dj paul Posted December 27, 2005 Share Posted December 27, 2005 Hey guys ive been searching the web forever for these and have just happened for stumble accross them. you can match these up with different compressor maps to find the perfect turbo. Also there are equations here, if you dont have an L28, to figure out your own flow rates and make your own flowrate map to match up. http://www.mygen.com/users/dbruce/myz31/TurboMaps/L28ET%20Engine%20Air%20Flow%20and%20Turbo%20Compressor%20Maps.htm Quote Link to comment Share on other sites More sharing options...
260DET Posted December 28, 2005 Share Posted December 28, 2005 Good find, should be useful. The one thing that concerns me about such calculations though is the volumetric efficiency figure which is apparently an assumption. I think that is the Ev figure, .85 to .80. There are quite a few things which can affect that figure significantly, cams, porting, etc. Plus it varies throughout the rev range being related to torque output. I don't know enough about turbos to go further, except to say that if I was using that information I'd try a few different Ev figures and particularly try and match them to an estimated torque curve. Quote Link to comment Share on other sites More sharing options...
dj paul Posted December 28, 2005 Author Share Posted December 28, 2005 well i believe what hes using is just pure stock Ev. yes i do agree that there are many different things that can affect that figure. well it varys throughout the rev rang by getting higher by the rpms (or lower i cant remember) http://www.ajdesigner.com/phpengine/engine_equations_volumetric_efficiency.php im not sure how to add in the other factors. Quote Link to comment Share on other sites More sharing options...
260DET Posted December 28, 2005 Share Posted December 28, 2005 I'm fairly sure that Ev is related to torque, I guess maximum Ev has some relationship with RPM and torque output. As I said, I don't know a lot about this subject but there does not seem to be a lot of info around on the Ev aspect. Anyway, you have to start somewhere and that site certainly has the goods to do that. Quote Link to comment Share on other sites More sharing options...
thehelix112 Posted December 28, 2005 Share Posted December 28, 2005 http://www.stealth316.com/2-air-fuel-flow.htm Check this link.. Plug in the values into the Mass Air Flow bit (Density Ratio is close to pressure ratio) The values agree in the volume air flow but the mass air flow gives significantly different values. Like 6500 at 20psi gives 50lb/min being PESSIMISTIC about Ev and DR. Being optimistic (85% Ev and 10% drop in DR because of heat) the value is 56.4lb/min. A 38% increase in the values plotted against those graphs. Also looking at the graph you might consider that the T61 compressor is way too big because when building boost the compressor is almost in surge, but more importantly in my book is that when you ARE in boost the compressor is becoming more and more efficient. Ie, reducing the increase in inlet temps when detonation is likely to be an issue. Who cares if its off the chart when its not in boost? I'd be checking the Mass Air Flow calculations he used before taking that information as gospel. Dave Quote Link to comment Share on other sites More sharing options...
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