Hoping to have the money to start buying parts the first part of next year. I'm trying to plan ahead.

TB size? Flow rate of 39.7mm TB vs. 46mm TB? How much air does the NA need to pull in for each runner? Keep in mind my cams and high compression plans.

Smaller TB would help out with low end intake air velocity, but how much top end airr flow will I sacrafice? I think the 39mm TB could be a good street size. Thought? Ideas?

Una salus victus.
He will triumph, who knows when to fight, and when not to fight. - Sun Tzu

Michael J. Kulaga
e-mail: Michael_97RS@2gntDSM.zzn.com aol IM: MJKulga
http://highlander.dsmpower.com/

All motor in the making.

Injen CAI, P&P Intake Manifold, Crower Stage 2 Cams, Hooker Header, GS-T Muffler, AFX UDP, S-AFC, 8.5mm Magnecor Wires, Crane Fireball HI-6DI2, FU/RU/RL STBs, TSW Blade 17x7.5, Bridgestone Potenza RE730, Front KVR Cross-Drilled Rotors & Carbon Fiber Pads

To Be Installed: P&P Milled Head, Rear Disc Brakes, Rear KVR Cross Drilled Rotors & Carbon Fiber Kevlar Pads, SS Brake Lines, AFX 55mm TB (re-installed once exhaust is done, intake was outflowing exhaust)

I think that an important part here is to make the transition from the TB to the runner smooth. So that means that your TB should be approximately the same cross section as a ported intake runner. I would use a round piece of aluminum pipe that is the same size as the TB exit. Then smash one end of the pipe into a rectangular cross section (to exactly match the ported intake runner). When everything comes together, you would have a very smooth flow from the throttle plate to the head. I suppose you would want to round the TB inlets to make it easy for the air to flow into it too. I'm assuming that on a high-output N/A application, keeping pressure losses to a minimum is best. Any sharp transition will turn into a loss.


Corbin

'95 ESI-T
HRC+FMIC+ETC...



Gimme fuel...Gimme fire...Gimme that which I desire

I think I've pretty much scrapped the idea of using the stock lower intake manifold as the bottom. After taking a closer look at my spare manifold and the autocadd file you sent, it doesn't seem like a logical choice. The rectangular ports would mean a large adapter plate (which I planned to autocadd and get CNC'd) that could cause clearance issues. The ports are not straight lined up straight in a row, so linkag eof the TB's becomes problematic at best. So I've resolved myself to a custom lower intake out of mandral bent piping. Since I was impressed with ERT when I saw them do the turbo downpipe, I'll offer the work to them first.

So I can get a good transition with a custom manifold and smooth flow. I have a couple choices for TB's and then totally custom linked TB set up. But it brings me back to the size of the TB's I think I'm actually leaning to the 39mm over the 46mm, even though that is what was used on the Neon Quad TB that produced very good results.

Una salus victus.
He will triumph, who knows when to fight, and when not to fight. - Sun Tzu

Michael J. Kulaga
e-mail: Michael_97RS@2gntDSM.zzn.com aol IM: MJKulga
http://highlander.dsmpower.com/

All motor in the making.

Injen CAI, P&P Intake Manifold, Crower Stage 2 Cams, Hooker Header, GS-T Muffler, AFX UDP, S-AFC, 8.5mm Magnecor Wires, Crane Fireball HI-6DI2, FU/RU/RL STBs, TSW Blade 17x7.5, Bridgestone Potenza RE730, Front KVR Cross-Drilled Rotors & Carbon Fiber Pads

To Be Installed: P&P Milled Head, Rear Disc Brakes, Rear KVR Cross Drilled Rotors & Carbon Fiber Kevlar Pads, SS Brake Lines, AFX 55mm TB (re-installed once exhaust is done, intake was outflowing exhaust)

Well, it is better to error on a smaller diameter throttle body for a street car.

Unfortunately you can't just divide up the area of the stock throttle body by 4 and go from there, that would make 13mm throttle bodies for the quad setup (which would work at maybe 200 rpms :) and that's it!)

We need to find the calculation of throttle body diameter/area versus CFM, but I can't find it anywhere (I could have sworn someone posted it on the board, I just can't find it. I seem to remember Bill Hahn posting it, but I could be mistaken.)

Anyway, taking 1/4 of the CFM airflow through the stock throttle body (which is pretty good) and applying that to each of the 4 throttle bodies would be a good starting point. Of course, you'd have to go a bit bigger for increased RPMs, and for different camshafts (how much is speculation at this point), but it will at least give you a place to start from....

if I could only find that calculation....

Well, if i did my math right:

Stock 52MM TB Area: 2,123 Sq mm

Quad 39.7 MM TB Cumulative area: 4952 Sq mm

Quad 46 MM TB Cumulative Area: 6,648 Sq mm

So if i'm reading these right, the 46 mm Quad TB would flow at any given rate, over 3 times the volume of air as the stock 52 mm TB at the same flow rate.

Using something that so outflows stock though, would Volumetric efficiency suffer or improve?

This link might help...
http://www.installuniversity.com/install_university/installu_articles/flowby/flowby_need_8.302000.htm

>So if i'm reading these right, the 46 mm Quad TB would flow
>at any given rate, over 3 times the volume of air as the
>stock 52 mm TB at the same flow rate.

I don't think it works that way. You can't just divide the area of the stock throttle body by 4 and get for small throttle bodies to equal that area to get the same flow. If you did that then to equal the 52 mm throttle body you'd have 4 throttle bodies 13 mm in diameter!

2123 mm^2 (area of stock TB) / 4 = 530.75 (area of each individual TB)

530.75/Pi=169 square root of 169 is 13, so 4 13mm throttle bodies

That would not flow at all. It doesn't translate directly from area to CFM a minute. We've got to find the CFM vs. area equation. I think either Gary Howell posted it or Bill Hahn, one of those guys did, I still can't find it :(

13mm throttle body? LOL, what's the point? That's the diameter of my freakin thumb! :thumbsup The concept of going quad is so that you get multiple throttle bodies that ad up to a larger diameter than your stock intake could ever come close to.

Guys are using Suzuki GSXR throttles for this...like 38mm each, total 152mm. It's a tuning nightmare, but you'll never find a 13mm throttle body, and it's a waste of all your time and effort to restrict the system with 4 throttle bodies that ad up to the same diameter of the factory system.

>Well, if i did my math right:
>
>Stock 52MM TB Area: 2,123 Sq mm
>
>Quad 39.7 MM TB Cumulative area: 4952 Sq mm
>
>Quad 46 MM TB Cumulative Area: 6,648 Sq mm
>
>So if i'm reading these right, the 46 mm Quad TB would flow
>at any given rate, over 3 times the volume of air as the
>stock 52 mm TB at the same flow rate.
>
>Using something that so outflows stock though, would
>Volumetric efficiency suffer or improve?
>
>This link might help...
>http://www.installuniversity.com/install_university/installu_articles/flowby/flowby_need_8.302000.htm

Ahh.. this is all good and fine, but last time I checked the engine didn't open all 16 intake valves at the same time.. apples and oranges. We know that the cylinder to achieve 100% VE will have to fill with .5L of air in the given cam duration.

I don't have an answer as to which throttle body size to use, but 4 stockers would probably make your lowend suffer but would scream on the top end.. however this can be adjusted for with different intake runners etc.

My advice is to get a good desktop dyno software and experiment with it. Most of the good software will have ITB setups in them. They are usually pretty accurate as long as your NA.. turbo they get strange just because there is too many variables involved.

Either that or bolt the thing up, and then start playing with spacers to lengthen/shorten the length of the runners till you tune it to the RPM you want. Something like the magnus 4g63 manifold.

-- WheatKing

Is this the formula we're all looking for:

CFM = Displacement X RPM X VE /3456

>Is this the formula we're all looking for:
>
>CFM = Displacement X RPM X VE /3456


That'd be it..

so we get..

Displacement = 30.25ci
RPM = 7300
VE = 75 (wild guess)

so the CFM per cylinder at 7300rpm would be approx 48CFM

-- WheatKing

I came up with this other link, that first formula doesn't look quite right..... http://www.toymods.org.au/throttle_body.html

>I came up with this other link, that first formula doesn't
>look quite right.....
>http://www.toymods.org.au/throttle_body.html


This formula works out the same as the other formula.. instead of multiplying by .5 to get 1/2 the revolutions, the other formula just doubles the amount that you divide by.. One less thing to input on your part.

-- WheatKing

Just got off the phone with Gary Howell. He recommended for a street/strip car, not going over 36mm, anything larger and low end would suffer.

He recommended a company called Kensler (sp?) but I couldn't find their site or info. If anybody has heard of them let me know, I don't want to bug Gary if I don't have to.

He runs 40mm on a 2.4L with 10k rpm motor...

Una salus victus.
He will triumph, who knows when to fight, and when not to fight. - Sun Tzu

Michael J. Kulaga
e-mail: Michael_97RS@2gntDSM.zzn.com aol IM: MJKulga
http://highlander.dsmpower.com/

All motor in the making.

Injen CAI, P&P Intake Manifold, Crower Stage 2 Cams, Hooker Header, GS-T Muffler, AFX UDP, S-AFC, 8.5mm Magnecor Wires, Crane Fireball HI-6DI2, FU/RU/RL STBs, TSW Blade 17x7.5, Bridgestone Potenza RE730, Front KVR Cross-Drilled Rotors & Carbon Fiber Pads

To Be Installed: P&P Milled Head, Rear Disc Brakes, Rear KVR Cross Drilled Rotors & Carbon Fiber Kevlar Pads, SS Brake Lines, AFX 55mm TB (re-installed once exhaust is done, intake was outflowing exhaust)

Thats sweet, a 10k 2.4L engine!!! Looks like Im gonna go 15000rpm ;) yeah right, lotto here I come.
Brent