at when building the cold side of the system.

I see we both agree Charge tubing should be the primary item when building a turbo system. I then size the TB accordingly. No need for a 90mm TB with 3 inch tubing.

[Dusty Bradford]

80mm proven to 8.40's at 3400# 1300+ hp (1300+hp)
90mm proven to low 7's at 200 mph at 3400# (2000+hp)
105mm proven to mid 6's at 230mph at 3000# (3000+hp)

[DonWG]

Originally Posted by Dusty Bradford

I thought we were talking TB's here

Charge tubing sizing is the first thing to look at when building the cold side of the system.

I see we both agree Charge tubing should be the primary item when building a turbo system. I then size the TB accordingly. No need for a 90mm TB with 3 inch tubing.

Your right Dusty. As far as sizing goes, I consider anything from the turbo to the plenum as one tube. When the TB is WOT, all it ends up being is part of the tube.

You can't be hurt too much if the tubing is a little too big. Too small is a different story.

Be sure and do the math for yourself.

[Dusty Bradford]

Originally Posted by DonWG

Your right Dusty. As far as sizing goes, I consider anything from the turbo to the plenum as one tube. When the TB is WOT, all it ends up being is part of the tube.

You can't be hurt too much if the tubing is a little too big. Too small is a different story.

Be sure and do the math for yourself.

Working in my field has made me look at many things from different directions. I work with line sizing, flow directions, heat exchange and the effects of pressure drop and back pressure. Things like that come in very handy when applying it to the race cars.

[BetMinesFaster]

Originally Posted by DonWG

The main point I'm trying to make here is, you'll never know if the TB and tubing sizes are undersized if you don't bother to do the math.

Bought Maximum Boost off e-bay, Ill read and do math.