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too low dyno numbers..

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Old 02-18-08, 01:15 PM
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too low dyno numbers..

So I got bored and curious today and decided to take my FD to a roll-on dyno to see what kind of numbers I'm pushing.. The results were WAY lower than I expected...

Of the several runs I did my base HP came out to be 284 (bhp) and 240 (rwhp). I don't know what PSI my turbo's were running at cause the t-joint they hooked up was broken, my commander marked .77 as it's peak on the final (heat-soaked) run.

I'm a little worried because, based on my mods, I expected to be somewhere in the 280-300 whp range.

My list of modifications so far is:

Greddy dual intakes
3" DP
High-flo MP
Apexi N1 Duals
Koyo Rad
Alum. AST (PFS)
Greddy SMIC (Intake temps started at 50, but dropped to 30 once fans got going)
Apexi PFC (Base mod map)
Datalogit
HKS Twin Power
Banzai Racing rear diff brace


There are other things done to my car, but those are the only ones that could/would improve HP.

From trolling all the merchants proposed power upgrades I *should* be putting out much better numbers. Would the fact that I don't have a tune attribute to this? or do you guys think that something more serious (**** compression) is to blame?

I didn't have a geek stick on me, so I will have to wait to scan my printouts and upload them..

Thanks,

Levi
Old 02-18-08, 01:18 PM
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well sometimes dynos can be extremly unaccurate (SP??) a friend of a friend has a turbo 5.0 stang. he was beating new z06's and ferrari's and such. he went to a dyno and made 194 whp lol. if u ask me thats NOT an accurate reading there. go to another dyno and try ur luck
Old 02-18-08, 01:30 PM
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I'm no big HP expert, but you're basing your expectations on claimed gains. Those claims are best case scenario. You don't even have a decent tune.

Best way to tell if it's your compression is to do a test.

GL
Old 02-18-08, 01:34 PM
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unless your car is tuned to take advantage of your upgrades, the gains will be small. and sometimes is not good for it
Old 02-18-08, 01:42 PM
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I made 290 rwhp on my car (similar setup as yours) 10 psi. 301 rwhp with a Steve Kahn tune.
Old 02-18-08, 02:00 PM
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fdeez: did you make 290 without any tune at all? or just a tune by somebody other than Steve Kan?
Old 02-18-08, 02:05 PM
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i assume he means it was tuned by someone else but when steve tuned it he gained 11 more hp over the orginal tune.
Old 02-18-08, 02:10 PM
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Originally Posted by fendamonky
fdeez: did you make 290 without any tune at all? or just a tune by somebody other than Steve Kan?

Yep, 290 with the base PFC map(a few tweaks here and there). Steve said the car was a touch on the lean side prior to the tune. His tune didn't give me much power but the partial throttle/drivability was much better.
Old 02-18-08, 02:18 PM
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Hrm, yeah... def worrisome than.

Not to mention I wasn't the one actually sitting in the drivers seat doing the pulls. Don't know what was going on inside the car during it.

Anybody know the truth of the disparity between PFC measured boost and the boost gauge?? My boost gauge will regularly read 12-13 psi while my PFC is reading .8 bar..

Yeah, think I'm def going to be calling tomorrow to set up a time to have my compression checked... that and source an apparent oil leak above my spark plugs.
Old 02-18-08, 02:18 PM
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How are you controlling boost? 0.77 kg/cm2 is roughly 11 psi. You should be able to run 13psi with the base mod map.

I would check your boost gauge with a MityVac and also calibrate your PFC boost settings - the default setting tends to under report boost.
Old 02-18-08, 02:30 PM
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Originally Posted by moconnor
How are you controlling boost? 0.77 kg/cm2 is roughly 11 psi. You should be able to run 13psi with the base mod map.

I would check your boost gauge with a MityVac and also calibrate your PFC boost settings - the default setting tends to under report boost.
Currently I am not doing anything to control it (I have a Profec B spec 2, just not installed). Oddly enough I have a very smooth transition between the turbo's and never spike/creep above 12-13psi, so I am not terribly worried about getting a boost controller on yet.

I have no idea how to calibrate my PFC boost settings (I was lucky to figure out how to lower my IDC in order to pass emissions over here).

I have BNR Stage 3's on the way, and will be going free flow with 850/850 and upped fuel pressure when the turbo's get here. I'll have a solid tune mapped in by England's equivalent of Steve Kan at the same time.
Old 02-18-08, 02:46 PM
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Originally Posted by fendamonky
I have no idea how to calibrate my PFC boost settings (I was lucky to figure out how to lower my IDC in order to pass emissions over here).
You will need a MityVac or the like and a Datalogit to calibrate your PFC's boost settings.


The PFC calculates absolute pressure in kg/m2 directly from the PIM sensor voltage. Absolute pressure is referred to as PIM in the PFC. The calculation is:

PIM = scale * PIMV + offset

The PFC displays gauge pressure in kg/cm2, which is calculated in the usual way by subtracting standard atmospheric pressure (10,332 kg/cm2) from absolute pressure and scaling:

Gauge pressure = (PIM - 10,332)/1000

Gauge pressure is what the Commander displays as boost, and is also what the Datalogit logs in its boost column, though inexplicably multiplied by 100.

To calibrate a map sensor one needs to determine both scale (how the sensor reacts to pressure change (measured in kg/m2/V)) and offset (the number required to zero the gauge at local atmospheric pressure, measured in kg/m2).

Assuming linear response away from the edges of the PIM sensor's range, scale can be calculated by taking two non-edge voltage values 1 volt apart (say, 2 and 3 volts) and subtracting the two PIM values corresponding to those values. Offset is simply the number required to zero the gauge at local atmospheric pressure.
Old 02-18-08, 02:56 PM
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what brand was it?

diff brand's of Dyno's make a huge difference... Dynojet will easily read 40-50 hp more than a Dyno Dynamics for example...

dyno's are better for measuring before and after.. and "gain in HP" rather than just raw HP numbers..

and also if u are only running 11psi.. than that's actually good

stock boost 10psi u were making 255hp when the car was new..

1psi more and 30hp+ is good..

if u mean 280WHP at 11psi than that's ****** GREAT
Old 02-18-08, 03:24 PM
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Originally Posted by Ottoman
what brand was it?

diff brand's of Dyno's make a huge difference... Dynojet will easily read 40-50 hp more than a Dyno Dynamics for example...

dyno's are better for measuring before and after.. and "gain in HP" rather than just raw HP numbers..

and also if u are only running 11psi.. than that's actually good

stock boost 10psi u were making 255hp when the car was new..

1psi more and 30hp+ is good..

if u mean 280WHP at 11psi than that's ****** GREAT
It was a Dyno-Dynamics type Dyno.

My AFR's started at 14.5 (2000 rpm) and had a steady drop till about 12.2/12.3 at 4700 rpms. They stayed at right around 12.0 until 7000 rpms where they dipped just below 12.0.

I am very happy with the AFR's, they were pretty steady and in the safe zone, so no complaints there.

Yeah, I def plan on doing this as a "before and after" type thing.. If I had money to burn I would HAPPILY make this into several different comparisons (no tune - tune, then stock twins - BNR's/free flow) but at 110 an hour and a hella confusing drive for just the power runs, and $170 an hour after a 3-4 hour drive for the tuning... thats alot of time and money this poor sailor doesn't have to throw away =P

The 284 HP was def Flywheel HP, not rwhp =( lol The Torque peaked at about 250 @ 5200 (ish) rpms. The 284 was at 6600-6700 rpms.

On a no-****, positive note.. my intake temps were a solid 40 deg through the ordeal, so I don't really need to worry about getting a front mount ^_^

Yet.
Old 02-18-08, 03:32 PM
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moconnor:

Your quote was pure japanese to me, lol.. I'll just ask the guys down at re:worx if they can get everything sorted out for me :-)
Old 02-18-08, 04:37 PM
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Im making 334 to the rear wheels on my FD. My mods are a Electramotive TechGT, 310 stainless exhaust, and a V-mount setup. All the work was done buy Defined Autoworks. My run was at 15psi. I also am using the stock twins with 80k miles on then or so, I have stock ports and a reman with 40k. When I bought my car it was well taken care of.
Old 02-18-08, 04:57 PM
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Originally Posted by fendamonky
My AFR's started at 14.5 (2000 rpm) and had a steady drop till about 12.2/12.3 at 4700 rpms. They stayed at right around 12.0 until 7000 rpms where they dipped just below 12.0.

I am very happy with the AFR's, they were pretty steady and in the safe zone, so no complaints there.
12:1 is actually pretty lean under boost for a rotary. 11:1 or so would be safer. Search in the PFC forum, for example, for many threads on this.

I'm surprised you are running that lean. With similar mods and the PFC base mod map I was getting AFRs in the low 10s under boost.
Old 02-18-08, 05:28 PM
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I guess I understand the way AFR'w work backwards than... I thought that the higher the number, the richer the mix.. and the lower the number, the leaner the mix..

That's no good =\
Old 02-19-08, 12:26 AM
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what Octane do u run? if it's 98 RON u can get away with high 11's low 12's

if ur 95 RON and below.. u might consider fattening it up a bit..
Old 02-19-08, 12:49 AM
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Originally Posted by fendamonky
I guess I understand the way AFR'w work backwards than... I thought that the higher the number, the richer the mix.. and the lower the number, the leaner the mix..

That's no good =\
ha i used to think that too before i learned
Old 02-19-08, 01:01 AM
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Originally Posted by Ottoman
what Octane do u run? if it's 98 RON u can get away with high 11's low 12's

if ur 95 RON and below.. u might consider fattening it up a bit..
I only use 94 Octane (98 RON). I get it on base for like 40p-45p a litre ^_^
Old 02-19-08, 02:50 PM
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Damn ur a lucky man :p u should siphon ur tank and sell it to ur mates :p
Old 02-19-08, 03:39 PM
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How does the car feel? Do you think it is running properly? Have you tested it against other cars to see how it performed? If the car feels "right", I would suspect that the dyno is messed up.

My car was dyno'd right before it went in for the rebuild. They said it put down about 220 to the wheels. I know it was closer to 280. That dyno was really off.
Old 02-19-08, 03:55 PM
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Lol Ottoman

Adam, honestly not sure as I have nothing to really compare it to.. (I could take my friends Porsche out, but that would be like apples and oranges). The car I owned before this was an old Prelude (real beast with the stock H22a ^_^)

I've run her against a skyline and spanked the R32, it feels good and strong (haven't been walked by anything yet, though I haven't done much, if any, street racing). Though she does have her quirks.. I'll be taking it down to re:worx next week (re:worx is one of the rotary specialist's on the island) to have a compression test done and a thorough look over, depending I may go ahead and have my boost controller and LC-1 put in and wired then as well (just to save me the hassle).

As far as the dyno being off, at this point I almost don't mind, so long as it is *consistently* off it will serve my purpose as a comparison of before and after. I'll pull my sig worthy numbers when I get the car tuned after putting on the BNR's, opening the exhaust all the way and cranking up to 15-16 psi for the daily.. I will use the same place because it's not too expensive for an hour, and it's the closest one to me.
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