I have a 91 speed density car that I am installing a turbo on. I am not really sure how to iron out the fuel metering. I will have a AFPR that has a 1:1 ratio. 1psi increase of fuel for 1psi increase of boost. I doubt that the AFPR and some VE tuning is going to cut it. If I have a 2 bar map, I still won't be able to tune over 1 bar in the VE table. Do I have that right? How do the supercharged cars with high boost on SD cars go about fuel metering?
there was some talk about the typhoon setup.. i might do some research on this.. that car was factory equipped to deal with pressures above atmospheric.. may or may not be worth looking into.
there was some talk about the typhoon setup.. i might do some research on this.. that car was factory equipped to deal with pressures above atmospheric.. may or may not be worth looking into.
Chris
:iagree:
I remember reading about a conversion to that ecu for l98's. Check the tunercat site and links from it. I think I found it somehwere in there. I remember it was a pretty simple conversion.
You need a 1:1 if you are gonna do all enrichment in the ecu. iF you stay with your standard ecu, your gonna need a cartech Rising rate FMU. This thing's job is to raise fuel pressure as a function of boost. I.e. an extra 10 psi for evry pound of boost. (actually its quite adjustable) But beware, lucas style disc injectors won't open over 70 psi or so. You need to use the pintle style, like Siemens injectors. They are compatible with VERY high pressures without issues. Also you will need a set of pumps from racetronix with a hotwire kit to get the volume at the (very 120+) high pressures you will need. And that is only at 7-8 psi. When you are ready to step up to the plate and turn the boost up, big injectors will be mandatory! Or you can run secondary injectors in each runner (even better!) with this thing http://www.034efi.com/034SupECU.html
Do this right from the beginning and you won't have to really screw around with the factory ecu. You do your boost retard with the MSD, you do your boost fueling with your secondary controller-all the way up to 3bar. :chevy
Once again... give my boy Mak a call at (707) 786-4094. His business (http://www.fasttrackperformance.com) is making cut-in harnesses for FAST and Accel DFI units. His harnesses allow you to use the FAST or Accel units in conjuction with your stock ECU. You are in luck because the 1991 Vette is supposedly the best year to have to use an cut-in auxilary ECU. I actually waited until I found a 1991 for this very reason.. Supposedly the optic spark technology that occured after 1991 isn't that great. Prior to 1991 I believe it was a MAF system... You should be able to get set up for around $2,000 or so.....It's not cheap, but its better than buring chips and screwing around with bandaids that don't really solve your tuning problems..I love my FAST unit....
with my setup i am running 15psi with a fmu from procharger and a stock fuel pump and a pump booster from ATI and a stock fuel pressure reg non-adjustable....and 30# injectors. Under boost it fuel PSI is 50 and my air to fuel is 12:1 to 11:8. But i stillhave to have my chip reburned from Ed Wright and then i lean it out from the FMU. So my 91 seems to run fine (little rich).
outline:
chip-Ed Wright
Fuel-stock fuel pump, ATI booster
Control - FMU, 30# injectors
Krivera,
Have you run your car on the dyno with the wbO2 after the new injectors and higher boost levels? If you have, and you are getting 11.8-12.0:1, then you are pretty much right on the money. I would be curious as to what you are seeing during the transistion from 3-12 psi. I bet you would be surprised as to what your AF ratio is doing through that range with the FMU. It takes a lot of chips to get on the money through the total RPM range and varying boost. I used to do the chip thing too.
BTF (bald turbo freak), is that controller the coolest ever or what? I really didn't look into that much before, but it seems that it would do a nice job of controlling an extra set of injectors. Now I would have to figure out what size the "stock" injectors should be and then the "boost" injectors. This seems like a much more economical FMU than alot of the others. As you know I am on a tight budget, but I will make this run regardless. If I did this, I could ditch the rising rate FMU right? I emailed that guy a bunch of questions. If he gets back to me I will share. You probably know everything he is going to tell me anyway.
Yes my car runs great i need to check some things here and i should lean it out a little and see what kind of power i am making with the 15PSI... :D the 11psi is 500rw
Krivera,
You have not run the wbO2 with the changes (different injectors, higher boost)? The 11.8-12.0:1 is for the old injectors and the lower boost level? If so, you are taking quite a bit of risk with higher boost and no reference to the AF ratio.
A car will run exceptionally well right on the ragged edge of detonation, until ... Many others can complete the story.
krivera, I didn't think you could get 500rw out of a stock pump no matter what you did to it. You have got to be close to running out of fuel if your not already.
Krinera,
Do you have an in-cockpit fuel guage? It would behoove you to check your fuel psi while under boost and see how steady the fuel pressure (and what psi under different levels of boost and RPM). I have a nice graph that shows the linear relationship of the ATI supplied FMU and boost reference psi. I am a bit surprised at some of your earleir posts where you speak of the fuel psi (low psi). I know on the cars that I ran an FMU (and 30, 38, 42 #/hr injectors), I was running fuel psi in the70-95 psi range depending on the specific car.
I would hate to see you melt down the engine you have just built, due to some unnecessary lean condition. Before the discussion comes of "good components", "proper tuning", and "I know that I am no where near lean condition/detonation", remember the last thing the members on this forum need is another person toughting the "detriment of the blower car". There are enough of these people already. Typically, people blame the blower, but in actuallity, they did not do their homework as they continued to increase HP.
The beauty of that setup is that you can leave the stock system the hell alone. All of it. Just use a 6BTM for the ignition retard. Use a set of SVO 30lb's in the secondary rail for boost. Entire management system solved. Cheaply! The only catch is you'll have to weld in injector bosses/rail mounts in your runners (very easy), and get another set of fuel rails. (ebay or from any high po catalog (jegs, summit,scoggin-dickey, pace performance) They just plumb them into your normal fuel system. Thats enough fuel for 20+ psi of boost and even more with bigger secondaries. Stock drivability (well off boost anyway) and hell's fury is only a foot stomp away! NO bandaids (fully laptop progammable), just a different way to skin the cat. :party:
Here is the reply from the 034efi guy. Nothing out of the ordinary, sounds straight forward.
Hello Todd, thanks for contacting us. Yes, the Supplementary ECU would be perfect for your application, that's what it was developed for. It has 2 injector drivers that could run 4 injectors per driver. You'll need a manifold reference via a vacuum hose, and an rpm signal from the hall sender in your distributor. I can supply the cable if you need, its just a simple comm cable available at any RadioShack or computer store. You'll need to build a simple harness for the injectors and power, ground, etc, pretty standard stuff.
Please check out the featured users section of http://www.034efi.com for many examples of customers using this product and some have their own sites about it as well.
My only concern in using the 034 auxillary fuel control is where the injectors will be located and how the fuel is introduced into the manifold. On my 2002 Suburban with an 8.1L Whipple had a auxillary injector controller and two 100lb/hr fuel injectors spraying into the intake manifold just behind where the throttle body was. The problem was that GM had designed that intake to be dry, just like all the other MPFI manifods on the other GM line of engines. In my truck the fuel distribution was poor to put it lightly. I had lean and rich cylinders, and this was confirmed using thermocouples on the exhaust to datalog the temperatures. Not to mention the truck would surge when it was in boost mode and the milage was lousy.
If you was to install the aux injectors next to the factory injectors to spray the fuel direct into the port that would be ok. And as long as you can control the injectors properly it should work. But spraying into the plenum in my opinion would not be a good idea. I just don't think that the fuel distribution would be very good.
The best way is to program the enrichment under boost into a ECM. You can use a 1227749 ECM from a Turbo Syclone or Typhoon S trucks. It has been done and works well. There has been several installations amoung the F body crowd using this ECM, in a Corvette you may loose the MPG feature on your dash and thats it. All other functions remain. And it would be all GM using a GM 2 bar map you will get GM reliability and drivability. There are even maps available for 3 bar MAP sensors using the 7749 ECM.
As for a fuel pump, I use a single large Bosch vane pump inside my tank. It has a boost actuated Kenne Bell boosta pump that throws 20 Volts to the pump when the engine hits 3 PSI of boost. That effectively overdrives the pump to 150% of rated speed and 150% of rated flow, pressure remains the same as governed by the AFPR.
I totally agree with you on the injector placement. I wouldn't go spraying fuel into a plenum that was never designed to flow (substantially heavier) air/fuel mixture. Distribution under boost is scary enough. I was recommending that they be placed half way up the runner in the tpi. I have even seen some applications that fired the second injector up instead of down for better atomization. That would help with overall packaging. Also using these injectors http://www.mmcompsys.com/includes/en...p?frameset=yes
really saves space. I use them in my LT1 (with new rails).
But you definitely have a point, a converted sy/ty ecu would work great as well. Top it off with an acceleronix impedience converter and you can rock the low Z squirters. Peak and hold injectors have way better drivability when you get into high flow rates. I had a set of 57lb high Z siemens injectors and they worked like S##T until I cranked up the injector offset/battery voltage table to get rid of the "lazy"opening times. Im told that low z injectors don't suffer from this issue.
The one cool thing about a secondary rail is- you don't neccisarily have to feed it from the same tank. :reddevil Alcohol anyone?
Cool link to the Magneti injectors! I was wondering where I could find some information on them things. As you may well know Edelbrock uses them injectors almost exclusively on their Pro-Flow systems. And they are sorta quiet as to the specs on their injectors.
One more bit of information you may get a kick out of. When using that SY/TY 7749 ECM you can retrofit the injector drivers with some large Fairchild MOSFET drivers that will drive low Z injectors with ease :) So how does that tickle you? Just think, low Z injectors, factory control capabilities, even 3 bar MAP for big boost and an ECM that would cost peanuts as compared to an FAST, or ACCEL when replacement time comes around. Even if it fails somewhere you can get one at most any AC/Delco warehouse or NAPA. This same ECM was also used in the turbo Pontiac Sunbirds of the same era.
Can you post some photos of your modifed fuel rails and extra injector setup on you LT1 I am sure a lot of us would love to see it!
I have some pics of the first stage MMinjectors and new rails, but I don't have a host server. I can email them to you privately if you'd like. My second Rail will be built into the new upper plenum. Im chopping off the top (the reason for the shortie injectors) and adding some plenum volume along with a ported LS1 F body TB. It's currently (2500cc) no where near the volume nessisary for 120+ Lb/min of airflow.
Unfortunately the replacement MOSFETS cannot be installed into a 94/95 PCM but if you have an earlier bank to bank system it is possible. The later 94 and up PCMs has 8 small drivers inside mounted neatly in a row, and there is no room for these Fairchilds plus there is no way to get them on a heat sink. Beleive me I looked into that one :) Cool, email me your pictures I would love to see how its done:)
Corvette Store
FMU's and speed density ?'s.
