brad black wrotewrt the eproms. the p8 eprom uses 16 rpm break points. i'm not sure what the maximum rpm figure you can use is (either logically written into the software, or practical in use), but you set the breakpoints to cover the rpm range you want to use. if you were going to rev it to 13,000 you'd have point 16 at 12,500 - 13,000.
it has absolutely nothing to do with whether the eprom is single injector or dual injector. that is a separate function.
it's quite possible that the eprom you are using is limited to 10,000 rpm. i don't have many of the dp eprom files, so can't check it. rev limit setting is also independent of rpm breakpoint values.
as a general comment and observation, and this goes towards the 748r head obsession comment i made last time, you seem to get caught up in some of the "race" stuff and proceed with a bit of a scatter gun approach. i wish you'd just step back a bit and look at the overall picture, and stop guessing/fantasising/convincing yourself about things like the eprom stuff, etc.
i think the inlet cam timing you're running is too far advanced. i think the exhaust, particularly those long, small diameter pipes into the mufflers, is hurting it. i like the longer inlet idea, but i'd try a lot longer than you have. go as long as you can fit in the airbox. but you also need to test stuff out on the dyno. make a couple of lengths you can swap easily. if you're worried about air supply, just piss the filter off and see what happens. or hold the tank up during a run. i think you'll find it's irrelevant.
or maybe, for whatever reason, it's just a bad combination. they're an odd cam set - the exhaust is a lot longer than the inlet. the engine is 24% bigger than a 748, so it's doing different things. looks to me like the power will climb again after 10,000 rpm, if you can get it to go there. you need to find out what the limiter is. maybe it has too much or too little spark advance, that can hurt dyno power too.
maybe you need to look at another ecu that you have full access to. i'd fit a single pick up alt cover and timing gears, so you can run a 1.5m from an ssie. that way there's no eprom and you can reflash as required.
the 854cc 748r i did had the torque peak at 8,000 and a final lower peak around 9,600. maybe it just needs a longer inlet cam. i'm rambling now.
griff851 wroteVizzards porting school is not a bad place to start to get the general idea. Looking at your pics, did you clean up around the valve guide, hard to tell from the pic. That is the choke and it serves an import purpose. It speeds up the air for the turn, and getting it wrong in relation to port diameter will have marked performance difference. In fact half a mm in any of the diameters makes a difference. This is also where the bowling Vizard talk about it also important. The bowl acts like a air spring for want of a better description, so care is needed just like choosing any spring for an application. Reading it early on has allowed me to get some outstanding results from the humble and not really so shit Bevel straight shot port.
36mm valves are good enough for the job.
I agree with Brad on your approach, a lot of time and money can go down the shit tube with a bolt on approach. You need to spent time staring into the oblivion thinking about what has to happen an when, then what’s available and what needs to be modified. Example i’m Using 748 throttle bodies bored out with modified transition ramps, because standard sizes didn’t fit the requirements. We lined up heads on the bench, 748, 748rs (thanks brad, that the one with different cams I was think about), 916, 916sp, and a monster head, just to look at how the factory thought about swept volume and port velocity. Shit i’m Still having regular discussion with bob on bloody cams. I end up using ST4 cams because of the inlet close, certainly not for the lift. The engine spins quite nicely to 12500 without any drama. Power from 6000, serious drive from 7500 upwards. So it pays to do your homework before getting out the cheque book.
Read Brads stuff, it’s incredibly good, fucking brilliant actually. But learn what’s happening and why, not oh he used this so it must be good. As soon as you start changing things, other variables come into play, like an orchestra it all has to work together.
Jeezus Christ Brad, you're a cantankerous old curmudgeon...if they ever make a movie about you Walter Matthau would've been perfect.
I had one question about 916 rev limits, which you couldn't answer, and then you go on a fukn tirade like Alf Stewart missing his "Snicker's" bar. I'm taking a "scatter gun" approach? You're the one saying the cam timing might be wrong....it could just be a bad combination...the exhaust might be hurting it....spark advance could be wrong...it has the wrong cam...yada yada.
So you and Griff would have kept the restrictive air filter?
Kept the fixed pulley's and resultant timing?
You like the crap 50's style OEM velocity stack's?
I guess you would have, 'cos fixing what look to me like obvious issues is taking a "bolt on" "scatter gun" approach.....despite the fact you know very little about the bike, and the research behind the changes. But then you think a single exhaust pulse travelling down a single 45mm exhaust header -> into the crossover -> splitting into 2 x 45mm tail pipes is restricted by the 2 x 45mm tail pipes, not the single 45mm header or ordinary crossover arrangement before them. Those 2 x 45mm pipes are equivalent to a 67.5mm single pipe (to double CSA increase diameter by 50%) so you think the equivalent of a 67.5mm pipe is restricting the upstream 45mm pipe.....hmmmmmmmm
And of course I'm testing stuff out on the dyno, what do you think i just did? But it sounds like you think I should be altering velocity stack length despite the fact I haven't found the power peak yet. Interesting approach.
So what is this "Big Picture" I should be looking at? The short stack picture that Griff prefer's or your long stack picture? And how does one form this initial picture without the 20 years experience you were obviously hatched with? We all have to start somewhere.
And guess what? The bike, despite your disdain, is actually pretty good. 20kg's lighter, an extra 20hp, I'd have taken that in a flash if it was offered when I started.
Both setups are as crisp as a new pound note, the previous iteration made OEM 851hp at just under 7krpm, and would have been an awesome road engine. The later setup makes OEM hp at 7.5krpm, has more legs at the top end and out drags an 848 on the straight over the hill at Barbagallo. And there's more to come.
But something is stopping it revving. A 916 makes peak power at 9krpm and from all accounts the riev limit is around 10krpm. The bike has a 916 eprom in it......so how is it a "Hail Mary" to think the eprom is the issue?
And no, an alternative ECU is not an option, the P6 GCR’s state that if injected “only the original system is allowed”. Hence my “fantasising” about eproms.
"Mate", this may be work for you but it's fun for most of us, something to pass the time while we're waiting for the kids to wheel us into the rest home and feed us our pureed steak with a spoon.
But you've a knack for taking the fun out of it. You are a font of knowledge, but you are a crap teacher. In fact you aren't a teacher, you're the class bully, "knowledge is power" and you just bludgeon people with it.
You don't like my bike? Don't comment.
You don't like me? Don't comment
But I'm done, I'd rather fuck it up myself and learn something from it than succeed with any help from you.
