zguy36 Posted February 22, 2006 Share Posted February 22, 2006 My last post on this subject was booted because I "don't play nice". Anyway, I appologize for being an *** and hope that this is some good information. I added an excel spreadsheet to the downloads section that will calculate the airflow of your engine based on real parameters that eliminates any guesswork at all. Yes, that's right, you don't have to guess the VE of your engine, you can directly calculate it for any RPM! http://forums.hybridz.org/showthread.php?p=613687#post613687 Quote Link to comment Share on other sites More sharing options...
big-phil Posted February 22, 2006 Share Posted February 22, 2006 WOW! That all Greek to me! I looked at it and have no idea what I'm looking at? Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 22, 2006 Author Share Posted February 22, 2006 Enter your values into the shaded regions. This is set up so that you can take values from a data log (you have to have a standalone to work this spreadsheet). The values of importance are injector size, ambient air temp, base fuel pressure, number of injectors, and the a/f column and the injector duty % column. A lot of the other junk such as RPM is so that you will have something to graph your airflow values against. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted February 23, 2006 Share Posted February 23, 2006 Doesn't VE differ from different setup or different engine? Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 23, 2006 Author Share Posted February 23, 2006 Yes, this is basically what this calculator is doing, calculating the VE of your engine. Instead of having a graph of VE, you get a graph of lbs/min so you can use this calculator to pick turbo sizes. Any engine parameter does not matter, as the calculations are not dependent on anything other than what I stated. This calculates the amount of air flowing through the engine, based on fuel consuption and air fuel ratio. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 23, 2006 Author Share Posted February 23, 2006 If someone wants to send me a datalog of a boost run and the parameters of their engine, I can enter all of the values into the spreadsheet and post the results. The spreadsheet is currently filled with values from an RX-7, hence the big injectors and high RPM. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted February 23, 2006 Share Posted February 23, 2006 Yes' date=' this is basically what this calculator is doing, calculating the VE of your engine. Instead of having a graph of VE, you get a graph of lbs/min so you can use this calculator to pick turbo sizes. Any engine parameter does not matter, as the calculations are not dependent on anything other than what I stated. This calculates the amount of air flowing through the engine, based on fuel consuption and air fuel ratio.[/quote'] but your lb/min will increase with a bigger turbo also. You can't base on picking a turbo on N/A VE as a turbo will throw the VE higher. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 23, 2006 Author Share Posted February 23, 2006 The VE of your engine will not change unless you make a modification that will change the breathing characteristics of your engine. One of the most popular turbo upgrades is changing from the stock t3 to a t3/t4 hybrid. Since you are not chaging the exhaust side, you aren't changing the VE of the engine. If you do change the exhaust side, your VE will change, one of the major reasons you get a power increase with a bigger turbo. Don't confuse turbocharging an engine with increasing your VE. If you are familiar with tuning a megasquirt, think about the VE tables that are used. They rarely go above 100%, and if they do it is probably because you have another parameter set wrong. VE is the percent air going into the engine compared to displacement. The proper way to look at this is not thinking that more pressure increases your VE. More pressure does put in a ton more air, but the efficiency of your engine stays the same. VE is the amount going in compared to the amount that would go in at that same pressure if the engine were 100% efficient. This calculator will tell you the exact amount of air flowing through your engine as it currently is. How it will perform with with a larger turbo, is still something that cannot be directly calculated. This calculator is however, tenfold better than the method used to calculate airflow that uses displacement, engine rpm, and a guessed VE Quote Link to comment Share on other sites More sharing options...
yo2001 Posted February 23, 2006 Share Posted February 23, 2006 You are suppose to change the turbine wheel on the turbo when you are going to a hybrid turbo to keep the back pressure before the turbine lower. However I guess good example is some of the mitsu turbos from 16G's from small 16G, big 16G to EVO3. exact turbine setup but EVO3 can flow about 10lb/min more due to size and design of the wheel. So using lb/min furmula, would it not increase the VE on EVO3 16G than small 16G? May be I'm thinking too much about other efficiency. Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 23, 2006 Author Share Posted February 23, 2006 Hmm.... I figured more people would find this information useful, but I guess it isn't useful to know the cfm of air your engine consumes. technicalninja, I have seen VE described two ways, one way as how you described it to me and another in the way I described it earlier. If you would like, I could just change the term to something else to describe the value I am using in my calculations. I guess it could be called pressure independent VE for lack of a better term. yo2001 Most of the hyrbid turbos that I have seen, at least when they are mild upgrades only change the compressor side and leave the turbine side. If you want a large exhaust side too, then that would defeat the purpose of combining two differnet turbos into a hybrid. I know this isn't only the case, but in this case, the pressure independent VE of the engine wouldn't change. I'm not exactly sure what you were asking about the 16g example, but yes, with the larger turbo, using my equations, the lbs/min would increase, provided you enter all the correct values into the spreadsheet. The pressure independent VE would not change though. The smaller, more inefficient turbo will be heating the air more and provide less dense air charge. The difference does not lie in the efficiency of the engine, but instead the efficiency of the turbo. This is a good point though, and I am going to have to do some more thinking on the subject to make my speadsheet directly comparable between turbos. As it sits now, it will only tell you how much air is being processed in your engine. What you can do with that is still left undecided. vbmenu_register("postmenu_", true); Quote Link to comment Share on other sites More sharing options...
Dave88SS Posted February 23, 2006 Share Posted February 23, 2006 If you want a large exhaust side too, then that would defeat the purpose of combining two differnet turbos into a hybrid. sometimes it's done to retain the same exhaust housing to eliminate the need for custom o2 elbow & ex mani. At least that's how I plan to play it Quote Link to comment Share on other sites More sharing options...
zguy36 Posted February 23, 2006 Author Share Posted February 23, 2006 back to the real question, is anyone interested in accuratly measuring the airflow through their engine? Quote Link to comment Share on other sites More sharing options...
NISMO619 Posted March 31, 2007 Share Posted March 31, 2007 so the biggest question is ! u do a hybrid turbo set up like me. Then u find out your 280zxt doesnt run right with the new turbo charger. 1 do u change the air flow sensor to run richer ? 2 if so how do u do it ? pictures please ? 3 i took off a t4 compressor wheel and cover and transplated it to my stock exhasut side turbo holy ♥♥♥♥ it worked ! problem is my oxygen temp sensder uint to my FAZE gauge reads LEAN now in stead of Stock . ? Quote Link to comment Share on other sites More sharing options...
zguy36 Posted April 8, 2007 Author Share Posted April 8, 2007 I am not really sure what you are asking.... You change your fuel setup to put in the correct amount of fuel, no matter what systen you are running. You need a wideband sensor to to this correctly. Playing around with the stock system is difficult to do. I scrapped it a while back and have no regrets. The full tunability of a standalone is truly the best way to go. A megasquirt is cheap to, so money isn't so much of an issue. Quote Link to comment Share on other sites More sharing options...
nismopick Posted April 23, 2007 Share Posted April 23, 2007 Zguy, awesome spreadsheet.... deffinately good info that I will be using to tune my engine. PS... Nismo619: You still owe WreckedJ30 a Z31T ecu or $$$. Quote Link to comment Share on other sites More sharing options...
Recommended Posts
Join the conversation
You can post now and register later. If you have an account, sign in now to post with your account.