Audiboy

I have located a source for an 8 psi fuel per lb of boost RRFPR which after some calculation is the minimum I need for an interim fuel source (just for Sear's Point this weekend). After than, it'll be done with 2 additional injectors and a piggy back computer. I would really like to say more, but before I do, I would like to point you all this post I made in the OT forum. No tricks, I am just heading off to church right now, I'll be back in late afternoon <ul><li><a href="https://www.audiworld.com/forum/m/other/msgs/27839.phtml">https://www.audiworld.com/forum/m/other/msgs/27839.phtml</a</li></ul>

Kevin K2

would likely exceed usual 80-90 psi at-the-rail limit for stock pump at high hp/flow, even at a high intercept pressure?

Audiboy

Yes it will hit rail as you said, so, after installing, I will measure fuel flow at the output of the FPR's in series, to see what fuel rate I get at fuel pressures of 51 psi (high vacuum condition), 58 psi (0 vacuum), and 8 psi increments above that (by pumping in 1 psi boost increments. I'll plot a curve to see how many gallons per hour the pump can do at varying pressures. I am also limiting initial boost to 4 psi (via wastegate tweaking) until my more stable solution of having separate injectors to add fuel is done.

I done some extensive calculations with excel ;P and with my stock injectors of roughly 200cc/min, unless I short circuit the injectors to have 100% duty cycle, the stock setup won't even be good for anything past 200hp without running lean - I mean 15:1 or higher lean. So, with duty cycles at 80%, a 6:1 RRFPR will work, but the closest I get is this 8:1, or drop down to a 3:1 sold by a tuner on this board.


I had been working with a local tuner (yes he is a "tuner" who fabricates custom engine soup ups for the local folk here). He supplies the parts (such as my turbo flanges), and I hope to get the fuel regulator this Wednesday. The local OSP SCCA folks know him as he had worked on their cars also.
He does his testing on the Sacramento strip, and last weekend, he showed his car where he buckled and cracked the frame of his rear drive Toyota - I was in awe! To reinforce the frame would put him in a higher class, so he would tone down the power instead. Last night, I was over his place (he works way past midnight) and he has a few projects for local drag racers. Including this DSM that runs mid 12's, wherein he is installing a larger turbonetics hybrid for another 150-200hp. The owner of the Talon was there too, so we were talking techie stuff. He hopes to hit the low 11's, high 10 second barrier in December.

Anyway, I mentioned this because he said something interesting to me - The little 4 bangers he works with - Honda's, Toyota's, Mazda's, Mitsu's have fuel pumps inadequate of supplying enough fuel to power these quarter mile pounders anywhere from 300 to 500hp. So he adds an inline Bosch pump which he takes from Audi's and Bimmer's to put out the required volume. For low hp budgets (boost 0.5 bar), he also uses FPR's of 8:1, 10:1, 12:1 depending on what is the base pressure, injector type, etc... Sometimes, they convert the map sensor and use GM ones - funny For 300hp+, he uses custom injectors (such as this 550cc on a 1.6L Honda), custom programming and piggy back computers - Again my source for this. He's got good experience and good stuff.

If I fail, he will take on my project as I just pump in the cash Well, that's our plan next year anyway as we relocate the battery in the back and stuff in a T3 or T4 in there. For now, I have a GT25, because they are cheap and easy to source.

Damn, 50 reliable hp is so hard on this car - but worth it Ok, off to welding more piping now. Oops, it's too early to go home yet.

Kevin K2

some say they get can get 90 psi out of it dead headed (blocked return), but that can't be held at high flows.

interesting info on fuel from dahlback racing. hp potentials based on fuel only:

ecu chip only ....... 220
+ FPR ............... 290
+ inj ............... 330
+ pump .............. 550

they go a long way before a pump upgrade. The extra 70 hp from the FPR is also with a bigger turbo ... mabe lower boost needed ... still seems like too much from stock inj's and pump.

your test is a good idea, but dangerous. most flow testing is done with another fluid. also, eng off tests will reduce battery voltage, and flow drops 4 gpm or so at higher pressures.

the regulator you describe would be used with a stock type regulator. It would have 4.0 bar ref setting, but still need stock for only 8 psi drop at idle. Vortec does make one that could have diff +/- limits, but it's about $300 or so, and a little too complicated...

seems like for drivability and big hp, you must do an injector upgrade, like 300 cc's, and use reduced base pressure on fpr (2.0 at idle), and use a chip to work with high gain RRFPR. At least rewire to pump, or upgrade. I'd try to do the most with 4 injectors, with perfectlt balanced flow, before adding 2 inj's to the mix.

fwiw, mazda gets a 550 cc injector to work on the later rotary idle duties, so that would be like a 380cc injector pulsing at idle for a 1.8L .

interesting project

Audiboy

pump and air compressor. My RRFPR is made by Vortec, and I am getting it much much cheaper - courtesy of the tuner.

Remember I have 6 inj (I saw your note saying 4). I cannot do injector upgrades because my computer will not know what to do with it (12V thing)

Here's a simple formula - well I don't use it, but it should give an idea of how much hp per injector (or cylinder) the fuel rate is capable of -
hp = cc / 5 I think that's what it is. Not sure if that is at 100% duty cycle, but it works ok - based on stoichometric or a little below it. Any more air, the car gets leaner. So, 550 cc/min injectors will be capable of over 400hp on a 4 banger, 600 on a six - there is no replacement for displacement - well, with a fuel pump(s) to match

Kevin K2

sorry, misunderstood. Point is best to get most from stock number of inj's, adding xtra 2 will not assure fuel gets properly distributed.

I'd use hp = cc/6 for turbos that run richer ....

anyhow, the 12V untouchable ecu ...

with a 2.2 basic reg'r, this allows 35% larger inj's w/o ecu's closed loop knowing the diff. Then use RRFPR to kick pressure up a bit. Match 85 psi at 6 psi boost ... (79/58)^.5 x 1.34 for
56% more wot fuel, vs stock, if pump keeps up.

power in up based on abs press ... +41% ideal, ignoring heat at 6 psi. Seems reasonable.

now if current ecu maxes at 70% duty cycle, you have room for more power and enrichment with reasonable control.

Don't think mega power in the cards w/o cr drop.

would an MSD BTM boost retard work with stock ign?

Clark@turbo5.com

On my 1.8t..

Stock injectors are 210cc in my car. That rating was made at 3bar from bosch. So.. Correct me if I am wrong here...

At 5bar that would be around 400cc. I hooked a Fuel pres gauge up in my car to monitor pres VS O2 volts.

At 20 inches of vac (idle) my stock 4 bar runs at 51psi. Once boost goes past 13psi pres goes to 80 psi. Thats system pres as measured.

5 bar is 62 psi at idle and goes to 80 psi at the same boost.

My adjustable FPR can be set for 2-5.5 bar. Guess what? 80 psi at high boost.

The 5 bar does increase part throttle fuel and does go higher faster but overal psi is the same on all FPR's past 13psi or so.

With my adjustable I was able to set the fuel trim perfectly. Its proven invaluable in fine tuning the mixture. I found that my car wants about 4.5 bar with Stock injectors.

Even at WOT for 5 miles in 5th gear Fuel pres stays at 80 psi so the pump seems strong that pres with 210cc.

I am running 310cc injectors now with my FPR set at 3 bar. Its the PES/GIAC setup. Garrett had to redo the injector MS to get it to run right. PES and Garrett spent alot of time getting it right.

I still do not drop Fuel Pres at extended WOT runs. What I DO notice is this: Switch your headlights on and the pump SLOWS way down. I can see this at idle. the pump still makes good pres but it does spike down.. At WOT at the drags you guessed it.. a bit less than 80 psi..

I will upgrade the wire to the pump. I am going to use a Bosch relay and some 10awg wire. Overkill no doubt but I bet I fix the problem.

One other thing I noticed is that if I run 1/4 or less of fuel in my tank Fuel pres drops. I noticed this as some detonation when my tank was low. Even stock/chipped I got this. I have No idea why this is unless the pump sucks air at times.

Anyways.. Just somethings I noticed that may or may not help you.

Clark

Audiboy

But I think, error on the new flow rate since it is proportional to the square root of the difference of new/old pressure, so I calculated 270cc at 5 bar if indeed it is 210 at 3 bar. I know for sure that mine are between 170 to 220 cc/min at 4 bar because that's how the manual asks to measure them.

I have a few excel charts which I'll probably post tomorrow since I just finished welding a few more parts and it is almost 1:30 AM, but anything lower than a 3:1 rise seems too lean for this car. Hence my quest for a different solution.

Again, this is interim, until I get a more stable setup. I'll use the extra fuel for now to cool it down, because I won't run an IC initially, the one I took off a junkyard is too big - I'll get one off an eclipse later for $20 I just tell them it's a heater core he he.

Audiboy

shot, next year. As far as MSD, I have seen only one person post about this in early '99, late 98 I think. I requested more info but he ignored me He has it for a 12V A4, including Nitrous, if I am not mistaken, so looks like that may work, which is also what I will investigate next year. I probably won't do a CR drop, unless of course I get really aggressive. One thing I would like to do first is optimize the heads (Vortrag) to get efficiency rating up. IC will be there later, so if I can keep the temps down as much as possible, maybe I will be safely away of detonation range without little or no cr drop. This tuner has a horiba too, so next year, we'll get serious. I keep saying next year, because he is 3 months backed up, which is ok with me. Then when we are done, I have to take it off for the smog check in September 2001 ;P

Kevin K2

~35%. key is balancing increased inj size with reduced basic FPR setting. The stock 4.0 gives you a good start. At low power/closed loop, the fuel squirted per ms is about the same, so lambda is happy. At wot, the RRFPR can kick in to deliver the goods.

You do need to know what oem max duty cycle for inj's is, to see howw much more air flow before proportional fuel delivery ceases.

------------

The BTM ($180) intercepts the coil (-) from the ign module, and delays it proportional to boost.

The 6A-BTM includes an CDI, and may be able to use a mag/hall trigger. Don't know the 12V sys.

Headwork is a great idea.

I had discussed a vortech SC 12V concept with cathleen, so a lot of this has crossed my mind before.

I have some other info .. e-mail if interested


kellehkj@earthlink.net