05HD

I was relating the story to show you can't always believe a dyno number. I have seen the same dyno with the same operator read huge differences on the same day. Most especially on dyno dynamics machines. They require the most operator input and therefore have the most inconsistent results unless the operator is really paying attention and knows exactly what they are doing.

RealQuick

iTrader: (14)

I question the dyno because the third graph he posted of the stock motor'd LT1 with bolt-ons made peak power @ 5800rpm according to the graph. No way that will happen with the stock heads/cam. When i had full bolt-ons I made 301rwhp/338rwtq and peak power was pushed up slightly from stock to 5300rpm.

I say take it to the track and see how it does.

imaboa

Since you seem to know so much about the Dyno Dynamics, why don't you tell me what exactly the dyno operator has to enter that is so different from other dynos?

How many of them have you actually tuned on?


Since there seems to be so much concern about the dyno number, bring the car back to the shop, and I'll give you all your money back on the tune if it dynos over 300HP.

- John

05HD

Load and ramp rate are the two biggest operator parameters that make a difference and are not present as variables on something like a Dynojet.

I didn't keep track but I'd guess I have used about half a dozen Dyno Dynamics machines. Apparently, you haven't ever used any other dyno, judging by your assumptions and questions.

05HD

I noticed that as well. It is most likely that the dyno operator was using a wheel speed calculated engine RPM input and didn't have it matched up very well. Yet another factor that can introduce major errors on a Dyno Dynamics machine.

trilkb

iTrader: (4)

does it FEEL like it has 20-50hp less then a stock lt1?

This has me worried, i just did my cam swap, i literally stood 3 feet back and chucked my cam into the block (it went in perfectly of course), put my cam retainer on, since i hadnt moved anything on the crank side of the timing gear i put the timing gear on the cam, and did it dot to dot. there was no "degreeing" that i did lol. i figured the thing can only go in one way seeing as how it has a dowel pin that goes into 1 hole on a cam timing gear, which then you would rotate untill 1 dot lines up with another dot on the crank timing gear lol. (correct?)

I asked LE about degreeing during install, he said if you dont have a degree wheel just go dot to dot.

As there is very little play in a timing set, obviously there isnt many other ways that the timing chain can go on other then the way it has to go on, and the teeth on the gears are spaced accordingly with the lenght of the timing chain.

Maybe im just crazy, or maybe i just think its fool proof (which would also make me crazy), but wouldnt you have to be something other then "dot to dot" to make it effect power that much?

Then you have rocker preload affecting power? some people adjust them with the car running based on sound, so wouldnt you either be way to tight or you would hear tons of noise right? Being way to tight i could could possibly cause a valve not to shut all the way?

im not trying to hijack, im just trying to understand all this, since im in the middle of doing these mods myself.

imaboa

I work about half the week on the Dyno Dynamics, and the other half of the week on a big drum DynoJet.

If you use the "Shootout" Mode on the Dyno Dynamics, there's no making mistakes with the ramp rates or correction factors. All NA V8 Cars get the same ramp rate. The idea behind the shootout mode is to make the Dyno Dynamics Machines read similar from one location to the next.

As far as the roller speed referenced tach goes, it works well for cars that don't have slipping clutches, and any error you see in the engine speed reference is in an acceptable range, and wouldn't have drastically affected the tuning of the vehicle.


The RPM referenced tach number won't affect the power reading on the dyno. You can run the dyno with no tach reference, and use wheel speed only, and the power will be the same. Bring your car to my place, and I'll answer any questions about the Dyno Dynamics machine you have.

imaboa

Any updates from the car owner while we are busy hijacking the thread with dyno arguing?

05HD

And you haven't discovered the differences? Is this your first week?

Clearly, none of the dyno graphs posted in this thread were done in shootout mode.

So, which is it? It doesn't affect it or it doesn't affect it drastically?

Last time I checked, a DD machine was using this-> torque*rpm/5252=power to calculate power. Anyone with a calculator can tell you if you put the wrong rpm in that equation, you get the wrong power out. Only an inertia dyno (dynojet) is measuring power directly. Dyno Dynamics, Mustang and most others are measuring torque and calculating power.

Did you show him how to use the "cntrl-x" while he was there?

SS RRR

iTrader: (2)

No it can't. It is physically impossible since an auto has a fluid connection between engine and transmission. If what you state "... not intentionally" having anything to do with the tool behind the tuning software, then I agree.

imaboa

Dyno was in shootout mode. Email me, John@sixsigmadyno.com, I'll be happy to send you the dyno data to prove it to you.

I'm glad that you google searched and found the equation for calculating hp. Now, if you were to actually show up at the dyno you'd see that the dyno will still give you power numbers without an RPM signal.

There's no sense in arguing with you, you obviously know more than anyone else on the internet. Congrats.

ahritchie

iTrader: (1)

Sorry, no updates on the car. My friend/mechanic who helped me with the car got too busy to adjust the valves and do the compression test; hopefully we should get it apart this Saturday. If he's too busy again then I'm just gonna have to pay somebody because I don't know what the hell I'm doing adjusting rockers/valves (never done it before) and I sure as hell don't have a clue about doing a leak down test. It's really pissing me off in the meantime I spent so much money fixing up this car for headaches like this and 241 RWHP so believe me I'm as eager as anybody to get this **** fixed ASAP. Luckily I have my LS1 car for a reliable DD. And about all the bitching about the dyno....I'm inclined to believe the dyno; it's definitely down on power, it will barely scratch 2nd gear....I've had this car since 1997 so I know how it feels when running right; it would bark the tires on the 3rd gear upshift stock and hang with LS1 cars no problem...it's sluggish when compared back to back with my LS1 Firehawk. What would be a decent price for a valve adjustment and leak down test if it comes down to paying somebody?

iWon

iTrader: (13)

How does the car run otherwise? You're saying it runs and drives perfectly but is way down on power?

SS RRR

iTrader: (2)

If that is truly the case that usually means an intake/exhaust restriction of some sort whether it be crap heads or bent/kinked/poorly designed exhaust.

RealQuick

iTrader: (14)

Either that or the graph was misrepresented and it is really of a small cammed LTx.

ahritchie

iTrader: (1)

Yea, it drives fine, just gets shitty gas mileage (10-11 MPG) and you can hear the roller rockers kinda clicking like a sewing machine when driving....I don't know if that is normal or not for a LT-1...I know my LS1 roller rockers are as quiet as can be. One thing I forgot to mention is that when rebuilt with the cam I accidentally got the wrong roller rockers that I bought off somebody on ebay....they were for an old school small block or TPI motor apparently (the seller claimed they were for a LT1 and I believed him like a dumbass ) two of them broke and fucked up/bent to hell two pushrods a few months ago...the pushrods were replaced and I bought the correct expensive ($320) 1.6 Comp Cams Pro magnum rockers (lesson learned: do NOT cheap out on valvetrain!)...possibly something else got fucked up when my rocker arms broke suddenly? I've got to get this thing apart ASAP bottom line.

LT14LIFE JT

iTrader: (1)

If the rocker arms broke while driving/running then its a good possibility that some pistons made contact with some valves, bending them. A compression test will definately give you the answer.

RealQuick

iTrader: (14)

Did you inspect the lifters as well?

SS RRR

iTrader: (2)

Yeesh... there is no LTx specific rocker. Far more LTx characteristics are shared with a SBC than not. I'd suggest doing some heavy research...
This is a good start:

05HD

If you do it right, it says shootout mode on the graph. It doesn't say that anywhere here. Feel free to post up here whatever you want to email me.

Do you have any idea how the dyno you use works? This is from your own website: I never bothered using a dyno without the information it needs to do its job, just to see if it would still spit out some numbers.

Ok. Get lost then.