DanaT

After screwing around the 951 for a while and just "guessing" hp, I was finally able to make some dyno pulls.

Mods: 2.5in Exhaust - no cat
Vitesse S2R turbo and MAF
80 some pound injectors
E85
Tial Wastegate
Forge BOV

Everything else doesn't help power (i.e iceshark cables, silicone hoses, new wiring loom, brakes, etc)


So without further ado...



This was dyno was "semi-corrected" the dyno shop uses 15% correction for turbo cars and using that, I can compare to other cars thayt are run there. For example, he said a GTR that was tuned running E85 made 530hp. A twin turbo viper on E85 made 600ish hp. These number are to compare to those.

Here was the conditions today:



Here are the data logs of the pull.



If you look at ZT-2 user 2 line, that is boost (i forgot to scale it before the run). It shows the MAP voltage (absolute) at about 3.60V. That is 19 pounds of boost (absolute).

Uncorrected HP at 19psi was 355hp.

I also did a low boost "street" setting that I use for 91 octane pump gas (the car is driven on the street at this setting). These number we uncorrected (corrected to the same scale above would have been 330hp).





The MAP voltage was about 3.0V so 13.5-14psi of boost.

Anyways, I thought overall was a good day.

Now I just need to get out to the strip..... Using uncorrected data of known data points (what I ran when I made 255hp uncorrected...103mph) and todays numbers I think I can break 115 (probably close to 117mph) at high altitude.

-Dana

DanaT

I forgot to add. My Curtis knock counter (tapped to KLR) showed 1 knock event on the dyno through all pulls.

-Dana

gregeast

Good stuff Dana, glad you decided to keep her

What dyno shop did you use?

DanaT

Here are some comparative numbers from the same dyno that are corrected.

http://www.theboostcreepltd.com/dyno.html

The last one (509hp) is a "stage 1" GTR

DanaT

Not sure I have decided to keep it. I just haven't decided to get rid of it. I figured I need to finish the project and get HP numbers and mph before I do anything...

See post above (i used the boost creep in Mead).

86 951 Driver

Those are some great numbers. Looks like it takes a while to spool that turbo. How bad is the lag?

DanaT

It feels much stronger than the old K27/6 as it spools.

You must remember, that spool up is really affected at high altitude. I would expect 1000 rpm sooner boost at sea level.

blown 944

Today was a horrible day to dyno. It was so hot here. Are you going up tomorrow?

DanaT

Horrible day or not, it came to when I could get dyno time and when I was in town.

Not sure if I will go up. Generally, I like to hit the track early but I have a dentist appointment at 3:30. I probably can't get there until 4:30-5:00ish if I go. Depends how much trouble I get in tomorrow (i don;t know what I will do, but I will do (or not do) something but the general in trouble with the wife stuff).

I think I will try and go.

mudbuddha

Nice numbers- must be fun on the street.

Paulyy

real nice numbers!

onspeed

Is there any reason NOT to use SAE corrections for dyno? And what's the difference between dynoing a turbo car vs an N/A car?

Den951

Great numbers Dana! I'm getting mine back on the dyno in late July I cant wait.

333pg333

Great numbers!
Curious about the ramp rates and 'mode' that the dyno was done with? I'm a bit confused about the semi corrected 400hp and then 355 corrected at 19psi though? What does correcting actually entail? When it's corrected is this still hp to the wheels?

95ONE

You would think I would be anxious to post an answer to this. Honestly, I changed my mind. I was going to post this in it's own thread. I even started a Post / Dissertation on the topic, but I realized that I had to convey about 10 different scientific calculations in order to explain fully how I EXACTLY come to my conclusions. It just became a ridiculous post that would almost rival the newest healthcare bill in dizzying complexity to glaze over even the most tenacious student. So much so in reality, I fell a sleep more than once before even getting half way through. So I will just touch base on a small detail with the following;

Here is only ONE example of how things can get really mixed up. The original poster noted that he was pushing 19 psia. I am sure he meant to say that he was running 19psi (19.9 or 20psi on the Zeitronix computer screen) over atmospheric pressure at his current geographic location. Because if he meant a true 19psia, (PSIA = psi absolute = gauge pressure + current geographical location atmospheric conditions - 12.2psi according to calculator link below) that would mean he was only running 7.7 psig, which is clearly not the case considering this set up and power numbers given.

What I'm about to explain next, as only one example of 3 or 4, might help everyone understand why they are running "less power" than others. We're not even comparing the proper pressure ratings when using the same "psi"!!!!

Your 19 psig is NOT the same 19 psig as mine if we are 5K ft in elevation apart if we are talking about what you are seeing on your gauge! (PSIG = psi gauge) I believe this is what Rogue was unsuccessfully trying to explain. - (MAYBE, I haven't verified this) And I unsuccessfully was trying to explain that I was taking into account gauge differences and doing math in absolutes to equalize the two. Let me explain further with math using this posters example.

His atmospheric pressure is clearly less. Using this simple web pages conversion function, CLICK HERE (there are absolutely more detailed ways, but this gets the job done decently) And using the numbers detailed on his screen conditions, I come up with an atmospheric pressure at his altitude and temp to be 12.2psi. Adding that to 19.9 psi gives us a PSIA of .. 32.1 psia. Keep that number in mind. 32.1 psia.

using today's conditions here in Houston, - 93 deg. F and 40ft alt. on the same calculator gives me an atmospheric pressure of (slightly rounded up from 14.67) = 14.7 Add in 19.9 psi of pressure over that = 34.6

So there you have it, two entirely different absolute pressures even though our gauges read the exact same thing!!!! (psig)

What does this mean? It simply means that I have the boost turned up higher than the original poster if our gauges are reading the same thing!
Here's the math;

Houston 19.9 psig = 34.6 psia
Original Poster 19.9 psig = 32.1psia.

Difference in pressure = 2.5 psi!!!! So to truly compare apples to apples, the original poster is running an absolute psi that would read 17.4psi on my gauge here in Houston.

what does this mean for Horsepower difference? It gets a lot more complicated from here, but it's obvious that 2.5psi less or more of boost will make 2 entirely different numbers on a dyno. I suggest turning up the boost 2.5psi to match the same absolute pressure I run when I see my 22-23psig numbers. Which for this original poster would mean running 24.5 or 25.5 psig. - Well, those that have a turbo that can handle it anyway. Of course, you will then only adjust your dyno to correct for about 3-6% or 103-106% depending on humidity, etc. - not 126%.- EDIT!!.. I saw 1.26 correction in the "Engine Tuner" print screen. That was NOT what Dana said his tuner corrected for, which was 15%.. A much more accurate description of a turbo correction factor. I still say a little less, but happy to see this number over the 26%.. Keep in mind, this is the great debate I keep having, and just my opinion, not proven fact (yet.. lol) That is truly only for an NA vehicle. (1.26% correction factor) And in this case, not quite that. Here's my math for that

Naturally aspirated vehicle can only take in what is in the atmosphere. In this case, there is only 12.2psi vs 14.7 here in Houston. (except I have 75% humidity vs 19% which gives a very very slight hp slant for the Higher altitude dyno) Using those two numbers; 12.2 divided by 14.7 = 17% less air or "correction" of 1.21. (12.2 x 1.21 = 14.8) Close, but not up to a 1.26. So I have to say this dyno is corrected for a naturally aspirated motor and not anywhere near proper for a turbo motor.

Like I said. This is just ONE of the many things I would have to explain on truly getting a firm grip on what is happening or has to be done to make a true apples to apples comparison from one altitude to another... on a turbo car.. Naturally aspirated is just plain and simple, and easy to explain. Turbo car, MUCH more complicated.