mc Posted January 15, 2006 Share Posted January 15, 2006 Bastaad, I recently scored a Begi [2025,i believe??] on Ebay for 80.00...i see you installed yours initially without fuel pressure guages and such....was there much hassle trying to dial iT in at first to get the required benefit???you seem to have the most experience using the BEGI.THX,MIKE. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 16, 2006 Share Posted January 16, 2006 I had a fuel pressure gauge installed long before I installed the FMU. I just opted for a cheap Home Depot solution, installed in the engine bay... Had I some extra money, I'd definately have preferred an in car gauge. At any rate, there's only one real way to tune an RRFPR and that is with a wideband 02 sensor. Really in the end the fuel pressure doesn't matter (well, within limits, you obviously don't want it too high, but just how much is too much is a matter of debate. I'm doing just fine at 75psi.). The number you need to see is the air/fuel ratio. I made it a point to get to the dyno within days of installing the RRFPR. Until I went in for tuning, I took it easy on the car, kept the boost and RRFPR turned down. You can't really tune it any other way unless you have your own wideband 02 or can borrow one. Once at the dyno, tuning the RRFPR is as easy as can be, there's really only the one adjustment, just turn it up until the desired air/fuel ratio is achieved. Be aware though, that you will end up with a pretty rich midrange... not the fault of the RRFPR, mind you... the stock 280zxt EFI loves to run really rich in the midrange all on it's own. Nothing you can really do about it accept upgrade to programmable EFI. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 16, 2006 Share Posted January 16, 2006 Sort of on topic: Baaast, did you ever try running a grainger valve in the RRFPR signal line to keep it from doing fuel pressure rise too early. I always thought that could be a sort of "band-aid" to the mid range rich spike. I know you had gotten those tuning discs from BEGI but you never tried them. I also did look for extra parts for the grainger valve but I don't have enough to build another one. I am seriously considering selling my entire 280ZXt fuel system in a few months to replace it with a Haltech. ...Nothing wrong with the stock fuel system but it is a limiting factor when you get around 15psi/260rwHP even with the BEGI and all the other fixes. Quote Link to comment Share on other sites More sharing options...
Guest bastaad525 Posted January 17, 2006 Share Posted January 17, 2006 I did try it but not at the dyno. I thought about it and I ended up figuring that it probably wouldn't make that much of a difference... as soon as full boost hits the grainger will go open and the RRFPR will 'turn on'. So during a WOT run, full boost hitting at like 3000 rpm, it's still gonna get rich between 3000-4000 like that. I figured the grainger may have helped out with part throttle, partial boost situations (keep the RRFPR from affecting fuel pressure until say, 7-10psi is reached), but without getting down to the dyno I didn't want to chance running too lean or anything so I decided to just put it back the way it was. Same deal with those disks... after a couple very long conversations with Trey over at BEGI (and him having conversations with Corky Bell himself) he was sure that by swapping the disks I could 'fix' the fuel curve and keep it from going rich so early. I just haven't got around to going back to the dyno to try it. Honestly, the car seems to run well enough, IMO, and I kind of like having it rich like that, running 14 psi on the stock T3 is gonna be hot even with the I/C, and on crappy 91 octane, plus that I have the timing a bit advanced for better off boost torque... I like being rich for the safety margin. Spiking 15-16 and dropping to 14psi I haven't heard one ping yet on the street or on the dyno. The way I figure it, as rpm increases and cylinder pressure decreases, less chance of detonation, in the meantime the air/fuel leans out as rpm increases. My peak hp is at around 5000 rpm and at that point I was at a nice 12:1 air/fuel ratio, so that works for me. I would love to try those disks out eventually but now that the car is for sale I don't see the point investing a lot of money on more dyno tune time (I'm sure we'd be talking a good 2 hours of tuning....) to figure it out. I never did end up getting that WBO2 for Xmas as I'd planned... anyways the disks are still sitting in an envelope on my desk. You have a WB don't you? You want me to send you the disks to try out? You gotta do two things though if you do, first one is a given, just let me know all your findings so I can forward them back to Trey, well... actually that's all... the second thing being by letting me know your findings, if you found a disk that worked perfectly you could tell me which size and I could get another one made for my own car. Poor Trey... LOL now that I think about it I feel bad he went to that trouble for me and I never even got back to him. Ah well, let me know if you want them. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted January 17, 2006 Share Posted January 17, 2006 I would definately try them out but I dont have a wideband to quantify them. I tune by ear, nose, and butt. When I had it on the Dyno at ZCCA 2005 I was pretty close to optimal mixture. I was only off by about 1/32 of a turn on the Begi to get more into the rich, safe zone. If the rich spot goes away from 3k to 4k, I will definately feel it in the powerband. I will PM you. Quote Link to comment Share on other sites More sharing options...
cygnusx1 Posted April 14, 2006 Share Posted April 14, 2006 If you add more boost then you will need two fuel pumps in parallel to make up to 75 psi which is good from around 10 psi with stock injectors. Actually two pumps in series. ----->----->----- to add pressure. In parallel you just add flow capacity. Quote Link to comment Share on other sites More sharing options...
nienberg.11 Posted April 14, 2006 Share Posted April 14, 2006 Or make your life a lot easier and get one high quality pump. Quote Link to comment Share on other sites More sharing options...
Pyro Posted April 17, 2006 Share Posted April 17, 2006 Cygnusx1 the two pump in parallel does add pressure because capacity is doubled. Believe me on this one, I tune my turbo car only with fuel pressure (lots of fuel pressure) and have a lot of experience with pumps. For example, pinch the return fuel line on a stock efi pump and it will make 80 or 90 psi. But under high flow it may only hold 55 or 60 psi. Now add another pump in parallel and the pressure can hold 70 or 75 psi during high flow conditions. So it does add pressure by increasing the volume at that certain pressure and therefore allowing more pressure. Of course the pressure can not go over the max the pump can produce. Yes, in series the pressure goes up like crasy (much higher than what one pump can make). Two stock pumps in series can make well over 100 psi! But if you drive the car everyday the feed pump will go bad in 5 or 6 months (if you use Z style pumps). I think the pump pulses beat each other up.???? But after both myself and my friends turbo Z killed 2 or 3 pumps in series. We now use efi pumps in parallel (as recommended by corky bell) and the pumps are much happy and haven't had a failure. I do however, feed my efi pumps (msd 2225's) with a low pressure mallory pump (comp110) which seems to not hurt the efi pumps. I have recently refined my pump system by using an oil pressure switch to power up my second efi pump after 6 psi of boost. I use stock NA injector and 95 psi of fuel pressure at 14 psi of boost. Quote Link to comment Share on other sites More sharing options...
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