jeffw
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| posted on 24/11/14 at 12:15 AM |
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quote:
Originally posted by Oddified
Just picking up on this old thread which i've been reading and a few other that jeffw had done regarding fitting the rotrex supercharger. If
like me people google info on supercharging with a rotrex these threads pop up so it might be useful.
Finally got round to fitting a 30-94 to my kitten, and like the zetec it's was in theory far from ideal for boosting as i haven't done
anything to it from running quite a good spec NA cosworth (250bhp ish). With accrallite pistons just shy of 12-1 compression, pair of Kent L1 cams
which are 306deg with plenty of overlap, big valve ported head etc...all wrong in theory for any boost!.
The main difference is i made up a water charge cooler as space is tight in the kitten!, Bell Intercooler core built inside the plenum, rad in the
front, with it's own fan controlled off the ecu from the air temp and it keeps it within 20 deg of ambient on the logs. I went for a calculated
pulley ratio for a conservative 6psi boost just to start with, but it actually makes just over 7psi. I've done the mappng (wide band, data logs
and det cans) and it all works amazingly well, the performance difference is immense!. Obviously not any dyno numbers, but the inner bank of injectors
hit 100% duty cycle long before the rev limit/full boost and they're 540cc/min so it doesn't take a rocket scientist to have a good guess.
I used tb's with 8 injectors so with both sets there's enough fuel. I'm very very very impressed with the superchargers as i'm
sure that a turbo set up on the engine set-up as it is would have been a none starter.
Ian
Sounds like a nice set-up Ian. The 30-94 should be good for 1.2 bar or so which leaves you a bit of headroom just yet. I'm running 660cc
injectors at 3.5bar if that helps.
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Oddified
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| posted on 24/11/14 at 09:04 AM |
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Initially i just wanted to get it up and running and aimed for 6psi just to be safe. The rev limit on the engine is set to 8500rpm so that knocks back
the maximum boost a bit with the air flow but i'm only spinning the supercharger at 83,000 and they're rated to 100,000. Looking at the
compressor map i could move it to 95,000 and it should make around 9 - 10psi and stay in an efficient area. I'm not so sure the gearbox is going
to live to long as it is though!, even though it's a Tranx type 9 straight cut.
I have 540cc/min on the inner row and 670cc/min on the outer row, set-up to use only the inner row up to 5000rpm+50% throttle and then a transition
into running both rows. The highest i've seen now running both rows is 61% duty, so i have enough fuel available even if i swap pulleys (which
i've just won on ebay! lol).
The main purpose was to get away from throwing a lot of nitrous into the engine when i did rwyb drag racing events which soon empties the bottles. It
also cuts out bottle heating, running out mid run, swapping bottles/reheating etc etc.
Ian
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jeffw
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| posted on 24/11/14 at 09:47 AM |
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I'm at 100k at 7000rpm and the 110k overrev at 7400rpm. You'll find that your water intercooler starts to struggle at 1.2/1.3 bar that
the supercharger is capable of. My injectors are actually 750cc (just checked) and no, your Trans-X will not last very long at 1.2 bar but it will
last longer than you expect. Shock loading while changing gear will be the killer.
I guess you would be looking at 450BHP or so at full boost.
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