JoshA

I agree, narrow band O2 sensors are pretty much useless. Wideband and EGT is the only way to get tuned properly.

Also remember that the volumetric efficiency will be at it's peak right around the torque peak of the engine. And we've seen how quickly these things fall on their face after 4000 RPMS. So it is unlikely that you will push much more than 500 CFM at 6000 RPM(18psi). It's really hard to say for sure without better VE information. But generally a long stroke, 2-valve motor like this is going to be pretty poor at moving air at high RPMS. I know that this is an old thread, but I was searching for some stuff and figured that I'd add my take. I'd be curious if anybody could convince me that this is incorrect before I go and buy a turbo sized according to these estimations. Right now, I'm leaning towards a TO4E-46 trim compressor. http://www.majesticturbo.com/20574-46.html My calculations put max airflow in lbs/min to be less than 40 @ 120 degrees, 6000rpm, 18psi.

This place sells Griffin cores and a variety of HKS end-tanks that fit. They have tanks that are straight up and down. I don't know much about the Griffin cores though. I'm sure that there are other places that have similar options using different cores and stuff somewhere out there. http://www.roadraceengineering.com/intercoolers.htm

[quote author=88BlueTSiquest If this is the case, then we are missing the slight fact that with the turbo, we are force feeding it with air. So technically, if the engine could just consume 500cfm's at first, we could very well force feed it another 100cfm's or more for a higher hp output. That's been the whole purpose of forced induction for years, cram more air in for more HP. Blue, cfm is a measure of volume. Compressing the air more will not increase the volume of air flowing into the engine, only the density. Of course density is power. The goal is to get the coolest air with the highest density. Zero, I have some maps that Chad sent me, but I don't put too much stock in them unfortunately they are not that valuable for picking a compressor wheel. He sent me TDO6-16G, TDO6-20G, TDO5H-16G, and TDO5-14G. Because these are three different compressor housings, you can't really use them as the basis for choosing the right wheel-only upgrade. I wish that Mitsubishi was as open regarding their turbos as other manufacturers like Turbonetics. If you search the web, you can find tons of maps for the various T3 and T4 compressor trims.

ZeroKewl9 said Actually, the calcualtion started with an "ideal" valvetrain. basically one that would allow the cylinders to fill perfectly. I just adjusted the curve to refelect the decreasing ability of the cylinders to fill at higher rpm. I really shouldn't have put any numbers in, because I don't have my notes handy and my memory may be off, or I may be recalling the wrong engine. I was talking about the engine exceeding 500cfm of "draw" <--electrical metaphor. Basically the engine moving more air out than the turbo can pump in and still maintain 15psi. I really need to rerun those numbers because that 500 was just a number that sticks in my mind, I'm not really sure at what rpm and at what psi that came from. I'll have to redo my calculations so that you can all see how I did it. I admit that most of my calculations were made from an "ideal" point of view. There are many variables and inefficiencies that I threw on the floor for the sake of getting an answer. Then I just used my sixth sense to adjust my curve to what felt would make up for the variables that i ignored. I'll try and find my scribbles this weekend or I'll sit down and do them again. I see people quoting the 500 already, but I don't even really remember if that was the right number.

I regards to the last 2 posts. Here's the way I see it. The CFMs are not that important. Two things matter temperature(density) and psi. The CFMs for which the turbo is rated will only tell you if the turbo is capable of maintaining that amount of pressure. I don't feel like doing any math here, so these are all fabricated numbers, but you can figure them out without much difficulty if you want. Lets' hold the PSI constant for the purpose of this discussion. In fact, let's say that our turbo is an electric powered unit regulated to maintain 15psi constant. The amount of air consumed by the engine is going to rise in a fairly linear manor with regards to RPM. Let's also say that our electric turbo is rated at a max of 500cfm @15psi. At a certain RPM, let's say 5000rpm, the engine will begin consuming more than 500cfm. The electric turbo will no longer be able to maintain the 15psi. It simply cannot push enough air to maintain the pressure. So is the CFM important? Yes in a way. But it really tells very little about the characteristics of the compressor. If I remember correctly, I calculated that the 2.6 can only consume around 500cfm at 15psi and 6000 RPM. As long as you don't exceed that cfm, your turbo will be capable of maintaining the 15psi pressure. What you really need is the compressor flow/efficiency maps. Then you can chart your estimated engine consumption against the efficiency map of the compressor to determine the correct compressor. One last factor in the equation that is difficult to calculate and leaves you to do some estimating. Take this... your intake is pressurized to 15 psi. You open your valve and the cylinder has a chance to equalize to 15psi also. It won't take in any more air than that. At high rpm, the valve is open much shorter and it is very unlikely that the cylinder will have time to reach equilibrium with the intake. The valve will not be open long enough to fill up. This is why the engine will only consume air in a fairly linear manor. As rpms increase the, the engine will become less and less efficient in consuming air. That's why we all need a nice roller-rocker cam setup. I'm still hoping that all of Tim_C's hard work and research will pay off and yield the ideal valvetrain for our Quests. I will gladly pay out the nose for one, as it's really the last piece of the puzzle we need to get the most out of the g54b. Thanks for providing a place to ramble. And if I'm all wrong, please let me know. Josh

Dang!! is that what that does ;D Now that I know it's there, I'll probably never use it. heh Thanks Gabe

Ok, here's one. How about teh ability to be nitified if a thread that you are interested in gets a new post, even if you haven't posted to the thread. I know that this might be impossible given that you are somewhat constrained by the "stock" capabilities of the yabb system. But it sure would be nice.

Oh, BTW, I like the new classless society ;D. It should help a little to keep people from posting worthless words just for the sake of moving up the status ladder. JoshA

I know that there was some talk about getting compressor maps on the site, but you could take it to the next level. Take a look at this most excellent excel spreadsheet somebody made. It would be awfully cool to have a simplified version of something like this on the site, maybe in the form of a Java applet. Of course, we would need all the maps for our compressor options. Anybody know the best source for the maps? Maybe I'll start tinkering http://home.attbi.com/~hyc/dyno/turbosize.xls JoshA