victor25

Does anyone have any flow bench numbers for the stock S4 intake manifold. I know that a few people have tested and modified them to make the individual tracts fow better and more evenly. But I am looking for the before numbers. I want to match the injectors to the stock manifold number as best as possible. As may of you know, even with a matched set of injectors there is a small difference in fuel flow numbers. I put the lowest flowing injectors to cylinders 5 and 8, but if I had a 1 -8 or best to worst flow rating of the manifold that would be Awesome!!
Thanks

victor25

Come on guys.... 70 hits and nobody have any answers¿¿¿

hacker-pschorr

The best numbers are from Todd's supercharged car with 8 wideband injectors.

His conclusion - you cannot "match" injectors to "fix" the intake. The air / fuel swing changes across the RPM range.
Where one cylinder might be lean down low, it may be rich upstairs.

After this test he immediately tossed out the LH/EZK and went with Autronic since it has individual maps for every cylinder for fuel and ignition.

It's the only way to fix this "problem" and you must have 8 wide bands (or fast acting EGT's) for the tuning.

Rob Edwards

Easy peasy:

hacker-pschorr

Don't forget, the heads need to be drilled out (where the EGT's are install on the 90+ heads) for the tubes to be installed.

However, since Todd did this (like 10 years ago??) there are new products on the market to do just this.

One of the best is from AEM:

You need two controllers $1227:
http://www.aemelectronics.com/wideba...controller-60/

Then eight wide-bands with their exnteded bung with heat sink: $833:
http://www.aemelectronics.com/wideba...n-30-2340-1225

If this system was around back then, I'm sure Todd would have went this route versus the copper piping method.

victor25

I was afraid that was going to be the answer. What I am mostly concerned about is the higher end of the spectrum. Say from 4000 on up. Currently I am assuming that 5&8 are the worse

hacker-pschorr

You shouldn't be, and considering the kind of product you produce, you should already be well aware of this.

The highest risk of engine destroying detonation is at peak torque, not HP. This is when the air / fuel and timing is most critical to prevent blowing up the motor from detonation.

At the high RPM area, other risks come into play involving the moving mass of parts and the speeds they can sustain, keeping everything properly lubricated and in balance. It's more of a mechanical threshold than a detonation one.
It all boils down to cylinder pressure (and volumetric efficiency) which is highest at peak torque.

The detonation threshold of a motor at peak HP is significantly different than peak torque.

Welcome to tuning 101, and maybe an intro to physics class.

This is why comments like "safe boost numbers" are so frustrating, since it's an irrelevant statement.

Now I'm not saying you cannot blow up a motor at high RPM's from detonation, but if you are trying to find the "best" area to be perfect with this experiment of matching injectors to cylinders, you are barking up the wrong tree.


That's dangerous, especially when you are playing with cars that belong to other people.

ptuomov

We already had a thread on this: https://rennlist.com/forums/928-foru...and-ideas.html

The reason why injector matching can't fix the unequal cylinder filling is the following. The runners are unequal length. The cylinders with 30 cm runners will fill better below 5000 rpm and those with 20 cm runners will fill better above 5000 rpm. The below is not measured data but a simulation, but it illustrates the effect:



By the way, there is one way to "solve" this problem. Do what the factory did, that is, rely on the knock sensors to pull timing from any cylinder that knocks and tune the car slightly richer than you would otherwise. Is it ideal? No. Will it work. It seems to work just fine, at least for boost levels below 20 psi.

Didn't Todd Tremel only really run into big distribution problems at very high manifold pressures?

victor25

Hacker chill dude .. I know all this. It was a simple statement sent from my cell phone, no need to bash the crap out of it. It's a little hard to go into something detailed typing with my thumbs.

And besides 4000 and up is where the most torque is with the supercharger dude!! . Plus this information is mostly for my sequential tuning project .... geez

TOUMO... yes thats basically what im looking for. With sequential conversion I want to adjust the injection time a little on the short cylinders below 4000RPM and above that it drops back to batch and having the heavier fueling injectors be in the better breathing cylinders. But accurate data would go a long way if I could plug that into the sequential programming

victor25

Tuomo your right, I should have just posted to that thread. It is a well beaten horse at this point, and obviously if anyone has that data they are not going to share it.

I will just end this thread and go to that one