alexrex20 Posted March 5, 2009 Share Posted March 5, 2009 why in the hell would you increase the injector size? adding a spacing under the TBI does not increase airflow. it adds more plenum space for the fuel to mix with the air. you people need to go to the library and read a book or 2. stop reading all the crap thats posted on the internet. that's why the trucks lean out when you add a TB spacer. perhaps you should take your nose out of the books and stick them under a few hoods. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 5, 2009 Author Share Posted March 5, 2009 If you're increasing the space where the air and fuel combines, you'd want to increase the amount of air and fuel, in order to have the proper air-fuel ratio. Larger capacity injectors will provide more fuel to mix with the greater amount of air. Link to comment Share on other sites More sharing options...
SixGuns Posted March 5, 2009 Share Posted March 5, 2009 that's why the trucks lean out when you add a TB spacer. perhaps you should take your nose out of the books and stick them under a few hoods. Ok, wait...before you guys get to each other's throats...adding a tb spacer is a means to an end...basically the equvalent of a poor man's high rise intake manifold. Which, does increase airflow through the throttle body because of a more effective venturi effect. Your MAS should catch this, but there are exceptions. So the engine runs a little on the lean side. Bigger injectors are a solution, and as a result, you will see a small power increase. And I know someone's gonna say it, so I'll head it off - no, it's not the same as the engine detecting colder air (denser) and accomodating with more fuel..that's the job of the AIT sensor (air intake temp), just like you have a barometric pressure sensor which performs a similar task. Link to comment Share on other sites More sharing options...
88pathoffroad Posted March 5, 2009 Share Posted March 5, 2009 I made my own TB spacers out of 3/8" UHMWPE and cut-to-fit gasket material. The new TBI base studs were hard to find and spendy! ($5 each x4) I didn't notice any difference after adding them. Meh. Link to comment Share on other sites More sharing options...
SixGuns Posted March 5, 2009 Share Posted March 5, 2009 Looks good, though. Was the white intentional? Is that the same material they were trying to make skid plates out of? Link to comment Share on other sites More sharing options...
88pathoffroad Posted March 6, 2009 Share Posted March 6, 2009 It was white material to begin with. Same stuff, yep. Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 6, 2009 Share Posted March 6, 2009 that's why the trucks lean out when you add a TB spacer. perhaps you should take your nose out of the books and stick them under a few hoods. youre not changing anything on the engine nor increasing its ability to flow more air, and on that note the nissan TBI injectors will flow more than enough fuel for the VG30 engine Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 6, 2009 Share Posted March 6, 2009 Ok, wait...before you guys get to each other's throats...adding a tb spacer is a means to an end...basically the equvalent of a poor man's high rise intake manifold. Which, does increase airflow through the throttle body because of a more effective venturi effect. Your MAS should catch this, but there are exceptions. So the engine runs a little on the lean side. Bigger injectors are a solution, and as a result, you will see a small power increase. And I know someone's gonna say it, so I'll head it off - no, it's not the same as the engine detecting colder air (denser) and accomodating with more fuel..that's the job of the AIT sensor (air intake temp), just like you have a barometric pressure sensor which performs a similar task. the factory ECU is programmed for a given injector size if you change the injector size you have to change the fuel map in the ECU or else you've just pissed your money away on injectors. Link to comment Share on other sites More sharing options...
alexrex20 Posted March 6, 2009 Share Posted March 6, 2009 youre not changing anything on the engine nor increasing its ability to flow more air, and on that note the nissan TBI injectors will flow more than enough fuel for the VG30 engine ok fine, don't stick your head under some hoods, but you should at least take your own advice and stick it in some books. a TB spacer adds air AFTER the throttle body, where the fuel is injected. if you have more air in the intake manifold but the same amount of fuel, you will have a higher air/fuel ratio - aka lean. this is the most basic concept of engine theory. for someone that's (supposedly) so learned on this subject, it shouldn't be that difficult to grasp. the factory ECU is programmed for a given injector size if you change the injector size you have to change the fuel map in the ECU or else you've just pissed your money away on injectors. well you've already pissed your money away on a TB spacer if you don't have supporting fuel mods, so what's the big deal? the ECU only has a small capacity to accommodate a rich/lean AFR (read through the upstream O2S), by adjusting the fuel map. if you're leaning it out to the large extent that a TB spacer will do, then you had better have higher-capacity injectors if you want to see any worthwhile results. case in point: 88path's VG30i has a TB spacer with stock injectors, and he saw no change in performance or economy. Link to comment Share on other sites More sharing options...
88pathoffroad Posted March 6, 2009 Share Posted March 6, 2009 I don't see a need to debate it so fiercely, alex. You get more flies with honey... Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 6, 2009 Share Posted March 6, 2009 ok fine, don't stick your head under some hoods, but you should at least take your own advice and stick it in some books. a TB spacer adds air AFTER the throttle body, where the fuel is injected. if you have more air in the intake manifold but the same amount of fuel, you will have a higher air/fuel ratio - aka lean. this is the most basic concept of engine theory. for someone that's (supposedly) so learned on this subject, it shouldn't be that difficult to grasp.well you've already pissed your money away on a TB spacer if you don't have supporting fuel mods, so what's the big deal? the ECU only has a small capacity to accommodate a rich/lean AFR (read through the upstream O2S), by adjusting the fuel map. if you're leaning it out to the large extent that a TB spacer will do, then you had better have higher-capacity injectors if you want to see any worthwhile results. case in point: 88path's VG30i has a TB spacer with stock injectors, and he saw no change in performance or economy. ok explain to me how a bigger plenum increases AIR FLOW? it doesnt, it changes the initial volume in the intake manifold. it does not change how much air the engine takes in during an intake stroke. period. once the air flow is established it doesnt matter how big the hole is the engine is still 3 liters, the cam lift and duration are the same, the ports have not been enlarged, the throttle body hasnt changed, the compression ratio hasnt changed, you havent changed the VE.... NOTHING has changed except you moved the TBI unit a little distance from the manifold. look up the formula for flow through an orifice, increasing the length (ie a TB spacer) decreases the flow at any given pressure. Link to comment Share on other sites More sharing options...
Kingman Posted March 6, 2009 Share Posted March 6, 2009 Even though they might be applicable, I don't really think they do any good. Though I will say that when we put a throttle body spacer on my old '88 Suburban 2500 350 TBI, there was a gain of about 2mpg without any lack or improvement in power. Which is good when you're driving something the size of the Titanic. Maybe it's because the engine makes enough power already to where a slightly leaner mixture won't affect it any? Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 6, 2009 Author Share Posted March 6, 2009 Scientific bickering aside, I think the fact here has been established regarding throttle body spacers: they are not very useful. Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 6, 2009 Share Posted March 6, 2009 Scientific bickering aside, I think the fact here has been established regarding throttle body spacers: they are not very useful. fine... save your money for headers, bigger exhaust, high flow cat, and some meaty cams... Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 6, 2009 Author Share Posted March 6, 2009 (edited) fine... save your money for headers, bigger exhaust, high flow cat, and some meaty cams... I didn't mean it like that, sorry. I was just trying to come to a conclusion for us all... I figure I'm going to just save my money for a JDM diesel swap and AXT upgrade kit. Then I'm going to tear apart the VG and beef it up to a 3.4L, port/polish, headers, cams, etc. and drop it in a HB pick-up or WD21! Edited March 6, 2009 by tekazgtr1984 Link to comment Share on other sites More sharing options...
nissandoms47 Posted March 7, 2009 Share Posted March 7, 2009 I dont get how a throttle body spacer adds more air after the throttle body. It just makes the TB 1" longer essentially... Whats the big deal? Everyone with a non S/C non dohc VG just needs to accept the fact that they're screwed, its not a race car, especially when running larger then stock tires. Having a manual trans is a little bit better.. Get a VQ. with a manual, like my pathy and it rocks. Link to comment Share on other sites More sharing options...
tekazgtr1984 Posted March 7, 2009 Author Share Posted March 7, 2009 /\ You make a solid point, Alex. But I'm going to be last person to hop on the VQ-wagon; I want to go turbo diesel solely for the fact it'll have killer low-end torque and sip fuel. I've come to terms with the VG being what it is. It gets the job done in my mind. Link to comment Share on other sites More sharing options...
shift220 Posted March 8, 2009 Share Posted March 8, 2009 /\ You make a solid point, Alex. But I'm going to be last person to hop on the VQ-wagon; I want to go turbo diesel solely for the fact it'll have killer low-end torque and sip fuel. I've come to terms with the VG being what it is. It gets the job done in my mind. What does it take to get your hands on a turbo diesel that will fit? The only one I can think of is a Cummins 4 cylinder but those are heavy. And the truth about the TB spacer is that it doesn't work. If it did, people would be actually using them. Simple as that. Yes it may change airflow into the cylinders but the computer not being able to compensate has nothing to do with the fuel injectors. The computer is not tuned for the different airflow characteristics and it may run lean or rich depending. Larger injectors will only mess up the tune worse. On a TBI engine it might help because of it being after the injectors (similar to using a spacer with a carb). Efans on the other hand I support. Its night and day with that heavy stock fan off the front of the engine. But I'm leaving mine just for the reliability. I put a Efan on my Sonoma because the stock computer could control it. Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 8, 2009 Share Posted March 8, 2009 What does it take to get your hands on a turbo diesel that will fit? The only one I can think of is a Cummins 4 cylinder but those are heavy. And the truth about the TB spacer is that it doesn't work. If it did, people would be actually using them. Simple as that. Yes it may change airflow into the cylinders but the computer not being able to compensate has nothing to do with the fuel injectors. The computer is not tuned for the different airflow characteristics and it may run lean or rich depending. Larger injectors will only mess up the tune worse. On a TBI engine it might help because of it being after the injectors (similar to using a spacer with a carb). Efans on the other hand I support. Its night and day with that heavy stock fan off the front of the engine. But I'm leaving mine just for the reliability. I put a Efan on my Sonoma because the stock computer could control it. Its called a nissan turbo diesel engine, they came in the terrano's and in some of the nissan commercial trucks.... google td27i Link to comment Share on other sites More sharing options...
nissandoms47 Posted March 8, 2009 Share Posted March 8, 2009 Yeah i also support the efan. If you can get a good reliable controller and good wiring and secure the fan to the radiator tight you should have no problems. Ive picked up so many maxima fans for under $30 bucks. Well worth the mod. Even on the VQs. Link to comment Share on other sites More sharing options...
shift220 Posted March 9, 2009 Share Posted March 9, 2009 Its called a nissan turbo diesel engine, they came in the terrano's and in some of the nissan commercial trucks.... google td27i I realize that Nissan did have a diesel engine in these vehicles but is it available in North America? I didn't think the terrano's were. I don't see many Nissan commercial trucks running around either. Just curious how feasible the swap is Link to comment Share on other sites More sharing options...
bitemedoughboy.com Posted March 9, 2009 Share Posted March 9, 2009 I realize that Nissan did have a diesel engine in these vehicles but is it available in North America? I didn't think the terrano's were. I don't see many Nissan commercial trucks running around either. Just curious how feasible the swap is theres usually a vendor on ebay with them, also try the used import engine places. swapping wouldnt be to bad if you had the tranny. diesels are fairly simple engines compared to an EFI gas engine. Link to comment Share on other sites More sharing options...
88pathoffroad Posted March 9, 2009 Share Posted March 9, 2009 Only problem is you can't get Nissan diesel parts in the US...or certainly not for cheap. Link to comment Share on other sites More sharing options...
SixGuns Posted March 9, 2009 Share Posted March 9, 2009 Only problem is you can't get Nissan diesel parts in the US...or certainly not for cheap. Add to the awesomeness the fact that if your state has smog testing, such as California, you can only swap in an engine that was available in the same platform (SUV, pickup, sedan, etc.), same make, same year or newer. Plus the fact that that engine wasn't available in the states would make that vehicle unregisterable, depending on what state you reside in. Link to comment Share on other sites More sharing options...
FUELER Posted March 9, 2009 Share Posted March 9, 2009 V8 Infiniti VH45 swap! the vg33 is ridiculous. i mean it can be made fun if you torture it hard enough. Just keep the pedal to the metal, revs high. i only have an intake and the top end is great off-road, im sure it would feel nice and opened up with an exhaust and hollow cat. vq35 is a whole different story, i think i'd be content if i had that stock. Link to comment Share on other sites More sharing options...
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