stony Posted June 19, 2005 Share Posted June 19, 2005 Smack me around but i wasnt sure how to list these in the classifieds if its an auction. min bid starts at 375.00 Need to upgrade my injectors and these wont do it anymore. they are top feed Denso injectors and will fit most top feed applications. they came out of my RB26. http://cgi.ebay.com/ebaymotors/ws/eBayISAPI.dll?ViewItem&item=7981974209 Quote Link to comment Share on other sites More sharing options...
S15 200sx owner Posted June 20, 2005 Share Posted June 20, 2005 Stony, out of interest, what power were you making with the 720's and at what duty cycle? Clint T Quote Link to comment Share on other sites More sharing options...
stony Posted June 20, 2005 Author Share Posted June 20, 2005 Dont know what the duty cycle was but we had to turn the Fuel pressure way up to keep it from getting too lean on the top end. It made 610RWHP .... I think if i really pushed them may have gotten 650 but i think they were close to being maxed. And just using all the math formulas for figuring injector size for projected HP says there too small. Quote Link to comment Share on other sites More sharing options...
S15 200sx owner Posted June 20, 2005 Share Posted June 20, 2005 Dont know what the duty cycle was but we had to turn the Fuel pressure way up to keep it from getting too lean on the top end. It made 610RWHP .... I think if i really pushed them may have gotten 650 but i think they were close to being maxed. And just using all the math formulas for figuring injector size for projected HP says there too small. Yeah from what i have read of late, way too small! Seems that maximum power is obtained at a duty cycle of between 60-70% & no more! Therefore, as an example, if you calculated that your engine requires 600cc of fuel flow per injector, then you should use 1000cc injectors, to leave plenty of head room on the duty cycle and not over work the injectors. I have been reading "Forced Induction Performance tuning" by Graham Bell, he goes into great depth with calculations for all this stuff. I have also been talking with a guy that runs a tuning shop here in NZ, he is a computer expert etc and has a RB30DET powered R32 skyline racecar, which is making 400kw at the rear wheels, he is using 1000cc injectors. Stony what size inj's have you replaced the 720's with? Quote Link to comment Share on other sites More sharing options...
stony Posted June 20, 2005 Author Share Posted June 20, 2005 havent decided yet. its either going to be 920cc or 1000cc injectors just depends on pricing.... i have heard the 4 digit injectors start getting real expensive Quote Link to comment Share on other sites More sharing options...
Cody 82 ZXT Posted June 20, 2005 Share Posted June 20, 2005 I have been reading "Forced Induction Performance tuning" by Graham Bell, he goes into great depth with calculations for all this stuff. This is a good book. Read it about 2 years ago. Quote Link to comment Share on other sites More sharing options...
S15 200sx owner Posted June 20, 2005 Share Posted June 20, 2005 This is a good book. Read it about 2 years ago. Sure is, when i'm finished reading it twice over, it will take pride of place on the book shelf right next to "Maximum Boost" Hey all joking aside, lots of great tech info and calc's etc eh. Clint T Quote Link to comment Share on other sites More sharing options...
S15 200sx owner Posted June 20, 2005 Share Posted June 20, 2005 havent decided yet. its either going to be 920cc or 1000cc injectors just depends on pricing.... i have heard the 4 digit injectors start getting real expensive Yeah you're telling me!, what do you guys in the US pay for 850cc plus injector over there? We are about NZ$250 each down here, ouch! Quote Link to comment Share on other sites More sharing options...
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