I am very open minded to the concept that the twin scroll is hurting my performance but from everything I have read and researched I can not find any data which supports such a proposition. I can agree that perhaps on our application twin scroll may not be as beneficial as on a V8 engine for example - however - from an engineering perspective the concept no doubt affords a distinct advantage, at least that is my feeling based upon my reading.

I am always open to suggestion and new ideas.

Al

 

At the end of the day, NOS is a great concept it requires a lot of effort from my experience.

Not to mention the time I did a back fire at ATCO and blew my intake, fmic and fmic up in one shot and also **** in my pants.

Al

 

I was wondering how long the "new and improved" david buschur would last. Thank you so much.

 

This is a technical thread - please refrain from going with nonsense

 

I'm using an MPFab manifold, which is somewhat similar to Shearer's work. Pics can be viewed here: Ted B's Setup

BTW Al, regarding the small difference between 40psi and 47psi with your setup, you're probably just plain out of turbine side at that power level. There could be other factors involved, but that's where I'd point my finger. There may be some merit to an earlier suggestion that your testing includes runs at 30 psi as well, just so the turbo has enough headroom in it so that improvements can be realized. If the turbo is out of puff at 40psi or if turbine side backpressure is high, a better head probably won't make a difference at that point, and the results could be misleading.

David, the reason why one sees a great deal of headflow data in the industry and virtually zero flow data for intake and exhaust manifolds is because unlike the ports and valves of a head, the potential of manifold runners and plenums is governed by pulse wave tuning. This makes for a complex scenario that cannot be gauged with a steady stream of air (i.e. a flowbench). Think of it as trying to determine the sound quality of a trumpet by just blowing air into the mouthpiece instead of playing it. It won't happen.

 

Dave are you saying you seen nothing from a increase of flow in the manifold from the bencg to the dyno?

I have flowed a bunch of manifolds over the years, and always flow them on the head. Usually it will knock the cfm down, sometimes as much as 40cfm. Port it, pick up a bunch of cfm on the bench, but only in the LS1 did we not see a increase of power. I also seen in rare occasions the manifold would actually only knock the head down 3-10 cfm. and porting did nothing. I like Ted's explanation. It makes sense, what doesn't to me is why it seems to not always be consistant from motor to motor.

 

Thats why they call it headGAMES Its a fascinating subject for sure.

I am sure excited by my project but the amount of tuning work I have to do is making my progress on my own car very slow.

Hopefully I can get moving on this.

Al

 

hey al what kind of ignition are you using i thought i seen stock coils in the first pic thanks.

 

AL..be happy you don't have time to work on your car. i have been trying to get to my own heads for my Vette for weeks, wish I had the time. But when I think about how the ecomony hit us earlier this year, and how everyone is slow or out of work or even closing up shop..we gotta take the work with a smile!

in the interm..we have some good conversation going on.

 

Yes - stock coils and wires with HKS twin fire - BR8ES plugs gapped tight

AL

 

I agree with you 100%, I really appreciate the passion and determination of our customers who have continued in the car performance and modification hobby despite the weakness in the overall economy.

I can only speak for myself when I say that I have not stopped my car modification process one bit and I am just as fired up as ever about my Evo and continuing to find ways to make it run better.

Al

 

See below

 

AHH,,, no, you sir are incorrect. Just plain wrong. First off, the ports in the head are subject to the EXACT same pressure waves as the manifolds. Your "pulse wave tuning" which I believe is called "resonance tuning" that you speak of is not isolated to the runners of the intake manifold. The pressure waves "bounce" off the back of a a valve and the low pressure zone ( as relative to the runners) in the plenum ( as an example of one sort of resonance). The entire length is subject to this phenomenon. A gasket between the head and manifold doesn't effect these waves. You are correct, however when you mention how complex these waves can be. In most four valve cylinders, there is multiple waves bouncing through the intake system. The closing of the exhaust valve causes a wave, scavenging from valve overlap can cause one, the intake valve closing can cause one as well. These waves happen in both the intake ports and exhaust ports. Further more, there can be yet another wave forms from the plenum through TB and intake ducting. Any area where volumes, and ducts come together is surely to create a resonance of some kind. The trick is to get all the resonance waves working in harmony and the rpm you want. This is how F1 cars achieve 140% VE. It's not magic, its science.

There are many ways to actually calculate these resonances, the easiest being some quick formulas for a helmholtz reso, while software packages like Ricardo Wave, and AVL boost, GT power, can calculate these based on 1D estimations, or be coupled to a decent 3D CFD package to get more accurate results.

Since I use the Ricardo Wave and Vectis package a lot, I can speak to the terrific correlation between the simulations and actual dyno results. The rough hand calculations, usually get you in the ballpark, but not nearly as close as Good software..

One more thing, If AL gets to test a lot of cylinder heads, I would wager that the best performing heads are those with more work focused on the valve seats and combustion chamber, rather than the ports themselves....

 

Just you you'll know, I frequently simplify concepts and terms for the benefit of the masses, which is why I resort to more visually descriptive expressions such as "pulse wave tuning". I am well aware of the role the ports, valves, valve timing, runners, plenum, and such play in the composite resonance scheme, but I deliberately chose to simplify the picture with an easily visualized analogy for this short blurb. Nonetheless, I should carefully note that the head isn't isolated from resonance if I implied otherwise. Thank you for the comment.


Which is exactly why I refrained from initiating a lengthy, heavy treatise on the complexity of resonance smack in the middle of Al's topic. Resonance is a tremendously interesing topic, and worthy of months of discussion and speculation, but not necessarily here.

Carry on . . .

 

Ricardo is soooooo dope, I wish I had a copy of a couple of their software packages.

Scorke