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Old 8th April 2007, 11:04   #121
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No. The cylinders get the required fuel they need.. What happens before the valve opens does not matter, as long as the total fuel getting into the engine is correct. In fact injection when valve is closed helps reduce intake valve temperatures and improve fuel atomisation..
Right, of course. I totally forgot injection is not direct.
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Old 8th April 2007, 16:38   #122
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How do you decide between choosing Alpha-N (TPS vs RPM) and Speed-Density (MAP vs RPM) tuning? Of course providing the standalone supports it? I'm not considering MAF tuning since I don't think most of the cars run MAF here anyway. What advantages do each of them hold over the other? Is S-D easier to tune? Because I read TPS values are not very linear compared to the lower RPM. But then it would not depend on the pressure inside the manifold, or rather the lack of it? Alpha-N is supposed to be popular with ITB setups. Some people also run a blend of S-D and Alpha-N tuning.
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Old 8th April 2007, 22:25   #123
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How do you decide between choosing Alpha-N (TPS vs RPM) and Speed-Density (MAP vs RPM) tuning? Of course providing the standalone supports it? I'm not considering MAF tuning since I don't think most of the cars run MAF here anyway. What advantages do each of them hold over the other? Is S-D easier to tune? Because I read TPS values are not very linear compared to the lower RPM. But then it would not depend on the pressure inside the manifold, or rather the lack of it? Alpha-N is supposed to be popular with ITB setups. Some people also run a blend of S-D and Alpha-N tuning.

Speed-density is a better system wrt emissions, mileage,drivability and refinement. When an engine is modified, for ex. with a wild camshaft ,different intake (ex.ITB) and/or exhaust design, you can get "reverse pulses" in the intake tract where the map sensor measures manifold pressure ( psycho and other dudes who work on exhaust and intake systems can prpbably explain better and in detail). Due to these pulses (actually pressure spikes), map readings will be "noisy" confusing the ECU, which makes it see an incorrect fluctuating load. So we can do one of two things -

1) We switch to Alpha-N mode, where load is based on the angle of throttle opening. Another reason to switch over is to suit the system, ex. an ITB setup without a common balancer pipe...... As you said, Alpha-N is not linear,and is harder to setup for best economy and emissions.

2) Use an ECU with the ability to filter out this noise


With the right tune, both the systems develop identical peak performance.

Each of them require a different approach to tune/map. Ease of tune is subjective, and i feel its a matter of how well the tuner/user understands the system.

Blending Alpha-n and speed-density is a nice concept, and there are many ways to implement this. Some of them are
1) Using an algorith that chooses the best load based on both readings
2) Using a switch-over kind of mechanism, where map readings are ignored when there are excesive pulses.
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Old 10th April 2007, 20:38   #124
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just wanted to share a good source for learning all about fuel injection systems:

Amazon.com: How to Tune and Modify Engine Management Systems (Motorbooks Workshop): Books: Jeff Hartman

I just got this yesterday and its an amazing book. i'd recommend this to anyone intending to learn more about EFI systems.
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Old 10th April 2007, 22:14   #125
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Originally Posted by ananthkamath View Post
just wanted to share a good source for learning all about fuel injection systems:

Amazon.com: How to Tune and Modify Engine Management Systems (Motorbooks Workshop): Books: Jeff Hartman

I just got this yesterday and its an amazing book. i'd recommend this to anyone intending to learn more about EFI systems.
Got my copy recently too!
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Old 11th April 2007, 01:20   #126
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Ok, help spread piracy and send me a copy too.
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Old 11th April 2007, 03:36   #127
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Originally Posted by rdkarthik View Post
Speed-density is a better system wrt emissions, mileage,drivability and refinement. When an engine is modified, for ex. with a wild camshaft ,different intake (ex.ITB) and/or exhaust design, you can get "reverse pulses" in the intake tract where the map sensor measures manifold pressure ( psycho and other dudes who work on exhaust and intake systems can prpbably explain better and in detail). Due to these pulses (actually pressure spikes), map readings will be "noisy" confusing the ECU, which makes it see an incorrect fluctuating load. So we can do one of two things -
1) We switch to Alpha-N mode, where load is based on the angle of throttle opening. Another reason to switch over is to suit the system, ex. an ITB setup without a common balancer pipe...... As you said, Alpha-N is not linear,and is harder to setup for best economy and emissions.
2) Use an ECU with the ability to filter out this noise

With the right tune, both the systems develop identical peak performance.

Each of them require a different approach to tune/map. Ease of tune is subjective, and i feel its a matter of how well the tuner/user understands the system.
what abt turbo engines ?
alpha/TP angle wouldn't directly relate to air quantity in turbo engine.
if we keep turbo engines in mind then the sensitive MAPs would be better off..

Last edited by chetanhanda : 11th April 2007 at 03:37.
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Old 11th April 2007, 03:48   #128
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Quote:
Originally Posted by rdkarthik View Post
Speed-density is a better system wrt emissions, mileage,drivability and refinement. When an engine is modified, for ex. with a wild camshaft ,different intake (ex.ITB) and/or exhaust design, you can get "reverse pulses" in the intake tract where the map sensor measures manifold pressure ( psycho and other dudes who work on exhaust and intake systems can prpbably explain better and in detail). Due to these pulses (actually pressure spikes), map readings will be "noisy" confusing the ECU, which makes it see an incorrect fluctuating load. So we can do one of two things -
just adding to that ..
..MAP sensor needs some minimum amount of difference between the intake and the atmosphereic pressure to indicate a load to the ECU, if we are running a crazy overlapping cam which hardly creates enough load at idle and low speeds for the MAP to detect then the alpha angle is more accurate in this case as it does not care how much vacum is being created.. the spluttering/lumpiness of the engine due to cams designed for outright top end power with a MAP would be more as it wouldn't have that much accuracy at low revs..
e.g look at cams on a dragster or offshore powerboat.. do their cams care abt smooth idle and low revs... ? alpha-n would handles these better than MAP..
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Old 11th April 2007, 23:44   #129
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Originally Posted by chetanhanda View Post
what abt turbo engines ?
alpha/TP angle wouldn't directly relate to air quantity in turbo engine.
if we keep turbo engines in mind then the sensitive MAPs would be better off..
Yeah, for turbos it has to be a map sensor capable of reading boost.

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Originally Posted by chetanhanda View Post
if we are running a crazy overlapping cam which hardly creates enough load at idle and low speeds for the MAP to detect
i guess it is " hardly creates enough vacuum "...... more the vacuum, lesser is the load.
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Old 13th April 2007, 04:28   #130
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Originally Posted by chetanhanda View Post
are running a crazy overlapping cam which hardly creates enough load
ok.. to be more accurate .."enough difference in atmospheric pressure and the intake plenum"
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Old 22nd March 2008, 01:15   #131
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..Bumping this thread up.
Guys, how about doing a virtual turbo build ?
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Old 22nd March 2008, 05:16   #132
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Originally Posted by chetanhanda View Post
..Bumping this thread up.
Guys, how about doing a virtual turbo build ?
Yes, i was thinking about bumping this thread a few weeks back as welll... a very interesting thread indeed.

If you do decide to do a virtual turbo build, i would suggest you do it in a new thread.

cya
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Old 22nd March 2008, 18:42   #133
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Originally Posted by chetanhanda View Post
..Bumping this thread up.
Guys, how about doing a virtual turbo build ?
Just finished reading this thread. Need to read it two more times to force all the meat into the top floor.

A new thread for a virtual turbo build is a ubercool idea. I suggest we start with a small turbo and comparatively low boost which a completely stock motor can handle and tune it with a standalone, running on pump gas- for street use only.

Later we can put in a bigger snail after throwing in forged internals (into the same base motor), upgraded valvetrain, sensors, boost controller and staged fuelling (!?) which will be a quarter-mile scrocher.

All we need to do is pick a good base motor to start with. Go on Chetan!!!

Last edited by doomsday : 22nd March 2008 at 18:44.
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Old 22nd March 2008, 20:49   #134
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Ok, help spread piracy and send me a copy too.
Soft copy of the same book is available on Google Books. Enjoy!!

How to Tune & Modify Engine ... - Google Book Search


Though the heading is 'Preview', the entire book other than the last 10 pages is available there.
EDIT: Oops!! In between pages are missing.

Great Book!!

Last edited by Rehaan : 23rd March 2008 at 00:37.
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Old 12th September 2009, 22:21   #135
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Default Bump! ooh, 1 1/2 years! , this must be my biggest bump ever!!

So did anyone actually execute the whole setup ? I've been thinking of doing it the DYI way on my OHC and it'd be great if someone could scare with me the risks involved and the worst case scenario so that i don't get kicked out from home if something awkward happens due to my eagerness.

Thanks in Advance!
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