# Dyno Numbes



## michaelskier (Aug 29, 2005)

*Dyno Numbers*

Had my first Dyno and tune today. Stock with a few bolt ons - exhaust and cai. Rolled in about 2PM, 83 degrees outside and a fully warmed up motor after driving an hour in traffic. Dynojet model 248C - Put down RWHP SAE Corrected *335.4* and *323.6* Torque on the first pull. 

Then had an 'LS2 edit' tune done. Put down *352.9* HP and *348.3* Torque after the tune. Does this sound good for the mods I have? Does anyone have any numbers from a totally bone stock GTO? Unfortunately, I did not dyno mine before I made my first mod.


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## dealernut (Oct 22, 2005)

Bring me THE SHEETS!!!!!!


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## YLRGoat (Jun 19, 2005)

Had my 1st Dyno at 300 miles, Bone stock....338HP/340TQ.......
added CPE CAI, X-pipe, & mufflers....Dynoed again 352HP/349 TQ....
Then had some tuning done @ 2500 miles........
365.61HP/362.11TQ.....all on the same Dynojet...

Tuning is the trick


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## Guest (Nov 24, 2005)

now yall just need to add the "right" cam and get into the low 400 range.


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## michaelskier (Aug 29, 2005)

So it seems my numbers may be a bit low?? They told me different dynos will give slightly different numbers and also that if they did a pull with the motor much cooler, then I would see better numbers.

Why is the flywheel HP only coming out to be about 402 after all this when it is supposed to be 400 from the factory?


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## Guest (Nov 24, 2005)

NO two motors from the factory will produce the exact same result and NO motor from the factory will ever make what its rated at. You got 2 extra hp and your worried?


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## edysinger (Nov 23, 2005)

_NO two motors from the factory will produce the exact same result and NO motor from the factory will ever make what its rated at. You got 2 extra hp and your worried?_

This is true, and there are governmental guidelines the variance has to be less than 5%. I've heard GM's internal goal is 3%. And yes, GM does have to prove it as well.


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## Guest (Nov 24, 2005)

almost every motor will make more than its rated at too.


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## michaelskier (Aug 29, 2005)

The 2 extra is after all of the mods I have done. Was asking because I thought they should be around 400 before any mods-am I missing something. All of this Dyno stuff is new to me.


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## Guest (Nov 24, 2005)

18% drivetrain loss for a manual puts you as follows:

you dyno at 335.4 and make 409.02 at the motor
you dyno at 352.9 and make 430.37 at the motor

you take your dyno number, divide it by .82 and arrive at your motor horsepower level.


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## 6QTS11OZ (Mar 27, 2005)

If you figure 15% drivetrain loss for the 6M, your results should put you right at 415 crank hp.


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## Guest (Nov 24, 2005)

15% thats pretty efficient! Most of the f-bodies were at 18%.


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## michaelskier (Aug 29, 2005)

Ah, there is the discrepancy - They have a stamp at the bottom of the dyno sheet where it says 12% drivetrain loss for a manual and 18% for an automatic.


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## Guest (Nov 24, 2005)

TWELVE ????????????????

oh come on, aint no rwd platform THAT efficient !!!!


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## michaelskier (Aug 29, 2005)

So after peeling the onion, the question emerges - What is the true drivetrain loss for the 05 GTO M6??


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## Guest (Nov 24, 2005)

Nobody knows for sure unless they yank the motor, dyno it, then put it back in the car and dyno again.


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## michaelskier (Aug 29, 2005)

Thanks for helping out, man. You have been very insightful on several of my posts. Appreciate it.


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## Guest (Nov 24, 2005)

its why I am here. To be as much help as possible.


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## Nemisis (Nov 4, 2005)

Your numbers seem pretty decent to me. I put down 330/333 with cai before tuning, after tuning was 356/363 with 900 miles on odo. I've also been using 18% for drivetrain loss, I saw that gmhtp used 13% but I thought to myself there's no way if that was the case, I would only be making 409 at the crank after tuning, cai. Someone was telling me about a magazine article where they took a ls2 from a gto and put the engine on the dyno and it made 430hp, they didn't say what mag it was though.


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## Doc GTO (Nov 29, 2005)

big_mike said:


> 18% drivetrain loss for a manual puts you as follows:
> 
> you dyno at 335.4 and make 409.02 at the motor
> you dyno at 352.9 and make 430.37 at the motor
> ...


From the research I've done the T56 has a 12% loss and the 4L60 is 18%.

Although, dynos do not win races! Take it to the track!


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## 6QTS11OZ (Mar 27, 2005)

Doc GTO said:


> From the research I've done the T56 has a 12% loss and the 4L60 is 18%.
> 
> Although, dynos do not win races! Take it to the track!


That is true. But the loss is measured through the entire driveline not just the trans.


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## Guest (Nov 29, 2005)

SOMEBODY needs to rip their motor out, dyno it, stick it back in and chassis dyno it.

Well, two people actually, one manual and one auto.


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## Doc GTO (Nov 29, 2005)

6QTS11OZ said:


> That is true. But the loss is measured through the entire driveline not just the trans.


Yep. That was the loss measured by MTI in Texas for the entire drivetrain. I just said T56 to make the diff between the M6 and A4. Sorry for the confusion.


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## gameover (May 13, 2005)

big_mike said:


> 18% drivetrain loss for a manual puts you as follows:
> 
> you dyno at 335.4 and make 409.02 at the motor
> you dyno at 352.9 and make 430.37 at the motor
> ...


If that's the case then I'm over 455hp at the crank! arty:


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## Guest (Nov 29, 2005)

ok, I have been corrected. an AUTO is dyno / .82 and a MANUAL is dyno / .88

So I learned something.


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## 6QTS11OZ (Mar 27, 2005)

Doc GTO said:


> Yep. That was the loss measured by MTI in Texas for the entire drivetrain. I just said T56 to make the diff between the M6 and A4. Sorry for the confusion.


No problem :cheers


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## Guest (Nov 29, 2005)

I dont know about yall but everytime I see that sig pic, I feel like I should just PUSH the car into the garage, like its a big button! lol


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## michaelskier (Aug 29, 2005)

MTI is who did my dyno numbers and tune, and as I stated in my first post, they had their stamp at the bottom indicating .88 for manual and .82 for auto. to calculate flywheel HP. So that means I am *barely* over 401 at the crank now and was less than 400 bone stock.  They didn't seem too concerned and said that the factory numbers on a motor are usually on the high side for marketing purposes - they take a motor they build for testing and dyno it while it is cool and try to get optimum numbers from it.


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## wile2k (Oct 29, 2005)

michaelskier said:


> They didn't seem too concerned and said that the factory numbers on a motor are usually on the high side for marketing purposes - they take a motor they build for testing and dyno it while it is cool and try to get optimum numbers from it.


I don't really buy that line. On an engine dyno, I'm betting that the LS2 puts out what it should. I think the problem lies in the chassis dynos used to arrive at RWHP. It seems no two are the same and no two operators work them the same. You can get different numbers based on what gear you dyno in, you can get big differences based on letting the car cool compared to hot lapping it, etc. Ever compare dyno numbers from a mustang dyno compared to a dynojet? There are several dynos around the country known as "heartbreaker" dynos because the numbers they spit out are way lower than others.

IMO, a dyno should be done before any mods are done to get a baseline, then re-dyno (on the same dyno, same gear etc) after the mods to arrive at an increase / decrease to judge the mod on. 

I also do not buy the 12% drivetrain loss, I think that is optimistic. Assuming a dynojet, most of the '05 guys are getting 335-345 rwhp. Again, assuming 400 is correct at the crank then that would indicate about 15%, which is a pretty common approximation for the M6. 

To the OP, I'd suggest just looking at the before and after numbers and being pretty happy with the gain. It is just too hard to compare numbers across so many variables.


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## michaelskier (Aug 29, 2005)

I tend to agree with this and have felt happy with the gain acieved. MTI also mentioned some of the same things you did with regards to dynos being different. Just wanting to understand better and see what others are experiencing. Unfortunately for me, I do not have dyno numbers when the car was completely untouched bone stock, but I have these before and after numbers now and will stick with the same place if I do anything else.


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## Holden (Sep 10, 2005)

michaelskier said:


> I tend to agree with this and have felt happy with the gain acieved. MTI also mentioned some of the same things you did with regards to dynos being different. Just wanting to understand better and see what others are experiencing. Unfortunately for me, I do not have dyno numbers when the car was completely untouched bone stock, but I have these before and after numbers now and will stick with the same place if I do anything else.


I know this is off topic but I have tried PM you Do 265s fit on rear without any mods? I was wanting to use 265/35/18 45 offset?
Thanx Dave


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## Guest (Dec 2, 2005)

big_mike said:


> almost every motor will make more than its rated at too.





big_mike said:


> NO motor from the factory will ever make what its rated at.


...

K I am confused LOL.... :willy: arty:


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## Guest (Dec 2, 2005)

basically I am saying if its rated at 400 it wont ever make that, it will always make more. understand?


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## Guest (Dec 3, 2005)

big_mike said:


> basically I am saying if its rated at 400 it wont ever make that, it will always make more. understand?



ahh k gottcha... :willy: arty: whootz 402 FTW !!!!! LOL


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## Thony216 (Sep 20, 2005)

It may make 400 in the Vette, but unfortunately I think the LS2 has a little less than 400HP as installed in the GTO - because of it's more restrictive intake plumbing, and possibly the crappy factory PCM tune.
According to some calculations I have, the GTO should trap at about 109 MPH @ 77 deg ambient - to be making 400 Net HP. I think it's actually making only 375-380 HP with the factory tune.


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## rushhour (Aug 3, 2004)

As stated - lots of variables when looking at Dyno numbers - so extremely hard to tell one way or the other.

That is why I depend on track times to see if I am going in the right direction. 

Case in point - dynoed my car on a hot (95 degree & 90% humidity) afternoon on a portable dyno @ ETown after a 45 minute drive - with no downtime. The numbers were depressing - 282 hp & 316 tq. This is on an 04 -A4 that historically was hitting mid to high 13.5's & 102+ at the track. Go figure. A few weeks later - I hit a 13.36 @ 104.77 and then a 105.17 - granted the weather was cool. But even corrected for temp & barometer - it was a 13.5 and 104 ( I always look at the corrected numbers - the only way to compare runs - this way the only variables are the driver & track surface).

So what should I believe? I think I will take the drag times over the dyno. No way that dyno number makes the 1/4 figures.


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## Guest (Dec 4, 2005)

my point exactly in another thread. My old camaro made 285 at the tires, 12 more than stock, and ran [email protected], which was .8 and 2mph faster than stock. HELL of a gain for only 12hp on the dyno.


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## rushhour (Aug 3, 2004)

Yep - way to much faith put into dynos. They are just one item. 

Better to run the car in the 1/4 then correct the numbers for altitude, baromter, temp & humidity.


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## rushhour (Aug 3, 2004)

For you guys that want to look at corrected 1/4 miles times - heres a good web site

http://www.modulardepot.com/density.php


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## Guest (Dec 4, 2005)

rushhour said:


> Yep - way to much faith put into dynos. They are just one item.


In all honesty, a dyno is used for tuning only. Its not really meant to do anything other than tune or brag about. 

Dont you agree?


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## rushhour (Aug 3, 2004)

big_mike said:


> basically I am saying if its rated at 400 it wont ever make that, it will always make more. understand?


 :agree Ford learned this lesson a few years back with their Cobra's if I rememebr correctly. They got their a*ses sued for over estimating the hp. So nowadays - everyone's HP figures are the minimum that can be expected - normally higher.


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## rushhour (Aug 3, 2004)

big_mike said:


> In all honesty, a dyno is used for tuning only. Its not really meant to do anything other than tune or brag about.
> 
> Dont you agree?


 :agree Yep - I use it mainly to look at my A/F over the rpm range and to check that nothing funky is going on. 

Love guys that tell me how much hp they are making - especially when all they see is my tail lights.  Just like when people take the mag articles as gossple when it comes to times.

I am taking the car back in a week or so to double check my A/F - should be hitting 12.9 now, was at 12.1 before.


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## Guest (Dec 4, 2005)

isnt stoichiometric 14.7:1 ??? Why so lean?

Also, there was a guy named David Chernicoff that had a LT1 TA with a ProCharger running 17psi. He was not on a stock block but on the day I was at the dyno, he layed down 617rwhp! Went to the track the next day, ran a best of [email protected] That is a 10 second MPH if he could have used all that power. So all he could do is brag about his power, but in no way able to use it.

Why not? He was on a stock 7 5/8 rear, 3.73 gear, and 275-40-17 street tires.

All that money for motor, and left the rest of the car alone. *hangs head in shame*


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## rushhour (Aug 3, 2004)

big_mike said:


> isnt stoichiometric 14.7:1 ??? Why so lean?


14.7 is stoichiometric - best for emissions - but not max power. Need to fatten up the charge a bit. 12.8:1 to 13.1:1 is considered best comprimise for HP & TQ. 

The problem with the GTO is that it is all over the place. Trying to remember if it starts way lean and then goes rich or the reverse - been a while. But it is no where near consistant.


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## Guest (Dec 4, 2005)

wonder if its just the LS1 or the LS2 also.

And, correct me if I am wrong, but the lower the number, the leaner (less fuel) the programming. You mentioned fattening it up. Just me being my observant self.


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## rushhour (Aug 3, 2004)

I always thought it was parts air to parts fuel. So 13.1 parts air to 1 part fuel. That is why the lower the first number the richer you get. 

Keep in mind the closer you get to 14:1 the bigger the chance of detonation.

That is why you see turbos & supercharger ratios in the 10.5:1 range versus 12.8-13 for NA motors. The FI motors need more fuel to stop detonation.


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## rushhour (Aug 3, 2004)

big_mike said:


> isnt stoichiometric 14.7:1 ??? Why so lean?
> 
> Also, there was a guy named David Chernicoff that had a LT1 TA with a ProCharger running 17psi. He was not on a stock block but on the day I was at the dyno, he layed down 617rwhp! Went to the track the next day, ran a best of [email protected] That is a 10 second MPH if he could have used all that power. So all he could do is brag about his power, but in no way able to use it.
> 
> ...


I saw the SLP GTO the first day it hit the track with their new 402 motor. Absolutely no traction. I don't if they did any better in the late afternoon (I left at noon) but I was doing almost as well as they were in the morning.


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## Guest (Dec 4, 2005)

Gasoline's stoichiometric mixture is commonly specified as 14.7:1 but the actual ratio varies as the petroleum fractions change with the seasonal blend. Engines are often run slightly on one or the other side of this chemically perfect mix. Fuel rich mixtures produce more power at the expense of hydrocarbon emissions whereas lean mixtures produce more nitrous oxides which are also pollutants. Most modern cars, for pollution minimization, use Fuel injection and an ECU (electronic control unit), rather than the older mechanical carburetor, to control the engine's air/fuel mixture. The ECU monitors the accuracy of the mixture with a lambda sensor placed in the exhaust stream. The ECU and Lambda sensor form a feedback loop to allow accurate adjustments to the stoichiometric mixture.


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## rushhour (Aug 3, 2004)

One of the problems I am now having is K/R - due to what appears to be winter formulated gasoline. Just started a few weeks ago. The extra oxygen formulation maybe driving the car over the edge every once & a while. I have started using only Ultra 94 and then putting in a bottle of octane boost to get it to 95 - just to settle it down. 

Nothing else changed on the car. So the only thing we can figure out is the winter formulation. Su*ks because I usually buy my gas from my brother inlaws Gulf station (so I get a break on the cost). Just the cost of high compression I guess.

Also putting it up on the rack next weekend - just ot make sure that it is not false knock from a loose exhaust - haven't heard anything - but who knows.


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## Guest (Dec 4, 2005)

all of my cars have had knock retard issues, I just programmed it out because it was easier to up the variable than hunt the culprit down.


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