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Coyote boosting basics, the facts:

Department Of Boost’s Commitment To Fact:

The performance automotive aftermarket industry, especially the forced induction portion is littered with “fuzzy math”, half-truths and in some cases outright lies. We see it every day, all day. In some cases we think that this problem is through ignorance on the part of the industry. In others it is obviously an attempt to muddy the water or a blatant lie to drive sales. It makes us crazy. It should make you crazy too.

We commit to you to always tell you the full truth and relay the facts as we know them. Do we know everything? No, of course not. No one knows everything about an entire subject. And new theory’s and methods are continually being discovered. Additionally more and more “wives tales’ or “internet truths” are being debunked every day. But we will give you the unvarnished truth as we know it at the time. And with a healthy fear of coming off as arrogant, we know a lot.

We will always provide you with technical data to the best of our abilities. We will never give you half-truths. And we will never lie to you so we can sell more product. This is our commitment to you.

Is It Really Testing?:

The first thing to get out of the way is the word “test” in the term “dyno test”. 99% of the time you’re not looking at a test, you’re looking at an advertisement. Dyno numbers are used to sell product. It’s as simple as that. Are dyno numbers worth something to you the consumer? Sure. Should they be looked at with a grain of salt? Absolutely. You’re being sold something, be aware of that.


We think that the biggest misconception about forced induction (FI), specifically positive displacement and centrifugal blowers is that there is any mystery to how much power they can/will make. Here is the deal, as long as the supercharger is even close to being sized correctly (as far as we know all the Coyote superchargers are) the supercharger will not be what determines how much power the car can make (excluding full blown race builds and HP numbers up over 850). A supercharger is an air pump, that’s really it. Some superchargers are a little more efficient at “this” and others “that”. But the big picture is that 10lb of boost out of ABC blower will make the same power as 10lb of boost out of XYZ blower. So unless you are going for crazy numbers, and ready to spend crazy money to do it at the end of the day it really doesn’t matter what blower you use. Here is why…

Generally when someone asks “How much power can I safely make with a Coyote?” they are asking at what point does the motor break because of mechanical load (horsepower). Up until recently and with most motors that was the right question. For example, the first limit with the 2005-2010 Mustang GT 4.6L 3v was 450-500hp where it would break the connecting rods. The 2007-2012 GT500’s first limit was about 725hp where it would break its connecting rods. That was the engines limit without pulling it out and replacing the internals with forged components.

When the Coyote came out something interesting happened. The motor got stronger (stronger than the 3v) so it could make more power before breaking. But, the Coyote has a very high compression ratio (11:1) and a new limit cropped up. The detonation or “knock” limit. The short version is that as a motors compression ratio goes up you need more octane (better fuel) or you will get detonation and break parts. High compression ratio motors can’t take nearly the boost that low/lower compression motors do on pump fuel. Because of the Coyotes high compression ratio the safe boost limit on premium gas (93 octane) is about 10.5psi. Any more than that you are flirting with detonation and engine damage. It is not about what the motor can “make” with the coyote, it’s about what the fuel can “make”. The first limitation you run into with the Coyote is fuel, not breaking parts.

So how much power can a Coyote make safely?:

-On 93 octane and about 10.5lb of boost and spinning 7,000rpm a Coyote will make about 550hp.

“But I have seen people make 650-700hp on a stock Coyote motor on pump gas!!!” you say. And here is where the “rub” is. Where the fuzzy math comes from, and some of the lies.


A Stock Coyote MOTOR can make more than 550hp on pump gas…….notice we said MOTOR, not combination. Boost is simply a representation of restriction. If you reduce the restriction you will make less boost, the same power, but less boost. So if you reduce the restriction you can spin the blower faster (which will make more power) and still keep the boost to/under 10.5psi. A very basic and widely used method of reducing the restriction is to use long tube headers, off road X/H pipe (no cats) and a high flow cat back system. Preferably something 3”. The reduction in exhaust restriction will drop the boost about 2psi. This means you can now spin the blower faster to make more power. 2psi is about 35-40hp. The exhaust is worth about 30-35hp. Now your stock Coyote MOTOR is making 615-625hp.

The “problem” with this little exhaust trick is that it introduces fuzzy math into the conversation. The blower isn’t really making more power. Well, it is, but all of the blowers are capable of upping the speed a little without running out of “breath”. What happened is someone introduced a $2000 variable (the exhaust) into the discussion but they are claiming “stock motor”. If you don’t know the exhaust is now part of the conversation you could easily make the mistake that XYZ blower makes more power than ABC blower does. But that wouldn’t be true. What made the difference was that one combo had another $2000 of exhaust into it. And that is nowhere near an apples to apples comparison. Unfortunately some supercharger manufacturers and vendors use this fuzzy math to give the impression that their product is better.

Dyno Numbers:

The exhaust trick is not the only way that fuzzy math happens. Dyno numbers are a HUGE factor when it comes to fuzzy math. Numbers from dyno to dyno are notoriously inconsistent. And that is when the dyno operators aren’t trying to tweak the results. Hot Rod Magazine did a great article on dyno’s and their results a few years ago. They took the same car (GT500) to 5 different dyno’s over the period of a couple days. Guess what happened? Lots of confusion. The car “made” between 577 and 656hp. Yeah, that’s right. A 79hp swing in results with NO changes to the car. Here is a link to the article if you want to read it (you should):

How much do you trust dyno numbers now? If you still put stock in them being some sort of “test” you’re delusional. Dyno’s were not designed to be compared to one another. Yeah, you can kinda sorta compare dyno to dyno a little. But they are not calibrated to a standard like let’s say a torque wrench. A dyno is designed to test the difference in changes when making modifications, tuning, etc on the same car at the same dyno facility. They were only ever meant to compare to themselves. For example. You take your stock Mustang to a shop. They dyno it stock. They then put a blower on it, some exhaust, etc. Then they dyno it again. The result that you get is the difference those parts, tuning, etc made on YOUR car, that DAY (or couple of days). The dyno is not magically calibrated to every other dyno on the planet so they can be compared to each other. There are dyno’s like that, but they are engine dynos (not wheels dyno’s) and mostly used by the car manufacturers because they do have a standard (consistent unit of measurement) that they need to adhere to. But having a calibrated dyno is not enough. The testing procedure also needs to be standardized and adhered too. If not, the numbers mean nothing. When you see dyno numbers for XYZ car with XYZ mod don’t forget that the tool used to measure the power (the dyno) and the procedures used to do the “test” are not standardized. If there is no standard, there is no consistency.

And that is only the tip of the iceberg when it comes to dyno’s.

Dyno numbers can be fudged. It’s very, very easy. Change a few parameters in the software and boom! More horsepower, just like magic!

The testing process can also be manipulated to show bigger gains or bigger numbers. That is child’s play. There is a massive difference between making a dyno run with the car stone cold, the hood open, huge fans blowing on it, a little more pressure in the tires, etc than driving the car in off the street, strapping it down, keeping the hood closed and running it with no cool down (you know, like every time you’re driving your car).

What you can away with on the dyno is different than what you can get away with in real life too. On the dyno everything is controlled and you have lots of sensors/data to monitor. On the street it’s far more “wild west”. You can get away with a couple more degrees of timing on the dyno. You can lean the mixture out a little more on the dyno. These are all things that will “make” more power. But you will not be driving around like that in real life. You don’t want to be that close to the edge.

Playing around with testing procedures can show 30-50hp with no problem.


We’ve seen one manufacturer make the statement that they test all of their stuff on 100 octane race fuel for “consistency”. Yeah, maybe they have more consistency when comparing their stuff to their other stuff. But running race fuel and a couple more degrees (or a lot of degrees) of timing doesn’t allow their numbers to be compared to everyone else’s now does it? They could be up 30-40hp.


And yet another trend that we have been seeing is revving the crap out of blown Coyotes to “get” those big numbers. One very cool thing about the Coyote motor is the twin variable cam timing. In short what this does is allows the computer to adjust the cams so they can act like a “small” cam or a “big” cam when needed. Which allows them to make more power over a wider range of RPM’s. This means you can rev the crap out of it and it won’t “run out of cam” like it would if they were fixed or single variable. Rev the 3v 4.6L past about 6000rpm’s and the power just goes flat. Rev the Coyote past 6,000, 7,000 even 7,500rpm with a blower on it and it just keeps making more and more power. Pretty cool, yes. But do you want to do that? Not if you want your motor to last very long you don’t. The loads on the crankshaft, rods and pistons goes up exponentially as the RPM’s increase. In short the load difference between 6,000 and 7,000rpm is a lot more than the difference between 5,000 and 6,000rpm. And the loads get real big up past 7,000. More load means more broken parts.

A lot of manufacturers and vendors are all too happy to rev the guts out of their motors to show you those big HP numbers. If they blow the motor up they are prepared to replace it. It’s the cost of doing business. They also don’t plan on doing that over and over again for tens of thousands of miles. Are you prepared to shove a new motor in your car every time it blows up because you were revving the crap out of it? Are you prepared to reduce the life of the motor and associated components (alternators for example) to “get” those big numbers? Are you made of money? No, who really is.

We have seen manufacturers and vendors rev stock Coyote motors to 7900rpm to show you a big number. 7900rpm!!!!! Are you nuts?!?!? You better have deep pockets if you want to do that.

The Coyote will keep on making power the faster you rev it. There is a big jump in power between 7,000 and 7,900rpm’s, up to 50hp. Some manufacturers/vendors will be happy to claim those big numbers up there. But are you ready to take the same risks?

What Mods Does It Really Take To Make Those Numbers?:

Lastly, what does it really take to make those numbers? This is related to the exhaust situation. Are those numbers “real” if you have to buy more parts to get them? For example we just saw a “test” done where “they” got another 90hp out of a “stock” Coyote with a blower. The problem is that to get that extra power they had to go with bigger injectors and fuel pump booster in addition to revving the crap out off it. Oh yeah, and a “splash” of race gas. We talked about revving the crap out of it and what that entails. How about the money for those injectors and pump booster? Where does that come from? The injectors were $960 and the pump booster $260…. for a total of $1220. It’s all good if you’re willing to spend that money for the extra power. But that doesn’t make that particular blower better. It just means that the combination was pushed harder with more money and very importantly, race fuel. Suggesting that particular blower can do something the others can’t or is better based on that “test” is ridiculous.


So you can make about 550hp at about 10.5psi spinning 7,000rpm with a stock Yote. If you want to make about 600hp you will be into about $2000 more in exhaust. If you want to make 700hp you will be into another $1200 in injectors/pump booster, have to run race fuel and rev the guts out of it. And that doesn’t even get near all of the other supporting mods you need to actually be able to DRIVE around with that extra power. How about a clutch? Maybe a transmission? Driveshaft? Rear suspension mods? Wheels and tires? There is a GIGANTIC difference between 550 and 700hp when it comes to the money spent. It’s not just a matter of turning the dial up all the way and letting it rip.

Take all “test” data with a grain of salt. As you saw from the examples above these “tests” can easily swing 100-150hp when you take things into account like more parts, testing procedures, dyno to dyno differences, etc.

Be careful when comparing/shopping for blowers. Unless you’re looking to spend a LOT of money and go for some stupid race car levels of power the actual blower (the compressor part of a blower kit) won’t effect how much power you can make on the Coyote much at all. What you should be looking at cooling, quality, packaging (how it fits) and don’t forget cost.

Thanks and enjoy your Coyote!!!

We have been getting some questions about this article. Some quick and easy, others more complex. We have decided to post up the questions (and answers) that are more complex and may be helpful to other people. Here they are:

The Question:

So you are saying on 93 octane fuel, you can only make 550 hp safely on the coyote? The same limit on the outgoing 4.6? Feel free to elaborate as I'm familiar with the thermodynamic analysis of internal combustion engines, but have trouble believing this. There are just way too many people out there making much more than that on pump gas. I'm not calling you a liar; just really not understanding that low of a limit without lowering the motor's compression. I know you know your stuff because I use to follow you religiously (you get the gist) on allfordmustangs before you even started department of boost.

Secondly, what do YOU suggest needs to be done to make 700rwhp (MAYBE like 675) with this motor and your manifold? That's really my lower limit once I graduate this December. If I can't make that, I'm not even going to go FI. My brother has a 500rwhp 4.6 with the on3 kit, and I'm just not satisfied with that.


The Answer:

Hey Garrett

I’ll try and break this down question by question.


Hero Runs:

The first thing to get out of the way is that we don’t count dyno “hero runs” as real data. If it can’t be replicated on the street at full operating temp where most people are driving their cars it’s not a real HP number as far as we are concerned. When we say “it will make 550hp” we mean it will make 550hp in real life. Will our 550hp make more on a “hero run”? Absolutely. But we don’t race dyno’s and we aren’t comfortable about padding numbers for the sake of looking cool.

We believe in under-promising and over-delivering. That is not the case from what we see in most of the industry. Most of the time we see the opposite. Just yesterday I saw a post buy a guy who got a blower kit for his Coyote. He was told it would make 650 rear wheel hp. It was installed, the supplied tune was used and it made…515hp. Yeah, the dyno could have been a little soft. But that is a LONG way off 650hp. An extreme example yes, not terribly uncommon though.

You Can Make Over 550hp With A Coyote On Pump Gas:

You can make over 550hp on pump gas with a Coyote. What you can’t do (unless it is a real happy dyno and a “hero run” for the ages) is make over 550hp on a 100% stock Coyote with most out of the box blowers. This limit is an octane/boost limit. In some cases it’s also a fuel injector or pump limit depending on the kit.

Safe Limit On The 3v:

The safe limit on the stock 4.6 3v is 450hp (some have pushed it to 500, some have paid for it). That was the rods breaking though, not an octane/fuel limit. If you forge the 4.6L 3v and leave the compression ratio stock (9.8:1) you reach its octane limit at about 17-18psi and 625-650hp. That is the simple version. If you drop the compression ratio when forging the motor (most do) you can push the boost to about 20psi on 93 octane. Most people stroke them to 5.0L when they forge them too which allows for the blower to spin faster (more power) while keeping the boost at 20psi. So there is more power to be had there. We’ve run our 4.6L 3v with 9.25:1 compression ratio to 776hp on 20lb of boost with 93 octane. That is a pretty special combo though. Combo being the key word here.

“But I have Seen People Make More With Pump Gas”:

“There are just way too many people out there making much more than that on pump gas.”

But are they 100% stock with a 100% stock out of the box blower kit? Was it done on a “happy” dyno? Was the tune safe? Was it a hero run? That’s where the “fudge factor” is at. You can absolutely make more than 550hp out of a Coyote on 93 octane. It costs more money in parts for the combination though. The focus of the article was to demonstrate that a lot of the time when comparing this blower to that blower the blowers aren’t what is actually being compared. What is being compared is the additional/supporting mods that it took to make that power. And in some cases the dynos and testing procedures are being compared too.

The Limit:

As far as the “limit” goes there is a little fuzzy math there too. What is the “limit” really? Is it when parts break? Is it when you get knock (pre-ignition)? Even one “knock”?

This is how we see the limit. The limit of the boost/fuel combo is when you have knock showing up in the logs (computer data). Even just a little. We don’t like knock. Knock is bad. There is another “rub” here too.

The ECU (computer) in the Coyote is really, really smart. Crazy smart actually. It’s amazing what is coming from the OEM’s stock and how much processing power they have. There is no way the stupid power numbers you see nowadays could be made without that sort of processing power. With some of that “smartness” comes the ability to find wiggle room when it comes to claimed power numbers though. Unlike in the old days when the motor knocks (to a point of course) it won’t immediately start damaging stuff. The ECU will detect that knock and pull back the ignition timing, richen up the fuel mixture or even close the throttle blades. Or a combination of all those. It all depends on what the computer sees for data. The ECU will “save” the motor from itself. This is obviously a good thing.

Here is where things get complicated and where you can see where a hero run can be worth so much power on the dyno.

The ECU also monitors things like cylinder heat temp (CHT) and intake air temp post intercooler (IAT2). This data will be combined with things like knock data and depending on the big picture it draws for the ECU it will pull no, a little or lots of ignition timing. Add fuel. Or just shut the party down by closing the throttle blades. When you’re on the dyno making a run with a 160deg CHT, a 75deg IAT2 and you get a bit of knock it may not pull timing, richen things, up, etc. But it probably won’t knock at all with temps that low anyway. It will NOT run at those temps on the street in real life though. The CHT’s will be more like 195-210deg and with most blower kits (not ours, ours are lower) you will see IAT2’s at 120-130deg. Real life is a lot different than on the dyno.

So what is the “limit”? The computer will obviously save the motor from itself, to a point. You could be driving around on the street down on power all the time from what it made on the dyno and it’s still “safe”. But is that really what you want to be doing? Leaning on the safeguards? Or do you want to set it up on the dyno, at street temperatures, and not lean on the safeguards? The former will show more power on the dyno. But it won’t make more power in the real world.

We feel that “the limit” is to be tested under real world conditions. Not fantasyland. The funny thing is that if you take a fantasyland/ hero run/ dyno queen that makes 600hp out on the street it will probably be SLOWER than the 550hp car that was set up for real world conditions on the dyno. When those safeguards kick in on the fantasyland setup they shut the fun down hard. The ECU is not correcting to “maximum safe street power at full temperature”, it’s correcting to SAFE.

We recently saw one of the manufacturers say (I can’t believe they said this in public) that their 650ish hp tune (I can’t remember the number exactly) was safe at 12.5psi because if it saw knock, high IAT2’s, high temps, etc it would simply shut the throttle a little bit. What I saw reading between the lines is “When conditions are perfectly favorable it will make 650hp at 12.5psi”. The problem is that unless it’s on the dyno or stone cold at the drag strip the conditions won’t be perfectly favorable and it runs around with the throttles closed a bit all of the time……making less power. So does it really make 650hp? I say no.

The Horsepower Thing:

This entire horsepower thing has gotten way out of hand over the past 15-20yrs. One ingredient is that there are a lot more dynos out there now. Another is the internet. And lastly it being leveraged as a sales tool. “Back in the day” we didn’t know how much power our cars made. We knew what we could beat in a race and maybe what it ran at the drag strip. There was no “dyno racing”.

We’re not huge fans of using 1/4mi times to measure a street cars performance (working on an article about this now). A good street car is not a good drag car. There are no two ways about it. And there are a ton of variables in a1/4mi elapsed time (ET) other than horsepower. Traction, gearing, suspension setup, etc. So ET is not a good measure of the cars performance. But MPH is. For the most part XXXhp will make XXXmph at the drag strip (in the same kind of car) regardless of traction, etc. Yes it will vary some, but not nearly as much as ET. If someone really wanted to know what sort of power they are making they can go to the dragstrip, run the car at full operating temp and see what they get for a MPH. I can’t tell you how many “600hp” cars I have seen run at the strip and only trap at 122-123mph. Guess what? That’s not a 600hp car, that’s a 500hp car. I don’t care what the dyno graph says.

What Would I Do To Make 700hp On 93 With A Coyote?:

The big variable in this answer is do you want to do this on a stock motor? The answer gets two completely different suggestions.

Stock Longblock Combo

Well, this will be on the edge. No two ways about it. You can push all of the factors in your favor and you will still be hard pressed to get a real deal 700hp out of a stock long block on pump. And then comes the question of how long will it stay together. It will be on the fuel and mechanical limit. This is the combo I would run.

-GT550-S197 Stage I
-2013 GT500 2.3L TVS blower (or 2.9L Whipple)
-A BIG TB. Something like the FPRR Cobra Jet
-A BIG CAI. Something like the 127mm JLT, if not bigger
-The biggest nastiest long tube headers I could find
-A full 3” off road exhaust with some sort of “straight through” mufflers
-Whatever it took for fuel system/pumps. I’m not real up on what will do exactly what and their limits. I would not rely and just a pump booster though personally. Some sort of big pump/pumps would make me feel better.
-ID1000 injectors
-The biggest nastiest heat exchanger I could get my hands on
-The biggest nastiest intercooler water pump I could get my hands on
-A quality harmonic balancer
-Billet oil pump gears
-170deg thermostat
-Urethane motor mounts

This will probably make a real 700hp. You will be spinning its guts out though. Probably past 7500rpm. And this combo will let go some day. It’s not bulletproof. It’s on the edge.

Forged Motor Combo:

This one is easier to hit 700hp with because of compression ratio and volumetric efficiency (which I’m not getting into here). It’s also not as scary because the chances of parts flying out of it are a lot lower!

-Forged bottom end with 9.0-9.25:1 pistons
-GT550-S197 Stage I
-2013 GT500 2.3L TVS blower (or 2.9L Whipple)
-A BIG TB. Something like the FPRR Cobra Jet
-A BIG CAI. Something like the 127mm JLT, if not bigger
-The biggest nastiest long tube headers I could find
-A full 3” off road exhaust with some sort of “straight through” mufflers
-Whatever it took for fuel system/pumps. I’m not real up on what will do exactly what and their limits. I would not rely and just a pump booster though personally. Some sort of big pump/pumps.
-ID1000 injectors
-The biggest nastiest heat exchanger I could get my hands on
-The biggest nastiest intercooler water pump I could get my hands on
-A quality harmonic balancer
-Billet oil pump gears
-170deg thermostat
-Urethane motor mounts

This will make 700hp on pump pretty easy. Even easier with the 2.9L Whipple. You won’t have to spin the motor as fast, but you can if you want. The forged bottom ends are a lot more tolerant of RPM.


A stock Coyote makes about 365-370hp. Your standard blower kit will get you 550hp for $6500ish and $4700ish for our kit (less during the group buy, even less if you do a Stage I and build it up yourself). That is 185hp for $6500 with other kits for a $$$/hp ratio of $35/hp. Our kit is $25/hp.

Going from 550hp to 700hp is ANOTHER 150hp. Almost the same jump that the blower itself made. That’s a BIG jump. The stock longblock combo will cost about another $5900 for 150hp for a $$/hp ratio of $39/hp. So it’s not at the point of diminishing returns, but it’s getting there. The forged combo is about $10,000 for a $$/hp ratio of $66/hp. That is well into the point of diminishing returns. And remember, this doesn’t include any labor.

IMO going from 550-650hp makes sense. It can be done at a fairly safe level on a stock shortblock and doesn’t cost any more than the original blower kit. Going from 650-700 is where the big bucks come out if you want to do it “safely”. That last 50hp, which will just be extra tire smoke 99% of the time, is just not worth all the time and effort.

I hope this answers all of you questions

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