Silent Posted November 11, 2005 Share Posted November 11, 2005 Su question. the ITS modded su's from ztherapy, or the full out race modded from rebello. same price on both of them. anyone have experience on either side of these? Quote Link to comment Share on other sites More sharing options...
PeterZ Posted November 11, 2005 Share Posted November 11, 2005 I don't know what ztherapy makes so I can't comment on those. I have liked the ones I have used and tuned from Rebello. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 11, 2005 Share Posted November 11, 2005 SUs modified for racing is/are not rocket science. Go with the vendor you feel most comfortable with after spending some time on the phone. Quote Link to comment Share on other sites More sharing options...
Ed260Z Posted November 11, 2005 Share Posted November 11, 2005 The biggest problem with the SU's is that the bushing on the butterfly wears out over time. Ztherapy replaces them with bearings. I'm not sure about Rebello. I've had the Ztherapy ones for about 6 months, and they work flawlessly. To tune a SU for race you need to change the needles. There not much else you can do to them. And then it's trial & error until you get what you want. The SU's are great carbs, although can be difficult to "fine" tune since you have to keep swaping needles until you get it right. If your useing this car for race only you may want to go with the tripple Mukinni or Webers. They are not that great for street driving, since they don't hold a tune for long. But they are a little easier to "fine" tune. Good Luck. Quote Link to comment Share on other sites More sharing options...
Silent Posted November 11, 2005 Author Share Posted November 11, 2005 well, im not sure what rebello does on their shaft bushings eitherm i know what ztherpy does to theres and i have some similar work done to mine on the car now, aside from the custom needles. the rebello seems to be getting more cfm out of them, im trying to keep it simple and reliable, i don't feel the need to rejet the car every two weeks with triples Quote Link to comment Share on other sites More sharing options...
johnc Posted November 11, 2005 Share Posted November 11, 2005 BTW... the good ZTherapy SUs are illegal for ITS because of the bushing replacement with a bearing. They can build them with stock bushings. Quote Link to comment Share on other sites More sharing options...
PeterZ Posted November 11, 2005 Share Posted November 11, 2005 I used to spin my needles in a drill press and shape the tapers exactly the way I wanted them. With a set of calipers you can plot what the dimensions are as the needle moves within the nozzle. It did take some time to know what works but after that smogging a Z was done as easily as tuning for performance. Quote Link to comment Share on other sites More sharing options...
Silent Posted November 11, 2005 Author Share Posted November 11, 2005 im going far beyond anything legal in any class, well for its at least Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 11, 2005 Share Posted November 11, 2005 Then why bother with SU's? Quote Link to comment Share on other sites More sharing options...
Silent Posted November 13, 2005 Author Share Posted November 13, 2005 Then why bother with SU's? simplicity. Quote Link to comment Share on other sites More sharing options...
briann510 Posted November 13, 2005 Share Posted November 13, 2005 The biggest problem with the SU's is that the bushing on the butterfly wears out over time. Ztherapy replaces them with bearings. I'm not sure about Rebello. I've had the Ztherapy ones for about 6 months' date=' and they work flawlessly. To tune a SU for race you need to change the needles. There not much else you can do to them. And then it's trial & error until you get what you want. The SU's are great carbs, although can be difficult to "fine" tune since you have to keep swaping needles until you get it right. If your useing this car for race only you may want to go with the tripple Mukinni or Webers. They are not that great for street driving, since they don't hold a tune for long. But they are a little easier to "fine" tune. Good Luck.[/quote'] Triple Mikunis will hold a tune for years and they are fine for the street. Dont let anyone tell you they wont. We have 6K hard driven race and street miles on ours and havnt touched them since original tune a year ago. They fire right up with no choke needed and run just fine no matter what the weather conditions with no adjustments needed to compensate. Quote Link to comment Share on other sites More sharing options...
JMortensen Posted November 13, 2005 Share Posted November 13, 2005 I don't know how much power they'll give over a modified SU, but IME it was a HUGE power gain over stock SU's. Quote Link to comment Share on other sites More sharing options...
johnc Posted November 14, 2005 Share Posted November 14, 2005 Yeah, but there's the coolness factor that SUs bring. Its especially cool after beating a 911 on the track and having the Porsche owner come over and ask to look under your hood. Two SUs make them shake their heads every time. Two SUs under the stock orange air box make them just walk away. Quote Link to comment Share on other sites More sharing options...
2126 Posted November 14, 2005 Share Posted November 14, 2005 Based on my personal experience dealing with Dave Rebello, which has been nothing but a good experience, the modified SU's Dave provides are intended for large cc L6 motors that require a larger fuel/air mixture for maximum performance. He bores them out to 50mm, install custom flat cross-section throttle shafts/butterfly, uses custom profiled needles, and gives you a product that looks too good to use. I'm sure I've not listed all the little things he does to them but one thing is for sure, these SU's look like jewery! 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.