triple B Posted January 30, 2008 Share Posted January 30, 2008 ok i am down to purchasing a turbo for my RB25. i was considering a garret GT35R but i have changed my build plans slightly and now i am considering a precision PT67 AKA a 37R i am still debating though. is the pt67 to big? it more than meets the horse power requirments as it supports over 700 HP. the GT3540r i was looking at is from jimm wolf and said it supported up to 680 HP here is an example of the precision http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&category=33742&viewitem=&item=170162330542&_trksid=p3907.m29 and here was the garret i was considering from jimm wolf http://www.jimwolftechnology.com/customer_part_detail.asp?PartID=438 I was hoping to hit the high 600's with my build when running on c16 race gas. both turbos will do this but i have a naggin feeling the pt67 is to big. i don't want to max anything out but i don't want my lag to be excessive. i want ball bearing but is there any real drawback to using a journal bearing turbo? any thoughts or suggestions would be helpful. even a better source in the USA for turbos where the pricing is better would be nice Quote Link to comment Share on other sites More sharing options...
Guest rbz Posted January 31, 2008 Share Posted January 31, 2008 I prefer garrett turbos. A friend of mine has a gt35r making almost 700hp on a rb25. Quote Link to comment Share on other sites More sharing options...
triple B Posted January 31, 2008 Author Share Posted January 31, 2008 yeah i am starting to lean towards the gt35r as it seems to work well on RB25's from what i have seen and researched Quote Link to comment Share on other sites More sharing options...
Z U L8R Posted February 1, 2008 Share Posted February 1, 2008 based on a friend's rb25 35r.... should be around 500rwhp@19psi on pump gas and should be able to get you close if not right at 600 with race gas and 24-26psi Quote Link to comment Share on other sites More sharing options...
05plsrt-4 Posted February 1, 2008 Share Posted February 1, 2008 For high 600's you may want to go with something larger than a 35R I decided on a T04R for my RB25 which is supposed to support up to 750hp. Quote Link to comment Share on other sites More sharing options...
BirdmanZ Posted February 1, 2008 Share Posted February 1, 2008 I would go with the GT35R, close to 500hp on pump gas in our light little Z's is a pretty wild ride. A shop not too far from me did a GT35R on a rb26 and they were getting full boost by ~4000 rpm. Quick spool plus over 450hp is going to be nuts! No sense in having anything super laggy, just ask Booztd3. Quote Link to comment Share on other sites More sharing options...
triple B Posted February 3, 2008 Author Share Posted February 3, 2008 yeah lag was my worry i am going to go with the 35R now i just have to find a good price on one:-) Quote Link to comment Share on other sites More sharing options...
MONZTER Posted February 4, 2008 Share Posted February 4, 2008 Have you seen this one? FP3582HTA Turbo http://store.forcedperformance.net/merchant2/merchant.mvc?Screen=PROD&Store_Code=FP&Product_Code=NTFP3582HTA Not cheap but, it is supposed to spool better than a standard 35r Quote Link to comment Share on other sites More sharing options...
Tony D Posted February 4, 2008 Share Posted February 4, 2008 Guys, LAG is the time it takes to build boost AFTER reaching boost threshold. It's nil in most modern day turbos. What you are concerned about is Boost Threshold, the point at which the turbo will build full boost. JeffP's GT35 will do full boost at 3400rpms, so I can believe 4000 on a 2.6L. Any point after 3400 in Jeff's car, and boost is instantaneous. There is no 'lag'... To appreciate what lag really is, you guys need to drive some stuff from the 60's and early 70's when you could full throttle it, and literally wait up to a second and a half to get ANY boost to kick in! THAT is lag. Things have changed. Lag really is a thing of the past. As for 35 or 37, I'd probably tend to go with a 37 if you think you realistically will have that much power to the rear wheels. A 35 is about all in a little past 500rwhp. And like Monzster said, there are some permutations of the 35 that will enable better spool, so if you want to tone down your power thoughts you can get something with a boost threshold below 3500, and nice on-boost throttle modulation for high horsepower track manouvres. Where are you in Midland, BTW? I bought my VW Bus from a guy off Salzburg. Next time I come for some time at the Lake, we should get together, I got a cabin on Huron up in Tawas. Quote Link to comment Share on other sites More sharing options...
synthtk Posted February 4, 2008 Share Posted February 4, 2008 I would go with the GT35R, close to 500hp on pump gas in our light little Z's is a pretty wild ride. A shop not too far from me did a GT35R on a rb26 and they were getting full boost by ~4000 rpm. Quick spool plus over 450hp is going to be nuts! No sense in having anything super laggy, just ask Booztd3. Curious... what manifold did they use for the 35R on the RB26? Is it in a S30? Quote Link to comment Share on other sites More sharing options...
BirdmanZ Posted February 4, 2008 Share Posted February 4, 2008 It was a custom built one. If you go here http://rbz32.com/forums/viewtopic.php?t=242 and scroll down you'll see it. It was for a RBZ32 swap. Quote Link to comment Share on other sites More sharing options...
triple B Posted February 5, 2008 Author Share Posted February 5, 2008 Guys, LAG is the time it takes to build boost AFTER reaching boost threshold. It's nil in most modern day turbos. What you are concerned about is Boost Threshold, the point at which the turbo will build full boost. JeffP's GT35 will do full boost at 3400rpms, so I can believe 4000 on a 2.6L. Any point after 3400 in Jeff's car, and boost is instantaneous. There is no 'lag'... To appreciate what lag really is, you guys need to drive some stuff from the 60's and early 70's when you could full throttle it, and literally wait up to a second and a half to get ANY boost to kick in! THAT is lag. Things have changed. Lag really is a thing of the past. As for 35 or 37, I'd probably tend to go with a 37 if you think you realistically will have that much power to the rear wheels. A 35 is about all in a little past 500rwhp. And like Monzster said, there are some permutations of the 35 that will enable better spool, so if you want to tone down your power thoughts you can get something with a boost threshold below 3500, and nice on-boost throttle modulation for high horsepower track manouvres. Where are you in Midland, BTW? I bought my VW Bus from a guy off Salzburg. Next time I come for some time at the Lake, we should get together, I got a cabin on Huron up in Tawas. this was the kind of advice i was looking for thanks i live right off of saginaw road its not to far off from salzburg actually pm me next time you are rollin through i can show ya the project Quote Link to comment Share on other sites More sharing options...
Z24O Posted February 9, 2008 Share Posted February 9, 2008 boost threshold is the point(rpm) whereby positive manifold pressure (boost) begins lag is the rate of rise of boost once you open the throttle many factors come into play in these equations,not the least of which is gearing/resistance an engine will build boost quicker(lower threshold and less lag) the more load it is under(due to a build up of heat in the exhaust side which in turn drives the turbine) so a heavier car,a taller gear,going up hill,towing something,etc it will also be more responsive with a smaller A/R turbine housing as the exhaust gas is driven at a faster velocity due to the smaller volume however if the compressor is forcing more air into the motor than the exhaust/turbine can flow(due to the restricted volume from the smaller A/R cover) then this leads to a build up of heat in the intake side due to backpressure which means you have to run less boost or detonation will result intercoolers and wastegates can help the above situations but are no substitute for matching the compressor and turbine flows to the eficiency/capacity of the engine this is part science and part art best way is to see what others have done and use this knowledge to pick what is right for you there is a good source of info about all things RB on www.skylinesaustralia.com most guys on there with RB25DET's that are running streetable GT35R's are using the 0.7 A/R compressor and 0.82 A/R turbine housings a properly designed tubular header has been seen to drop boost threshold by as much as 1000rpm compared to factory manifolds(see 6BOOST's threads on www.calaisturbo.com.au) hope this has helped some of you Quote Link to comment Share on other sites More sharing options...
triple B Posted February 9, 2008 Author Share Posted February 9, 2008 yeah that was some good info man thanks i actually got the turbo today i decided on a PT67 and i had it built with the .81 exahust A/R here she is Quote Link to comment Share on other sites More sharing options...
Racinjitter Posted February 10, 2008 Share Posted February 10, 2008 Very Nice snail you got there.... I am jealous. Quote Link to comment Share on other sites More sharing options...
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