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2tight Racing
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411 Posts
Discussion Starter · #1 · (Edited)
All videos have -15% offset reading on mustang dyno
Thanks to Andrew Ho and the crew at iTurboWorks




Here's the specs:
E-85
Stock long block
CompTurbo CT580 triple ball bearing turbo
AEM V1
id2000 injectors w/ titan fuel rail
wotm triple walbro pumps
SP racing intake manifold
HKS 280 cams
Titan cam gears
Custom front face exhaust manifold
HKS racing wastegate w/ 22 psi spring
4" intercooler with 3.5" in 4" out piping
Custom full 4" exhaust
HKS DLI w/ ITW Bracket
Tial Q Bov


587rwhp @ baseline 20psi = 675rwhp actual reading


726rwhp @ 26psi - 835rwhp actual reading
 

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Lets go Nets
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2,956 Posts
nice dude. what compressor wheel? Im running the 79mm HE79 i believe it is. are you running a billet wheel?
 

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Hardtopper
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2,478 Posts
Judging by the HP my guess is 70-74mm?? Complete guess though based on RWHP.


That's an 80mm...! 835WHP at 26psi doesn't seem too out of line if it's a 'conservative' tune. Looks like it needs at least another 2000RPM to be useful, though.


Can someone explain to me the purpose of the offset reading?
 

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Premium Member
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11,269 Posts
That's an 80mm...! 835WHP at 26psi doesn't seem too out of line if it's a 'conservative' tune. Looks like it needs at least another 2000RPM to be useful, though.


Can someone explain to me the purpose of the offset reading?
No, he posted 764 at 32 psi! And FYI we just tested some new precision billet 71s that put down 903 at 34 psi.
 

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Hardtopper
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2,478 Posts
No, he posted 764 at 32 psi! And FYI we just tested some new precision billet 71s that put down 903 at 34 psi.


I was referring to "726rwhp @ 26psi - 835rwhp actual reading". I don't understand why the dyno is displaying 726 but he's calling it 835 'actual', though. Which is it? :scratch:
 

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Premium Member
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11,269 Posts
I was referring to "726rwhp @ 26psi - 835rwhp actual reading". I don't understand why the dyno is displaying 726 but he's calling it 835 'actual', though. Which is it? :scratch:

Well if he made 726 @ 26 psi and only 764 at 32 then he is picking up a whopping 38 hp for 6 psi or about 6 rwhp/psi which tells me he is out of turbo.... No way is it an 80 mm. I do not understand the 15% thing either as we also have a mustang dyno.
 

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Hardtopper
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2,478 Posts
Well if he made 726 @ 26 psi and only 764 at 32 then he is picking up a whopping 38 hp for 6 psi or about 6 rwhp/psi which tells me he is out of turbo.... No way is it an 80 mm. I do not understand the 15% thing either as we also have a mustang dyno.

Yeah, I agree with you.... but...


CompTurbo CT580 triple ball bearing turbo

That's an 80mm by Comp nomenclature.
 

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2tight Racing
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411 Posts
Discussion Starter · #15 ·
sorry for the late response to everyone. I'll try to answer as much as I could regarding the questions everyone has. I'll also let the tuner chip in regarding the data..

1. when i mentioned -15% offset reading, the dyno reading was off by -15% as told by the owner of the dyno.
2. it is an 80mm turbo by compturbo
3. full boost starts @ 5500rpm
4. testing ends at 7800 rpm
 

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Lets go Nets
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2,956 Posts
sorry for the late response to everyone. I'll try to answer as much as I could regarding the questions everyone has. I'll also let the tuner chip in regarding the data..

1. when i mentioned -15% offset reading, the dyno reading was off by -15% as told by the owner of the dyno.
2. it is an 80mm turbo by compturbo
3. full boost starts @ 5500rpm
4. testing ends at 7800 rpm
i have an idea. you're in Illinois right? Why don't you drive to SP and use their dyno...would put an end to the 15% conversation...

second, do you have any headwork? U should keep revving to 8500 or so, you're losing quite a bit of HP as you can see. 280 cams and all.
 

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Registered
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747 Posts
I think what he means is Mustang Dyno's have been known to read lower than say a Dyno Jet. Don't know how the 15% has been worked out. Maybe Larry could confirm or deny this. I do know that on my friend's AWD Mustang Dyno my MK3 did read a good 30whp lower on his dyno. I only know this because we had people saying their cars had dyno'd more on other dyno's. So we went to another friends shop on close to the same weather conditions, two days after the MD and the DJ was higher.
 

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Super Moderator
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10,842 Posts
The whole idea that Mustangs read lower than Dynojets is an internet myth, much of it promoted by shop or vehicle owners who are disappointed with their dyno results. It's been said many times that dynos are just tuning tools but, on SF, if you cannot post a "number", you are less than worthy. In point of fact, there is more user input/adjustability with the Mustangs than the Dynojet. My engine builder/tuner has both and my cars have dynoed within 5 whp on either dyno (same day, same fuel, same tune, same weather, etc.). There is always the implication that the higher reading dynos, be they Dynojet, Supertech, Mustang, Dyno Dynamics, or what have you, are less accurate and the lower reading dynos more accurate. There is nothing to support this supposition other than guys trying to explain certain dyno results they feel do not fit the SF norm for cars with similar set-ups. If a guy is going to use the 15% offset employed by the shop owner in this instance, why dyno at all? Just find out what guys with similar set-ups have dynoed in the past and just post a number. It's difficult enough comparing results from the same type of dyno in facilities across the country. There are even more uncontrolled variables when you are trying to compare different types of dynos in different facilities with different cars, set-ups, fuels and tunes, so as to make such comparisons fruitless and completely useless. Geez...

Ken.
 
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