in the link 4A-GTE the turbo section says that the guy used the rb20/25 turbos because of pulse per cycle. i was discussing this with other friends and we cant figure out WHY the turbo would spool (is that even the correct term in this case?) alot faster on a smaller engine displacement?
eg.
RB20DET 6cyl (2ltr 6cyl turbo)
2000cc divided by 6cyl = 333.3
333.3 pulse per Cyl
RB25DET 6cyl (2.5ltr 6cyl turbo)
2500cc divided by 6cyl = 416.6
416.6 pulse per Cyl
4A-GE 4cyl (1.6ltr 4 Cyl N/A)
1600cc divided by 4cyl = 400.0
400.0 pulse per Cyl
without putting any thought into it cause i cant be bothered so i could be wrong, but i would have thought pulse cycle would have nothing to do with the engine capacity, rather the number of cylinders and the engine rpm. wouldnt what your talking about be the displacement of each cylinder???
I may be wrong but in that article I dont think it says that a smaller displacement engine would bring the turbo on faster. I think it is just a crude guestimation at to what turbo would suit the 4a motors displacement and rev capability.
For instance I put a ct20 on thinking that it came off a 1.8L 3tgte so it should have the flow capability. WRONG
So I went the other way and got a turbo off a vg30 thinkin 3L motor heaps of flow Came on boost at 4000rpm bit laggy.So i had that modified with a back cut wheel and a godzilla exhaust housing and now boost comes on full tilt at 3000rpm.
What Im trying to say that two turbos made for the same motor even by two different companys could have complete different flow caracteristics.So just choose one that can flow the exhaust volume with good response rate and see.But i may be wrong...
Wed, 30 June 2004 03:10
