dyno numbers and other questions
Thread Starter
Launching!
Joined: Oct 2004
Posts: 214
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From: Chandler, AZ
dyno numbers and other questions In February 2006 I got my Z dyno'd with a FM catback, lid, SLP CAI, K&N. Made 305 hp and 312 tq (STP). This was on a Superflow dyno, in Camarillo CA (close to sea level), and I had switched the 80-series FM muffler out for a straight-through SUV single-in/double-out. No tuning was done; this was only to see what power the car made.
Yesterday I dropped off the car to be dyno'd and tuned after installing LTs and a ported TB. I also installed new NGK TR55 plugs since that was a good time to do that. This particular shop used a Mustang dyno. My before-tune numbers were 249 hp and 263 tq, and my after-tune numbers were 260 hp and 275 tq. This shop is in Chandler AZ, which is approximately a quarter-mile above sea level. This shop used HPTuners software to install the tune, and they said they had to pull timing out because of it knocking on the third pull. I don't know what was adjusted, but quite frankly, the car does not feel much if any faster than before the LTs were installed. (I know that's a subjective statement, but it's all I've got for now.)
It has almost 95,000 miles on it now and I am the original owner. It still has the 3.42 gear. Does anyone have any ideas about why their is such a significant difference in the hp/tq numbers? I am thinking that some of it has to do with the different dynos (I searched here to find discussions on that, but did not see a definitive way to compare the two); and perhaps some of the difference is due to the altitude. Anything else?
Yesterday I dropped off the car to be dyno'd and tuned after installing LTs and a ported TB. I also installed new NGK TR55 plugs since that was a good time to do that. This particular shop used a Mustang dyno. My before-tune numbers were 249 hp and 263 tq, and my after-tune numbers were 260 hp and 275 tq. This shop is in Chandler AZ, which is approximately a quarter-mile above sea level. This shop used HPTuners software to install the tune, and they said they had to pull timing out because of it knocking on the third pull. I don't know what was adjusted, but quite frankly, the car does not feel much if any faster than before the LTs were installed. (I know that's a subjective statement, but it's all I've got for now.)
It has almost 95,000 miles on it now and I am the original owner. It still has the 3.42 gear. Does anyone have any ideas about why their is such a significant difference in the hp/tq numbers? I am thinking that some of it has to do with the different dynos (I searched here to find discussions on that, but did not see a definitive way to compare the two); and perhaps some of the difference is due to the altitude. Anything else?
First of all alot of people will use dynos and super inflate the numbers to get new people to use their shop. I wouldnt trust any dyno numbers unless its a mustang or dynojet. or a real good shop.
first / you want to make sure the people you tookthe car too know what the hell they are doing.
Is your clutch going out? stock clutch?
check for SAE correction
I would try a different tuner. I dont trust tuners.
first / you want to make sure the people you tookthe car too know what the hell they are doing.
Is your clutch going out? stock clutch?
check for SAE correction
I would try a different tuner. I dont trust tuners.
Thread Starter
Launching!
Joined: Oct 2004
Posts: 214
Likes: 0
From: Chandler, AZ
Wow - didn't get email notification of the replies; thanks all.
No leaks in the exhaust; the shop corrected those that were in the y-pipe. I had no problems installing the header gaskets (new GM) or the header bolts (stage 8).
Clutch is a LS6 replacement with 20k miles on it. The shop was able to verify 140 mph on the dyno with no problems. Don't know what gear but I presume 4th.
Second shop's printout did not state type of correction factor used. I will have to call them.
I'm contacting a local tuner that has a good rep as well and will see what he has to say.
Both shops came with good references, but since the first shop is back in CA I don't see me taking a road trip just to compare (although I would like to). The second shop pulled timing because on the third pull they got spark knock. They also said that the car had too much timing (didn't tell me the amount) but said that was common in 98-99 models.
I should also take the car to the dragstrip and see what it will do.
No leaks in the exhaust; the shop corrected those that were in the y-pipe. I had no problems installing the header gaskets (new GM) or the header bolts (stage 8).
Clutch is a LS6 replacement with 20k miles on it. The shop was able to verify 140 mph on the dyno with no problems. Don't know what gear but I presume 4th.
Second shop's printout did not state type of correction factor used. I will have to call them.
I'm contacting a local tuner that has a good rep as well and will see what he has to say.
Both shops came with good references, but since the first shop is back in CA I don't see me taking a road trip just to compare (although I would like to). The second shop pulled timing because on the third pull they got spark knock. They also said that the car had too much timing (didn't tell me the amount) but said that was common in 98-99 models.
I should also take the car to the dragstrip and see what it will do.
i'm a real numbers kind of guy and those are very low (not correct) your car maybe was pulling back timing to drop off power like that. M6 cars dyno higher than my A4 on conserv mail tune dynajet 336 rwhp and mustang 321 which that club dyno day a 2003 cobra ran 329 rwhp stock on the mustang. i believe stock you should be 295-310 with a dynajet and 15hp less on a mustang. with your mods and A/F around 13:1 at least 330rwhp. since my better tune i'm at 13.1:1 i ran 349.8 rwhp (before TB). and still missing a few bolt ons. just my 2 cents.
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Some mustang dyno are way off. 2004 viper put down 400-410rwhp on a local mustang dyno (rated at 510hp). So your numbers are not that bad..should put you around 320hp assuming your numbers are 22% off like the mustang dyno I did...
I'm guessing you'll be putting down nice numbers on a dynojet. Dont be fooled by dyno numbers. Compare with other cars with good dyno scores and youll see where you stand. Or make a pass down the 1/4 and check your time slip.
You would benefit a lot from an LS6 intake.
I'm guessing you'll be putting down nice numbers on a dynojet. Dont be fooled by dyno numbers. Compare with other cars with good dyno scores and youll see where you stand. Or make a pass down the 1/4 and check your time slip.
You would benefit a lot from an LS6 intake.
Thread Starter
Launching!
Joined: Oct 2004
Posts: 214
Likes: 0
From: Chandler, AZ
I'm not trying to put too much stock in to the HP numbers, but I was still surprised at the difference.
They didn't mention it, but what do y'all think - maybe my valvesprings are toast? I haven't beat on the car that much, but now that the car has been moved to "toy" status that will occur more.
Thread Starter
Launching!
Joined: Oct 2004
Posts: 214
Likes: 0
From: Chandler, AZ
Ok, finally got a chance to evaluate the exhaust upgrade. According to my butt dyno, there is a decent to significant improvement! 
I think one of the things that was confusing me is how much smoother an LS1 accelerates compared to a Gen I SBC.
I'm still going to get the second tuner's opinion, but for now I feel a little better.
I think one of the things that was confusing me is how much smoother an LS1 accelerates compared to a Gen I SBC.I'm still going to get the second tuner's opinion, but for now I feel a little better.