BRAD D Posted January 24, 2003 Share Posted January 24, 2003 o.k. Tell me if I’m stupid of if you think this is not proper. As some of you might know I am in the middle of a RB26DETT swap. The point that I am now at is the intercooler plumbing. The RB’s intake is just over 3†ID as well as the turbos Y-collector. So I got some 3.25†ID bends from www.sharpeproducts.com . To graft in to my Apexi GTR core’s end tanks. And some connectors from Hoover at www.turbohoses.com, if you guys need connectors and other turbo parts call him. He has a L28 that has almost 500rwhp on 91oct gas So my question is, 3.25†ID is pretty darn big do you think this will have a negative affect on my HP #’s and lag time. Keeping in mind that it is a twin and turbo and the runs of pipe are not that long, and at one point I will be running around 18psi through it with upgraded turbos. Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 24, 2003 Author Share Posted January 24, 2003 The car will be a street car, with some time on the 1/4 mile. I would like to some day have 550hp @ the wheels, to get there i would get better turbos and injectors some were under 700cc. That is what i would add to the car, but as it sits it will have 3" SS exhaust and down pipe, SDS, Apexi GTR intercooler, and a open intake with no MAS and one or two K&N filters. I just looked at a stock GTR core on Ebay and it had 80mm or 3.149" Ports, so i think i will be O.K Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 24, 2003 Share Posted January 24, 2003 I agree with those power level goals and such it shouldn't be a big deal. If you have Corky's book then I know there is some formulas in there for calcualting the right size. If you need me to I can look it up. Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted January 25, 2003 Share Posted January 25, 2003 WOW, 80mm! My 1jz-gte HKS intercooler only has like 2 1/4" inlet/outlets on it.. I was just looking through that book, "How to build your sohc nissan/datsun engine" and the 280zx turbo race cars had small diameter intercooler piping, I'd say 2 1/2.. Found the intercooler piping section in the Maximum Boost pages 61-62.. Says here that "I suspect this number (the airflow velocity in the tube that should not be exceeded) is around Mach .4, or about 450 feet per second, since drag, and therefore flow loss, increases significantly after this." Scottie may have made one of these excell spread sheets before, but I thought it'd be easy enough to make one of my own. Click here for the Excell xls file to calculate the numbers. If you want 550 to the wheels I think that's like 660 at the crank with the 3.149" pipe (80mm) that's only 305 ft/sec, 336ft/sec with 3", 484ft/sec with 2.5" which is over the 450ft/sec number. Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 25, 2003 Author Share Posted January 25, 2003 I do have that book but i lent it to a buddy, so is Corky saying to stay close but not over 450ft/sec? Is it the same for two turbos? you think they would move more CFM? I dont know??? This is my Apexi Core This is a stock GTR core 80mm! Quote Link to comment Share on other sites More sharing options...
Tony240ZT Posted January 25, 2003 Share Posted January 25, 2003 Pretty looking core. I was wondering the same thing about keeping close to the 450ft/sec. He just says not to use larger tubes than you need, "little drag is created in smooth tubes with gentle bends. Larger tubes will only add to the volume of the IC system, and that is not a good thing to do." Stuff we already knew, but ya I wish there was a number that would be great to try and stick to. ASFAK same would apply for any amount of turbos, it's the acculated velocity that counts. Anyone have any personal experience with high horse power setups? My little L6 making sub 300 numbers would probably be happy with 2" Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 25, 2003 Share Posted January 25, 2003 Tony, thanks for the program. I ahev 2" pipe right now and it looks as if you can get real close to 400hp with it. I think I'll leave it alone for alittle longer. Nah I think I'll upgrade this summer. Brad, I love the look of the Apexi intercoolers. Any details on where and how much? Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 25, 2003 Author Share Posted January 25, 2003 it is 24"x11"x3.5" and it is 588$ from www.xs-engineering.com i did not think that was too bad of a price Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted January 25, 2003 Share Posted January 25, 2003 That does sound alittle big but, alteast it wouldn't be to small. What kind of HP#'s are you planning on running? What do you do with the car? IS it an all out drag car? Street car where response would be effected? Quote Link to comment Share on other sites More sharing options...
Scottie-GNZ Posted January 25, 2003 Share Posted January 25, 2003 I would say on the TB side you want to at least match the TB bore i.d.. On the compressor, 3.5" is overkill but I really do not know if it will hurt although I cannot believe it will not hurt velocity. I am willing to bet your compressor outlet i.d. is less than 2" so whats to gain by stepping it up to 3.5" From my compressor I use a 2"-2.25" hose, a 2.25" pipe with the last 3" blown out to 2.5" to match the I/C and eliminate the extra cost of a 2.25"-2.5" hose. On the TB side I use a 2.5" pipe to a 62mm TB. Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 26, 2003 Author Share Posted January 26, 2003 This is how the turbos dump out at 80mm in this manifold (on the right side with the red tag on top). And the RB has six TBs that are feed by a manifold that has an 80mm hole. You would think that 80mm is overkill but it is stock. Quote Link to comment Share on other sites More sharing options...
Bob_H Posted January 26, 2003 Share Posted January 26, 2003 I guess we ought to look at what Stony is running. However, we need to factor in his tube runs are very short,(top-top each side). I have made the commitment to run a different car at the first Feb event, so I have a few more weeks to work out the bugs in the intercooler side,(piping, size of intercooler, etc..). Ideally, I want to find the same type of intercooler as Stony has. That is as big as we can fit in front of the radiator. I'm still up in the air. I think if I can't find a setup similar to Stony's, I'm gonna run 3 inches. Not real thrilled about the .5 inch step-down at the outlet from the turbo's, but I guess it must be dealt with. -Bob Quote Link to comment Share on other sites More sharing options...
Bob_H Posted January 26, 2003 Share Posted January 26, 2003 I just had some thought on the overall velocity in the "system". Yes, we want to keep the velocity in the piping below 400 some odd feet per second so the drag isn't a large effect. However, the faster it goes through the intercooler, the less time to transfer away its heat. The slower it goes, while being a negative effect from the point of system volume, means it spends a bit more time in the intercooler. May not be a huge amount of time, but more time is more time. Food for thought. -Bob Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 26, 2003 Author Share Posted January 26, 2003 My runs of piping will be just as short as stony's with the top feed end tanks. I will try to get you some photos of the intercooler in the car with the piping tack welded on later this week. I am working on my car a lot now, because my bud with the body shop has entered me in the world of wheels at the end of march. and i will be in Arizona for a week in Feb. Quote Link to comment Share on other sites More sharing options...
BRAD D Posted January 26, 2003 Author Share Posted January 26, 2003 You do have a good point there Bob. And about the size of the intercooler i will make my 24x11x3.5 core fit, it will be tight but it will work. Quote Link to comment Share on other sites More sharing options...
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