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Dyno Results

wombat

Full Member
Joined
Nov 23, 2002
Messages
159
Location
Jonesboro, AR
Well, I took the Av for a few pulls on a DynoJet this afternoon.

I wasn't too impressed with the numbers I came up with at first, but after searching through some old threads and finding out that the losses through the drive train are quite substantial on the beast maybe the numbers are not too bad after all. Still, I've spent a reasonable sum so far for such a small gain... :-[

The best run of the 3 came up with 235.4 hp and 253 ft-lb.

I really wish I'd had the sense to get some stock numbers but at the time I hadn't planned to go crazy with the performance mods.

I know I still have a little room for improvement as the Predator is still not tuned optimally... and I also think the guys there were kinda rushing things just to get me in and out...

Of course, that Radix is still tapping me on the shoulder... >:D
 
Did you dial in the fuel while on the dyno with the predator?

Headers will make it run rich, and the predator base tune was not tuned for headers. ?You can get a bit more power if you lean it out. Headers=more air flow=O2 sensor seeing lean= PCM dumps in more fuel=Rich condition......Scott
 
NightOwl said:
Did you dial in the fuel while on the dyno with the predator?

Headers will make it run rich, and the predator base tune was not tuned for headers. ?You can get a bit more power if you lean it out. Headers=more air flow=O2 sensor seeing lean= PCM dumps in more fuel=Rich condition......Scott

Didn't get to play much with it... like I said the guys seemed to be in a rush to get me out. It was close to quitting time and they seemed to be pre-occupied with the valve job they were doing on a '02 Z06. I'm not too concerned about it as I'm still not finished with the upgrades anyway.

Actually though, the AFR was indicating lean up to about 4400 rpms and then it was looking only just slightly rich above that.
 
Leaning out your mixture is not the correct course of action here. If the sensors are seeing things a bit leaner, it is because it is leaner with the headers. The PCM should be trying to richen things up.
 
Wombat,,,

Those are respectable numbers ... I'm sure you know that the Pred does not change any "closed loop" fuel mapping... only wot ...

These 5.3's are notorious for leaning out over time due to top end carboning ... If you have stayed on top of the motor's cleanings (like a can or 2 of berrymans every 5K) then you should be clean and it's then probably the headers as steel said ... I would like to know what your LTFT's (left and right) were right before wot ... They need to be as close to zero for the best power right before the pcm goes open loop ... "Plus" numbers mean the pcm is adjusting for a lean condition, and negative means it's adjusting for rich ... The pcm has a target of 14.7:1 AFR during part throttle... If you are running lean, and the LTFT's are in the 10 to 12 range as you lay into wot, you have the potential for more power at wot... But if you are running in the 5-8 range, re-mapping the part throttle won't be worth it ... IMHO ... Which can only be done with LS1Edit ...

If you are gonna play with the wot afr, I would get autotap so you can see where you're at ... Too many variables on a dyno will intercede if you just jog the afr around and don't know other pertinent info from the pcm ... But hey, don't fret those numbers for the mods you have ... especially in the summer ... tit for tat, you would smoke my av ... >:D

11H
 
Wombat

With the MODS that you have already done to the engine, surprised that you haven't changed out the rocker arms to performance grade, something like the SLPs 1.85, as I have seen on some earlier posts...
dichris
 
It was confirmed for me by James at RWTD that the predator indeed does effect part throttle fuel mapping and timing (Could he be wrong). ?That is why most of us who have a Predator feel a positive change from off idle to cruise (they changed something at lesser throttle positions,as user who tried 87 octane gas got part throttle knock retard, at a minimum they bumped the timing), that you will not feel with a Hypertech with its 75-85% throttle position settings. ?I know that I could feel a difference the first time I stepped on the gas. Did not feel that with a Hypertech.

A Quote from James: "Also, it seems many people have been spreading rumors about our tuning and attempting to state things that are untrue. First, our tuning tunes at ALL throttle positions throughout the entire rpm band, and at all throttle positions. We tune for optimum driveability, and safe maximum performance".

Thanks, Scott

P.S. They fixed the 1-2 shift issue on the Predator!
 
It was confirmed for me by James at RWTD that the predator indeed does effect part throttle fuel mapping and timing (Could he be wrong).

No he's not wrong... I re-read my sentence... Sorry it was spoken a little wrong... The Diablo Predator DOES change part throttle timing/fuel mapping... BUT it is a "canned" performance tune and not adjustable... It can only be re-written by diablo or an authorized diablo tuner (like james) ... Then his customized "tune" can be uploaded in place of the original "tune" that came with the unit...

Also, just as an fyi, Hypertech "used" to adjust partial throttle settings for timing and fuel back when they had a disclaimer on the box that said "for off road use only" (like in '96/'97)... When they got soo big, that didn't cut it anymore ... This is my opinion, but if diablo gets big, they may not be able to get away with the "off road use only" disclaimer in their manual ... That "emissions legal" certification may become an issue when you become a big player ... IMHO ... So for now, Diablo is the one to get if you value the part throttle tuning ... >:D

*** At the user end, Air/Fuel ratio and timing advance can be adjusted but only at wide open throttle ... (Open Loop) ... You can add timing or add fuel in the advanced feature set, but it won't impact partial throttle at all ... ***

Sorry for the mixup--- I should have spoke clearly...

11H

p.s.

NightOwl, you mentioned above that someone ran 87 octane with the pred and "bumped the timing" to get rid of partial throttle spark knock? ... How is that when the user adjustable timing feature only changes wot settings? ... I'm glad they ironed out the 1-2 shift ... That's a big reason why I sent mine back ... What is the software version with that update?
 
11H- any idea what is causing the carbon issue on these engines?

?
What I meant was: it is obvious that the predator effects part throttle closed loop or you would not get a knock at part throttle with lower octane gas. Not that you can adjust part throttle timing.

The 1-2 shift issue was my main concern prior to purchasing the predator. The version is still 1.03, but as James told me they corrected the shift issue in the current version. ?As he said "it was a problem". ?A member of this forum stated sometime back that he had the 1-2 issue with v 1.03 and he downloaded a new file and the problem was corrected. ?They have now changed the program in the shipping v 1.03 to make this correction. ?I can tell you it shifts firm and sharp at WOT from 1-2. ?James said they tweak the canned programs as they find issues, kind of a running change. ?Since most of my driving is not at WOT, I was more interested in the predator that effects off idle and cruise, you know what I mean? ?
 
dichris said:
With the MODS that you have already done to the engine, surprised that you haven't changed out the rocker arms to performance grade, something like the SLPs 1.85, as I have seen on some earlier posts... ? ?
dichris

I can tell ya, the thought has crossed my mind on numerous occasions... I'll probably end up with 'em sooner or later... The headers made the exhaust note quite a bit more "noticeable" - and these things are supposed to change it even more... >:D

I actually came this close [picture thumb and forefinger about 1/8 inch apart] to trying to send the Predator back for credit on a Radix, but I really need to hold out for now. Maybe later this year or early next.

My Eaton posi and gears arrived yesterday and I need to see about getting them installed next week. I can't wait to see what sort of difference that makes after I get 'em properly broken in.

I'm really wanting to go to some kind of electric fans, whether they be Flex-a-lite or second hand LS1/LT1 fans or whatever. That'll most likely be next on the list.
 
11H said:
Those are respectable numbers ... I'm sure you know that the Pred does not change any "closed loop" fuel mapping... only wot ...

I only realized they were reasonable numbers after reading one of your older posts... Yes I've come to understand the Predator's limitations. I contemplated LS1Edit and EFILive but I didn't want to have to mess around a whole lot at first. The Predator gets me up and running with minimal fuss.

11H said:
These 5.3's are notorious for leaning out over time due to top end carboning ...

Would this explain why I saw quite a bit of carbon deposits on my plugs when I pulled the Direct Hits?

11H said:
If you have stayed on top of the motor's cleanings (like a can or 2 of berrymans every 5K) then you should be clean and it's then probably the headers as steel said ...

I may have to look into this.

11H said:
I would like to know what your LTFT's (left and right) were right before wot ...

The next chance I get to "play", I'll try and check it out.

11H said:
If you are gonna play with the wot afr, I would get autotap so you can see where you're at ... Too many variables on a dyno will intercede if you just jog the afr around and don't know other pertinent info from the pcm ...

Yep, I've already figured Autotap or EFILive would be a worthwhile investment. I would just need to get a new battery for my laptop...
 
I probably should have tried to condense all my responses into one post... Oh well...

NightOwl said:
The 1-2 shift issue was my main concern prior to purchasing the predator.

...

They have now changed the program in the shipping v 1.03 to make this correction. ?I can tell you it shifts firm and sharp at WOT from 1-2. ?James said they tweak the canned programs as they find issues, kind of a running change.

Well I don't know if my Predator has the "fixed" 1.03 tune, but I can tell you, that with the shift kit and Corvette servo installed and the Predator, the shifts are all quite impressive - certainly way better than stock in my opinion.
 
Carboning? We don't need no stinking carbon !

I have no idea... Neither does the GM hitters here ...

(i.e. Both service managers, area Rep., and shop foreman with 15 yrs driveline experience... And that's just one dealership... LOL)

But, I will share my observances about the issue since I have had 3 5.3's and one 4.8 , and have tinkered with them a lot ...

Some of this is speculation but if you connect the dotted lines they make sense...

I have known for some time that the new vortecs burn oil... Some a qt every 3K and some a qt every 1K ... All the guys I have talked to that burn bad (not blue out the tailpipe/pcv valve fix guys) babied their trucks the first month... I have had 4 of these motors and have ran them hard on accel and decel the first 50 miles or so, (NEVER RED-LINED THOUGH) and not a drop until my avalanche (it burns 1 qt every 3500 or so, but I haven't tried the pcv valve fix yet) ... I learned that the first 20 minutes of run-time (after cam run in) on motorcycle motors that you have to load the rings fore and aft using the cross-hatched honing of the cylinders as an aid to good ring sealing... Rings and bores cannot be perfectly mated 100% and that roughness will "mate" the surfaces ... I have seen guys baby their bikes and they have filthy oil in no-time due to the blow-by ... Also, when the piston goes upward, it draws some crankcase gasses with it, and if the ring seal is not good, it will "draw" some of this into the combustion chamber... This theory along with the rumor that GM has poor bore concentricity and piston slap leads me to believe that if you have poor ring seal, that it's not just fuel you are burning in the cylinder...

So, in short, it may be that if you have a ring seal problem that has excess tolerances, a light and easy break-in that didn't seal the rings 100%, and have to get de-carboned every 20,000 miles, then you might be an oil burner at the same time... A parallel may be drawn... The hard part to nail down is the fact that people need the decarboning at various times... What IS a given is that there is noticeable "piston slap" when the de-carboning is done because it's part of the "cold spark knock" TSB ... Truck is knocking, technician performs TSB by decarboning top end, and knock goes away for another 20,000 or so (on most trucks...lol) ... What gives?

Is it a carboning issue? Or is it a reverse blow-by issue? ... I couldn't tell ya ... But it makes you think ... Remember the older 350's? like the LT1 vette and camaro? ... You never heard of these buring oil or carboning up did you? ... Heck no... I pulled down a LT1 with over 100K on it and the rings were mostly shiny and the piston skirts weren't scuffed hardly at all... They had hypereutectic pistons and short lands too... But never "carboning" bad enough to alter a/f ratios ...

I will say that I have never believed that the plug wires on the new engines could be improved upon... But I'll share a story...

My avalanche has had what has seemed to be a wrist pin clatter on one cylinder when I listened through the driver's wheelwell after it was hot ... It came in and out intermittently ... I started listening to other 5.3's at the service drive, on the street, and anywhere I could... The all did it to some degree... I replaced my wires with Taylors about 5,000 miles ago... When I pulled the plugs, the ground electrode was black with carbon, but the center and insulator was pretty clean... I just pulled my plugs after 3K and the whole insulator, ground electrode, and bottom 2 threads are clean... The whole plug is white except the bottom 2 threads... And guess what... No more knock in the well when hot ... Is this coincidence? ... Uhhh ... I'll say that the oem wires are at about 600-750 ohms/ft ... and the taylors are 50 ... With the performance increase I felt going to new wires and the lack of knock, I am willing to bet a soda that the new wires are providing a better burn in the cylinder than before... Now, take a cruddy oem wire that starts new with 700 ohms resistance and add 20,000 miles ... I think you get where I'm going...

I will say, that I have ran this passed the guys at the dealership and they have all installed new Taylors on their trucks... (almost all)... They all comment that the 5.3 has no more lag on bottom and the response is better... I'm waiting to see if they need decarboning in the future... I guess in my wholly nuts brain of mine, that the increased ignition intensity may help burn "whatever" is getting in there that can at times cause buildup...

I am no longer running berrymans every 3K in the gas, and my truck runs beautiful at idle ... I used to be able to see and feel the choppy idle after about 3K and no berrymans... I would run a can through and the truck was back to smooth idling and snappy performance... This is coming from a guy who can feel a gnat hit the windshield... LOL... Call me crazy, call me whatever... But you asked, and I gave my outlandish slant ... :eek:

11H
 
I have always had a gut feeling that it was oil burning causing the carbon issue. ?I run redline 5w-30 because of its high easter content and its higher flash point. Also its high Moly content will plate the cyl. walls and increase ring sealing. ?I have less than 10K and it uses no oil what so ever. ?And I did baby my engine, changed oil at 500K - 1000k and 3000K. ?

The only engine noise I have is during a warm restart, passanger side wheel well, sounds like a lifter bleeds down and ticks for about ten seconds or so. ?Did I read someplace about a lifter bleed down issue on some 5.3s? ?I replaced the oil filter with a K&N filter that has about the best flow rate of any filter and it did shorten the amount of time of the ticking. Have you any info on this type of ticking? ?

Thanks, Scott
 
I can see now that if we work the same hours we're gonna be dangerous... Hope gandolphxx is ready for the increased activity... LOL

To address the lifter... I was a mobil 1 fanatic for years ... All of a sudden Castrol wins a big battle as to what the industry defines as "synthetic" ... They win, and the whole industry has gone from either poly or ester to group II or II+ base oils and have been calling it syn... Now that Exxon owns Mobil and after this whole Castrol thing, I saw their Flash point numbers fall from 470 to 450 ... Some lube insiders think this meant a fall in base oil quality with their supersyn line ... Bye bye M1 ... I now use Chevron 10W-30 which has a 450 Flash and a low -33 pour point... All their specs match new M1 close to a T ... With the new GF-3 requirements closing the gap on true syns and the fact that they have closed the gap on the "wanna-be" full syns, I'll pay $11.33 a case and change every 3,000 thank you ... But Chevron has no moly as does Pennzoil or others ...

I have been an RP fan for a long time too until I had a lifter start making noise at cold start for about the same 10 seconds... I switched back to (old) mobil 1 and it went away ... I haven't used it since... I have been using the good old chevron (great specs) and a product called Militec... It has given me "better ring seal" and a 2% or so dyno increase with a friend's Camaro... (same as RP 21) ... I have done extensive research on Militec and have gotten to know the owner Brad G ... The govt. uses it on many levels as a friction reducer... It contains no solids, ptfe's, or marketing wizardry ... The guy is rich beyond belief and is riding on a reputation started in 1988 ... I have been using it in my vehicles for a while and it's awesome... I know an engine builder who uses it on V12's and will never build an engine without it... Check it out some time...

http://www.militec-1.com/

I know RP has some moly in it... I don't know why it would affect a lifter though... Maybe try some conventional oil for 3K and see if it goes away... ???
Mine did...

I don't think your ticking is filter related... Although I would use a PF-59 (blue) or the gold or silver version of the PF-59 ... It has an anti siphon design that holds a quart or so inside the motor for start-up ... I've pulled one apart and it is different from a couple aftermarkets which don't have the valve... The old '99 filter recommended was the PF-58 which had no anti-siphon and it caused warm motor knock ... Might try that ...

11H
 
Wombat, those are good numbers but I was hoping that with all you have done you would be higher in the 3's. I would expect the headers and Programmer to give you at least 350 alone. Maybe I'm expecting too much.

This raises a concern of mine. Now that I'm done with the exterio I am at the beginnings of my Performance modification program. Considering Bang for buck, you get more Horsies for the dollar out of a Kenn Belle blower alone than the amount you get from Headers, Exhaust, FIPK, Programmer, TBS, Direct Hits, and Electric Fan together.

The only thing is that $400 here and $500 there is a lot easier to swallow than dumping $4,000 + in one shot.
 
Powersurge said:
Wombat, those are good numbers but I was hoping that with all you have done you would be higher in the 3's. I would expect the headers and Programmer to give you at least 350 alone. Maybe I'm expecting too much.

This raises a concern of mine. Now that I'm done with the exterio I am at the beginnings of my Performance modification program. Considering Bang for buck, you get more Horsies for the dollar out of a Kenn Belle blower alone than the amount you get from Headers, Exhaust, FIPK, Programmer, TBS, Direct Hits, and Electric Fan together. ?

The only thing is that $400 here and $500 there is a lot easier to swallow than dumping $4,000 + in one shot.

I wouldn't expect too much from all that I've done. I had initially hoped to see around 270-280 rwhp, but that was before I found out a stock Av probably puts out no more than 205 rwhp. The important thing to note is that I've added the extra power without really affecting my gas mileage (except for when I'm preforming my WOT tests ;D).

Sure, the bang for the buck is not as good as just going FI, but I'm interested in the total package... all of what I've done so far is just preparation for the SC. >:D
 
Wombat said:
The important thing to note is that I've added the extra power without really affecting my gas mileage


but I'm interested in the total package

That's a good point. Most of your mods if I'm correct advertise more HP's, torque and better fuel efficiency.
As far as the total package you mentioned your right there also. It's a lot more fun to add something here and something there than dumping a blower into the truck and calling your performance modification plan complete.

You've done good!!
 
A small thought from a trans-atlantic perspective. . .NOS can make 150hp on a 2500 for about $600. Now THAT is bang-for-buck!
 
Wombat-

I thought I'd offer a little info which might help dyno-testing your AV. Once upon a time, I operated a DynoJet inertial rolling-road dyno. It was a pretty cool piece of equipment, but the software was truly awful. Here's what we learned:

1.It was vitally important to run the same kind of session with a vehicle each time if we were doing back to back comparisons. We usually tested race cars which had no thermostats, and this made it very difficult to ensure constant water temps, but we had to do it. a differnece of 20 deg. F in operating temp at the beginning of a dyno pull made a lot more difference than changing wires or filters or sometimes even carb jets.

On an AV, it would be much easier, just make sure the truck is at normal operating temp before you begin (that's water temp) and let it sustain that for a few minutes to get the oil temp up to match. A quick drive around the block after the water reaches temp should do it, then strap it down to the dyno. Start all your sessions this way. If you did one "cold", that one would show different numbers, and that would hamper comparisons.

2.The next reason to do the drive-around-the-block is that since the dyno is reading rear-wheel horsepower, not only is there driveline loss, but that loss is also variable. Rear-diff fluid viscosity varies with temp, too. It's harder to push the gears in a cold diff, usually. This was also hard to manage on the race cars, since they all had diff coolers. What a headache! Tires work the same way, always check the pressure, make it the same every time. Do the rear brakes drag? there goes some HP.

3.There is one thing which can help, though! The DynoJet, at least, has a driveline-loss-measurement function. The operator *should* know how to do this. At the "top" of a run (the really scary part), the truck is shifted into N and the whole thing coasts down from speed by itself. Your operator should know if there are any contra-indications to doing this on an AV.

What this test gives you is the friction at speed of the tires, axle and driveshaft. If this changes, you can factor your result by it to correct them. Change tire type to one with less or more frction? Do this measurement, and then you can make all your results match.

On a rwd manual-trans car, you can do this test by just putting in the clutch, and then you get to measure the actual coast-down friction of the entire driveline. Using this, we could get pretty darn close to engine-dyno numbers, which was a good way to check ourselves. Almost ever vehicle of this type with street or road-racing tires had right at 20% loss, and we never saw even a slight difference in changing lubricants, unless we went down drastically on viscosity. (just like you'd figure.

Hope that helps!
 
Welder,

Bravo ! ... The Dyno shop my friend owns does most of the things you mention to try to ensure consistent runs... Another thing that is really important is alignment on the rollers... If the car is not at a perfect 90 degree angle to the rollers, then there is "more" loss...

The coast-down in neutral from what I have been told is largely dependant on when the operator gets off the gas ... I don't know... But it sounds like a good way to assume the loss percentage !

Also, you mention the properties of the Dynojet ... Just something to add: Running in a higher gear will net a higher HP number ... 1st gear vs. 2nd gear (or even 3rd) ... inertia "averaging" or something like that is how the dynojet works ... Running a 5.3 2wd in first once made 192 RWHP, and running in 2nd made like 214 RWHP ... No one has been able to explain why the DynoJet works this way in terms I could understand ... Maybe the inertia of the driveline shows up with less loss in a higher gear ? ... LOL

11H
 
Oh, good point, the 1st vs 2nd vs 3rd gear thing!

One thing to keep in mind is the fact that the additional reduction of 1st gear in the transmission (along with additional shaft deflection, etc., will be coupled to additional friction losses. But...not that much, one would think.

Also, and this would take somebody with a lot more smarts than me to figure out, there is the torque-convertor issue. Without some aftermarket programming, we can't get convertor-lock-up under full throttle (right?), so we are fighting those losses as well. When we hit the gas, pressue inside the convertor rises between the vanes, and stores energy (most of which is then lost, it's not a rubber band)and a dyno reading taken at that moment is wildly inaccurate. This condition improves somewhat over the next seconds. Does this account for some of the loss in 1st? Maybe at the very beginning of the run, but surely things have stabilized by the top of 1st.

Hmm. I have a good buddy who's a calibration engineer at GM (got any tough question?), I'll ask him.

Oh, a P.S., when we used to test race cars (we did many, many more race vehicles than street cars -that's where most of my experience is) with manual trans, there was *very* little diference in the different gears, although it was always less in the lowest, and very similar in 3rd-6th. We surmised that this was due to shaft and joint deflection causing mild binding and friction losses in 1st, as well as a little tire slippage.

 
The results I posted at the start of this thread were obtained in 2nd gear. The first run they tried in 3rd but they ended up hitting the speed limiter (raised to 125mph) before hitting the rev limiter...

And something just occured to me... how does the traction control know when the wheels are slipping? I don't recall whether they turned off the traction control. I would assume that if it were on, then the vehicle might think the rear wheels were spinning while on the dyno? I would also assume they were knowledgeable enough to know to turn it off? Would definitely result in some tainted results...

Hmm...
 
Welder,,,

I don't know of a single (oem or equivalent) converter that will lock-up under wot in any gear ... There might be something to the converter and torque multiplication or something...

It was explained to me a while back that the greater the driveline loss, the greater the difference between a low vs. high gear run HP measurement ... I think it has something to do with the Dynojet's accel averaging over time design ... (think that's spoken right)

Example: ?A Z28 LT1 with an A4 and 4.10's will show less peak HP than the same with 3.23's ... The curve is different too ... Now we're talkin the same tranny here, same motor ... The LT1 may like a shallower gear better and hang on to it's curve longer ... ??? ... The 4.10 spools and tops faster, but it's HP in that app is usually lower ... Hmmm ... Is it physics? or is it Dynojet ?

I got a headache ...

11H
 
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