Rotrex C30-94 or C38-61
11-05-2015, 06:54 PM
#22
Not overkill. 1.2 bar at redline. Need cams and headwork.
Rotrex C38-61 on a 2004 Mazdaspeed Miata - YouTube
Rotrex C38-61 on a 2004 Mazdaspeed Miata - YouTube
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11-06-2015, 02:51 AM
#23
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Join Date: Sep 2008
Posts: 60
Total Cats: 4
Not really. 18 deg timing on top, 11.7 AFR, IAT +30C from ambient. Wiseco 9:1 pistons.
I had it setup with a waste gate to bleed off boost but never needed it. It was comparable to my 3071 setup above 6K but hard to tell when bost (and tq) follows the rpm. Maybe 300whp ?
I had it setup with a waste gate to bleed off boost but never needed it. It was comparable to my 3071 setup above 6K but hard to tell when bost (and tq) follows the rpm. Maybe 300whp ?
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09-19-2018, 04:46 PM
#26
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Join Date: Jun 2015
Location: San Diego
Posts: 8
Total Cats: 0
Okay- since someone "revived" this thread... I just got the C38-61 set up on E-85 about a month ago, so I was overly optimistic on the timeline, but not on the power output. Feels like a sport bike engine.
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09-04-2020, 10:42 PM
#29
A C38 would be total overkill on the 1.8, like filling your tea kettle by holding it under Niagara Falls. A few years ago, a guy on the other Miata forum (aaronbc) was getting 300+ whp on a built 1.6 using a C30-94. I watched a couple of his hillclimb videos, the car was a rocket.
I want to replace my C30-74 with a -94 and restrict it to limit max boost to about 10 psi. My goal is to fatten the midrange a bit but keeping max whp around 215-220. I recently changed the 90mm pulley on my setup (made a shade over 200/176 @ 9 psi) with a 75mm. The change in usable power was substantial. By "usable", I mean the powerband started 1000 rpm lower with the 75mm than it did with the 90mm, making 3 psi by 3000 rpm and rapidly going past 12 psi by 6000. I don't know what the numbers were, didn't dyno it, but it felt like I had an extra cylinder.
I want to replace my C30-74 with a -94 and restrict it to limit max boost to about 10 psi. My goal is to fatten the midrange a bit but keeping max whp around 215-220. I recently changed the 90mm pulley on my setup (made a shade over 200/176 @ 9 psi) with a 75mm. The change in usable power was substantial. By "usable", I mean the powerband started 1000 rpm lower with the 75mm than it did with the 90mm, making 3 psi by 3000 rpm and rapidly going past 12 psi by 6000. I don't know what the numbers were, didn't dyno it, but it felt like I had an extra cylinder.
That was meeee.
I miss that car, should have never sold it.. :'(
I bagged the absolute living hell out of that car, and it never skipped a beat. I am and will always be a big rotrex fan.
Working on a little toy with a buddy now a STOHR sports racer with a GSXR1300 engine and were considering throwing a rotrex on it.
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