NotoriousREV

Don't forget that US rolling road figures never seem to map onto Uk figures either. I guy I know in the US has a bug-eye with remap, de-cat, FMIC and STi injectors and had a dyno read out of 330hp at the wheels @ 1.2 bar. As far as I can work out, a US "at the wheel" figure is roughly equivalent to our bhp at the fly figure, based on figures I've seen for a lot of cars, not just one or two.

CirrusWRX

Interesting what you bring up for the multiplier, because in my example that would put the US PPP on par with the UK PPP. However, I don't think I SHOULD use a multiplier of 1.33 since the dyno that this comparison must've been run requires a different multiplier to equate properly. Check out this out:

AWD Dynamics Dyno:
Typical WHP Output Stock 2002 WRX: 162 - multipler = 1.40

AWD Dynapack Dyno:
Typical WHP Output Stock 2002 WRX: 175 - multipler = 1.30

AWD Mustang Dyno:
Typical WHP Output Stock 2002 WRX: 180 - multipler = 1.26

AWD Dynojet Dyno:
Typical WHP Output Stock 2002 WRX: 190 - multipler = 1.19

So to approximate a 280HP at the crank (what we believe is the crank HP for a WRX that reads 160awhp stock, and 200awhp after modification) we see the following:
AWD Dynamics Dyno = 200awhp
AWD Dynapack Dyno = 216awhp
AWD Mustang Dyno = 222awhp
AWD Dynojet Dyno = 234awhp

Now without trying to get off topic, my personal opinion is that one of these dyno's is probably "correct" and the rest are simply "off" for one reason or another. A HP is a mathematical constant, like gravity, and it's not open to interpretation. Unfortunately, each dyno company has their own "interpretation" of what they feel wheel horsepower equates to, and while they all think they're right, nobody really knows for sure who is "most right." Therefore, we have to use the multipliers to adjust accordingly. Of course, each DYNO reads slightly different no matter how well it's calibrated, but on the whole, I think it's safe to say that if the vendors say a stock car was tested circa 160awhp, and the PPP2 tests at circa 200awhp, chances are it was with a AWD Dynamics Dyno or similar performing system, thus yielding a crank HP of approximately 280HP.

Kyle

PS. a few weeks ago, a not-so-well-respected tuning company hosted an "open dyno" house, and allowed people to get baseline runs for $50.00. People who had mods making anywhere from 200-220awhp on other dyno's were coming back with graphs that showed peak of 150awhp. The guys operating the dyno claimed theirs was the most accurate one in the world. Go figure.

CirrusWRX

EvilBevel - As of right now, the single comment is all I have to go on. I agree, I am skeptical, but I have no further evidence to back up the claim until we see what they present/announce. You can understand why I am EXTREMELY anxious to see the results.

I also agree that a 40bhp increase @4000RPM would not only be unwise, but nearly impossible. I was just using it for an example. Obviously, peak HP is a key - it depends on what the peak looks like. If it looks like mount everest, then "peak HP" is pretty much a useless claim, as the power is useless. This is like the "dyno kings" over here -- they don't care how the car runs or performs, so long as it makes the most digits on the dyno. Likewise, I'd gladly take a car that is slightly down on peak HP that makes a nice smooth curve (or even near-flat!!). But I digress - we will just have to wait for the results.

NotoriousREV - I have a feeling the guy you know is overexaggerating a little bit. On the stock turbo (over here) it is basically impossible to get more than about 315HP at the flywheel. The stocker just won't do much more than that before detonation and flow rate become the bottleneck. If he's claiming 330awhp with those mods, he'd be making nearly 400 bhp flywheel on a dyno that "reads high" or nearly 465bhp flywheel on a dyno that reads "low." You do the math and tell me if the stock turbo is capable of making that kind of power

NotoriousREV

Unfortunately, it is open to various correction factors which can vary from dyno op to dyno op and country to country.

CirrusWRX

^no doubt - point well taken. But a disparity of 32HP between the lowest and the highest makes one think SOMEBODY isn't doing such a scientific job of measuring. So until somebody figures out which is the "most correct" way, we will just have to use the various multipliers accordingly.

Pete Croney

Kyle

Sorry, I should have been clearer. The RR day I was refering too was one in the UK, not your data.

jmgelba

Have you taken into consideration that BHP and HP are different??
There is international horsepower and metric horsepower too. The ratio for international and metric is 1:1.01
So if BHP were to be international horse power, 225(UK WRX)x1.01=227.25 227hp is the stated output of a US WRX.

Therefore a 36bhp gain from PPP, in US terms would be 36x1.01=36.36hp, what happened to the other 3.64hp?

Still searching for BHP to HP conversion as all that above may be totally wrong.

Also, are gear ratios different? I cant remember hearing anything like the number of failures of UK transmissions versus US transmissions. Perhaps the transmissions are different?
Whats the standard weight of both market cars?
Regarding boost on my car, standard except with the intake silencer out, im seeing 14.7 psi constant untill high rpm when it tapers off.

[Edited by jmgelba - 9/18/2003 7:17:02 PM]

CirrusWRX

I'm sorry - I actually didn't realize there WAS a difference between HP and BHP - it's my fault for referring to them being interchangeable. They were always so close that I didn't realize there was the 1.01 difference.

Here's what I have found per SUK and SoA, and converted everything so they would be "equal":

Subaru UK:
Power: 225PS (so 227HP?) @5,600RPM
Torque: 221 lb-ft @4,000RPM

0-62mph: 5.9s

5 speed manual Gear ratio's
1 - 3.454
2 - 1.947
3 - 1.366
4 - 0.972
5 - 0.738

Curb (Kerb?) weight: 3075lb


Subaru of America:
Power: 227hp @6,000RPM
Torque: 217 lb-ft @4,000RPM

0-62mph: NOT listed on SoA's website, but C&D says 5.4s - so 5.9s from Subaru would seem logical

5 speed manual Gear ratio's (not listed, but confirmed many times over)
1 - 3.454
2 - 1.947
3 - 1.366
4 - 0.972
5 - 0.738

Curb (Kerb?) weight: 3085 lb

Gearing appears to be identical, peak HP on the UK model appears to come on 400RPM's earlier. Torque is at the same RPM, with the slight edge going to the UK model. The US model appears to weigh 10 more pounds, which makes sense since Americans are fat, we need the cars to match our belly's.

If somebody has evidence to dispute the gearing or HP or whatever figures, please post up. Otherwise, I say the cars are CLOSE to being identical, though there are most likely some differences that we cannot entirely pinpoint. Perhaps it's just ECU tuning with your slightly better fuel that gives the UK the edge. Maybe it's something emissions related. Tough to say, but on paper, they look very very very close.

jmgelba

1ps=736W=1.013hp

1hp=745.7W=0.987ps

1kW=1.359ps=1.341hp

So 225ps x 1.013 = 227.925hp

The differences are all very small but as you can see from both posts, it acounts for 225ps or bhp vs 227hp, but not 36bhp vs 40hp.

The 10lbs shouldnt make a difference, but i think the 400rpm lower would certainly account for a difference, although probably not the greater part of the difference.
In order to find the larger part of the time difference i think you should look at the curve of hp, lbft etc rather than peak and where it appears in the rev range.

I dont have times or dynos to prove it but my car dose have a totally different characteristic in the US versus my UK car. It feels slower, more laggy, less top end by far - i struggle to get 125mph on a really long straight road, closed and private of course!! It moves around on the road and is very unsettled by comparison. Cirrus - to give you an understandable comparison - i was out handled by a Lincoln Towncar!! For the Brits, thats like being outhandled by, oh, thats say, an early 90's XJ6. Basically a matress!!

Its interesting to note that there is more torque available on the UK cars, but less of the transmission woes.

pat

There appears to have been some weirdness going on with the drivetrain loss calcs on the rollers, however the power @ wheels was comparable with other rollers (like Power Engineering). This was most evident where a car gained 40 BHP by running in a different gear; if the drivetrain loss was spot on then the reading (barring heat soak) would have been the same, the higher power @ wheels figure in the lower gear being offset by lower drivetrain losses, to get the same crank figures.

Would suggest that the best approach is to DeltaDash similar cars, here and in the US, and then compare. Suspect that if the US cars don't pull as hard then they're pulling timing out, of course this would be obvious from the DDash logs.

A 40 BHP increase at 4000 RPM is achieveable on a WRX. That'de be an increase of 52 lb/ft, add that to the 220-ish it makes out of the box and you're at 272 lb/ft. That's still less than the 291 we've seen from a TD04L based MY01 WRX, and a loooong way shy of what can be done if the turbo and injectors are changed (given the right combination, one could reasonably expect a 100 BHP increase at 4000 RPM, but that *does* destroy the transmission). To date the most efficient power figures I've seen was 321 BHP at 1 bar of boost on a JDM STi VII. I've also seen an MY01 WRX pull 250 BHP at 0.8 bar These are all on ECUTEK with standard internals.

Cheers,

Pat.

CirrusWRX

But isn't it a 40bhp increase at 4000RPM a LONG way from 40bhp increase at 5600 or 6000RPM where peak is currently at? I believe you when you say you've seen a TD04 make 291 lb/ft, and while I also can concur that with injectors, fuel pump, and turbo, the engine can go much further, but I think that's beyond the scope of this thread.

I am interested to know how a stock WRX pulled 250bhp at .8 bar. How is this possible? If stock is 227 @14.5ish psi, 1 bar, how did it manage to get ~25 more bhp's with less boost? It was really done with ignition advance by itself via ECUTEK, or were there also other modifications (ie. exhaust?)

[Edited by CirrusWRX - 9/18/2003 10:30:21 PM]

Apple

Just to add another bit in about dynos - just because it's "calibrated" doesn't mean it's correct unless either:-

a) it's been adjusted after calibration to bring it to a known, traceable standard which I guess could be difficult / costly with someting like a full car dyno in a "local" garage (do trading standards have any jurisdiction over the equipment and results?),or

b) you see the calibration data deviation sheet and relate the figures on the day to a "true" reading, e.g. indicated 200bhp is actually 210bhp w.r.t. national standards under "idealised" test conditions etc. For example, on turbos there's ways of converting flow rates at test conditions back to "normalised" results to enable comparison - this gives known a baseline and anything else is a waste of time as you can argue until you're blue in the face but it ain't the same

This might give some info on whether you believe dyno to dyno comparisons in different parts of the country with "unknown calibrations" are viable...

Apple

mutant_matt

Cirrus,

Somewhere back in this thread you asked about proof (data) to show Boost on UK PPPs? The trouble is, I have some DeltaDash traces of such a car but because the PPP for the MY01/02 WRX (it may have now changed and it deffo has for the MY03 WRX) uses/used a Boost clamp, the ECU never sees the real boost value. However, from an installed Boost guage, I can see that a decatted (including up-pipe) PPP'd MY01 WRX peaks about 1.4 bar and holds about 1.3 bar and I think a "normal" PPP peaks 1.3 and holds 1.2.

If the MY03 UK WRX is claimed as 225 PS then that is 221.9 bhp.

Matt

CirrusWRX

Hey all - just wanted to let everybody know that Prodrive USA released their report. If you care to read it, check out http://www.prodrive-usa.com/stage2.pdf - any thoughts/comments from your side of the coin?

Apple

Very interesting - but does it answer your gripes?

Are you selling up and moving to the UK for a proper PPP version?

We have to take into account the effect of compressor inlet temperature when testing turbos and have to convert the data to "universal" units so that it can be applied in differing countries around the world - India, UK, USA etc otherwise as stated by Prodrive, it's nigh on useless.

It may seem that the report contains a few cop-outs but that's almost the nature of what you're trying to compare - there are differences between the two countries / PPPs / fuels etc which slew the results - I'm just glad ours is better

Apple

john banks

The stock WRX does not hold this boost at peak power. People tend to quote their midrange held boost figure which correlates with torque. If peak power is at 5600 or 6000 RPM look at what the boost is there. Tunes for small turbos tend to taper off at the top and end up giving similar peak BHP and lbft figures on Subarus.

If you run 0.8 bar everywhere, the torque would be poor, and the power pretty respectable.

[Edited by john banks - 9/27/2003 7:49:27 PM]

Brit_in_Japan

Cirrus - everything I read in the Prodrive US report makes sense IMHO (a pity they didn't overplot the first two graphs though). It's also a pity they didn't include the torque figures. You should back calculate torque from the HP figures as it would be useful to have them. After all torque = acceleration, not power. Clearly there is still a perception that the cars you are driving with PPP2 don't feel like you have the advertised 40HP extra - but what does 40HP feel like if it's generated at a different engine speed ?

I haven't extracted the torque figures, but as power is a maximum at 4600rpm with the PPP2 and at 6000rpm with the standard engine, it doesn't take a genius to work out that peak torque is coming in much earlier with the PPP2.

If you are worried whether the PPP2 is delivering what was advertised then maybe you need to do *another* dyno test, try to follow the testing procedure as per Prodrive report (hood up, make sure sufficient cooling - 80mph fans) and religiously stick to a procedure. Do the tests using

SAME engine
SAME dyno
SAME dyno operator
SAME ambient temperatures (as near as humanly possible and cooler rathern than hotter, <15 degC) and follow the
SAME procedures for the tests

Video the tests to verify that the procedures are followed. What you want to look for is the relative performance between standard and PPP2 engines, absolute figures are less important (you can argue endlessly about absolute figures). Then if you still have a clear gap between the 40HP advertised and what you measured, go back to Prodrive USA with your results.


However it looks to me like to get the most out of your PPP2 WRX you want to keep it in the torque band, and that means shifting up much earlier than with the standard car.

Just my opinion.