Issue with dyno numbers...

[knowfreed0m]

Ok so here is ths story.

I Dynoed back in April 2005 with the following mods on a Dyno-Jet, here is the sheet with STD Numbers:

2.80'' Pulley
MAFia
Predator-Tuned by: AMAZON RACING
Magnaflow C/B
K&N FIPK
MGW Shifter

(Disregard that A/F that was when Rick was first begining to tune my car so it was a little wacky then.)

Since then I have added these mods:

4-piece Billetflow Idlers
2lb. Metco Lower
O/R Prochamber
Centerforce Clutch
LFP H/E
Steeda Double Hook Quadrant
LDC Free play kit
Fiore Firewall Adjuster

I went to dyno again this past weekend in cooler weather and here is what i put down on a dyno-jet with SAE numbers:

So my question is why did I lose HP? The A/F is dead on at a safe level. My Max Timing is 21* and that is dead on. My Fuel pump is not being maxed.

The only thing that I could think of was that my clutch adjustment might have been too loose, or the dyno was reading very conservative?

I have no other problems and the car runs like a 450+rwhp car.

Any suggestions of help would be awesome! op:

 

[ViciousJay]

heres what i see asnd are betting on...

1. you got maddddd belt slip, get a aux idler
2. also your not running a port and that there will then get you over 500 hp

 

[PhillyCobra]

STD correction gives you about 4 or 5% higher #'s than SAE. So your 422 SAE hp would be 440 to 445 STD. Your hp is about the same, but your torque is up (495 SAE is about 515 to 520 STD), which is what you expect from spinning the SC faster. You don't gain hp because the blower becomes less efficient the faster you spin it, and hp is proportional to rpm. You have awesome torque at low rpm. Therefore, I think your results are as expected.

 

[CobraBob]

The first thing I noticed was that your signature says your numbers are 460/500 but the numbers on the two charts are different. Where's the chart for the numbers shown in your signature? Second, I noticed that you used a different dyno. There could have been an issue with either dyno that could affect the numbers. It is better to use the same dyno when comparing mods/numbers if possible. Also, your first dyno sheet obviously was with a faulty A/F ratio so it is kind of like comparing bad green apple to a healthy red apple. Had the A/F on both charts been close to being identical (at least showing healthy curves) it would be a lot easier to analyse what the problem might be. Can you post the missing chart?

 

[CobraBob]

STD correction gives you about 4 or 5% higher #'s than SAE. So your 422 SAE hp would be 440 to 445 STD. Your hp is about the same, but your torque is up (495 SAE is about 515 to 520 STD), which is what you expect from spinning the SC faster. You don't gain hp because the blower becomes less efficient the faster you spin it, and hp is proportional to rpm. You have awesome torque at low rpm. Therefore, I think your results are as expected.

Yep, using the 4% difference, the RWHP number from the first chart (SAE) would be around 430. But the SAE RWHP number from the second chart with the addition of the 2 lb. lower is way down....to only 422rwhp. Something is wrong. Only 422rwhp with a 2.80 upper and a 2 lb. lower? Something is definitely wrong here.

 

[PhillyCobra]

I think the 448 hp STD on the first run would translate to 420-425 SAE-- SAE is 4 or 5% less than STD.

 

[BoosT_AddicT]

It's the Dyno... I have been to Cartek tuning in Davie and their dyno reads higher than anyone elses. Go back and dyno your car again at Cartek and you will see what I'm talking about.

 

[knowfreed0m]

Ok thx for quick responses.

On the 2nd Run I added full Billetflow Idlers and a new belt so I highly doubt it's belt slip.

The 460rwhp and 500rwtrq was just an estimate number I have in my sig because that is what I *thought* I would be making with the addition to the new mods. Obviously that is wrong and That is comming outa my sig..

Im running 16# of boost on an unprted blower which I know would benefit greatly from a port. That run I Iced the blower down, let the car cool, and added ice to the I/C Resivoir and I still only made 422rwhp :shrug:

The only thing that makes sense is a combination of Cartek's dyno reading high, and D'agastino's dyno reading conservative. That plus the whole STD vs. SAE thing.

Im really not that concerned about numbers because they are just numbers. As long as the car runs strong then Im happy

I plan on porting the blower, then going back and re-dynoing again to see what she makes.

 

[PhillyCobra]

You'll get more hp when you port. Not having an increase in hp as you spin faster than a 2.80 upper on a stock Eaton is, IMO, totally expected, even if you get a nice increase in torque, as you did when you correct the #'s for SAE versus STD.

 

[knowfreed0m]

It makes sense now when considering not having a port. It's like running 23psi on a Turbo that becomes maxed out at 20psi...

I guess I thought with a completly cooled down car and cool weather it would make more power.

 

[03yellow]

I added a 4lb lower with a 2.76 with out a port. My #s and boost went up to 16.5lbs. without cats.

Pre lower I was at 442 after the 4lb lower I went to 475 and after the port It went over 500.

You should expect your #s to go up with your new mods;just like every one else who is overspinning their blower with alower and no port.

Your tq looks good and that may indicate your clutch is ok as well.
You feel you have elimated belt slip and a/f issues.

You stopped making power at 4800 and your graph goes bumpy up top.

My bet is somthing is slipping: belt,tires, or clutch.

PS:If your car was hot during the later runs it will pull a bunch of timing.

 

[knowfreed0m]

The first run was on a 100% cooled car. The car was parked 3 hours before the first run. The second and third run werw bout 20 min apart and the entire down time I had ice on the blower, and in the resivior.

The clutch is brand new with about 2k miles on it and doesn't seem to be slipping, although when I tightened the cable via my fire-wall adjuster my power went up some :shrug:

I have a brand new belt with full idlers and my boost pegs the stock gauges and doesnt move at all until I let off.

I datalogged all runs via Predator and each time the max timing was 21-22* and as you can see from the graph the A/F is a straight line at 11.8.

The last option could be tire spin but I doubt it?

Im gonna get a quick little vid up of the dyno run...

 

[LTHL PSI]

Araman,

Its definitely because Cartek Dynoed using STD numbers while we use SAE. I did not know they Dynoed STD, if I would have converted the numbers to STD you would have made close to that. Not to mention your Torque would have been over 500. No biggie, I would not sweat it to much. As long as the car hauls ass I would not sweat it.

Thanks,
Derek

 

[knowfreed0m]

Araman,

Its definitely because Cartek Dynoed using STD numbers while we use SAE. I did not know they Dynoed STD, if I would have converted the numbers to STD you would have made close to that. Not to mention your Torque would have been over 500. No biggie, I would not sweat it to much. As long as the car hauls ass I would not sweat it.

Thanks,
Derek

Thx Derek for chimming in. I didn't know you could swap to STD numbers, but either way numbers are only numbers.
Ya after reading some responses I pretty much got over it, the cars runs solid so I'm happy. You guys got a great shop/company going over there and I will definalty be stopping by more often :beer:

Oh and once I get my blower sent out for porting Im gonna need some Tires (2- Nitto 555R 315/35/17 and 2- Nitto 555 275/40/17) and a set of GT pumps to go along with the port. So Ill be in touch with you regarding those parts.

Here is a quick clip:
Movie_0001.wmv

 

[CobraBob]

I think the 448 hp STD on the first run would translate to 420-425 SAE-- SAE is 4 or 5% less than STD.

Opps! You are correct. It was ME that had it backwards in my head. LOL! I corrected my post.

We know about the issue with the STD numbers being higher than SAE, but it still doesn't explain why he is not seeing more power from either dyno. With the approx. 15.8 lbs. of boost he is getting (should be getting) his RWHP should be at least 460. And more likely in the 470-475rwhp area. Overspinning the blower to where he is at now wouldn't result in a loss of power going from just the 2.80. I'm not trying to rain on his parade. If he is happy with the power end of conversation. And sometimes we place too much emphasis on dyno numbers. I am just concerned that his numbers on paper (two dynos) seems to be down so much.

 

[03yellow]

Generally I would agree, however your 2nd Graph looks off after 4800 rpms and your hp should be much closer to your Tq level ( its a differential of 73.6... thats very strange).

If both #s were down I would blame it on the different dyno.

Somthing is not quite right...I think your missing out on 50 rwhp.

I wouldnt have it checked if it was just a little low on hp and tq but its way off.

It would be worth the $ to take it somewhere and have it dynoed tuned.

Do your have your 2nd TQ curve?

Araman,

Its definitely because Cartek Dynoed using STD numbers while we use SAE. I did not know they Dynoed STD, if I would have converted the numbers to STD you would have made close to that. Not to mention your Torque would have been over 500. No biggie, I would not sweat it to much. As long as the car hauls ass I would not sweat it.

Thanks,
Derek

 

[sambandit]

I am sure Derek can check the runfile and comvert the numbers to STD if that makes you feel better. That's why I wish all dyno operators would use SAE, since that is the industry standard IMHO. STD is always higher though and that's why some shops always use that...

 

[03yellow]

sam have you ever seen the tq at 495 and the hp at 422. What do you think?

I am sure Derek can check the runfile and comvert the numbers to STD if that makes you feel better. That's why I wish all dyno operators would use SAE, since that is the industry standard IMHO. STD is always higher though and that's why some shops always use that...

 

[sambandit]

No haven't seen quite that desparity. Even though the car is unported, it still should be in the 450-460 HP range. Could be some blow out or belt slip. Notice at 5000 RPMS where the cars power starts to do funny things, and the A/F dips richer. That usually says blow out or belt slip to me. TQ sounds right on to be, and with the slip or blow out figured out and 23 degrees of timing up top which is perfectly acceptable on 93, he would be up in the 450-460 range.

 

[03yellow]

Blow out= Spark or fuel?

No haven't seen quite that desparity. Even though the car is unported, it still should be in the 450-460 HP range. Could be some blow out or belt slip. Notice at 5000 RPMS where the cars power starts to do funny things, and the A/F dips richer. That usually says blow out or belt slip to me. TQ sounds right on to be, and with the slip or blow out figured out and 23 degrees of timing up top which is perfectly acceptable on 93, he would be up in the 450-460 range.