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which EFI intake design should I do?


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#1 luvemfast

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Posted 12 June 2008 - 10:08 AM

Hey there, I want to build a custom Aluminium intake manifold.

Which of these concepts should I continue with?

Also, i have many choices of throttle bodies to use.
RB20 (dia 60), RB25 (dia 65) or Q45 (dia 90).
Which would be best for an L28 (to be modified in the future)?

(I hope the attachments work.)

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#2 Hunter

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Posted 12 June 2008 - 11:35 AM

KISS principle (KEEP IT SIMPLE STUPID)

Go the first one it is easier to make.

Just ensure it has the same diameter as your Throttle body. This will ensure you get very little presure drop when the air enters the chamber. Therefore your boost pressure will be maintained throughout the whole system.

It also has less welds in it and will give air a smoother air flow. Even though the flow will be disrupted at the 90 degree bends on the intake cones. But the intake cones will straighten the airflow out again.

HUNTER

#3 Lurch ™

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Posted 12 June 2008 - 06:51 PM

Tripple carb or homemade manfold with motorcycle throttle boddies.

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#4 Hunter

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Posted 12 June 2008 - 10:40 PM

looks good, how about you make an intake that is like headers in reverse?

#5 Lurch ™

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Posted 13 June 2008 - 12:28 AM

looks good, how about you make an intake that is like headers in reverse?

Can you please explain that comment better?

#6 luvemfast

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Posted 13 June 2008 - 07:47 AM

looks good, how about you make an intake that is like headers in reverse?



Funny you mention that Hunter.
One of the draftsmen here at work suggested the same thing. He says he has done one before on a friends car. Where he 3D lasercut stainless tube and tig welded it together. All 6 tuned pipes straight from the throttle body.

Back to my original question.
My main concern that using the Q45 throttle body would be too big. I have spoken with a few mechanical enginneers here at work, they all think that it will be ok to use.
So I am thinking of another design of plenum that is tapered to increase air speed as it approaches the intake runners.
Will keep you posted.

#7 Hunter

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Posted 13 June 2008 - 08:41 AM


Funny you mention that Hunter.
One of the draftsmen here at work suggested the same thing. He says he has done one before on a friends car. Where he 3D lasercut stainless tube and tig welded it together. All 6 tuned pipes straight from the throttle body.

Back to my original question.
My main concern that using the Q45 throttle body would be too big. I have spoken with a few mechanical engineers here at work, they all think that it will be OK to use.
So I am thinking of another design of plenum that is tapered to increase air speed as it approaches the intake runners.
Will keep you posted.



Lurch
as explained above 6 separate pipes too each cylinder. basically like header in reverse. just the pipes would have sharper mandrel bent radius's and all join together at the AFM. Also each pipe to each cylinder must be the same length so that each cylinder is working against the same friction factor.

With the throttle body, the engine will only use as much as it is going to use. even if it is not using the full capacity of the Q45. I don't think this will affect it? As long as your plenum has the same capacity as the Q45.

In underground mine ventilation which is very similar to intake and exhausts, tapering the intake will increase the air speed, but will also increase the pressure and therefore friction that the engine has to over come.

In a mine ventilation fan the bellmouth increases the fans efficiency, by straightening the the airflow and making it laminar (smooth). Also on the output side of the fan an evase (pronounced evahzae), which is a cone shaped object that starts the same diameter of the outlet then increases in diameter, this increases the power produce by the fan by holding onto the pressure for longer when venting to atmosphere.
This type of exhaust i used on top fuel dragsters.

When you have designed this up I may have to get you to make it in stereo so I can buy one off you. ;D

#8 Hunter

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Posted 13 June 2008 - 09:15 AM

Some pics of the above explanation.

This particular fan moves "250 cubic meters of air per second"

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#9 modular9

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Posted 13 June 2008 - 11:35 AM

I too have been looking at designing some sort of intake system so will be looking on with some interest.

Hunter : thanks for the information


#10 Hunter

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Posted 13 June 2008 - 01:23 PM

This type of exhaust IS used on top fuel dragsters. Not I :-\


#11 stevo_gj

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Posted 13 June 2008 - 05:36 PM

hey hunter you dont have to write a new post, just click the modify button next to your old post and change the spelling.

should save you some time  ;)

#12 luvemfast

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Posted 15 June 2008 - 03:56 PM

I think it's a no brainer as to which throttle body to use.
Now just need to design the plenum to suit.
Will also use injectors from RB20.

From left to right.

Q45, RB25, RB20 & L28

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#13 Hunter

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Posted 18 June 2008 - 06:29 PM

cheers stevo I was wondering if you could edit posts and there it was infront of my eyes LOL

#14 Hunter

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Posted 20 June 2008 - 12:36 AM

Found some interesting threads on HybridZ for you

http://forums.hybrid...ad.php?t=128284

http://forums.hybrid...ad.php?t=126916

#15 Hunter

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Posted 21 June 2008 - 05:26 AM

Couple of pics I found on a US Ebay auction. this is for a triple webber setup but good for ideas.

http://cgi.ebay.com/...sspagenameZWDVW

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#16 luvemfast

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Posted 21 June 2008 - 03:09 PM

Been reading bits on the web (thanks for the links Hunter) and Race mag has gone into intakes in issue 13 and 14.
I will have to re-design. I am starting to understand more about the theory now, its not as simple as having larger diameter runners and plenum. There is high and low pressure waves to "tune". Volume available and so on.

Here is a pic of a 1:1 plot of a design to check for room.

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#17 Hunter

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Posted 21 June 2008 - 11:49 PM

Another pic I found. most likley has air horns inside the box as per the webber setup

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#18 nat0_240_chevZ

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Posted 22 June 2008 - 09:56 PM

yes tune for a 3rd heimholtz wave front approx 260mm total runner length IIRC.. for a 4800rpm torque surge, plenty of discussion on hyridz inclusing the formula to use and how to use it if interested....

nat0

#19 Hunter

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Posted 22 June 2008 - 11:02 PM

Post the link up on this forum

#20 modular9

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Posted 23 June 2008 - 10:58 AM

Been playing with this http://caelinux.com/CMS/ and it is free works well but I now have compiled it so i can use it on my everyday Linux computer but the live cd works really well if you dont want to run linux all the time.

These guys are doing a turbo one but it looks like they have done a little work with airflow.
http://forums.hybrid...ad.php?t=127863
http://forums.hybrid...ad.php?t=127653
not sure if they are the ones that nat0_240_chevz is talking about but they have been handy with the mucking about i have been doing in caelinux.

Also The heimholtz principle is really interesting. I dont normally get all up with wave fronts and physics and air flow but it really is interesting reading even for someone who isnt the sharpest tool in the shed like me  ;D




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