what's needed for p8 and dual inj?

got2dv8

Just curious what is needed to make use of dual injectors with a '90 851. Would I need a complete harness? Or is there a harness that can be used with the stock one? Not wanting to debate the need for dual injectors, just wanting to know what is needed to use them. Computer will be mounted in stock rear seat position. Have a p8 that I would use. Would I just need the matching bike harness of whatever the dual injectors came from?

Thanks in advance,

Robert

brad black

the p7 can run them as well as the p8, it's the rear offset map that the p7 doesn't offer.

it needs wires from the ecu for the two injectors, that's all. you could run an extra little loom of two wires to the throttle bodies if you find out the pins to use and can source some terminals to use in the big connector. you'd need to tap into the power source for the other injectors and get some connectors, but they're easy to get. that way you don't need a new loom. it'd need to be sp3 or earlier loom to have the same general large connectors, later the 1991 have the big flat amp ones from memory. and a dual injector eprom to suit.

got2dv8

SP* pin numbers for secondary injectors??

brad black wrotethe p7 can run them as well as the p8, it's the rear offset map that the p7 doesn't offer. it needs wires from the ecu for the two injectors, that's all.

That makes sense, I never thought of that duh, the early SP were P7.

brad black wroteyou could run an extra little loom of two wires to the throttle bodies if you find out the pins to use and can source some terminals to use in the big connector. you'd need to tap into the power source for the other injectors and get some connectors, but they're easy to get. that way you don't need a new loom. it'd need to be sp3 or earlier loom to have the same general large connectors, later the 1991 have the big flat amp ones from memory. and a dual injector eprom to suit.

Ok, so the P7&8 can run duals and all it takes is finding the signal pins. My understanding from what you explained is the injectors are always powered and it is the signal from the ecu that tells them when to fire/open/squirt..

I've given up my other engine project and now intend on building an SPS motor... in my eyes and from what I've read one of the best motors Ducati ever produced for the street.

If anyone knows the pin numbers for the secondary injectors that would be great! SP owners???

Robert

mikesps

injector 1, horizontal, pin 32
injector 2, horizontal, pin 35
injector 3, vertical, pin 33
injector 4, vertical, pin 18

they share a common 12V supply with the fuel pump

Mike

got2dv8

awesome thank you!

Robert

got2dv8

any advantage of dual injectors?

I have both dual and single injector throttle bodies. Is there any advantage with a slightly modified engine by having dual injectors? I understand that the single injectors offer enough open time per RPM for what my motor requires. But since twin injectors have much more headroom, wouldn't that be advantageous? Would atomization be any different? And.... would tuning be more difficult or the same?

Robert

ps. Yes, Steve I have read many posts of yours and the great power achievements with singles. Not debating that point...😄 😄 😄 only wanting to know if it's worth keeping my duals or selling them.

marvin

I don't know much about it but have read that if they aren't sequential (ala 996) that they sputter at low flow levels and don't atomize the fuel very well. Sequential using a P8 is, I am sure, better. Mark T set one of his Corse bikes up with the sequential injectors. I know it took him a long time to get them mapped correctly. PM him and ask. I don't think he checks in here all that often.

brad black

imo everything written about 996 running badly at low rpm on dual injectors is bullshit. there were two specific issues with them that i came across, one wacky and one software.

1/ the roll on missfire. specific to strada cam 996. if you haven't ridden a 996 with the missfire then you really won't have any idea what it's like, it's that unique. one fix was to run them on one injector. the other to reduce the exhaust closing clearance to 0.05mm. both work.

2/ "jumpy" at low throttle, caused by the software given an acceleration enrichment like increase in spark advance that decayed over a short time. std eprom thing, drove me nuts every tmie i rode one around under 2,500 rpm or so.

a well set up dual injector 996 runs just fine down low, as does the sps cammed 996s (euro spec). they may be more susceptible to fuel quality as a dual compared to a single perhaps.

on the 851 end feed injector throttle bodies the duals are no good specifically because the oem injectors used - red and black - are too small. 851sp eproms have FF on the fuel map at 7,000 and 8,000 rpm, the biggest number possible. to get around it, the corsas ran 5 bar fuel pressure. so they need bigger injectors, a pair of the std strada green ones would be fine. you might be able to find some modern design higher flow multi hole things, but the later pico series are smaller in the body. you just need to find an injector supplier who can match up what you need, there's plenty of them around.

although, fitting a pc3 on a red injector bike will work, as the FF represents the marelli software max of 17ms (8.5 per injector), not the actual time available. so the pc3 would stretch it without issue as it modifies what comes out of the ecu. 8.5ms is less than the cycle time until 13,000rpm or so. at 12,000 rpm there's still 10ms of cycle time, so you could stretch the pulse 18% then, or 41% at 10,000rpm (12ms). you have to wonder why they used those red injectors.

green end flow are the same rated as the later green 916 style ones, so should do 120hp ok. although a smaller engine revving harder may have more need of duals even under 120hp due to cycle time. if it takes you 12ms to make 120 then a 996 at 8,750 is fine, but a big cam 851 at 12,000 might not be sort of thing. especially as general efficiency tends to drop as rpm rise, so you have fuel required per cycle for the same power increasing and cycle time decreasing.

the difference between single and dual p7 and p8 map is just a number in the software, it's easy to make them one or the other. whereas a 1.6m map is factored by a number in increments of 1/32 from 1 down to (not sure), mv run 37.5% of the map number from memory. 996 is 0.5, 748r and some 996s 0.625 i think (996s dp is). not sure if you can go bigger than 1 either, never tried it.

i personally wouldn't bother with the duals because of the extra effort needed to fit them. i don't see any advantage in using them as opposed to using a higher flow sinlge injector, but there's no disadvantage either. i guess restricting the range of duration the injectors have to deal with is not a bad idea if possible, but i've not seen any real evidence of it in practice.

the iwp069 injectors (yellow band) in the shower bikes run down to pretty short durations in 748r and 749, but for an engine that has drops of fuel rolling around the throttle blade at idle (not at all atomised) they can idle amazingly clean and lean, idling stably much leaner than a non shower bike will ime. although i have been told the iwp189 (?, pink band) with 12 holes from the later bikes are better in low pulse width delivery.

i'd fit bigger injectors over raising the fuel pressure significantly too, but that's just a personal preference.

the software just cuts the fuel map number in half above a certain pre set pulse width and runs both injectors at that halved pulse width, so tuning shouldn't be any issue at all.

sorry if i've rambled.

marvin

Great read Brad! Thanks for the info!

Mr.R

marvin wroteGreat read Brad! Thanks for the info!

+1 On that!
I'll add that the top WEBBER man over here (in the UK) told me that the Greens are good for 65bhp each, so a 130 bhp motor shouldn't have any problems using single Green injectors per cylinder.
I use 54mm TB's with single Greens, with the fuel pressure upped to 4 bar and at no time did they use anywhere near max' available time (the peak was around 70%) to make 116 rwbhp at 9,500 using 996SPS cams in a 33/29 valved 851/916cc motor.

When using a PCIII usb with duel injectors and a P7/8, the PC only adusts one injector per cylinder to alter the fueling.

Steve R

MarkT

Just checked in- so I am late on this. As I always find-Brad is correct- for the P7/P8 you just change one number to get them to fire sequential duel injectors-- then you have to set up the maps. I also agree with Brad and Steve that duel injection is often not required.

I only went that route because I like doing things the hard way. I had rebuilt a Corse motor into a 984 using stock 888 cams and a shaved 900SS crank for a short tracks. I really did not need to go with duel injectors- like Brad-and Steve pointed- they are not really required on low rev motors that do not put out over 130 hp. In fact I was running a stock 888 TB and single green injectors using a map I got from Doug L with no issues for two years before the bug to use the original Corse TB kept calling me. I only had P8 duel injector Corse maps for G and 431 cams and a SP4 map to pick from as a baseline. The Corse maps have different break points and of course go to 12K which I did not need. The SP4 could have been my best choice but it was for a P7 and I had been using a P8 box and did not want to mess with conversion. I ended up using my P8 single injector map as a baseline and changed the map to fire both injectors. I could have started out with any of the Corse maps but I knew that the single map would run fine under 6K and only wanted to mess with the top end. It took time at the local dyno and track time to sort out a map that felt as good as my single injector setup--I sent my maps attempts as well as my O2 data out to Doug just to drive him crazy. He sent me back a map that nearly killed me on the track since it would go so lean at part throttle the bike would almost shut down going into a corner-- probably cut the times in half across the map just for fun. I think he did it to pay me back for bugging him with doing something so dumb as to going to duel injection. I played with the FP and the map and in the end the dyno showed no real improvement over my single injection set up -- I was just happy to equal it. So the only advantage was my motor used the corse TB which is what I was compelled to do.

You can use the 888 or 916 greens- red are fine up to about 112 hp but even on my SP2 I turned up the FP up to about 4 bar along with a SP4 chip to eliminate all the flat spots I had with the stock SP2 chip. The early chips were pretty crude. The real cure is to stick in green injectors with the SP4 chip.

Steve- 70% duty cycle is a good max number to hit- sounds like a good setup.