I got a problem. What the F could make my HP and TQ curves look like this???
Here is my Spark map....
Im using 75lbs/hr injectors, feed by a walbro 255, with 12gu power wires. Fuel delivery is not the issue. besides, i always have good AFR's thru my entire powerband.
Im running a 4-1 header from R. Seibernick, with 1-7/8" primaries, going to a 3" collector. After this, i have a flex pipe, then a 3" "Y" dump cutout valve going to atmosphere... so, backpressure is non-existant.
I have a LS1 TB infront of my TB, so, starvation cannot be an issue.
I have 14PSI infront of AND behind my FMIC. Piping is 2.5". then goes to a FMIC that is 3x32x12. its about as huge as i can possibly fit in my front bumper. AIT's before FMIC are 250+. after= about 10* above ambient. I also have meth/water injection, 300cc's per minute.
Im running an 086 stock head, with HO cams, again, people have pushed more air thru this setup with no problems.
I have new timing hardware, timing has been checked many times to verify still In Time.
I have remote mount coils from a DSM turbo car. 2 step colder plugs, gapped at .030".
so far, it seems like if i take away timing, i lose power. but if i add timing, i lose power... so i beleive my timing is pretty good atm.
I just dont understand how the motor can be making good power down low, then just give up and flat line. no-one else's supercharger dyno's look like this garbage. any ideas? I dont know what to do from this point.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
Is that a G-tech dyno simulator kinda thing ?
I'd say if it is it's mounted wrong and you're picking up bumps on the road or other...lol
11.92 @ 122.69 MPH Rotrex Blower / Intercooled / Water-Meth / 100% Daily Driver / 381 WHP
lets pretend you dont see the "bumps" in the road, and focus on the HP plain out at 4400 RPM's, and the TQ fall off a cliff. that has nothing to do with a bumpy road.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
You are really using that and not a real dyno for tuning?
butt dyno is a lot cheaper!
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
shawn... seriously? for someone who takes the time to get before and after IAT's from intercooling i would at least assume you would take it to a true dyno for results.
what some computer says your putting out without actually reading what its actually putting out is completely different.
189whp? i dont think so... unless you have a completely junk engine? and i somehow doubt that.
Every time I scream "Release", I mean it, you know it. I feel the day. Black 7.
Lol, G-tech being taken as acurate.
And Does you car weight exactly 3000 lbs on the dot. or is that just a guesstimate?
it wieghs 3000lbs with me in it, a half tank of gas, on a precision truck scale at work that wieghts tractor trailors, rounded to the nearest 10lbs.
lets approach this from a different angle then since ya'll wanna knock the gtech... i ran a 14.68et @ 98.7mph... what say you? I think it should be capable of a MPH of 115'ish.
anyone that could be helpful would be greatly appreciated.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
I ran 14.6 NA
Take it on the Dyno with some tuning software!
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
ok, so maybe i just dont get it...whats the dyno gonna do for me? I still dont understand what i would be paying 75.00 per hour for.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
So you can see if your tuning is actually doing something?
come on, its what motorsports COMPANY'S do... so there just wasting there money?
Chris
'02 Z-24 Supercharged
13.7 @102.45 MPH Third Place, 2007 GMSC Bash SOLD AS OF 01MAR08
086 head + HO cams should = power well through 6k rpm. If you want to assume the tuning is adequate, then it must be a hardware problem. Cam timing? compression?
Just noticed one more thing about your build - are you really running 7.5:1 compression pistions? If so, i'd say that's the reason right there.
Nukkinfuttz wrote:ok, so maybe i just dont get it...whats the dyno gonna do for me? I still dont understand what i would be paying 75.00 per hour for.
For one, it would probably show a lot smoother power curve. Unless you're actually feeling that while you're driving. In which case, I would do a datalog.
Jon Mick wrote:
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum.
well, i need to make a little adjustment to my problem. After making this Gtech Dyno run, i installed a FMU to the fuel system. I previously had only a vacumm referanced stock FPR, so as you can imagine, when i go into boost, i techically lose some fuel system differential pressure acting across the injector. it would look something like this.. 50PSI at the rail, minus 14PSI in the manifold, = 36PSI of pressure differential acting on the injectors. I figured that running such a large injector (75lbs/hr), that this low differential pressure was probably cuasing the fuel to puddle out rather than make a nice spray pattern. I was right. I added the FMU, raised my fuel rail pressure to 14 x 2 = 28 + 50 = 78 - 14 = 64 PSI of differential pressure across the injectors. the results were immediate. I increased my WHP by 30HP. after some more tuning to lean it out to compensate, and get back to 12:1 AFR, i gained another 10HP, totalling 230WHP. again, this is all at 4400 RPM's. It still falls on its face after this point. however, i have not done another dyno graph run with the Gtech, instead i have relied on the Megasquirt datalogging to get this information (which to date has always been right on que with the Gtech. )
I find it difficult to believe that my engine will only do 230. I do think there is more mystery in the tuning than the hardware (in the engine specifically) .
Think about it... it makes 230... BUT THATS AT ONLY 4400 RPMS! a stock quad HO makes about 115HP at the same RPM. So, thats a 115WHP difference over stock AT THAT POINT. but, i definately feel it jerk my brain out its socket when i first stomp the pedal, but i do feel it plane out and stop pulling. that is also definately happening.
i am no married to the idea that my timing is right... in fact that is the one damn thing i really cant find any good info on tuning. if there was some way to PROVE my timing was not ideal, then i would love to hear about such a test so i can perform it and see for myself.
i think over the next days, im going to throw my current tables away, and copy in some tables that are posted here from people showing HPtuners screenshots. I think my idea of how a timing table should be if different than what im seeing in these screenshots of HP tuners. For instance, i see that the stock tune keeps advancing all the way to redline, where as megasquirt says to put it "ALL IN" by 3000rpms. if you really set and think about it, that just cant be right... as the engine speeds up, the relatively constant burn timing of gasoline would need to be started earlier in the sequence as RPMs rise, so you land your peak cylendar pressure at 15*ATDC. megamanuals say ALL IN BY 3000...WHY? I think i will disregard MS manuals on this issue and go with what makes sence, and what makes sence is what i see on the HPtuners Stock timing table screenshots.
am i on the right path with this?
i need to change that. Im now running 8.5:1 ratio pistons. but, in my opinion they are still too low for only 14PSI. I think i can fix that problem with a smaller pulley.
but, i'd like to start making heads or tails of the TQ curve before i do anything else.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
So at least part of the problem was hardware. I'd still say low comp pistons + relatively big cam = messed up torque curve.
I know its not easy to change now, but could you run 10:1/10.5:1 on pump gas?
You make a good point on the megasquirt timing issue. usually forced induction timing flatlines with respect to load, but still increases with increasing RPM, if that makes sense.
that makes perfect sence, i believe that is a good way of saying what i was thinking. that seems to be what "should" be right, but its a real bitch when the megamanuals say something like, all in by 3k. it makes me wonder if im missing something important, and maybe i should just do what they say, becuase all the other info is so in depth and accurate, why question this issue? but i still feel that what you are saying is more true than what the megamanual is saying.
yes, the FMU issue cuased me to think..."damn, if something so small on the grand scheme of things can pwn me, maybe there is some other item im missing/not using right too" This is why im am here asking, becuase maybe a fresh set of eyes/brains will see whats missing and point me in the right direction. becuase in my mind, ive done everything correctly (except timing table)
could you elaborate on the relationship that compression ratio and cam size have on TQ curves? im all ears.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
well, i spent some time tonight hashing out a whole new table. What i did was took a screenshot of HPTuners 2.4L High Octane stock tune and programed my map from 0-100 KPA using it as a guide. Then, i built the 101-210KPA area by removing 1* per 2PSI, but continued to follow the advancing curve of the original table.
I have no idea what this will do, but it should be cool to check out. I think this is more "right" than what i have been working from.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
Well i don't have the personal experience of working with "big cams", but i've read that high lift/high duration cams will lower the dynamic compression ratio, so static compression can be higher than with a more stock-ish cam. In other words, low compression pistons with a bumpy cam can result in a mismatch of the powerband.
I would do some more research on this one before making changes. It looks like you're gonna make some big progress with the timing maps
How do you have your injector staging set up? I had mine on Simultaneous and 1 squirt per cycle. I set it to Alternating and 2 squirts. Seemed to smooth the engine out, and helps keep your fuel pressure up since you're only opening half the injectors at a time.
Jon Mick wrote:
i find it amusing that SHOoff has nothing better to do but follow me around & be an unhelpful dick in even cross-forum.
shooff- yeah, when i started out, i was set to simu/4, but i have since changed to alt/2. your right, it didnt really pick up any power, but it sure did smooth things out, nice quality idle, and smoother reving.
M90'd Built LGO-15 PSI
http://webstarts.com/quadper4mance
I'm no expert, but that timing map is a start in the right direction, of course you will have to dial some of the timing back due to knock (mid range rpm mostly)
The second maps look better. Anything below 100kpa should in theory look similar to an N/A car as there is no boost pressure yet- although that wont affect WOT power you need to start working with a decent base.
What kind of timing hardware/setup are you using?
Have a screen shot of VE by chance?
_
Now with northstar V8, IRS, 20's n 22's
