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Old 10-01-2006, 11:07 AM   #126
FalconRS
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All it takes is someone who knows how to design a cam to call up Delta. This might be a good opportunity for SubieSport to head over to Delta and work with them to design a high-revving cam. Grinding a cam is no problem for them. You can send them any stock cam, the specs you want it to have, and they'll grind it to those specs for the same price as one of their off-the-shelf grinds. That's what Delta really does, custom grinds. If Subiesport is willing to take on the R&D process, it would be a no brainer upgrade for anybody buying an AP RS.
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Old 10-01-2006, 09:58 PM   #127
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Kay so, I've read the white paper over a few times, I've also been following the boards here for a little over a year now, and a full two years over on RS25.com, plus my own experiences with non-subies. I've got a few points of contention regarding the white paper, and all the very liberal tossing about of power numbers and what does what. Keep in mind with everything here, I'm talking about n/a power only. So all the WRX fanboys can keep their traps shut about what worked on their buddy's WRX. Different ballgame altogether. When you get into forced induction and spray and whatnot that opens up a whole other can of worms and I honestly have not followed the boost community aside from the odd RS Frankenmotor turbo build.

According to this big white paper article, which does a nice job of outlining what's out there and how extensive your options really are, here's the gains you can expect from various mods. Here's the common bolt-on list:

Intake: 10 hp
Catback: 10 hp
EL Header: 12-15 hp
Tuning: 10 hp
Cam: 15-18 hp
LW Pulley: 3-5 hp
LW Flywheel: 3-5 hp
Ground Kit: 2-4 hp
TB Spacer: 4 hp
===============
Total: 69 to 81 hp
Wheel: 55 to 66 whp (assuming 25% drivetrain loss)

SubieSport's 2005 RS Project Car has all of the above, minus the TB Spacer, but with headwork, higher compression, coated pistons, balanced bottom end, and an assortment of thermal coatings and such. Total gain over stock: 50 whp.

Now, I'd like to point out, that from the above modlist, a catback makes NO POWER on its own, much less 10. Even with headers, you're looking at 5-6 tops. It's of course dependent on other mods, but we're talking on a bolt-on-wonder here. Which brings their total down to the 50 whp gain SubieSport got, but the modlist is still substantially shorter and cheaper, and only the low-end of the horsepower gain range is there, that's supposed to be the MINIMUM gain from these mods, isn't it?

Now let's take a look at the tuning. No matter how you slice it, PP6 is constantly fighting with the ECU for control. This fight gets more prevalent the further beyond the 2000 model year you go, as ECU's became more advanced and more adept at fighting changes to an engine. Even with the new injector driver to allow "stand-alone" fuelling, they're still fighting for timing and a host of other functions. With AP RS, you're tuning the actual ECU, meaning with AP RS, the ECU is no longer a roadblock to making power. You're getting exactly what you ask for from the ECU, so with AP RS, each mod should theoretically be able to make as much as it is capable of making. This would hold true for the I-Speed reflashes for pre-05 models as well. The ECU no longer stands in the way. Yet even with a host of mods over and above the complete bolt-on catalog, we're still not making anymore power.

My reasoning is this: The gains so many people run around making are based on skewed information. Before I'm hung for saying this, hear me out. It's very rare that you see a mod tested on a bone stock car vs. it's stock counterpart. Meaning, when intakes are tested vs. stock, there are no other mods to the car such as headers, AFC's/piggybacks, high flow cats or track pipes, etc. Very often the actual reality is not seen, and let me illustrate this. Also, I'm not using factual numbers, I'm using easy numbers to add and subtract with to illustrate a point. So, here's the scenario...

When you add a header to a stock car, you might get 5 hp. Unfortunately you didn't test it. You buy an intake, you head down to the shop for a baseline run, say you put down 115 whp. You install your new intake, and lay down 125 whp. Well then, the intake is good for 10 whp! Amazing! Hang on now. Let's turn around and do it in reverse. Intake on a stock car. You might get 5 hp, but we don't know because no baseline was done. So now you've bought your header, head down to the shop, baseline 115 whp. Throw the header on, WOW! 125 whp! The header is what made the 10 whp! Fantastic! Well, no. Now we do a proper baseline on the stock car, lay down 110 whp. Install your new header/intake, and oh my, only 125 whp? But everybody on the forums say each part is worth 10 whp. What the hell?

You can't write a white paper saying this part is good for X horsepower, because over the years results have become so skewed by missing information, outrageous vendor claims, or just newbies that don't know any better, and see a gain and say, "That guy got 10 whp from his intake!" that the misinformation runs rampant and people inevitably end up being let down when they go to install a mod and don't see the results, or "feel" results, but when put to the test, the results just aren't there.

My advice to you is this, you have a few options:

1. Research very carefully. Find out what combinations work and make power. Remember that because that guy got 20 whp from I/H/E on his '00 doesn't mean you'll get the same on your '05, but realize it might be possible. If you want to make improvements to a combination, make sure you document them and give substantiated PROOF that it's in fact an improvement.

2. If you've already started modding, and want to know what kind of power your car makes, put it on a dyno. Don't look for a similar setup and say that's what you made. Even if it's an identical setup, you may have made more, you may have made less. You don't know if that other car was dynoed on Mt. Everest or in Death Valley.

3. Build a car so it looks the way you want it to, sounds the way you want it to, and hopefully goes the way you want it to, and don't worry about what you're putting to the pavement at the end of the day.

For the record, I opted for #3. I built my car for a certain road I drive regularly. Took the car back to that road a couple weeks ago, and it killed that road. I don't know how much power I have. I don't know what my skidpad number is. But I know I can take Suicide Bend at 90 kph. I'm thrilled.

Now I know what a lot of people are going to say, "You haven't answered any hard questions, you've just created more questions!" Well yes, that's true. With the reading and debating I myself dove into over my time in the suby community leads me to DaVinci-Code-like deciphering. Trying to weed out the skewed numbers and changes to the cars and their engines and ECU's over the years to get to cold hard facts is virtually impossible at this point. Go out there, build your car, and you show us what it can do. At this stage that's the best we can hope for.
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Old 10-02-2006, 04:27 AM   #128
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I'm going to add one thing to your post for you there Falcon. Yeah dyno numbers are nice, but they can be skewed in many different ways. We've already seen it in this thread. The only way to see if you actually making more power is to go to the drag strip and run the car when it's stock, and then after mods. Trap speeds don't lie.
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Old 10-02-2006, 09:19 AM   #129
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Originally Posted by X4 SRT View Post
I'm going to add one thing to your post for you there Falcon. Yeah dyno numbers are nice, but they can be skewed in many different ways. We've already seen it in this thread. The only way to see if you actually making more power is to go to the drag strip and run the car when it's stock, and then after mods. Trap speeds don't lie.
I actually use a hill outside a town near where I live. At the base of the hill is a 70 kph limit sign, and at the top right after it levels back off there's a 100 kph sign. Car in 5th doing exactly 70 kph when I hit the first sign, foot to the floor, check speed when I hit the 100 kph sign. But the results of that pull mean nothing to anybody but me. And even that can be skewed by wind direction and strength, gas in the car, etc, much like track can be skewed by those same factors. But at the track, your launch can skew your numbers. Where you shift can skew your numbers. A dyno is skewed by changing conditions from one day to another, or even within the same day. Like police radar guns, they fall out of calibration and the shop you're visiting might not be keeping on top of it. There's a local dyno here where they've been known to "adjust" the calibration themselves in the middle of a tuning session because the customer wasn't seeing the numbers they'd hoped for. And with all the shops out there, I'd find it hard to believe if you tried to tell me they were the only ones who'd ever done this.
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Old 10-02-2006, 10:43 AM   #130
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Quote:
Originally Posted by FalconRS View Post
Intake: 10 hp
Catback: 10 hp
EL Header: 12-15 hp
Tuning: 10 hp
Cam: 15-18 hp
LW Pulley: 3-5 hp
LW Flywheel: 3-5 hp
Ground Kit: 2-4 hp
TB Spacer: 4 hp
===============
Total: 69 to 81 hp
Wheel: 55 to 66 whp (assuming 25% drivetrain loss)
I always see this, % of drivetrain loss, would it be the case that it only takes "x" amount of force to drive the wheels and that the loss of HP through the drivetrain would be a constant and not a %. For example, if a person can bench 250 lbs he exerts "x" amount of force to bench 100 lbs. Now if said person increases his max bench to 300 lbs, he would still be exerting the same force to bench 100 lbs as he did when his max was only 250 lbs. Wouldn't the same thing hold true in the force used to rotate ones tires on a car?

Also, things like a LW Pulley and Flywheel wouldn't add the power to the crank. They add power to the wheels due to the lower rotational mass. Its like adding a set of LW wheels. They'll add WHP, but not CHP. Please correct me if I'm wrong here.

Last edited by pudnana; 10-02-2006 at 10:49 AM.
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Old 10-02-2006, 10:50 AM   #131
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Originally Posted by pudnana View Post
I always see this, % of drivetrain loss, would it be the case that it only takes "x" amount of force to drive the wheels and that the loss of HP through the drivetrain would be a constant and not a %. Also, things like a LW Pulley and Flywheel wouldn't add the power to the crank. They add power to the wheels due to the lower rotational mass. Its like adding a set of LW wheels. They'll add WHP, but not CHP. Please correct me if I'm wrong here.
Driveline loss is typically a percentage, not a fixed amount. Rotational energy is lost everytime it's transfered through a gearset, a belt, etc etc.

As for the rest of the numbers, I took them directly out of the original white paper posted, specifically to point out flaws in the original writing. And you've illustrated another one. Thanks.
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Old 10-02-2006, 11:11 AM   #132
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Well. my car will be done this week or so I hope. Struggling to figure out how to make the car the absolute quietest without sacrificing power (dual functional exhausts on an rs anyone? :ㅤD I dunno what will actually be used at the moment). Got cams, pnp heads, pistons, who the hell knows what else. Basically, I just gave andrewtech the car and said Make meh powa! Well, finally looks like that day will be here soon to see what happened with it. Will post soon as get some sort of idea about it.
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Old 10-02-2006, 11:17 AM   #133
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Originally Posted by atech_rallyrs View Post
Well. my car will be done this week or so I hope. Struggling to figure out how to make the car the absolute quietest without sacrificing power (dual functional exhausts on an rs anyone? :ㅤD I dunno what will actually be used at the moment). Got cams, pnp heads, pistons, who the hell knows what else. Basically, I just gave andrewtech the car and said Make meh powa! Well, finally looks like that day will be here soon to see what happened with it. Will post soon as get some sort of idea about it.
True-dual exhaust would only be possible with a full-on stand-alone EMS, as you'd need an O2 sensor in each exhaust stream. Not impossible, but difficult. Good luck dude.
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Old 10-02-2006, 12:09 PM   #134
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Just do it right, otherwise it's not as effective as a good single exhaust(read double can be worse in performance). An X pipe is very important for maintaining/getting good power.

Read:
http://www.superchevy.com/technical/...t/0505phr_exh/
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Old 10-02-2006, 12:51 PM   #135
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Dunno. Think we are doing standalone, I honestly dont have a clue. Just that "stuff" has been done.

edit: That article on exhaust mechanics is pretty interesting. Ive moved on from that article and am hunting down more information as we speak. Definitely appreciate the link!

Last edited by atech_rallyrs; 10-02-2006 at 01:05 PM.
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Old 10-02-2006, 01:32 PM   #136
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http://forums.nasioc.com/forums/show....php?t=1080151
http://forums.nasioc.com/forums/show....php?t=1089089

Kinda my compelation of data so far. I've got an excel spreadsheet of all the data from that article and just going through all the different sizing/flow stuff and nailing down some optimum numbers. I'd post it, but it's just a big mess

Fine, I'll throw it on here, but it's really, really messy just kinda pulling out all the data from the article(well a couple more too, but cover same stuff in a slightly different manner) The pipe length tuning stuff on the other page is just me fiddling around with the idea of tuning length vs speed of sound, but speed of sound varies by temp, so it actually varies...would have to know "hot" temp under normal operation. I added some charts of the data for easy reading of some of the data. It really is neat stuff, gets you thinking.
http://www.gigafiles.co.uk/files/626...ero%20Loss.zip
(had to put it in a different format to host...so zip it is)
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Old 10-02-2006, 02:21 PM   #137
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Quote:
Originally Posted by LetItSnow View Post
The question that stands is... Will enough people want to purchase an AP and cams that will run to 8000 RPM? COBB has to decide whether to make those high-breathin' cams.
Rob,
I know you will view this with skepticism, but Jeremy at Cobb has already stated that they are working on a more peaky cam for th SOHC Ej25. That will also be coupled with a revised design of their headers. I don't know that this will be intended for mass production, but is a "race" build they are currently working on.

And I would like to add one simple comment to the previous argument about drivetrain loss and dynos. The one thing that invariably gets left off is the "drivetrain loss" to the dyno itself. Making the example of our local dyno where stock RS's run 95whp against a factory rated 165. 70hp loss to drivetrain would be silly. But just like going to a lighter pulley lets more power go to the wheels, it does take power to spin the rollers on the dyno. This is why there are such HUGE variances in percieved driveline losses from dyno type to dyno type. It always gets ignored and just called "driveline loss"...
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Old 10-02-2006, 04:48 PM   #138
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Shouldn't the dyno be calibrated to acount for its own inertial/friction losses? It would seem silly not to.
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Old 10-02-2006, 05:00 PM   #139
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Originally Posted by Back Road Runner View Post
Shouldn't the dyno be calibrated to acount for its own inertial/friction losses? It would seem silly not to.

There are dyno operators who run calibrations that spit out SAE corrected Crank HP numbers, but that tends to be less accurate than just letting it read what it reads. And it's also subject to manipulation. For years there have been rumours that some of our most reputible vendors manipulate their dyno numbers for bragging purposes. With math, you absolutely can back out the impact of the rollers on it, but you can't actually remove the impact. As has been said earlier, a 1/4mi run or an uncorrected dyno run, with known before and after numbers tend to be the best way to get a good solid idea of where the crank HP number really lies..
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Old 10-02-2006, 08:25 PM   #140
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What about the types of dynos? I know Dynojets are inertia based dynos and people seem to consider them a little high. I had my car dynoed on a Dyno Dynamics dyno that's generator/motor/whatever driven. I think it works off feed back or something instead, and you can do things like maintain constant rpm and hold and measure torque output, things that can't be done with an interia based dyno. Are there advantages for particular types? The shop owner tested the dyno back when he first got it with some old Toyota something, put out like 60whp, basic. He ran over a dozen runs and got only a .2HP difference throughout(testing repeatable accuracy). I thought it was interesting.
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Old 10-02-2006, 11:40 PM   #141
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Quote:
Originally Posted by FalconRS View Post
According to this big white paper article, which does a nice job of outlining what's out there and how extensive your options really are, here's the gains you can expect from various mods. Here's the common bolt-on list:

Intake: 10 hp
Catback: 10 hp
EL Header: 12-15 hp
Tuning: 10 hp
Cam: 15-18 hp
LW Pulley: 3-5 hp
LW Flywheel: 3-5 hp
Ground Kit: 2-4 hp
TB Spacer: 4 hp
===============
Total: 69 to 81 hp
Wheel: 55 to 66 whp (assuming 25% drivetrain loss)
If it's been said once on this forum (and every other automotive forum, for that matter) it's been said a thousand times. You can't take performance gains for individual modifications and add them all together. As your own example later in your post (admittedly with made up numbers) demonstrates, modifications may or may not complement each other, so the total gain isn't going to equal the gain from each individual part. That's just basic performance tuning knowledge, and I'm surprised you'd bring that up as though we should be surprised the SubieSport car made only 50hp over stock instead of 55-66whp.

Quote:
Originally Posted by FalconRS
Now, I'd like to point out, that from the above modlist, a catback makes NO POWER on its own, much less 10. Even with headers, you're looking at 5-6 tops.
Are you saying a full exhaust (headers/cat/midpipe/muffler) is only good for 5-6hp? If so, you're off by quite a bit - 14hp has been dyno proven by me, and I'm not the only one. The evidence has been available on this forum for over 4 years now. And yes, that was on an utterly stock car.

Quote:
Originally Posted by X4 SRT View Post
I'm going to add one thing to your post for you there Falcon. Yeah dyno numbers are nice, but they can be skewed in many different ways. We've already seen it in this thread. The only way to see if you actually making more power is to go to the drag strip and run the car when it's stock, and then after mods. Trap speeds don't lie.
Trap speeds aren't very repeatable, though. A typical night at the strip for me would have trap speeds +/-1mph. By the ol' racer's thumbrule of 1mph in trap speed is 10hp, that's a 20hp swing in a single night. I agree that 1/4mi runs can show you in general how the car is performing, but to say a 1/4mi is more truthful than a dyno is incorrect IMO.

Quote:
Originally Posted by pudnana View Post
I always see this, % of drivetrain loss, would it be the case that it only takes "x" amount of force to drive the wheels and that the loss of HP through the drivetrain would be a constant and not a %.
People generally throw out a % for drivetrain loss, but it's really somewhere in between a constant number and a %. I did a bunch of research on this a few years ago to satisfy my own curiousity and I posted it on some automotive forum, but I don't remember where. Gears have frictional losses and windage losses (from the lube oil they're spinning in), and those two types of losses react differently as the amount of power put through the gears goes up. And when we're talking about chassis dynos, with the exception of the Dynapak, part of the "drivetrain losses" are due to rotational losses and frictional losses in the wheels/tires - those are going to be pretty constant, since the RPMs at which we're dynoing are the same. I think that I came to the conclusion that the drivetrain losses would be closer to a % than to a constant number, but you can't say a stock 227hp WRX that had 25% losses (56.75hp) would still have 25% losses if it were pumped up to 400hp (100hp). Would it have 15% losses (60hp) or 19% losses (~75hp) or ??? It would take some dedicated testing with chassis and engine dynos to figure that one out.

Quote:
Originally Posted by Back Road Runner View Post
An X pipe is very important for maintaining/getting good power.

Read:
http://www.superchevy.com/technical/...t/0505phr_exh/
An X-pipe on a 4-cyl isn't going to do anything for you. On a V-8 they're great (improve performance, reduce drone, and sound awesome - what more could you ask for?!) - I'm looking to get one installed on my Mustang in the near future. But a 4-cyl doesn't have exhaust pulse timing anywhere near what a V-8 has, so there's no benefit to be had with an X-pipe.

Quote:
Originally Posted by Back Road Runner View Post
What about the types of dynos? I know Dynojets are inertia based dynos and people seem to consider them a little high. I had my car dynoed on a Dyno Dynamics dyno that's generator/motor/whatever driven. I think it works off feed back or something instead, and you can do things like maintain constant rpm and hold and measure torque output, things that can't be done with an interia based dyno. Are there advantages for particular types? The shop owner tested the dyno back when he first got it with some old Toyota something, put out like 60whp, basic. He ran over a dozen runs and got only a .2HP difference throughout(testing repeatable accuracy). I thought it was interesting.
Dyno Dynamics dynos and Mustang dynos are both load-bearing dynos. As BRR said, you can control the load and RPM, which means a load-bearing dyno absolutely cannot be beat for effective tuning. For instance, I can hold the car at 2500 while going from cruise throttle (say, 10%) all the way to WOT in however many steps I want to use. That's great for creating/modifying tables in an ECU that are based on load and RPM, and there's no possible way to do that kind of thing with an inertia type dyno like a Dynojet.

Based on what I've seen with my dyno runs, a Dyno Dynamics will crank out numbers approximately 15% lower than a Dynojet. I compared numbers across the board and that 15% seemed pretty constant from 2500rpm all the way to 6500rpm. It's a ballpark figure, of course, but should give some idea of how much variation you can see.

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Old 10-03-2006, 12:17 AM   #142
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I know the X pipe helps equalize pressure, but yeah, not sure about the pulses and effectiveness for a 4 cylinder versus 8 cylinder. However, I'd think with any dual exhaust, it would probably help. Of course, I don't know crap, so my knowledge so far is from whatever articles/comments/etc I've come across online. I figure I'll read "Scientific Design of Exhaust and Intake Systems" at some point in the future, suppost to be a great book for exhaust design.
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Old 10-03-2006, 02:59 AM   #143
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Originally Posted by LetItSnow View Post
Trick of it is, even with cams designed to run within the stock redline, the AP allows the engine to make as much power at 8000 RPM as it did at 6200 RPM before tuning. There's still plenty to play with up there.

The question that stands is... Will enough people want to purchase an AP and cams that will run to 8000 RPM? COBB has to decide whether to make those high-breathin' cams.
I had to weigh in on this. Basically no, the AP cannot overcome physics. If you only get so much air at point X (in our case peak power is at 6200 rpm) and then as you rev the motor you get less and less (which is what is happening in our motor right now past 6200 rpm) you cannot "tune" the engine to make more power or the same power than you did at your peak power because you don't have enough air.

Yes we have the bottom end to rev to 8000rpm... it makes WAY less power at 8k than at 6200 so to rev that high is just masturbation for the sake of revving. We don't know at this point if it is the cams, intake or the heads that are the bottleneck, or if there even IS a bottle neck but the cams seem most likely. We are discussing what next. I think our build shows in a very real-world way what bolt-ons can do with good EM. I would like to have seen what the motor would do without head work but whatever.

We think the cams are the culprit simply because of the nature of their design which is for a car where the rev-limmit can't be changed and they did great when that was what our car was. Now it's not. Now we have options. Stay tuned, we'll build it and you can read about it so that you can do it the way you want the first time.

Just to give some examples when we did I/H/E and a pulley and all that we made something like 10-15hp over stock which was 113whp on our car. Adding EM (PP6 at that time) made a bit more. The big difference was cams which put us at ~130whp. We can compare our stock pulls and our now pulls and everything in between (same dyno throughout the build) so it really goes to show that you can't just add claimed hp increases for all your parts and call it good. There are a few little blips in our build though. Our TWE headers got smashed so we had to switch them out and we did the Rallitek EL headers and the full catless catback at the same time. Then we put a built motor on top of these parts. Now we have no idea if the exhaust is ideal or not, but I doubt it would have decrease performance. But maybe there is a better header/exhaust combo out there?

However, since we only made 130-140whp before the build it is safe to say that the higher compression and headwork is what gave us the real boost in power so I think it is safe to say that 130-140whp is about the limmit of a stock block with spicey cams and all the bolt-ons. HOWEVER, that is measured on one dyno on one car, on one fuel type at ~sea-level etc.

Last edited by MeanEditor; 10-03-2006 at 03:14 AM.
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Old 10-03-2006, 09:38 AM   #144
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If it's been said once on this forum (and every other automotive forum, for that matter) it's been said a thousand times. You can't take performance gains for individual modifications and add them all together. As your own example later in your post (admittedly with made up numbers) demonstrates, modifications may or may not complement each other, so the total gain isn't going to equal the gain from each individual part. That's just basic performance tuning knowledge, and I'm surprised you'd bring that up as though we should be surprised the SubieSport car made only 50hp over stock instead of 55-66whp.
Thank you for picking up on that, as that was the entire point of my post and why I took issue with the white paper.


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Are you saying a full exhaust (headers/cat/midpipe/muffler) is only good for 5-6hp? If so, you're off by quite a bit - 14hp has been dyno proven by me, and I'm not the only one. The evidence has been available on this forum for over 4 years now. And yes, that was on an utterly stock car.
Read again, I said a CATBACK on a STOCK CAR (stock header, stock cats) won't make any power. A catback added to a car that already has the header and cats replaced with aftermarket parts will make 5-6. It could be more if the car is heavily modified, but again, I was talking about bolt-on cars, not race cars.
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Old 10-03-2006, 09:42 AM   #145
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The Cobb/Rallitek/OBX design seems to be the favorite. TWE seems to be geared for the high rpms most, but the Rallitek you're using seems to provide better power throughout. Piping sizes are the same between all of them, 1.65" primaries, 2.25" collector, so maybe it's just a matter of pipe length. I talked with a Rallitek guy over on RS25, and he gave the general concensus that the Cobb/OBX/Rallitek style were generally better liked, but then again, TWE's expensive and so few people run them. I have yet to see a dyno graph of a car with one(non-turbo).

I like the idea of one part complementing another. It's something people kind of forget. The limitation is where the bottleneck is. This could be your intake, your muffler, your cams, cats, wherever. The hugh variety of parts you add only goes up to the limit of the bottleneck. An example would be me saying aftermarket cats give 10HP. Well, if I use the stock exhaust manafold, I may see near nothing. If I run an aftermarket manafold with stock cats, again, I may only see a little bit. Yet, when I combine them, I see the gains. Then I may it a bottleneck at the muffler. Upgrade the muffler and I get more. One or even two of those upgraded may only show partial gains. It's the system as a whole that defines what is capable.

On a note of EM, it's a really good idea to look into aftermarket options. Seriously, it will pay it's weight in gold.
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Old 10-03-2006, 10:50 AM   #146
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MeanEditor (whom I am guessing is Ryan under a new screenname?),

I think my car and dyno results helps to support the point you are trying to make. I ran the spicy cams for nearly 2 years before I did the headwork, and have before and after dyno runs. What I found with my car is that the headwork just bumped the powercurve. It didn't shift it at all, and my peak HP is made at pretty much the exact same RPM's that is was at before the headwork. This suggests to me that it's the cam that's setting that point.

Pat Olsen,
Regarding the drivetrain loss? I think it actually becomes very close to a constant at higher power levels. The problem with our datasets is that as NA guys we don't have enough power to get up into that power level where it becomes constant. I am pretty good friends with Xephyr, and he tracks all this kind of stuff VERY closely on his personal car and models stuff over and over and over. What he has found on his personal 400+whp vehicle was that above around 300whp his driveline losses were pretty much the same number of HP regardless of if he's at 300whp, 350whp or 400whp. Basically, in his experience, it's between a 70-75hp loss due to driveline and dyno inertia...
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Old 10-03-2006, 12:33 PM   #147
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I am Travis the managing editor. Ryan is still ricochet.
That is interesting about your cams as we have more HP now than we did before. That could just be the function of the higher compression coupled with headwork and better EM.
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Old 10-03-2006, 01:29 PM   #148
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I am Travis the managing editor. Ryan is still ricochet.
That is interesting about your cams as we have more HP now than we did before. That could just be the function of the higher compression coupled with headwork and better EM.
Travis,
I think you misunderstood. I picked up almost 13whp from the headwork. What I am saying is that my peak HP continued to be at 5800rpm, both before and after the headwork...
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Old 10-03-2006, 02:12 PM   #149
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You are right, Matt. The cams will dictate the personality of the motor. Make changes to the timing of the cams and you'll see changes in where the curve moves to in relation to RPM.

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Old 10-03-2006, 05:31 PM   #150
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Pat Olsen,
Regarding the drivetrain loss? I think it actually becomes very close to a constant at higher power levels. The problem with our datasets is that as NA guys we don't have enough power to get up into that power level where it becomes constant. I am pretty good friends with Xephyr, and he tracks all this kind of stuff VERY closely on his personal car and models stuff over and over and over. What he has found on his personal 400+whp vehicle was that above around 300whp his driveline losses were pretty much the same number of HP regardless of if he's at 300whp, 350whp or 400whp. Basically, in his experience, it's between a 70-75hp loss due to driveline and dyno inertia...
Thanks, Matt, that's good info. Intuitively that has always made more sense to me, so it's good to see some real numbers that would seem to back up what my brain thinks.

Pat
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