ITB Intake Manifold interest
10-06-2009, 09:16 AM
#167
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10-09-2009, 12:17 PM
#168
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It's allive!! Fired it yesterday. Still have detains to work out. Throttle spring
return bracket... Oh... that's about it! Still yet to drive and tune the car.
return bracket... Oh... that's about it! Still yet to drive and tune the car.
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Mike or Dave Lindsey
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Mike or Dave Lindsey
www.lindseyracing.com
U.S. 1-877-943-3565
Other 1-405-947-0137
10-09-2009, 12:22 PM
#169
Nordschleife Master
Well I for one will say it... it sure is pretty... I like pretty...
And it looks like the throttle return spring bracket you have fitted seems to be working alright... my only concern with it would be longevity.
And it looks like the throttle return spring bracket you have fitted seems to be working alright... my only concern with it would be longevity.
10-09-2009, 12:55 PM
#171
Rennlist Member
Looks good, Mike. Every think about an e-gas setup? I assume anyone who gets that isn't running the stock computers...
Does the strut tower brace still fit?
Does the strut tower brace still fit?
10-09-2009, 12:58 PM
#172
Rennlist Junkie Forever
Looks good.
And good thing you kept the MAF.
Should tune real easy.
I'd be interested in close up photos of the links between the throttle bodies. Most of the time these have a teeneee bit of play. The problem is that if that's the case, you need light return springs on each butterfly to keep them perfectly synched as you open and close the throttle.
That's one of the problems we had when we used the TWM 3003 series on the 911 engines and other ITB setups in the past.
TonyG
And good thing you kept the MAF.
Should tune real easy.
I'd be interested in close up photos of the links between the throttle bodies. Most of the time these have a teeneee bit of play. The problem is that if that's the case, you need light return springs on each butterfly to keep them perfectly synched as you open and close the throttle.
That's one of the problems we had when we used the TWM 3003 series on the 911 engines and other ITB setups in the past.
TonyG
10-09-2009, 01:34 PM
#173
Nordschleife Master
Faster throttle response yes, but always thought that one of the main benefits of itb's is to be able to tune the intake tracts to match the engine. From the moment the intake valve closes the individual intake pipe acts as a closed end pipe, length (L) from the center of the valve stem to the end of the throttle body or trumpet. This produces a wavelength of 4xL in a closed-end pipe. This wave has odd harmonics (3rd, 5th, 7th, etc) that travel back down the individual intake pipe and force air back towards the intake valve producing a supercharging effect.
What everyone seems to overlook is that the trick to all these itb systems is to match the length of the intake pipe to take advantage of this "free" boost. Get it wrong and it will work against the boost you are supplying and you will lose power. So to get the intake tracts the optimal length you need to know the duration that the intake valve is closed and work out the number of seconds it takes to complete the duration at max torque rpm (or max hp rpm for track cars). That is the exact time you want a harmonic to feed air back into the cylinder. You can then work out the exact length of the intake required to produce this effect using the speed of sound in air.
Another consideration is that the position of the injectors is critical. Feeding the fuel at the back of the valve heads produces good power to about 5000rpm. Going any higher you really need to feed the fuel further up the intake or use duel injectors.
There are many other considerations that come into the equation, throttle body diameter, CFM, venturi bodies, etc. This site has some useful info: Jenvey
BTW, 9m did a nice tuned-length set-up for the na a while back but nothing came from it:
-Mike
What everyone seems to overlook is that the trick to all these itb systems is to match the length of the intake pipe to take advantage of this "free" boost. Get it wrong and it will work against the boost you are supplying and you will lose power. So to get the intake tracts the optimal length you need to know the duration that the intake valve is closed and work out the number of seconds it takes to complete the duration at max torque rpm (or max hp rpm for track cars). That is the exact time you want a harmonic to feed air back into the cylinder. You can then work out the exact length of the intake required to produce this effect using the speed of sound in air.
Another consideration is that the position of the injectors is critical. Feeding the fuel at the back of the valve heads produces good power to about 5000rpm. Going any higher you really need to feed the fuel further up the intake or use duel injectors.
There are many other considerations that come into the equation, throttle body diameter, CFM, venturi bodies, etc. This site has some useful info: Jenvey
BTW, 9m did a nice tuned-length set-up for the na a while back but nothing came from it:
-Mike
10-10-2009, 08:46 AM
#174
Race Car
Faster throttle response yes, but always thought that one of the main benefits of itb's is to be able to tune the intake tracts to match the engine. From the moment the intake valve closes the individual intake pipe acts as a closed end pipe, length (L) from the center of the valve stem to the end of the throttle body or trumpet.
The biggest benefit I see from ITB's is the ability to run much more aggressive cams without losing all civility.
Otherwise you are right. From the looks of it, I would expect the intake in question to move the torque peak out to the right a bit.
01-10-2010, 11:49 AM
#176
2nd Gear
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Faster throttle response yes, but always thought that one of the main benefits of itb's is to be able to tune the intake tracts to match the engine. From the moment the intake valve closes the individual intake pipe acts as a closed end pipe, length (L) from the center of the valve stem to the end of the throttle body or trumpet. This produces a wavelength of 4xL in a closed-end pipe. This wave has odd harmonics (3rd, 5th, 7th, etc) that travel back down the individual intake pipe and force air back towards the intake valve producing a supercharging effect.
What everyone seems to overlook is that the trick to all these itb systems is to match the length of the intake pipe to take advantage of this "free" boost. Get it wrong and it will work against the boost you are supplying and you will lose power. So to get the intake tracts the optimal length you need to know the duration that the intake valve is closed and work out the number of seconds it takes to complete the duration at max torque rpm (or max hp rpm for track cars). That is the exact time you want a harmonic to feed air back into the cylinder. You can then work out the exact length of the intake required to produce this effect using the speed of sound in air.
Another consideration is that the position of the injectors is critical. Feeding the fuel at the back of the valve heads produces good power to about 5000rpm. Going any higher you really need to feed the fuel further up the intake or use duel injectors.
There are many other considerations that come into the equation, throttle body diameter, CFM, venturi bodies, etc. This site has some useful info: Jenvey
BTW, 9m did a nice tuned-length set-up for the na a while back but nothing came from it:
-Mike
What everyone seems to overlook is that the trick to all these itb systems is to match the length of the intake pipe to take advantage of this "free" boost. Get it wrong and it will work against the boost you are supplying and you will lose power. So to get the intake tracts the optimal length you need to know the duration that the intake valve is closed and work out the number of seconds it takes to complete the duration at max torque rpm (or max hp rpm for track cars). That is the exact time you want a harmonic to feed air back into the cylinder. You can then work out the exact length of the intake required to produce this effect using the speed of sound in air.
Another consideration is that the position of the injectors is critical. Feeding the fuel at the back of the valve heads produces good power to about 5000rpm. Going any higher you really need to feed the fuel further up the intake or use duel injectors.
There are many other considerations that come into the equation, throttle body diameter, CFM, venturi bodies, etc. This site has some useful info: Jenvey
BTW, 9m did a nice tuned-length set-up for the na a while back but nothing came from it:
-Mike
Mack
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01-11-2010, 08:14 PM
#178
Burning Brakes
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Doesn't BMW do a blended map with all these new high performance M cars with ITB's? I think they have the butterfly RIGHT against the head, and a plenum behind them that collects through a MAF. The plenum is volume tuned. Maybe even variable volume....lol They also have the variable TPS going to the computer as well. Seems like you'd need to make a piggyback for variable TPS and MAF - do your blending calculations there - and then insert data to the DME. LOTS OF WORK to do this right.
