-------------------------------------------------------------------------------- I think it is time to step it up a little more. My Jeep is not slow but running with Pauls vortech supercharged jeep and Steves 426 stroker it is hard to be fast. I recently got offered the sponsor ship from PPP which unfortunately I had to let pass since I was not convienced it was the smartest move for me at the time and ended up being too pricey. Wish we could have worked something out. Here is the deal, I want to eventually add force induction to my build. What do you guys recommend a 440 or a 426? Why? Does anyone know any numbers the 440 puts out? Also, if Pauls Jeep is running 8 pounds on stock compression and is making good power why go low compression? Thanks
IMHO, a 426 would be a better choice. The 440 has not been on the streets very long, and I would be concerned about the cylinder walls failing. JMO. Now, if Paul is running 8psi, he is running on borrowed time. The top ring and the connecting rods just won't hold the pressure of the added boost (even with great tuning). It is not a question of it, rather a question of "When". Now, if you are going to add F/I and build a rock solid bottom end, do it the right way by lowering the compression. This way you can add loads of HP by adding high boost. Also, if you are going to add FI, and build the motor for the FI, then do both at the same time. Again, IMO.
I think the only 440 available is a sleeved 6.1 block. It cost lots of money for very little, if any power increase. IMHO, I would run a stock compression, oh yeah, I am. If you would ever decide to take the SC off, or run without one for awhile the 10.3 compression ratio will run much stonger NA. Low compression, high boost is for race cars. I will be able to make make big HP with low boost.
Both of you bring up good points. The 440 I was looking at is not sleeved it just has a bigger stroke than the 426 and less bore than the 426. As far as the compression does it really make a big difference to run a 8.8 compression compared to a 10.3? Hal, that is the reason I would like to run a 10.3 compression because by the time I run the f/i my engine will have some miles on it. As, I can't do both at the same time.
I lifted this from the below link. Very useful info. http://www.motorsportsdigest.com/tech/forced2.htm Boost -vs- Compression Almost as fast as a supercharger (or turbo) can be bolted on, the question of how much boost can be run is sure to come up. When building up a motor to be supercharged, you've got the issue of just how much compression to run. Both of these questions relate to essentially the same set of equations. Assuming that all of the other requirements of the motor are satisfied, the compression -vs- boost aspect is not all that difficult. All things being equal, there are only three ways to make more power - increase displacement, increase cylinder pressure, or increase rpm. It is the primary responsibility of a supercharger to increase cylinder pressure, while also, to a degree, increasing the effective displacement of the engine. As the supercharger supplies the motor with a more dense air charge, it allows for the ability to burn additional fuel. By adding a supercharger, additional air should no longer be a problem, which will also help to increase rpm. Ensuring that there will be enough additional fuel to maintain the proper air to fuel ratio, as well as controlling spark timing, will be the key to getting the most from a supercharged combination. All motors have a static compression ratio based on the components (heads, pistons, etc...) its made of. This is the amount that the air inside the cylinder is compressed. It is a ratio of the cylinder volume at BDC to the volume at TDC. When a supercharger is added, additional air is forced into the cylinder effectively raising the compression ratio. The result of this is called effective compression. The formula for finding the effective compression is very easy: ((boost psi / 14.7) + 1) x motor compression = effective compression. The effective compression formula allows a supercharged motor to be compared to a normally aspirated motor. For the most part, a supercharged motor with the same effective compression as a (similar) normally aspirated motor with the same static compression should have about the same overall power. This may bring up the question that if the overall power should be about the same, why go with a supercharger? The main advantage of the supercharger is that it allows for a moderate compression level during normal driving (off boost) while allowing for very high compression levels when needed. Obviously a high compression motor of about 14:1 makes a lot of power, but it would never survive daily driving. A lower compression motor is great for daily driving, but greatly reduces the potential for power. The supercharger allows for higher compression levels than could be used without a supercharger, while still offering the benefits of a standard compression motor. Many street supercharged systems will go beyond 18:1 effective compression under peak boost. Under race conditions, many supercharged race motors will go well beyond 25:1 effective compression. Both of these levels are far beyond what could be done reliably or cost effectively without a supercharger. This brings us back to the question of just how much boost or compression can, or should be run. Obviously there can't be a simple number that could be used for every application. This is why it's so critical to chose the proper components. It's not necessary to build a low compression motor to use a supercharger, but the correct parts are still necessary. The biggest factors will be in things like head bolts (or preferably studs), gaskets, and the strength of the other engine components. It goes without saying that the incredible power that a supercharger can add, can easily start breaking things. It is very important that as the boost levels rise, the need for a stronger crank, rods, pistons, etc... becomes very critical. Many people forget this as the motor itself is relatively mild, while the supercharger pushes it well beyond the practical limits it was intended for. Now, back to the compression issue. Anyone who has looked into supercharging has heard that you need a low (static) compression motor. This may have been true once upon a time, when roots type (positive displacement) superchargers and carburetors ruled the land, but it's not so necessary now. The problem with a low compression motor is that it relies heavily on the supercharger for its power. An 8:1 motor is definitely not going to be a power house. Sure, you can throw 18 lbs of boost on it and get some real power, but why? A higher compression motor of 9:1 or even 10:1 will have much more power without the blower. Then, with less boost you could easily have the same overall power - only it would be much more usable. Both of the motors (8:1 with 18 lbs boost and 9.5:1 with 12 lbs boost) will have almost the same effective compression and about the same peak power. The big difference will be where you see the power, and how much of a demand will be placed on the supercharger. Obviously, the 9.5:1 motor is going to have far greater torque and low end power as the boost is only starting to come in. It is also going to be much easier to find a blower to survive at only 12 lbs of boost -vs- one that would have to put out 18 lbs of boost. It is now very easy to see why a higher compression motor with lower boost is becoming so popular. Please understand that when I say higher compression and lower boost, there are limits to each. Going over about 10:1 will make the amount of boost that is usable drop quickly to the point that the supercharger is somewhat wasted. In my opinion, anything less than 8 lbs of boost is a waste of a supercharger. Going over 10:1 will also make daily driving with pump gas much more difficult. In this same way, compression levels much under 9:1 will require substantial boost levels to make massive power gains. This would require boost levels that are very demanding of a supercharger. This is truly unnecessary. This isn't to say that the lower compression / higher boost set-up doesn't have a slightly higher potential for power, because it does. A lower compression motor has the ability to contain more volume. This can be an advantage, but is such a minor one that it's not necessarily worth the effort - unless it's for an all out race motor. Even then there are limits for the same reasons as the street / strip motor. Once again, the compression -vs- boost issue. For a car that will see the streets (actually for most applications), the best thing to do is start with a motor compression that is high enough to make the horsepower you want for normal driving. Don't rely on your supercharger to make all your horsepower. With a good motor compression, add as much boost as is safe for your particular application. Decide on a final effective compression, and work your way back through the formula to find your maximum boost level: ((effective compression / motor compression) - 1) x 14.7 = boost. With the proper fuel system and related engine components, an effective compression of 16:1 to 18:1 should be more than workable. For heavily modified cars, effective compressions over 20:1 should be very carefully considered. Remember, even Indy cars only run about 18 Lbs of boost and reasonable static compression levels. Technology has come a long way and modern day supercharging should take full advantage of this. While these opinions are not exactly the most popular, they are based on facts and real world performance. While there will always be those who continue with tradition and stick with what was done in the past, it is those who reach for something more that are winning races. Often times, some of the best advice can be found from those who have done what you want to do. All too often it is those who know the least that offer the most advice. After having been involved in supercharging for many years, I have heard it all. Most of it was worthless. It was often the least mentioned things and trail and error that have been the most rewarding. Hopefully this information will help to explain some of the most misunderstood aspects of supercharging. Copyright © 2007 MotorSports Digest
Hal makes a good argument, however running lower compression than a 9.5:1 is for race cars only. lol I have been running 9.5:1 for nearly three years. Of course I do not plan on ever going back to N/A. Now, Trojan's Chally is 8.5:1 and his motor (without the blower) is a MONSTER, so it is possible to run a low compression with good power. All depends on WHO builds it. Hal has not shared EVERYTHING about his motor. Not only is is built for a twin screw, but a very large shot of go go juice. The cam is a MONSTER. lol as is his head and intake work. Probably one of the BEST made. IMO. My only advise is when you have the motor built, have it done right and with "Quality" parts. You get what you pay for. Good luck and be sure to start a build thread.
great read, thanks Hal. Also, I see you are running 10.3 motor and plan on a twin screw. If you don't mind how many pounds you think you will throwing at it?
I'm really impressed with how my car runs NA. As Ron said, his motor is 9.5 CR which is not really considered low compression. I would run the 10.3 stock ration or no lower than 9.5. The higher to compression, the better the performance NA. Sounds like you need 10.3. Steve's motor is 10.3 also. We have the same Arrington shortblock. Only difference is he had the heat coatings. Again, to me that is more a race car option. Not much on the street, probably 5. Track, eventually between 8 to 10 tops. We'll see. I still want to retain my N2O, so probably can run low boost all the time, unless I get stupid. LOL
Oh okay so you are running the arrington bottom end. I think arrington is the way I will be going also just not sure if I want the 440 or 426. Ron, Thanks for the advice. Well since the only supercharger for the Jeeps at the moment is the vortech I would like to see what it would do at eight pounds which I believe is standard with the kit.
426 Stroker from BES/HHP is the motor I recommended, 14 cubes aint worth it Imo, 20k for a Stroker, Ill pass. And for some reason my 8:5.1 comp Stroker is faster then any high comp stroker Ive seen N/A other then Jeremys special car. Last Stroker from Arrington I heard about had scratch's in the cylinders walls after 10k miles. Right now I think no one builds a better, Stronger, Motor then BES/HHP. just my 02 cents! :bye:
I believe the scratches are because of all the coatings everyone thought they had to do have. Not necessary for a street car. They are designed for race car motors, not daily drivers. Arrington is taking care of it I might add. HHP/BES motors are top notch. I'd put my build up against anyones. You pobably would have got 10's with a 10.3 Chris. Everything is getting better, especially the tunes. Jeremy's car was old tech, built before CMR. They pursued low DA also, not sure what the DA was when they got their best, plus they strip out alot of stuff. I'm sure if they bring it out with a new setup, it will be quicker yet.
Trojan your car is bad ass hands down. If I could go that route I would in a heart beat but they seem to be pretty expensive. I know I know you get what you pay for.
That's flywheel HP. On and engine stand dyno, not RWHP. That 440 has 11.00 CR and is built for a engine swap. Not for our cars. Not aware of one built specifically for our cars. Doesn't mean they can't do it. Excellant price on it. http://www.arringtonengines.com/p-1025-440-hemi-crate-engine-by-arrington-engines.aspx
Quoted from link above... I have highlighted some points of interest in the write-up. As you can see, your Dyno graph is for the upper end of the 440. And I am sure that if you want the max power built 440, that 13K price tag will go up as well?
I can hook you up with a BES for a great price, Cheaper then anyone, Am I in trouble? Call me anytime Bro!
