Time to go Stage II!
- Thread starter Alky V6
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Yea, go back about 80 pages or a 1000 posts ago. I am sure that was stated earlier. Question, why the 102mm throttle body? Most of ( that I know) the fastest GN's use the 90mm body. The 90mm Accufab is on my purchase list. The interest surrounding your build is incredible, 112 pages!!! Nice!
I think its a good size TB, the HP goals here are not the ordinary S2 setup, I don;t think it would hurt.
102mm matches a 4 inch up-pipe perfectly.
It's definitely not so overkill if I can notice a slight power change when letting off the throttle a little. I noticed this on the Stage I combination.
If it were overkill, then letting off the throttle a little shouldn't really affect the power output, I think.
I could be wrong.
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The throttlebody is set as forward as I dare on this new intake design to give more length and some taper for the airflow to make the turn to properly feed the front most intake runner (number 2 cylinder).
Also, the size of the throttlebody slows down the airflow exiting the throttlebody, compared to a smaller diameter throttlebody.
The slower airflow exiting the larger diameter throttlebody will make a turn to that first runner easier with less chance of excessive turbulence and pressure drop.
Also, the size of the throttlebody slows down the airflow exiting the throttlebody, compared to a smaller diameter throttlebody.
The slower airflow exiting the larger diameter throttlebody will make a turn to that first runner easier with less chance of excessive turbulence and pressure drop.
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More pics of the positioning of the throttlebody. I often study pics like this for a long time before I come up with how I will be fabricating something. This one is a tough one. The last difficult fabricating job of this project
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ttypewhite
Well-Known Member
- Joined
- Oct 1, 2001
- Messages
- 4,156
Looks good Donnie, can that throttle body make it under the hood? That would look really nice if it was all concealed.
I'm positioning the throttlebody to use the existing hole in the hood. The uppipe won't stick up out of the hole the same as last time, but it will use the hole in the hood.
New thinking now is to mount the throttle body more remotely, over the inlet of the turbo, and taper the piping after the throttle body, through the turn to the plenum and have it to about the width of the main plenum body by the time the piping reaches the point where the throttle body is now shown in the most recent pictures. This should also allow clearance so that I can close up the hole in the hood. Just for you ttypewhite!
The long, gradual tapering of the piping after the throttle body to the main intake plenum body should cut down turbulence and low pressure zones inside the plenum, in the area of the intake port runners, to a bare minimum.
It is going to be a major metal forming job to accomplish this last major fabrication project on the intake manifold, but when all is said and done, it will surely be a design with very little compromise in the way of assuring that each intake runner is equally supplied with clean, pressurized intake air. WFO!!!
This should also give me the plenum volume I'm targeting. 250-300 percent of engine displacement. (just a lot of freakin' volume)
The long, gradual tapering of the piping after the throttle body to the main intake plenum body should cut down turbulence and low pressure zones inside the plenum, in the area of the intake port runners, to a bare minimum.
It is going to be a major metal forming job to accomplish this last major fabrication project on the intake manifold, but when all is said and done, it will surely be a design with very little compromise in the way of assuring that each intake runner is equally supplied with clean, pressurized intake air. WFO!!!
This should also give me the plenum volume I'm targeting. 250-300 percent of engine displacement. (just a lot of freakin' volume)
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ttypewhite
Well-Known Member
- Joined
- Oct 1, 2001
- Messages
- 4,156
Atta boy Donnie!!! 
The next step will be to build an elaborate metal forming buck to used to form this tapered tubing with a bend, and front section to the main intake plenum body. I'll start out the rib work with cardboard, then transfer the pattern to plywood pieces.
Don,where does your theory of air volume inside the plenum come from. I am still reading up on runner lengths and plenums. I have a very large lid from the tunnel ram pictured above , it made the cut from what I was told ,10 different designs. A turbocharged road race engine with mechanical injection and threaded for NOS. While the lid was in storage something heavy was sitting on top of it and I have to get it popped back out an rewelded in some spots.
I have picked up tidbits of information from here and there, in several books that I have in my library, and on the internet. I participate on another BB that has a great technical discussion on intake manifold design for turbocharged engines. A few engineers have contributed, and continue to contribute on that particular thread. Some have shared interesting computer aided flow dynamic studies on particular intake configurations, including various throttle body mounting distances and angles.
Even so, I will be the first to tell you that I am, by no means, an expert on intake manifold design, although, it is something that has intrigued me for quite some time.
From what I have gathered, an IR intake system where the intake runner inlet is open to the atmosphere (no plenum) tends to provide a broader and flatter torque curve.
A helmholtz intake system (helmholtz resonator), which is an extreme example of using the intake manifold to fine tune the engine, uses plenum, intake tubes and chambers of specific sizes and lengths to provide peak power tuning at a specific rpm range, which tends to be narrow, with the chance that power may be hurt outside of the specific rpm range.
What I've picked up from my reading and studying is that if you want to cancel out pressure pulse tuning within the intake plenum, in essence try to emulate an IR (independent runner) intake system to provide a broader, flatter torque curve, then you want to provide as much intake plenum volume as is practical (space constraint limitations) to help dampen the pressure pulse waves bouncing around inside the plenum. You want the intake runner to feel as if it is breathing into the open atmosphere.
An intake plenum volume of 2.5 to 3 times the engine displacement volume for a V6 engine configuration is a figure that I have seen a few times. Once in a book, and once on the internet. It's not a figure that I've arbitrarily come up with on my own.
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I just wanted to be the first to wish you a happy anniversary! The traditional TWO YEAR ANNIVERSARY 
gift is cotton, so you might want to give Jack a call. Lol! Hopefully, we're not waiting anther year for some results. Let me know if I can be of any help.
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gift is cotton, so you might want to give Jack a call. Lol! Hopefully, we're not waiting anther year for some results. Let me know if I can be of any help.Posted from the TurboBuick.Com mobile app
Don't rush on my part. I'm anxious to see what kind of ET you throw down when she's back together. Although, the longer you take the faster everyone else is getting. It's a good thing you and Tony never locked anything up.
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