Z-Dreamer Posted February 3, 2008 Share Posted February 3, 2008 Found this cool calculator from another site, check it out! http://www.squirrelpf.com/turbocalc/ Mark Quote Link to comment Share on other sites More sharing options...
Six_Shooter Posted February 3, 2008 Share Posted February 3, 2008 Hmmm, interesting. Quote Link to comment Share on other sites More sharing options...
Kash Posted February 6, 2008 Share Posted February 6, 2008 That's great! Quote Link to comment Share on other sites More sharing options...
Kash Posted February 6, 2008 Share Posted February 6, 2008 Looks like I need a T04E with the 50 trim for my application. Question: How much of a difference does the compressor AR makes, or should I say, what is deciding factor when it comes time to choose the AR for the compressor housing? Do I need a .50 or a .60? Is the .60 physically bigger externally than the .50 whereas I might have clearance issues on my L28? Or is it same size externally but flows more air at the same efficiency as the .50 would with the same trim? Would like to nail this part right before I decide on the final spec’s. Thanks. Ken Quote Link to comment Share on other sites More sharing options...
jgkurz Posted February 7, 2008 Share Posted February 7, 2008 The calculator seems excellent at first but when I plug in all my data it isn't not even in the ball park. I know a fair amount about my car including an accurate HP output based on the dyno and at the dragstrip. BTW, the HP field is crank HP not wheel HP. I'm still playing with the numbers but it's not been accurate so far. I'd like to know if someone actually feels the output of the tool is accurate. Quote Link to comment Share on other sites More sharing options...
Z-Dreamer Posted February 7, 2008 Author Share Posted February 7, 2008 The calculator seems excellent at first but when I plug in all my data it isn't not even in the ball park. I know a fair amount about my car including an accurate HP output based on the dyno and at the dragstrip. BTW, the HP field is crank HP not wheel HP. I'm still playing with the numbers but it's not been accurate so far. I'd like to know if someone actually feels the output of the tool is accurate. jgkurz, If you have questions about the calculator, contact the site that produced it, they would be happy to help you. Mark Quote Link to comment Share on other sites More sharing options...
jgkurz Posted February 7, 2008 Share Posted February 7, 2008 jgkurz, If you have questions about the calculator, contact the site that produced it, they would be happy to help you. Mark After playing the with the numbers more I was able to get an output that was closer to my expectations. The only variable I don't trust is the BSFC. I estimate my car is about .55. The tool suggests it's at .43. That's extraordinarily efficient if it's true. I have no way to validate the BSFC number other than to compare other engines that have been officially tested. Supposedly an efficient turbo gasoline engine is about .55 -.60. Using those numbers skews my results greatly. Oh well. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 7, 2008 Share Posted February 7, 2008 For the BSFC, if you click on the "more" link it will show you ball park numbers to choose from. .55 seems decent to use. Mario Quote Link to comment Share on other sites More sharing options...
TimZ Posted February 7, 2008 Share Posted February 7, 2008 For the BSFC, if you click on the "more" link it will show you ball park numbers to choose from. .55 seems decent to use. Mario I don't think that John needed help choosing a representative BFSC - he already knows what turbo he is using and how much power he is making. He's saying that the calculator doesn't give the correct results unless he puts in an unrealistically low number for BFSC. I'm seeing similar results, btw. The maps don't reflect my experience unless I use a BFSC of about 0.4. I know from experience that my engine is running in the neighborhood of 0.6 BFSC. The calculator is saying that I would need to run 47psi of boost to reach the numbers that I get at 26psi. EDIT: I am noticing that if I play with the intake temperature and volumetric efficiency numbers the results look more realistic, but I had to use a VE of 115% to get in the ballpark with BFSC=0.6. Maybe my cam is working better than I realized... Quote Link to comment Share on other sites More sharing options...
mtcookson Posted February 7, 2008 Share Posted February 7, 2008 but I had to use a VE of 115% to get in the ballpark with BFSC=0.6. That's a major issue I've been having lately when trying to calculate power and such (outside of this calculator, trying to match compressor maps with my engine and figure out what kind of power I'll see). We know that VE basically increases with boost, I'm wondering if maybe that needs to be added in these types of calculations to get realistic numbers. For instance... I'm working with a VG30E(T). Basing off of another person's dyno, they had ~452 whp at 5,500 RPM at 20 PSI. This was a 7.8:1 CR VG30ET with head work, valves, cams, modified intake manifold, exhaust, etc. To get those numbers I had to put in a VE of 95.5% in my calculator to get the right numbers (though my calculator doesn't take in near as much data as this one so the number will be even higher). Another thing that isn't taken into account is compression ratio. Take that engine above, it has a 7.8:1 CR while I'll be running 9:1, which should be more efficient but I don't know how that would change the numbers.... it just seems like there's no good way of properly calculating this type of stuff. Seems mostly to be just a get in the ball park then throw it on and see if it works kind of deal. With some stuff I'm wanting to screw with I'll be messing with spooling characteristics that will put me close to the surge line of my choice and if my VE calculations are off this will either throw me into the surge area or I'll be further away from the surge line making it not quite as optimized as possible. Hopefully that doesn't sound too confusing but I'm hoping maybe someone could throw in some insight on calculating the volumetric efficiency in a boost situation as well as how compression ratio affects this (to make it even worse, you really should calculate the dynamic compression ratio). Boggles my mind a bit too much. Quote Link to comment Share on other sites More sharing options...
mario_82_ZXT Posted February 8, 2008 Share Posted February 8, 2008 I don't think that John needed help choosing a representative BFSC - he already knows what turbo he is using and how much power he is making. He's saying that the calculator doesn't give the correct results unless he puts in an unrealistically low number for BFSC. Woops brain fart. I read it wrong... Quote Link to comment Share on other sites More sharing options...
jc052685 Posted June 18, 2008 Share Posted June 18, 2008 so my question is does any one know if there is any and where to find such data on the l28et as I cant seem to. Info such as bsfc VE and shuch info for this table to be usefull? Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted December 9, 2009 Share Posted December 9, 2009 I want to know if this is a good turbo to use based on the information I put in there: http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.78&pr3=2.48&pr4=2.48&pr5=2.48&pr6=2.48&pr7=2.48&airflow0=2.6&airflow1=9.9&airflow2=18.7&airflow3=29.2&airflow4=34.7&airflow5=37.8&airflow6=40.5&airflow7=41.1&product_id=109 Just seeing if I'm doing good at reading the compressor maps. Quote Link to comment Share on other sites More sharing options...
e_racer1999 Posted December 10, 2009 Share Posted December 10, 2009 I want to know if this is a good turbo to use based on the information I put in there:http://www.squirrelpf.com/turbocalc/graph.php?version=4&pr0=1&pr1=1.07&pr2=1.78&pr3=2.48&pr4=2.48&pr5=2.48&pr6=2.48&pr7=2.48&airflow0=2.6&airflow1=9.9&airflow2=18.7&airflow3=29.2&airflow4=34.7&airflow5=37.8&airflow6=40.5&airflow7=41.1&product_id=109 Just seeing if I'm doing good at reading the compressor maps. From your pressure ratio looks like ~350-400 hp, no? The 3076 is indeed an excellent compressor for modest HP goals on L-series. Much better overall fit than the GT35R IMHO. Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted December 10, 2009 Share Posted December 10, 2009 What I was shooting for was 375 hp out of a 2.5 liter. Max power at 6500, max torque at 4500, with 7000 Redline. I like how the graph is because the 6500 (I'm assuming the red dots are RPMs in 250 increments) is in the middle island while the reast are at least close by. I just wanted confirmation because I've never had to pick out a turbo before. Quote Link to comment Share on other sites More sharing options...
jeffp Posted December 15, 2009 Share Posted December 15, 2009 I took a look at the calculator and it to was not quite right for my known engine output power. The thing that surprised me was that the line for my power and compressor map were off as well. I did not have to run 45psi of boost to get 650 crank hp, more in the line of 22psi. I did all of my calculations from John Lawlors book and that got me to where I wanted to go. You will have to use a number of different calculations, but for the most part it is very accurate. The thing about a turbo size question: 1) what is the static compression ratio. 2) what is the swept volume of the cylinder. 3) what total compression ratio do you need to make that cylinder reach you hp goals. hp/6 cylinders= power of one cylinder. 4) once you have the compression ratio, then you need to calculate the total air required. 5)with total air required, static compression ratio, final compression ratio calculated, you then need to calculate the pressure ratio you will need to make the cylinder produce X amount of power to get to the target compression ratio to make the desired power per cylinder. 6) with total AIR required, and pressure ratio required, then go to your compressor maps and select the best fit turbo. Then comes the give and take of how well the turbo will spool, when it will spool, what is the efficiency of the turbo at your desired hp and rpm range, and go for it. If the turbo manufacturers can do this and build turbo's all day, why cant we do the same thing? I mean required air, based on the cylinder size and swept volume of a cylinder based on all the required givens to calculate hp per cylinder is all you need to make a very informed decision for turbo size. Guys this stuff is not magic, it is calculated and you would be very surprised how accurate it is. Play with the formulas that are available to you and figure it out. Sure a quick calculator is nice, when they work, but it is not required. anyway, I think I would be WAY over 650 crank HP with 45psi of boost. Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted December 16, 2009 Share Posted December 16, 2009 I was using the equations from Garrett's website before I found the link to this calculator and I was getting the same results. I'd have to check out that John Lawlor book. Quote Link to comment Share on other sites More sharing options...
AkumaNoZeta Posted December 16, 2009 Share Posted December 16, 2009 Is this the book you have? http://www.amazon.com/Auto-Math-Handbook-John-Lawlor/dp/1557880204/ref=ntt_at_ep_dpi_1 That was the only John Lawlor book I found that related to automobiles, the rest were like changes in the educational system in 1970 and "social history." Quote Link to comment Share on other sites More sharing options...
jeffp Posted December 17, 2009 Share Posted December 17, 2009 That is the book. Quote Link to comment Share on other sites More sharing options...
B00STDZ Posted December 24, 2009 Share Posted December 24, 2009 I don't think that John needed help choosing a representative BFSC - he already knows what turbo he is using and how much power he is making. He's saying that the calculator doesn't give the correct results unless he puts in an unrealistically low number for BFSC. I'm seeing similar results, btw. The maps don't reflect my experience unless I use a BFSC of about 0.4. I know from experience that my engine is running in the neighborhood of 0.6 BFSC. The calculator is saying that I would need to run 47psi of boost to reach the numbers that I get at 26psi. EDIT: I am noticing that if I play with the intake temperature and volumetric efficiency numbers the results look more realistic, but I had to use a VE of 115% to get in the ballpark with BFSC=0.6. Maybe my cam is working better than I realized... Kind of off subject but... http://www.turbobygarrett.com/turbobygarrett/news/race_updates/GTX_R_Turbochargers.html Time for an upgrade? Quote Link to comment Share on other sites More sharing options...
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