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Discussion Starter #41
Not sure if this is something that you want to write up anything on or not but I find intercooler sprayers (misters) interesting. There's 2 types, the "soak it down with a good spray" type and the "mister" type. From what I've read the misting type is harder and costlier to build but the fine mist works better for evaporative cooling. The question at that point is, whats the cost difference between a good sprayer setup and a good wmi setup? And, does that difference justify the running one setup over the other?
First I want to say that many sprayers are actually illegal to use on some tracks and roads whereas water/methanol injection kits are not. The cost to setup and operate is far more than a water/methanol injection kit. The effectiveness of sprayer setups are also lower. They do not tend to lower IAT as much and have no benefits like adding extra fueling, octane, knock suppression, cooling, cleaning, etc like water/methanol injection kits do.

Now if you have a water/methanol injection kit already on the car you can easily setup a water sprayer for the intercooler as well. Or use the rear washer pump on the car already for a cheap intercooler sprayer setup on any VT. But I've seen little benefit from doing such when I can setup a VT on the oem intercooler now that will struggle to see above ambient IAT even when beating on the car. :)
 

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First I want to say that many sprayers are actually illegal to use on some tracks and roads whereas water/methanol injection kits are not. The cost to setup and operate is far more than a water/methanol injection kit. The effectiveness of sprayer setups are also lower. They do not tend to lower IAT as much and have no benefits like adding extra fueling, octane, knock suppression, cooling, cleaning, etc like water/methanol injection kits do.

Now if you have a water/methanol injection kit already on the car you can easily setup a water sprayer for the intercooler as well. Or use the rear washer pump on the car already for a cheap intercooler sprayer setup on any VT. But I've seen little benefit from doing such when I can setup a VT on the oem intercooler now that will struggle to see above ambient IAT even when beating on the car. :)
Right. Running a sprayer on the track can be dangerous and shouldn't be done.

The main benefits would be they are cheaper (I'm talking about a water sprayer where I think you are talking about co2 or no2) and that you aren't adding another failure point. If your IC sprayer fails its no issue. If your wmi system leaks into your intake then it could be big issues. Of course thats why you make sure your system is set up correctly...
 

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Discussion Starter #43
Right. Running a sprayer on the track can be dangerous and shouldn't be done.

The main benefits would be they are cheaper (I'm talking about a water sprayer where I think you are talking about co2 or no2) and that you aren't adding another failure point. If your IC sprayer fails its no issue. If your wmi system leaks into your intake then it could be big issues. Of course thats why you make sure your system is set up correctly...
When talking water intercooler sprayer they're not even in the same ballpark for benefits or iat drop as water/meth or CO2/N2O sprayers however are cheaper to setup and operate. Less to fail as well. But like you said if setup the right way then a failure will never mean any catastrophic damage.

Unreal the number of water/meth kits I see setup unsafe on the VT that I work on and/or tune. I've tuned many VT that has a kit setup advised by a major vendor and tuned by the same vendor. Not only is the car way down on power generally compared to my first tune revision, but IAT are not near what they can be due to improper setup, vacuum and gravity is drawing fluid into the intake manifold when not needed, and there are no fail-safes setup in the kit.

This is what you get when you combine someone who does not know any different that just wants to save $ who is being advised by someone with a big company name that treat you as a number to make $ that has no clue how to setup something properly nor care about the car setup before tuning it.

Dealing with this exact scenario now with a member here to tune and resolve issues with the water/meth kit remotely. After the first tune revision I sent and some knowledge shared on the water/meth setup the owner said he feels like he was jiped by the vendor. At least I did not have to say that.

Unfortunately I see this a lot but due to the overwhelming misinformation in the community people tend to result to popularity votes instead of data/facts to make their choices. Also in some areas of social media it can be difficult to get all of the data/facts as there is little shared overall and many times the cons can be sensored/deleted by those usually associated with the cons. Bell of a business plan if you ask me. Hahaha!
 

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Yup. Intercooler sprayer you might be able to get to ambient if all is perfect. Otherwise, a 10-20 IAT drop would be really good. WMI is obviously better. It's just comparing the cost to benefits. If you can't afford to to set up a wmi kit right, is it worth the risk? Would a well setup water sprayer be better in the long run?
 

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I remember this vid from a whiles back, but always wondered his IAT drop

 
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I remember this vid from a whiles back, but always wondered his IAT drop
I would be curious to know as well. That is the "soak" type sprayer. Which is not ideal. You can see a mist blowing away in the breeze. Ideally that is what the spray should be. I've even heard spraying the mist forward is best so that it more evenly mixes in with the air circulating over the intercooler.
 

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Discussion Starter #47
Yup. Intercooler sprayer you might be able to get to ambient if all is perfect. Otherwise, a 10-20 IAT drop would be really good. WMI is obviously better. It's just comparing the cost to benefits. If you can't afford to to set up a wmi kit right, is it worth the risk? Would a well setup water sprayer be better in the long run?
Anything that helps and setup safely is worth it if you're ok with the cost. Something unsafe is not worth it. Cost can vary a great deal and still be safe but the benefits can vary greatly as well.
 

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Discussion Starter #48
The water sprayer type intercooler coolers are more limited than the CO2 or N2O variants due to the avg core temperature that can be achieved. Even supercooled water/meth does not compare to the temperature of CO2 or N2O decompressing and sprayed onto the core.
 

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I remember this vid from a whiles back, but always wondered his IAT drop

Looking at this setup you might as well consider this to be no better than driving in the rain. 😂🤷🏼‍♂️
Track tech would not allow you to use that or even venture out onto the track with a setup like that. 😉
Wmi is the way to go for sure. 👍
It's also nice to see a great informative discussion like this on a forum. Seems to be a lost art these days.
 

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N2O is the most efficient cooling when injecting into the engine than methanol injection. Also N2O is way more costly to use than methanol injection. Can run both no issues as long as setup and tuned correctly.

Not many VT out there can take advantage of N2O to the point of making it worth the investment. The one I'm building I'm toying with the idea of having N2O wet shot on it with a big single G35-900 or G35-1050 turbo to get to 1k hp. Not quite sure the path yet I already have the N2O kit designed and mostly made.
I'd like to see the application of a 50shot in a setup like mine. Bring back a race in 3rd gear if it's close lol.
 
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Discussion Starter #51
I'd like to see the application of a 50shot in a setup like mine. Bring back a race in 3rd gear if it's close lol.
Can tune the ecu on a 16-17 DCT VT with stock turbo to rip the transmission apart much less needing to add N2O to help. :)
 

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Discussion Starter #52
Here is an example of an actual VT with water/methanol injection vs what a sprayer would need to get the avg intercooler core down to in order to make the same power. This is not exact but will be in a close ballpark. 84°F avg core temperature drop or -14°F avg core temperature on a 70°F day. When you consider the temperature and volume of a sprayer effect on the core vs the volume and temperature of ambient air and super heated charge air from the turbo you can see how even these avg core temperatures would not be realistic.

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Discussion Starter #53
Here is good information re cam timing for a turbo application, which the intake and exhaust cams can be tuned individually in the VT, meaning potential gains in all areas of the power curve. This is due to increased volumetric efficiency by tuning the cams properly.

Simple cam tuning rules for BOOSTED engines:

  • Advance intake and exhaust => more low-RPM power, less high-RPM power
  • Retard intake and exhaust => more high-RPM power, less low-RPM power
  • Less overlap => lower EGTs, faster turbo spool, less fuel
  • More overlap => higher EGTs, slower turbo spool, more fuel

Boosted engines don’t like overlap. The incoming cold air and fuel cools down the outgoing exhaust charge, condensing the exhaust gasses. This is VERY counter-productive in a turbo application since the engine needs no help from scavenging to fill the cylinder. I've heard this being called "turbo chill".

Cool, condensed gasses in the same space push less hard on the turbo, causing lag. HOT gasses are better at spooling the turbo, thus the advanced exhaust timing to open the valve sooner in the power stroke. This steals some of those hot, expanding exhaust gasses to help spin the turbo a little faster. When the piston is near the bottom of the bore, hardly any energy is going into rotating the crank anyway, so stealing expanding gasses won’t hurt anything. The retarded intake just helps cut down the overlap further.

Retarding overall cam timing: Retarding overall cam timing is better for high-RPM power. This is because the valves are closing later. The intake valve is closing AFTER the piston has started to travel back up the bore for the start of compression stroke. This is terrible at low RPM because the intake air velocity is low, and air that was once in the cylinder is now being pushed back into the intake manifold and causing turbulence.

At high-RPM, the rules change. Air has weight, and thanks to Sir Issac Newton, we know that once it is moving, it doesn’t want to stop moving. This means that the air can continue to flow into and fill the cylinder, EVEN AFTER the piston has begun to travel UP the cylinder bore. This can allow an engine to exceed 100% volumetric efficiency, if even by a small amount.

Advancing overall cam timing: Advancing overall cam timing is better for low-RPM power. This is because the valves are closing a little sooner. The intake valve is closing AT or NEAR when the piston is at the bottom of the bore for the start of the compression stroke. This is great at low RPM because the intake air velocity is low and easily affected by changes in the direction of piston movement in the engine. Almost as soon as the piston gets to the bottom of the bore on the intake stroke, the valve gets slammed shut so no air can escape as the piston begins to travel back up the cylinder on the compression cycle.

At high-RPM, this may become a restriction since the air has inertia and responds a little slower to pressure changes, potentially choking the air flow to the engine a little.

Here are two intake and exhaust cam timing maps for a gen 1 VT.

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Here is information related to the oem cams in the gen 1 VT.

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Once I get some more cam tuning testing done I'll post here to show the benefits from certain changes.
 

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On the timing maps what are the rows?
I am particularly interested in verifying that there is a notable shift in cam timing at 3000 rpms while cruising. I notice a marked decrease in mileage once I cross that point and have always assumed it was related to cam timing.
 

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Discussion Starter #55
On the timing maps what are the rows?
I am particularly interested in verifying that there is a notable shift in cam timing at 3000 rpms while cruising. I notice a marked decrease in mileage once I cross that point and have always assumed it was related to cam timing.
Row: Absolute load %
Column: Engine RPM

Realize that at 3k rpm that there is 4x the wind resistance as say 1.5k rpm that kills mpg on top of other frictional and mechanical losses on top of lower volumetric efficiency. All of this requires more power/load which means lower mpg. Some of this can be made up for in the tune though. This is why I can achieve 10-15% less mpg on E85 than 93E10 but be using 35-40% more fuel.
 

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It's a noticeable difference on my dashboard mpg readout pretty much exactly at 3k. Might be related to TC lockup (or unlocking) too.
 

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Discussion Starter #57
Here is the base ignition map. Higher values mean higher timing which will mean more efficient burn thus better mpg. With a constant trend higher with higher rpm and lower as load/boost increases it will not be altering the mpg that greatly in most cases.

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Here is an intake cam map. You can see that the trend of it is not great related to rpm or load/boost. This being higher or lower in certain areas, especially withing similar air flow ranges, while making rather large jumps in timing, can vary the volumetric efficiency of the engine quite a bit which will change not only power output but mpg as well.

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Here is an exhaust cam map. You can see the trend is good and smooth in most of the map but part of the map has big swings in areas of similar air flow. This can also cause cause power output and mpg changes.

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Keep in mind that both cams are tuned separately but work in unison with each other to determine the overall volumetric efficiency at any given point. Also keep in mind that the oem tunes the cars for emissions and mpg in a certain area, but not all areas, and for sure do not tune for power.

Cam tuning is something that most tuners never touch. This is partly due to them not knowing what changes are needed to see benefits and partly due to many oem tunes being close enough to not see huge benefits. In the VT they can see benefits in power and mpg when tuned correctly.
 

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Discussion Starter #58
These are things to keep in mind regarding much of the NA section of the maps. The NA section will primarily be in the 75% load areas and lower.

Simple cam tuning rules for NATURALLY ASPIRATED engines:

  • Advancing both cams => more low-RPM power, less high-RPM power
  • Retarding both cams => more high-RPM power, less low-RPM power
  • Less overlap => more low-RPM power, less high-RPM power
  • More overlap => more high-RPM power, less low-RPM power

In a naturally aspirated engine, the extra overlap is called "scavenging". Scavenging is using the out-flowing exhaust to help draw in the next intake charge (partially causing lumpy idle).
 
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