Guest bastaad525 Posted November 4, 2003 Share Posted November 4, 2003 Has anyone used an FPR from a 300zxTT on an L28ET? Does anyone know how much higher or lower of pressure the TT's FPR is set to run at vs. the stock L28 ET's? A friend of mine said he's used the TT's FPR on L28ET's running 10-13 psi of boost with good results, and that off boost driveability didn't suffer. I'm thinking of trying one of these as I can get them relatively cheap ($50-80) vs. $150-200 for an adjustable unit. Also, for anyone that uses an RRFPR on their turbo... I know that the RRFPR has a setting that can be changed, which effects the amount of fuel pressure increase per psi of boost increase. Whereas a regular FPR will increase one psi of fuel pressure per 1 psi of boost. So what I'm wondering is, how many psi of fuel do you have your RRFPR's set to increase, per each psi of boost? I'm thinking 2 or 3 psi of fuel pressure per psi of boost would be enough, but then again, I really dont know much about it! So I just wanted to see how you guys set yours Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 4, 2003 Share Posted November 4, 2003 I stated on your other post I think a RRFPR needs to be tuned using a wideband and a dyno. Unless you can log fuel pressure while driving, there is no way of knowing what pressure you've set the thing. And I can point out ScottieMIZ who is still running the AFM without a RRFPR and is well into the 12's, with 420cc injectors. And as far as I'm concerned, there is nothing wrong with the factory regulator unless you want adjustability. Quote Link to comment Share on other sites More sharing options...
fl327 Posted November 4, 2003 Share Posted November 4, 2003 factory regulator is fine for a good while. if i didnt get a great deal on an adjustable, id be still running factory fpr for sure. its just that the one i have now has a guage!! increasing fuel pressure wont get you any further than a tuned stock setup as far as daily driving goes, not saying you can spike it up really high and get away with some more boost, but i dont think its safe. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 5, 2003 Share Posted November 5, 2003 That's what I'm looking at, more boost. I'm hoping to get my I/C modified this weekend... maybe installed within a month if I'm lucky. Once the I/C is in I'm hoping to turn the boost up to 13 psi or so if I can do that safely. Bigger injectors are not on my radar as of yet... I really want to just about get to the limit of the stock ones, close to 250hp at the wheels. If I can do that with stock FPR then that's even better... thought I needed the adjustable FPR after 10psi of boost though, intercooled or not? I would definately be heading to a dyno after installing an RRFPR though, was just looking for a baseline to start with. I realize you can't just throw one on and go and expect it to be set up perfect. Actually that's the whole point of the adjustable FPR to me... I mean, as it stands right now, if I go to a dyno, what all can I really 'tune'?? Um... timing... and... boost I guess if I find out I'm running way too lean/hot or that I have some safety margin there maybe to go a little higher... but... what else? I find all the times I've been to the dyno the thing that gets 'tuned' the most is fuel, or fuel vs. timing. And right now fuel is the one thing I really dont have much way of tuning, unless I start messing with the AFM... which I think is a bit limiting, and never really accomplished much on my N/A ZX. I know a standalone computer is the better answer here, but is out of my price range now, whereas FPR's can be had relatively cheap, and would at least give me some flexibility... but again, if you guys say I dont need one, then hey, that's another $200 I dont need to spend I ask again though, what about a stock 300zxTT FPR? Anyone used/know someone who's used one of these and benefitted from it? Again, this would be an even cheaper mod, less than $100 easy... I know it can support higher boost, I'm just wondering about it's off boost fuel pressure, if it's going to make around town driving sucky. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 5, 2003 Share Posted November 5, 2003 I ask again though, what about a stock 300zxTT FPR? Anyone used/know someone who's used one of these and benefitted from it? Again, this would be an even cheaper mod, less than $100 easy... I know it can support higher boost, I'm just wondering about it's off boost fuel pressure, if it's going to make around town driving sucky. It may be a cheap mod, but what's the point? The stock regulator bypasses enough flow for a Bosch pump at stock pressures - that's all it has to do. Your worst case flow conditions for a regulator are at idle when it has to bypass flow almost all the fuel from the pump (low pressure is when you get greatest flow from the pump). If you are intercooled, you can EASILY run 12 or 13 psi at sea level with stock fuel system. Get a cheap Bosch or Walbro hp pump. The next upgrade is fuel injectors. Then it gets expensive. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 5, 2003 Share Posted November 5, 2003 Heheh I'm not really sure what the point is to be honest! This is just another one of the hundreds of things that have been recommended to me... and as usual anything recommended to me outside of these forums is promptly put here and questioned by me, to see if it's just BS or something worth pursuing. As was the case with the mod I asked about last week, of routing the valve cover and crankcase breathers into the exhaust... a mod I thought seemed rediculous and utterly useless... which turns out many people here think it actually WILL benefit and even create, or rather free up, some extra power. In this case, the person who recommended the 300zxtt FPR, backed up his claim with these 'facts': The stock FPR will increase fuel pressure at a rate of 1psi per 1psi of boost. HOWEVER, the unit was designed with 7psi in mind, so at higher boost levels begins to get less effective (though he did not explain exactly what was the limiting factor... WHY does it start to become less effective??) and may not be increasing the fuel pressure as much as it should be. He claims that this is one of the biggest reasons why people who dyno their turbo motors, at 10psi or more without ANY fuel system mods, always run lean at the top. A 300zxtt FPR, on the other hand, was designed to handle 14psi or more of boost, and will keep increasing fuel pressure accordingly, at these levels. He also claims that this FPR wont hurt driveability of the car off boost. I asked how this is possible, given that the 300zxtt must obviously need more fuel, even in cruising, and he said that it gets more fuel by way of larger injectors, that the FPR runs at around the same base fuel pressure. This is what he told me... seems to all make sense, but again, I wouldn't do any kind of mod like this first w/o getting some second opinions from you guys here If it DOES work how he describes, it would seem to be the perfect solution for more fuel on the top end, at least, up to the limitations of the injectors and fuel pump. A better pump is very high up on my list also. I really dont want to get into anything more major than that right now... bigger injectors aren't even on my to do list as of yet... the car is pretty quick as it is right now, enough to where it's really testing my courage sometimes, and I figure at BEST it's only putting 200hp to the wheels, probably a bit less... if I can hit 250hp and not have to change injectors, I think that will be good enough for me. That's always been my goal, on paper, from the start... 250hp, 0-60 of 5 seconds or so, and a mid to low 13 second 1/4... in a easily daily drivable car. My target car was the current Corvette... not the Z06, just regular Vette. Once I get there I'm done for a good long while, then it's time to get a house, and other things I've waited too long to do. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 5, 2003 Share Posted November 5, 2003 It's BS. Stock regulator will regulate fine at least to 14 psi boost. Many others have run upwards of 20 psi with a stock FPR. I've replaced mine with an adjustable one now, running 16 psi with a custom fuel rail and bigger injectors. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 5, 2003 Share Posted November 5, 2003 My setup with Z31 ECU went lean at 14-15 psi spike (hitting 13:1) with stock fuel pressure. I got the A/F under control (in 11.8:1 to 12.2:1) with 44psi static pressure and 12 psi of boost. (spiking 14 psi ) But I am moving alot more air with my turbo than a stock T3 though. (I think) Hey Sleeper, Can't you run more boost in higher altitude than a sea level since there are less air, more to be compressed Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 5, 2003 Share Posted November 5, 2003 Hey Sleeper, Can't you run more boost in higher altitude than a sea level since there are less air, more to be compressed Yes. I'm being conservative. About 2 psi more to run the same equivalent air mass. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 5, 2003 Share Posted November 5, 2003 Okay I wont spend the cash then. But, this opens another question then. If the stock fuel system, stock injectors, stock FPR, AFM... everything... stock, can supply enough fuel for up to 250hp or so, why is it that many people I've talked to who run a relatively 'conservative' boost of 10psi, which isn't enough to get to that 250hp, have had issues with running too lean on the top end? I've heard this from people who were running the 10psi non intercooled (Jersey, before he installed his I/C, felt the car was leaning on top when he would run his car at the track... from the track times he posted he was putting around 205hp to the wheels) and from those using an I/C (Tyson 280zx, who dynoed his car with a WB hooked up and saw it go way lean above 5000rpm... by the way he only put 191hp to the wheels at that same dyno session, both of them quite a bit shy of the 250 that the stock efi is supposed to be able to handle). Is this something that will vary wildly from car to car? It seems to be very common... and is baffling to me. If the fuel system was running out of steam for these guys at 10psi, intercooled or not, how can it safely support some 50+ horsepower and 3-5psi more boost, than what they were at, w/o some sort of mod to supply more fuel? When I add my intercooler, will I safely be able to raise the boost from 10 to 13psi w/o worrying about running lean, and w/o performing any other mods? Again, my efi is pretty much bone stock, so I have no way to 'tune' in extra fuel to support the extra boost... can I trust that the stock efi will suffice? Not trying to be argumentative Sleeper... you are by far the most vocal and helpful person when it comes to me and my questions so believe me when I say I'm not trying to be an ass or anything. Remember that all this turbo stuff is very new to me and I'm just trying to learn it and make sense of it, and not blow up my engine in the meantime. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 5, 2003 Share Posted November 5, 2003 There is not definative answer to how many PSI you can run on a certain setup. Just too many variables. Just dyno the car, and see the answer for yourself. TonyD told me once, "until you dyno with WB, you are just blindly guessing." Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 5, 2003 Share Posted November 5, 2003 which is true!!! I agree 100%! which brings me back to WHY I want an adjustable FPR... or SOMETHING, because I DO want to go to the dyno, and see how the car is running, and see how much power it's putting out, BUT, if I go to the dyno the way it is now, and see that things aren't right, there really isn't much I can do about it... except for the sucky options of turning the boost down or retarding timing or whatever... I want to get better, not worse, and so I'm looking at 'cheap' ways that I can put SOME flexibility into the car, or some better something, anything, that would benefit the fuel system and make sure that no matter what, the car isn't running lean and I DONT need to turn the boost DOWN. Quote Link to comment Share on other sites More sharing options...
yo2001 Posted November 5, 2003 Share Posted November 5, 2003 Having tunabitly is always good IMO. I still have my AFPR. It has come handy on a dyno. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 5, 2003 Share Posted November 5, 2003 Most people who install an adjustable FPR say "I want more fuel at boost". So they dial in more fuel pressure, and run richer across the rpm band, and possibly avoid detonation at the top end because of the cooling effect of additional fuel. This isn't the reason I use an adjustable FPR. I installed on in my car because of my new MAF setup. I installed the MAF sensor in a larger pipe, which is essentially the same as tightening a spring in an AFM. The effect is the air measurement is smaller for the same amount of air, and the result is less fuel is injected - LEAN. But if you install larger injectors, you run richer. Combine the two, and you balance out the two effects. The only way to fine tune this balance is with fuel pressure. I used a wideband on a dyno to dial in a 12:1 a/f mixture with 43 psi static fuel pressure. I would like to think I did not succumb to superstition or hear-say, and bought an adjustable FPR for the right reasons. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 5, 2003 Share Posted November 5, 2003 which is the reason I'm looking into an RRFPR instead of just a regular adjustable FPR, so that I can increase only the fuel pressure under boost... I AM understanding this correctly right? That IS what an RRFPR does isn't it? Anyways I think I found a better solution and possibly cheaper too... if it will work with my car... HKS S-AFR I see them going for $100 on ebay. Quote Link to comment Share on other sites More sharing options...
SleeperZ Posted November 5, 2003 Share Posted November 5, 2003 which is the reason I'm looking into an RRFPR instead of just a regular adjustable FPR' date=' so that I can increase only the fuel pressure under boost... I AM understanding this correctly right? That IS what an RRFPR does isn't it? Anyways I think I found a better solution and possibly cheaper too... if it will work with my car... HKS S-AFR I see them going for $100 on ebay.[/quote'] HKS will be way easier to tune. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted November 6, 2003 Share Posted November 6, 2003 yeah I think so too... no springs or diaphrams to change or adjust. I'm really leaning towards that HKS now IF I know for sure I can use it on my '82 ECCS, which from what Yo2001 tells me should be no problem. I've found the HKS S-AFR as cheap as $80 on ebay and the RPM signal converter is about another $50... altogether less than a decent RRFPR, and way more flexible. I swear that thing looks like the coolest, most useful piece of equipment I've EVER seen for a performance oriented car for anywhere near that price.... man if only I'd found out about them sooner. Quote Link to comment Share on other sites More sharing options...
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