/4 2.0 throttle body "overbore"????, dyno proven improvment??? |
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/4 2.0 throttle body "overbore"????, dyno proven improvment??? |
Mueller |
Nov 3 2003, 12:42 AM
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#1
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914 Freak! Group: Members Posts: 17,150 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
Anyone ever do back to back testing with stock and then a bore'd out throttle body??
stock dia: 45.10mm average overbore diameter??? I'm guessing 50mm, it looks like I could bore mine out to 53.50mm...hmmmm (IMG:style_emoticons/default/smile.gif) motor to have higher than stock compression, custom R.A.T. cam and Megasquirt...... |
fiid |
Nov 3 2003, 12:45 AM
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#2
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Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
Aye - what was up with the Engel cam?
Rich @HPH sells overbored throttle bodies and seems to think they are a good idea. About as high subjective praise as you can get. Fiid. |
Brad Roberts |
Nov 3 2003, 12:46 AM
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#3
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Yep. Mike Harris and I tested it on his HPH built BP 2.0 last year.
Worthless on a stock engine with racing header. I could see how it would be needed for a engine that requires MORE air. This is why I have Andy working on the actual engineering flow numbers for the stock intake. I want to know EXACTLY what numbers the factory had to determine the stock intake manifold and stock throttle body. B |
Brad Roberts |
Nov 3 2003, 12:47 AM
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#4
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
Mike.. I may want the Engle FK cam.
B |
Mueller |
Nov 3 2003, 12:54 AM
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#5
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914 Freak! Group: Members Posts: 17,150 Joined: 4-January 03 From: Antioch, CA Member No.: 87 Region Association: None |
Hey b,
the cam is just sitting collecting dust (IMG:style_emoticons/default/sad.gif) do you have any extra t/b's? I could bore 'em out to a few different diameters if you want for testing, I also want to clean up the shaft and the trottle plate, lots of resistance with the current setup.... I got those "iris" throttle body parts (IMG:style_emoticons/default/smile.gif) Attached image(s) |
Brad Roberts |
Nov 3 2003, 01:22 AM
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#6
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914 Freak! Group: Members Posts: 19,148 Joined: 23-December 02 Member No.: 8 Region Association: None |
I want drawings.. not throttle bodies.
I'm tired of "experimenting" or using parts that are "supposed" to work. I want real numbers and real answer for this crap. Not guesses. B |
Britain Smith |
Nov 3 2003, 01:34 AM
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#7
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Nano Member Group: Members Posts: 2,354 Joined: 27-February 03 From: Hillsboro, OR Member No.: 364 |
Hey Brad...we also have the elgin cam sitting up there that would work well in NA trim...
-Britain |
Mark Henry |
Nov 3 2003, 08:10 AM
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#8
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that's what I do! Group: Members Posts: 20,065 Joined: 27-December 02 From: Port Hope, Ontario Member No.: 26 Region Association: Canada |
Brad, I love to see those numbers when you done. (IMG:style_emoticons/default/pray.gif)
I have no swap experience, but in the little seat time that I had, my SDS 2.0 with an old C-25 cam and 42mmX38mm valves was rockin. Just got a lot of tweeking still to do. But then anything would be an improvement over my old "snorting" 75hp 1.8 Ljet (IMG:style_emoticons/default/beer.gif) |
r_towle |
Nov 11 2003, 03:47 PM
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#9
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Whats the progress on this topic?
I would really like to see these numbers. Rich |
r_towle |
Nov 11 2003, 03:50 PM
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#10
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Sorry for the questions, but Who is HPH???
Could we add them to the vendor area?? Rich |
seanery |
Nov 11 2003, 03:53 PM
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#11
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waiting to rebuild whitey! Group: Retired Admin Posts: 15,854 Joined: 7-January 03 From: Indy Member No.: 100 Region Association: None |
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SirAndy |
Nov 11 2003, 04:40 PM
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#12
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Resident German Group: Admin Posts: 41,815 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(r_towle @ Nov 11 2003, 01:47 PM) I would really like to see these numbers. as soon as i get this damm server running right ... Andy |
Jake Raby |
Nov 11 2003, 07:08 PM
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#13
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
When I tried it we lost HP.
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r_towle |
Nov 11 2003, 07:50 PM
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#14
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
Im thinking 2270 with a bigger throttle body and MPS/Head Temp resisitor and fuel pressure tuning.
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Jake Raby |
Nov 11 2003, 08:32 PM
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#15
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
it'll never feed it.
Tried it tons of times! |
r_towle |
Nov 11 2003, 08:37 PM
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#16
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Custom Member Group: Members Posts: 24,624 Joined: 9-January 03 From: Taxachusetts Member No.: 124 Region Association: North East States |
how big have you gone Jake?????
DJet driven??? Rich |
Jake Raby |
Nov 11 2003, 08:43 PM
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#17
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Engine Surgeon Group: Members Posts: 9,398 Joined: 31-August 03 From: Lost Member No.: 1,095 Region Association: South East States |
All the ones that have stayed D Jet have been 2056 or smaller....
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fiid |
Nov 11 2003, 11:17 PM
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#18
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Turbo Megasquirted Subaru Member Group: Members Posts: 2,827 Joined: 7-April 03 From: San Francisco, CA Member No.: 530 Region Association: Northern California |
I bet you could get a megasquirted 2270 to run really nicely, and that might benefit from the larger throttle body. I wouldn't get too far into tuning the D-jet - (IMG:style_emoticons/default/barf.gif)
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SirAndy |
Nov 11 2003, 11:35 PM
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#19
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Resident German Group: Admin Posts: 41,815 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
QUOTE(fiid @ Nov 11 2003, 09:17 PM) I bet you could get a megasquirted 2270 to run really nicely, and that might benefit from the larger throttle body. I wouldn't get too far into tuning the D-jet - (IMG:style_emoticons/default/barf.gif) stock throttle body is plenty big ... will post numbers soon, Andy |
SirAndy |
Nov 18 2003, 12:10 AM
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#20
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Resident German Group: Admin Posts: 41,815 Joined: 21-January 03 From: Oakland, Kalifornia Member No.: 179 Region Association: Northern California |
ok, back to this issue. i have never seen a aftermarket "overbore" throttlebody but brad tells me they just use a stock TB and bore it out to a larger diameter.
running the numbers on the stock TB and looking at the shape of the original TB, it becomes quite obvious why this "modification" is not only NOT giving you more HP, fact is it will decrease your HP! and here is why: CFM (cubic feet per minute) is the amount of air your engine will "pump" through at a certain rpm. using the stock 2.0L (us-spec) engine as a reference, that would be ~170 CFM @ 4900 rpm (or 4829 Liter/min). this is the theoretical max if your engine had a VE (volumetric efficiency) of 100%. normal street engines have a VE of around 85%, meaning the 2.0L actually only pumps about 128 cfm. this is due to a lot of factors, like friction and turbulences and restrictive air intake and exhaust. (as well as valve size, of course). now, CFM is calculated as Area (in sqft) * Feet per Minute (velocity), where Area is the diameter of your intake, in our case, the throttle body and "Feet per Minute" is the speed (velocity) of the Air. sooo, overboring the stock TB will give us a bigger Area, thus, we get more CFM, right? Wrong! the stock TB has a special shape that introduces a "venturi" effect, which increases the velocity of the air going through the intake which results in a actual increase in CFM. if this shape is "bored out" to gain a bigger diameter, you'll loose the venturi effect, and at best, you'll end up with no gain, but most likley, you will even loose a few CFM. sooooo, what we need now is someone who has access to a flow-bench so we can confirm (or not) the theoretical numbers we have and come up with the correct size Throttle Body and intake runners and valves-sizes and exhaust system for various T4 engine-combos. anyone? Andy |
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