Well I am usually anti DYNO, as I rather use the track for results.. but I am thinking of making some changes this winter and wanted
a base line.
Jus recently put my WB in I bought a long time ago and noticed this - But with alot of spin on street tires and traffic - is kinda hard to get a good reading due to A/E tapering out and such.

Anyway first pass on dyno using their WB had me at 13.5 pre 5500, at 5500 tapering to 12.0ish by 6000 then back up to 12.4
by 6400. But to look at my PW, it changes very little - nor does it reflect the same pattern.

Now for the PW - 9.2-9.3.s Which is about 99% at 6400
Thats surely a problem, but is it the problem?
At 5600 where the problem begins, its only I think 86% DC - Anyone think that would be the problem?

And for the results it was only 386 - But it was really flat,
Making 367 at 5000 and peaking only 386 at 6300
But dropping to 352 at 5700! when it went rich, then decends back up.
The peak really does not coincide with vehicle weight and trap speed. Even at my worst trap speed, I have myself @ 404 at wheels after 21% driveline loss.
Best would be 430s - And judging off similar cars I would be there as well. Unless it that my HP is that flat and the car is just that effecient.
I made 1 N20 pass with 150 shot making a 524 at 5800 then it spun. That would be close to right on but still low with trap speed and ET. But run got shafted so it may have been right on.

According to calculations, I would have made (On the same day)
538 at wheels @ 133 trap speed, and subtract 117 HP from that
and would have me at 421 with the 124 trap speed I had natural that day. works out pretty perfect......


Hmmm, JUst found another problem - Using conditions from their dyno, The DA is 3500 ft, And corrected vs actual is only 0.2HP on their sheet..

 

The PW not changing could be the stock 8D code limiting the PW if your not using the fix.
That exactly how it looked on the bench.
More rpm and constant PW. And 9ms sounds about right.


I've often wondered why people don't notice this.
All I can come up with is that the extra rpm some how adds enough fuel to make it less noticeable.
Also I've read about cam timing can make the motor go rich on top due to reversion. The guy knew what he was talking about afa cam timing.

I've got a PE table that works beyond 6400 if your interested.

edit: If the VE is tapering off at that rpm, the pw should follow. In case your having a display error of some kind.
Provided your PE table isn't canceling that out with an increase.

 

Its not the fact that the PW is not changing - I'm saying that the PW is staying the same but car is getting richer.
You do not need more PW for RPM, more RPM does not mean more fuel per pulse, it just means pulse more often. So being that its staying the same the A/F should as well or close.

I had been doing some figuring, for me to trap just 125, my car could only weigh 2950 to do it with 385 hp. There is something wrong.

I am really interested in the 6400 VE table, that would be great!
My ve is set up with most Fuel at 4800 for peak TQ then tappers off - A/F is doing just the opposite.

 

Just as, an injector isn't linear at short *on* PWs, they do the same thing at short *Off* PWs.

The 90% Inj DC is only a suggestion, and when in doubt use much less, if you want to be in the sweet spot of the injector. Various designs might be a little better then another, but unless you get to a resonsible PW, you'll be subject to that sort of thing.

Might even have to step up to a double pumper fuel pump.

If you're going to try and stick with what you have, then hammer the DC to well over 100% so they don't do the momentary lean thing, as they go static. That's not the way to go in my book, but just a hint on not knocking too many corners of the pistons.

This isn't to say there aren't other issues.

 

I've been doing some personal research for a part I'm making for my car and it's brought about a lot of cool data regarding linear solinoids. The ones I'm looking at aren't exactly like fuel injectors but they're similar enough. Now for my point; electric solinoids like high voltage, they suck at high duty cycles (force is invers prop.), and at the end of their stroke they are the weakest .
As this might not be exact, I'm willing to bet that with the larger saturated injectors the max desired duty cycle gets lower. Where as 19# might be good with 90% the same design flowing 36# might only be good with 85%. I need to look into it more so I could be wrong.

 

I do not run the at 99% - I actually have not logged car at wot for a long while and just realized that they are.
I have been looking for new injectors - maybe 38-40's currrently
using 30's

Anyone have any ideas or explanations why the A/F fuel did what it did?

Also just noticed something real weird on 3rd dyno pull, car made 379 @ 5500 ---- 350 @ 58 ------then 381 @ 6300

 

here,
This was after I leaned out from 5600 on, but never touched before 5600 - this one made 379 @ 5500, then 350 @ 5800, then back to 381 @ 6300

 

You leaned it out too far by the looks of it. Maybe even picking up some detonation causing the power drop.
The other explination was in Grumpy's reply. The injectors become very unstable above a certain duty cycle. Running them static or very close too it will cause all kinds of weird things to happen. The coils sometimes lock-up open.
The only reason for the ability to run out of injector at say 5500rpm and then have enough at 6000rpm is that the volumetric efficiency has dropped significantly meaning at 6000rpm it's not digesting much air volume/time wise. Hence the drop in horsepower and the rise in AFR.
If you look at the curve of how long the injector has to fire based on RPM you'll see why this can be true.
People that run small injectors and don't listen to those that preach bigger is better... well they're just stupid. Don't be one of those people . Get the right sized injectors and gain back the control. Those remarks aren't ment for you, they're just ment as encouragement. Imagine if that guy that blew up his 2nd, or was it his 3rd now(?) motor had used the right sized injectors instead of trying for 10's with 24#ers... he might have been well into the 10's instead of burdening his family.
Please keep up the good work. You're doing an amazing job!

 

Thanks,
It was just weird to me that It starts at 5500 - I see by reading grumpy post and your that maybe 86% is to little time. I can imagine why it would go rich there after only beacuse the inj may just be staying open.
I just thought it was funny that it went so rich even though VE and PE enrich and PW are = from 5500 and up.
I also think that its weird that the car runs so strong and pulls hard all the way. even though it says power dips, because I like you am sure you know your car very well. I have been running this combo for 3 years now.

I will post other graph later from first run, that one starts out much richer and gets way rich - Thats the tune I always run. power dips just about the same.

I deffinetly know and have known I need bigger inj. - Just have not realized its been that bad I guess.

I am kinda thinking the PE is on the leaner side but when inj become static its get real rich..
Anyone have inj. for sale?

 

I've seen 36# injectors for sale below $300 new for the set. 42# all over the place because of those blow Ford trucks .
I remember reading somewhere about some people having issues with the 42# injectors in batch fire mode... don't hold me to it though, my memory isn't perfect.
The other alternative is to invest in upgrading a 730 to use peak & hold injectors. That way you can get those low pulse widths and faster opening rates which yeild a wider dynamic range .

The more I think about it, the more I feel your issue might be valve float. With a high ramp cam like the one you're running... it's possible you're causing the springs to resonate at that "dip" in the powerband. I wish I knew what the AFR would look like with valve float, then I could be of more help. No matter what, get bigger is the moral of the story.

 

The simple just looking at the data explination with a flat PW is more individual cylinder pumping efficiency @ 5500, equating to leaner AFRs due to the increased airflow. At 6000, the pumping efficiency drops, and the AFRs fall since there is less air available given the fuel. At 6400, the pumping efficiency comes up a tad, and the AFRs lean out.

This also seems to line up with the dyno result. My first impression is maybe its some sort of wacky valve train resonance causing valve float thing as well.

EDIT: Looks like JP stated the explanation for the AFRs further up

 

I'd suggest the Mototron 60 (65) PPH ones.
They're high Z, and I've run them in batch fire mode on my V6 just fine.

The 42s are just the worst injector for being none linear at short PWs.

Mike at:
http://www.fuelsystemparts.com/items~Cc~INJ.htm
has always treated me, as well as other folks well on both prices, and service.

These are what I'm using.
http://www.fuelsystemparts.com/itemd...OR~eq~~Tp~.htm

 

I never felt mine float.
Felt the same after I swapped to plenty of spring.
Check the wear pattern on the valve tip.
If it has a * pattern instead of a - then they have floated.

I chewed up spring shims in mine so don't wait too long.

I PM'd you.

 

I noticed 2 things here that may help. I have a similiar setup and participated in a dyno day that included a number of LT1 cars. First the LT1 intake which for practical purposes are similiar to the MiniRam had 2 peaks on the higher performance cars. The first is the well known 5200RPM the second is a 5600RPM secondary peak. If you are peaking then your motor may be looking for more fuel at that peak. I am also running AFR heads and I see similiar rich lean scenarios. My guess is that you may be seeing a combination of your intake with the AFR's causing this.

 

AFRs get erratic with valve float and trend lean.

Some stock ls1 valve springs do a harmonic thing around 5700rpm, some do, it most don't. There is some credence to what your saying, looking at that power curve taking a step back and looking at valve float would be the smart thing to do. I've never seen a rich AFR create such a erratic tq output.However if the engine is truly as lean as it look to be then output will be down.

The last thing to consider might be lifter pump down. I am assuming this is a hyrdualic roller. With to stiff of a spring lifter pump has been seen on the spintron at 5200rpm.

 

It's next to impossible for the intake to have it's resonant tuning peaks at both 5200 and 5600. That's too close together for a sbc or any domestic v8 for that matter. You're probably seeing the exhaust tuning peak... long-tubes do a good job of resonating in the 4500-6000 range. The cam really dictates the resonance frequency but the 1st order, 2nd order, etc can't occure at 5200 and 5600 .

 

Wait until I tell Chris about this.....

 

Its deffinetly not valve float,
I have had much much lighter springs that were only seeing 150/360 at full lift because I thought my current 190/500 at full lift could be sucking HP. The car ran identical ET/MPH with both springs. So I went back to stiff springs as insurance.
Also its a solid roller, so not lifter compressing either.


I need to go out and play once roads clear here, It mat just be an A/E thing as its only being hit in third and not for very long...
And its weird, when car leaves line its usually on the rich side - smoke aparent, Or black Souit as the 24lb inj. guy used to say
Which I used to say, better black smoke then detonation when he would say my 30s were over injecting

Also the fact that the HP figures don't come to close to the ET/MPH vs weight I am seeing.
Especially if it dropping back down between 5500-5800 -

Like I have said the car has no flat spots except above 6600 - due to inj. going static. Runs extremely consistant and strong.

The whole day was a mess, made (6) passes because dyno would not record either RPM, Tire speed, Or A/F for 3 of 6 runs
and spun on N2 pass.

JV, I had bid on a set of Lightning inj's a Month or so ago but missed by a few dollars. Been looking budget route as X-mas, May wedding comming and blah, blah.

 

Those dyno curves do look odd when I take a second look. It looks like its about to kick some serious *** by the time it gets to 5k but it just goes flakey after that.

 

BTW, if it's only going lean in 3rd gear... might take a look at the fuel pump pressure while it's on the dyno and at the track.

 

What kind of timing are you running out there? What type of igntion system, just out of curiosity?

 

Thats what i thought,
And the fact that the dyno weather station gave a 4500 ft da, and corrected numbers are only 0.2 higher?



Had already been checking that prior after install of booster pump for n2,even with a really rich 150 shot stayed constant @ 43 - even on tip in.



Msd dis, 6AL, COIL, with stock module as MSD one caused misfire for some odd reason, replaced with stock and all was well again.

Initial set @ 16 and matching in prom, 36 degrees total natural.
36 degrees from 2800-4000 for launch then 32 there after with 150 shot on pump gas.

 

The misfire part is interesting. Maybe its a lack of power issue or some other fault that is causing the ignition to malfunction. The load on the system is much higher at high RPMs. Theres alot of dwell at those RPMs since its firing so fast, if I recall.

 

Don't have to believe me but that is what I saw. I really don't care if it is the intake, exhaust, cam, heads, or a combination of any of those. It is well known that the peak for the LT1 intake is 5200. There were 3 LT1 cars there 2 showed the same thing the other one was a stock LT1 it peaked at 5200 and dropped off. The dyno shown here looks like similiar to the modded cars the exception that it appears skewed up 300 RPMS or so. My dyno run went way lean also so far I have increased the PE 30% and I am still lean. My AFR is going richer in the upper RPM's same as this dyno. If you are running a TPI chip you may want to look into a 92-93 LT1 Bin for PE and AE tables to get some ideas of the differences. Keep increasing the PE or set it to what you want then adjust your VE tables until they are in line with what you are showing. Do not discount the flow of those AFR heads. As a friend of mine says "The more you give them the more they want". I can send you a bin for comparison if you like but my cam and engine size are no where close to yours.

 

there is one other thing to think about. Missfires definately show up as lean on a wideband. if your missfiring even a small amount then it is very the engine could loose a like amount of power and have the AFR showing to be so lean. The injector static comments could be true but i would be hard pressed to belive that at 86% DC 30# injectors have become erratic in operation but being as they are saturated drivers anything can happen. Coil saturation and disaption on nitrous seleniod become a problem at 65% dc but we are talking about a motor assebmly with 10x the mass ans current requirements and if the scales hold tru you shouldnt have trouble till you hit roughly 90% dc. the problem might not be the injector in a static situation but the injector driver and snubbing diode don't have sufficient current disappation.

i might be inclined to belive that you have some fule rail cavitation and or rail pulsing. What rails are you running ?

 

What happened with you claims about having proof about how the OBDII stuff uses the MAF?. Seem like when asked to support your claim with materials you allege to have, you took off.

No need for your normal nasty reply, just posting the data you allege to have to support your point, is all that's needed.

 

Well if my sources are correct then some birdy sent you an email containing said information. but you deyning the reciept of it is fairly shady.

 

Well that's impossible to say that the Lt1 intake peaks at 5200. . It only peaks at that RPM because of the CAM timing and heads. Put an Lt1 intake, completely stock, on an engine (no matter the displacement) with a cam with 242/242 lift @.050 and it will NOT resonate at 5200rpm. Heck, even on a completely stock Lt1 it's not set at 5200!!! Heat soak changes the rpm at which it resonates because the speed of sound is directly linked to air temperatures. Some compainies are using code that takes this into consideration. They're that accurate (or **** depending on your outlook).
So please, do not say the Lt1 is set at 5200 just because you saw it on a chassis dyno. Not only do the chassis dyno's add a ton of variables but they also aren't exact. I know with small similar cams the Lt1 intake does resonate there but it isn't the same with THIS cam!

Funstick, I do believe, when somebody wants you to "post" the data, it doesn't mean e-mail it to them.

 

Good point about misfires, and I do know they cause lean readings - good point for others as well. However, that was the MSD module, I sent back, they claim to have sent another and same thing. But that was 2 years ago.
Stock module works great, it could be possible about misfires but car "Runs great, and is very consistant" no mechanical problems noticable at all.
Fuel rails are standard Mini Ram, And car runs well with extra fuel demand with 150 shot. So there should be no problem with fuel delivery.

Who knows, maybe there is a slight misfire causeing a huge dip in dyno graph that may not be noticable, or as extreme under normal load. I really doubt it though.

As for the 5200 RPM intake wall WITH lt1 "Which I do not have",
That probably did happen, but only incidental.
There are to many variables that predict peak HP In mostly this order I, but not always.
Intake, Cam,heads,Cubes, exhaust. ect, ect.
Intake is a huge one, But it just depends when its max velocity and or flow or peak effeciency is achieved with your combo.
For instance my combo on a 350 would make peak about 6700.
Ect, Ect.

 

Whatever!

http://www.compcams.com/Community/Ar...?ID=1737510521

http://www.compcams.com/Community/Ar...p?ID=-61543841

 

In not so techinical terms it gets progressivly harder for the spark to jump the gap as cylinder pressure builds. This combined with the increasing duty cycle that comes with higher RPMs can push things over the edge. From the graph, there is definatly something causing it to break up early. IMO, Id consider it worthwhile to eplore all the possibilities

The fact that it misfired with one module is something definatly worthwhile to explore.

 

FWIW, ive run into similar issues caused by power distribution problems or other issues. Motor ran ok, but it just sort of went flat at higher RPMs due to a weak spark. Long story short, once the ignition was fixed it had much more power and pulled alot further out then it did before.

Is it your problem, who knows...

 

Please do not let the Module sway any thinking here - with that module, car would not rev past 4000 - it was much more than a miss fire.
And do not take this wrong, as everybody is trying to help but...

The car runs terrific, great - pulls very hard - no noticable flat spots! Has been running the same for 4 years now, alot of street and track miles... Very consistant and strong.
I really do not think its a Ignition problem as it runs great with a 150 shot as well.
This is not a new combo, nor am I performance def... Maybe I am.
Here is a vid, If you can find a flat spot - Let me know.

http://media.putfile.com/1009

This was with a very, very rich 150 shot on pump gas, only giving about 117 HP.

I really appreciate the help, I just think had my car been losing 15 HP in the middle of its powerband, I surely think I would feel it.

 

Yes, but the dyno graph points to a problem. From the looks of it, there is somehting thats just lopping the peak of the powerband off. With that cam it should pull farther then 5.5k or so, or at the very least, fall off more smoothly rather then trailing off into nothing. Regardless of the cause, I think it deserves further investigation, or at the very least a pull on another different dyno as a sanity check.

 

Remind me to turn the sound down before playing any new downloads....

What do your data logs show?, if it's still pulling hard going thur the area your worried about?.

I've yet to see a dyno be useful for more then noting trends, once you're done with one, you still have to verify the tune, in car.

 

why doesnt that "someone" post it up themselves unless they fear looking like a fool.

 

Grumpy - Remember to turn down sound before next D/L.

Well one of the reason I dynoed the car is because I think I am pulling engine, for some bearings and hopefully not more, but I am sure there is going to be scratches...
Anyway I wanted to throw it in my Camaro which is 100 or so lighter, with a th 350 but a little tighter stall to compare... Oh yeah, a carb as well.

Then throw the p600 on with some 116 and see how much it makes, As roads are bad, racing is over and I need to tear something apart before I go nuts.

 

i own a dyno and i have to agree with you on this one. a dyno is a tunning tool. It only allows you to chart gians and loss's. i have a very nice dyno mustagn 1750 De with full load of sensors for TQ drive shaft converter slip etc and even its accuracy could be questioned occasionaly. one thing that might not occur to alot of folks is trans fluid heating and tq converter slippage on a dyno.converter performance can actually change a good deal over the course of a pull on a loading dyno. even a heavy intertia dyno can heat a converter up pretty good.

 

OK News flash!!!!
I have no Idea how this was like this nor for how long...
I used (2) intake gaskets stacked in order to line up ports better
instead of waiting for a double thick 1205.

Look what happened,
Its weird ir ran as well as it did, And believe me - you could not tell driving. And o2 bung is on opposite side - But I had just welded one in the passenger side for mine and the Dyno WB.

Here it is, my camera sux - hope they are clear enough.

 

This happen on both 2/4 and 6/8 ports, the gaskets went opposite ways of one another, though its hard to see.

 

thats why i always use weather strip adhesive on one side of the gasket.

 

I stopped using it cause its a MF'er to clean. But effective.

 

Clean and torqued are the key words.
It never amazes me watching how guys crank down on nuts, and bolts going way over spec..

Not saying anyone around here is quilty, just an idle observation.

Might inventory a couple sets of the correct gaskets.

 

That is crazy Man, there was sooo much left in that combo.

 

Huh... I guess once the speed in the intake runners/ports picked up enough it mustve just started pulling air from the adjacent runner and going lean at times.

 

That isn't as bad as it looks.
If it's just cross talking between ports it wouldn't change the tune drastically. Be glad you caught it before it pulled in from the crank case!

 

Actually when removing I noticed a couple were loose, I always re tighten, but with duel gaskets it must have compressed alot more over the years.

 

I have to inspect gaskets tomorrow, it looks like 6/8 had alot of oil residue around walls, Unless it was just rich suit.

Did not have alot of time, as G/F was yelling "we have to leave"
Will look more tomorrow when I finish unbolting and pull engine.

 

I hope,
Don't tell chris

 

doubling up gaskets???? I guess you got lucky that the coolant port wasn't leaking into any cylinders.
It looks like larger injectors are still needed.