Doing my 5.3 stock motor build. Debating intercooler vs no interooler.
Seems like the guys breaking records on SBE have no intercooler so really makes me think about adding a intercooler to mine as i want tosave as much weight as possible.

Thoughts?

 

My blazer didn't have an IC. My last twin car started off with out an IC & that went high 10's on 10#'s. Not planning on adding one to the Goat right away but I am going to run water/alchy on it.

 

I'm going to go out on a limb and say that the record breakers are using a very efficient turbo or turbos to make the power they are making non intercooled. A more efficient or larger turbo may make a certain amount of boost with little heat whereas a smaller or less efficient turbo might make the same amount of boost but the heat is trough the roof. I'm sure others will chime in. IMO I think intercooled vs. non intercooled should be taken into consideration during turbo selection for reasons previously mentioned in an effort to keep IATs reasonable. But then again, some don't let high IATs bother them.

 

Wouldn't you agree when selecting a turbo you should shoot for as efficient as possible in the intended operating air mass/pressure ratio?

 

Most of the SBE non intercooler E85 guys are recording IATs in the mid 200s.

 

I would, however, I'm FAR from an expert by any means. I researched and picked a few brains when I started my project in regards to going non intercooled. I was told by some, from their experience, that the same turbo I have would Have a sweat spot about 16-17 psi in my application. Not that it wouldn't make anymore psi, it'd just pump a ton of heat with it. If I were to change to a different turbo (t6, bigger compressor, etc) I could make over 16-17 with less heat. So I kept my turbo and went intercooled. That's my example FWIW.

 

you will make the most power with the largest mass of hot as possible air you can squeeze into the combustion chamber without having it explode in a disastrous mess.

E85 goes a long way to preventing that "disastrous mess". However, we must ask ourselves, or the density losses due to increased temperature of incoming air worth the additional response and decreased exhaust gas back pressure? For you see, as you restrict the incoming air with an intercooler, and do not be fooled: more effective intercoolers are generally more restrictive, you add exhaust gas backpressure since the turbine is responsible for forcing the air past the intercooler and into the engine. So this all comes down to the application, and whether or not you can test / monitor such things as Exhaust gas pressure(EGP) vs inlet temperatures vs turbine speed, and so forth. Most do not have this capability and so are "blind" and these are the individuals you see giving advice "yeah sure it will work" but they have no idea if there is anything better because of lack of data.

SO lets run an example.
You have a homemade exhaust manifold from Schedule 40, its kind of cramped. Stick a traditional 60-1 on it with a reasonable size turbine and go for 15psi of intercooled boost. You may find your EGP is higher than your intake manifold pressure, lets say 24psi on the exhaust side. Since you are using E85, timing is around 15* btdc and the engine is making 530rwhp with a mostly stock head and cam. Intake temps are 115*F during boost, and 127*F off boost cruise.

So lets modify the intercooler, take it out completely.

You first notice how much faster the 60-1 seems to spool. This is due to the reduced plumbing volume between the compressor and engine. Your car gets up and goes about 700rpm sooner. It complements the cramped design of the log styel manifold. Your EGP also dropped to 21psi from 24psi, engine VE improves because of this (the intake pressure is still 15psi) and you pick up 40rwhp for a total of 570rwhp at the same boost. Intake temps are 150* but the engine is fine because its on E85 and EGT is sitting pretty at 1180*F.

: data : shows us that by reducing EGP by manipulating plumbing volume we can increase response AND power with the same boost pressure, and that it outweighs the density loss of incoming air due to the increase in temperature caused by not having the intercooler in this case. It will depend on the turbocharger, manifold, engine, all of that whether it works this way or not.

Lets run another example where removing the intercooler was a bad idea for the sake of completeness.
Same mostly stock engine, this time we install a really high flow exhaust manifold, tubular custom pieces with twin well matched T04E 50 trim turbo chargers, almost the same overall flow as a single 60-1 at 15psi of boost (looking for around 60lb/min) together total. Again E85, intercooler, and 15* btdc of timing. Due to the magnificent manifolds, EGP is only 20psi, and IAT are barely 110*F We already have more/better spool characteristic and RWHP output as the above final example: around 600rwhp. But just to see what happens, lets take off the intercooler.

As expected, spool increases and EGP drops. But it is not nearly as noticeable as it was on the other setup. EGP drops to 18.5psi, and IAT rises significantly to 150*F. Our gains to VE are minimal because EGP was relatively low to begin with, we only pick up 18 horsepower from that side. However, due to the increase in air temp and loss of density, we lost 25 horsepower going from 105*F to 150*F on the intake side. Overall there is a net loss of power once the engine is at full boost, and it gets worse as the turbocharger approach their limits.

It can go either way, we need data to be sure. Do not trust anything without getting solid data.

 

Need low back pressure and alot of turbo to keep charge temps down. (AKA an efficient setup) Usually means twins or a huge single. Either of those options will add about as much weight as decent small IC. To "max out" a SBE gen3 motor on E85 you don't need a huge heavy A2A unit anyway. This or the TV185 series would be plenty!

http://www.treadstoneperformance.com...rcooler++500HP


Could also consider a really small A2W unit. you could put the water tank in the back of the car and the IC back under the dash or even further back. Which puts the weight where it will do you some good. Could put something small like this in the wiper motor area on the FB.

http://www.ebay.com/itm/CXRacing-Uni...RS134V&vxp=mtr

Injecting a TON of meth pre compressor seems to do amazing things as well. 4GPH of meth will drop overall charge temps roughly 18* on a setup like yours and up the octane considerably. You can use this calculator to calculate how much meth would be necessary to bring the charge temps down to reasonable levels (usually under 220* is fine) Then you could run a 5 gal tank of methanol + the pump in the rear to get some weight in the back as well.


http://www.stealth316.com/2-turbotemp.htm

I'm guessing with your setup you'll end up having to add weight in the back to get it to hook well anyway. Theres no weight over the rear in those cars to start with.


The ones I was talking to pegged out the GM iat sensor at 255 before the 1/8th!

 

I get Ya.

You have to pick a point where you intend to operate it, pressure-wise, then match it best you can with the expectation that it's going to move out-side of higher efficiency above or below certain thresholds.

Dropping charge temps via alternate methods, to accommodate a given energy balancing, shouldn't be confused with mass density the compressor puts out.

Ideally the charge temp should be largely impacted by pressure increase from a mass volume change rather than heat generation from compressor inefficiency.

There's always an adiabetic number, factoring in all the variables, how close you can get to that in terms of energy balancing is what is important.

 

The point of methanol/water is to drop EGT not charge temp. Injecting 120* water into 120* IAT still has an EGT lowering effect as the water moves from 120*F to 212*F because it's heat capacity it absorbs a large amount of energy.

Density and temperature coming off a compressor should not be a problem if the turbo is sized correctly per the application. If you have charge temp issues then yeah, intercooling works. But if you are seeing a high IAT without an intercooler, while also having a reasonable EGT, especially when using something like E85 as a fuel, there may be little to no benefit to intercooling it, as I pointed out you may raise the EGP by putting resistance in the air path, and lengthen the time it takes to spool. The air will get cooler but the engine will lose VE, you might break even at best. Most people never tried their setups without an intercooler so they have no idea what they are missing because of it.

I am only suggesting we follow a trend of data. Find someone who knows their EGP, EGT, IAT, on E85, without an intercooler. Compare their engine's output (assuming they are not lying about it, get a dynojet output graph if possible) with other known setups that have intercoolers. Etc... You cannot tell just by looking at the build sheet. This is how you build statistical relevance for a particular cookie cutter setup. We would never cobble something together with hopes that it works; we should find and copy a proven setup that outperforms all others in the areas we need most (economy, reliability, power, etc) .

 

I get that your trying, but you really don’t have a clue. You are trying to regurgitate things you’ve read without understanding them. There is so much misinformation in your posts It would take me all day to correct them. When someone takes the time to do so, you respond with miles and miles of BS and don’t listen anyway. Stop copy and pasting half the internet on your posts and get a grasp on basic concepts. Then get some experience and come back.

1.) The point of meth injection is not to lower EGT’s. The point is to raise octane/slow burn and cool CC temps to prevent CYL pressure spikes. Which charge cooling does, especially if injected in the volumes I’m talking about pre-turbo. It’s proven, end of story.

2.) No one is talking about water here. This is a totally different subject.

3.) Density and temp are ALWAYS a problem without an intercooler at standard compression levels. Common conditions with 100* inlet temps and a 70% efficient turbo system (better than most of us have) will put turbo outlet temps around 275* per bar of boost. There is always a benefit to cooling charge temps that high. E85, straight methanol, or otherwise. Hot air is in efficient, period. Experience and very basic physics proves this without a dyno sheet or specific examples. Injecting pre-compressor increases the efficiency (mass flow) of the turbo itself. Meaning less exhaust energy is required to drive the unit.

Lastly we aren’t talking the typical 50/50 water meth kit on the market. They don’t put out the volumes needed for effective charge temp reductions on a non-intercooled LS engine power levels.

 

I do not run a intercooler ,but I use E85 . Mine works well as many others do. So you could build your set up without one , try it ,if it doesn't work well put a intercooler on it. I never made a pass on race gas on this set up,so I don't know how hot it would be.Build stuff ,try different stuff ,have Fun

 

ebay cooler at the very least, your ring lands will thank you

 

That is the result of which lowering the EGT does, you are slowing the reaction rate of combustion by cooling it, and EGT goes down as a result.
Cooler IAT by itself is no guarantee you are not going to ping. Sometimes the IAT drops and suddenly the engine needs to be re-tuned or re-timed. Colder air by itself is desired because of its weight per unit volume.
2. When you say "cool CC temps" is that not the same thing as "less egt" ?

water is just to put things into perspective. You do not need fuel to lower combustion temps (you can use fuel, but you do not need to) Why would I waste money on fuel when I can inject distilled water? That doesn't make sense.


there is no such thing as a standard compression level I am not even sure what that means. Have you developed some kind of formula I am unaware of? Or model for reaction rates of various fuels? This is what you are implying.

I agree and if you see my example I am using 120* and 150*F as novel temp rise indicators (safe ranges) I would never expect 200*F+ to be reliable in any configuration ( I would certainly take measures to improve this number before attempting any performance output). The farther the temp is from our ambient the more I would look for ways to transfer that energy to the surrounding, even if I had to string a bit of conducting copper from the head to the wind outside the car or make my own ice cooler heat sink to sit on it. In racing and competition these are the edges that win races. Put a cap on my displacement but do not cap my ability to transfer energy to my environment.


Actually hotter air contains more energy, we will make the most power with the largest mass of hot-as-possible air we can squeeze into the chamber. If the octane is insufficient that is another problem all together- but it does not change the simple fact that temperature is energy. Realize the contradiction between trying to get rid of it and trying to use it up. We want to use as much as we can, but any excess that would make the operation dangerous should be discarded for safety. The more we throw away, the less we have, but the safer our operation becomes. If you can harness ALL of it, that would be ideal, Ambient temp EGT's ftw no doubt.

So does pre-intercooling with an ice water intercooler. So does after cooling with an ice water intercooler. So does spraying ice cold water into the turbo. So does letting the turbo cool off between runs. Many methods to do this. I, for one, have an opinion that compressor wheels do not like tiny droplets of water hitting them at 80,000rpm so I am against injecting liquids pre compressor. (but I have no testing! perhaps you might provide some data and change my opinion) You can change the efficiency of a turbo post-compressor by creating a boost leak, for example. This is just an example of how post compressor situations can modify the efficiency of the compressor wheel.


This I have no idea and NO proof of. Do you have some kind of proof? Because increasing the density Of air should make it heavier, which should make it (weigh more) harder to sling off a compressor wheel.


Charge temp reduction is not the main point of water (it may occur as a side benefit). It might help, but that is not where the "magic" happens. It happens in the combustion chamber where it absorbs energy (mops up the EGT) and slows the reaction, also creating steam (so they say it helps but I do not know) preventing a violent explosion. This should be simple to prove. Take an engine with 120*F inlet temps and inject 120*F water, and see that detonation resistance is still increased significantly. Methanol is a fuel and must be treated separately, because of its "octane rating" so the mass of methanol to regular fuel ratio is going to change optimal combustion temperature ranges. For example an engine running 80% or 100% methanol can probably use a higher compression ratio and higher IAT than a 100% gasoline engine even if the gasoline and methanol is the same temperature, I think this is what you are trying to say. I believe the specific heat (capacity) of methanol is around half, or just over half of what water is, yet that is no problem and has little to do with it's ability to help in other ways.


video about it from aem

Notice at 2:25 he says, "but thats only part of the story"
Also notice that for water to change to gas it needs around 212*F (or more under boost pressure) so injecting it into 150*F inlet temps might not help cool them off much (since it cannot evaporate and carry away its full heat capacity at that temperature although we all know that some water is always evaporating even at room temp from any puddle so really this is a calculus problem where there is always (even in a freezer, that is why your ice cubes shrink and peas freezer burn) some minimum escape velocity possessed by some population of water molecules which is able to break away from its partners and be alone, "evaporated"). They really ride the "air inlet temp" thing but I think that is mostly marketing, as many people are under the impression this is the sole reason and look for such tactics/details when purchasing a system.

 

I know I shouldn’t bother, but it’s a slow day at work...

 

I just fixed alot of what I wrote for clarity already much of this has been addressed. All valid for clarifying points and I think if you re-read you will find it much clearer, thanks for taking the time to respond. As additional info it is nice to finally meet someone who is spraying pre turbo that claims mileage is no concern. I am curious what is the most miles, what kind of miles (daily drivers might have 100k with much less boosting), what sort of turbo and I would really love to see pictures of the blades, most definitely. I am a reliability freak and was never willing to find out the hard way.

Also, I don't just say cylinder temps or combustion temperature because it sounds flashy and dressy, like I am trying to be big a shot with some special working knowledge and special tools that can read combustion temperatures. I don't want it to sound that way at all, so I am using EGT which is something we are familiar with, and everybody has access to, and is essentially the same thing (minus whatever temp drop occurs along the way) and that, again, is a feature of the EGT we need to be aware of in order to be successful in using it.

I just thought of something. I remember seeing a mini fridge for the glove box in a car once. Why wouldn't we install a mini freezer for our methanol/water mixtures? Use less methanol to keep it from being dangerous and inject at sub zero temperatures? I almost feel like this is a great solution to people stuck with pump who want real power. Has anyone ever seen this? If you are looking for an IAT drop, the starting temp of the mix is a key feature, if ambient temp is 110*F for example...

 

This is an excellent point.

Whats to keep in mind is the latent heat value of Meth brings a pretty good endothermic physical process of vaporization.

It is logical to conclude then at a given higher rate of mass, in the same volume, it must be traveling faster... right?

The thermal transfer impacts the induction velocity of air mass in a given distance to the low pressure area of the compressor.

I am a firm believer in the utylizations of dual fuels. It only makes sense to use the benefits of each fuel type in a harmonious balance, using the advantages of physical & chemical properties in a given engine dynamic.

 

Hot air does have more energy. But not much. Lets say we have a 6.0 engine at 6k RPM.

6L x 6000RPM / 60 seconds / 2 revs per cycle = 300 L / second = 0.3 m^3 /s

Ok, so how much energy is required to heat 300L of air by 100F/56C?

1.1389 kg/m^3 x 0.3 m^3 x 1005 J/(kgK) x (93C-37C) = 19.2kJ

19.2kJ/s = 25.7 HP.


Given VE losses, we are talking ~20HP to heat the volume of air passing through the engine from 100F to 200F. That is the most you could extract from the extra heat (which you cannot).

You know what has really high energy density? Gasoline/E85.

Lowering the temperature of air from 200F to 100F makes it 18% denser. So you can put ~18% more fuel in.

The LS2 was factory rated at 400hp at 6k RPM. 18% of that is 72 hp (not that you would be getting 400 hp at 100F IAT, but you get the point).

 

Thus why phrased it specifically: "the largest mass of hot as possible air" I thought it was fairly clear. Also I am not sure you can go 1:1 air mass to fuel mass ratio that way (I am not sure, you might be right but I have not attempted the calculation) don't we normally say there is some mass:mass of air/fuel ratio? 18% more mass of air with an 11:1 air fuel ratio is not 18% more fuel is it? You threw a wrench and I am not sure I am awake enough to catch it.

 

Intuition should tell you that dribbling a little meth in at a lower temperature will make no difference to the vastly greater air mass. But lets look at the numbers.

ok, so we established above that we are talking 0.3 m^3 of air a second for our 6.0L engine at 6k RPM (assuming perfect VE for simplicity). At 100F that is 0.342 kg/s air mass.

Our 4GPH meth injection -- ~ 16L/hour = 0.016 m^3/hr

Density of methanol is 791 kg/m^3. So 12.7 kg/hr. 3600 seconds in an hour. So 0.0035 kg/s of methanol.

i.e. there is a 100:1 ratio between air mass and methanol mass.

Injecting methanol at -40F would bring the IAT down one extra degree F compared to injecting methanol at 60F.

i.e. pointless vs the extra weight of a fridge and the power drawn from the engine to run it.