Tvs 1900 lsj build
But with our head flow, that getting into the range of very hard. Which means we get to the point where to get more in you really have to just run crazy pressure ratios. Trouble with roots blowers is that once you get over a pressure ratio of 2 (aka 15 psi of boost) efficiency normally tanks because the boost starts to leak between the two rotors. The tvs has a higher threshold because of the helix angle on the rotors and some other stuff. Even the normal m62 is higher than that because of the coating and close tolerance on the rotors. That said to really push the pressure ratios you can run it has to be a twin screw, or something I havent seen done before, dual stage. Which would be 1 blower feeding a 2nd blower allowing for a total pressure ratio of 4, though cooling becomes an issue wish this.
But with our head flow, that getting into the range of very hard. Which means we get to the point where to get more in you really have to just run crazy pressure ratios. Trouble with roots blowers is that once you get over a pressure ratio of 2 (aka 15 psi of boost) efficiency normally tanks because the boost starts to leak between the two rotors. The tvs has a higher threshold because of the helix angle on the rotors and some other stuff. Even the normal m62 is higher than that because of the coating and close tolerance on the rotors. That said to really push the pressure ratios you can run it has to be a twin screw, or something I havent seen done before, dual stage. Which would be 1 blower feeding a 2nd blower allowing for a total pressure ratio of 4, though cooling becomes an issue wish this.
Again, your basing this off a stock/mild cammed LSJ with either a gasket matched/smoothed exhaust ports. I don't blame you though, since I havn't shown you anything.
When I ran the TVS 1900 on a box stock LSJ, with a stock exhaust manifold, 2.5" catted dp, and stock catback with a stock intake. I was on a 3.6" pulley boosting 24-25 psi by 7000 rpm.
This placed the tvs 1900 far out of it's efficiency island... spinning it to a mere 12,600 rpm and robbing easily 100hp per the chart below.
I'll leave you with this for now, and let you think about it.
When all is said and done, the m62 on 2.5 pulley (typically 19-21 psi on a stock head and cams) will be 10 psi, most likely less.
and for the 1900:
8000 rpm x 6.78 crank (ati dampener) / 3.6 = 15.066xxxx S/C RPM
Last edited by 100% METH; Jan 27, 2012 at 04:49 AM.
No, riddles and I'm not saying the 1900 wont work, just that I think thats the limit we could really use based on what we can actually flow though the head. After seeing these graphs I changed by backup plan from m90 to this if I dont get 350hp on my theoretical build, like the engine builder program says I will. I should see if I saved that engine because it would be real easy to pop this blower on it so we can start guessing power for realz. Based on the 2nd graph there, I'm guessing you're going to somehow see the pr1 to pr1.1 area for boost.