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Old 02-01-2001, 02:59 PM   #1
Layman
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Post COBB power packages...

Hey all,

I was checking out COBB's site and noticed the little package deals they have. The stage two package seems nice, but I'm curious about the power output. I've heard that COBB is a reputable business, but will an ECU, breather mods and a pulley really add ~30hp? Additionally, will a cam add the additional ~20hp they promise? If so, it sounds like RS owners can be pushing about 220 N/A hp for only $2300. That's one hell of a deal!

<IMG SRC="http://www.cobbtuning.com/images/dyno-cams3.jpg" border=0>

So are these numbers accurate, or am I a newbie falling for marketing?

Also, I've heard about a "second gear problem." Does this infer that the stock tranny can't handle a lot of HP? Whereabouts is the threshold for the stock tranny?

Thanks in advance.
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Old 02-01-2001, 03:27 PM   #2
Overtime
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Cobb's power package ratings are more estimates of power increases to the flywheel than any sort of hard dyno result.

There have been...mixed...results with dyno'ing headers/catback/intake/pulley. What I think everyone can agree on is that the improvement with strictly bolt-ons is negligible compared to the improvement with cams or forced induction.
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Old 02-01-2001, 03:29 PM   #3
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My cams are arriving tomorrow, and I will be able to tell you how much power via the "butt dyno" on saturday or sunday (I am installing them myself). Do a search for Cobb Cams, and you should pull in a couple threads from ColinL and Jon Bogert regarding their power output.

As far as the second gear problem; well, second gear is inherantly weak. If it is abused, it will break. I think everybody has decided that its the half shaft flexing under load which is causing the problem (that and an unstrong gear). The half shaft flexes and unmeshes the teeth of the second gear, causing the teeth to shear. Just a theory, so don't take it as written proof.
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Old 02-01-2001, 03:51 PM   #4
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Um, OT the cams are dyno proven and it's linked right here in the discussion!

Now the dyno chart does show MPH instead of the usual convention of RPM, but since we *know* this is 4th gear we can figure out what RPM range the cams start to make a difference at, and we can see how large that difference is.

Now as to 30HP from an intake, pulley and ECU... Maybe. Since you can't really dyno a cold air intake (the car isn't moving, thus you get hot air) I would say that at least half of that claimed power gain would come from the ECU alone.

I think instead of the ECU headers and exhaust would be a better move. Actually, how about headers and exhaust in addition to everything else?
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Old 02-01-2001, 04:06 PM   #5
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Colin,

The ~30hp increase (18-20%) is said to come from the power package II, which consists of:
Stromung Single Tip
Performance Muffler System**
Stromung 57mm Intermediate pipe
K&N Replacement Air Filter
Power Pulley Kit
Borla Stainless Steel Header system
Cobb Tuning Piggy-back ECU

It seems reasonable to me. Then the cam is supposed to add "a +14 PEAK HP GAIN to the wheels and +13 ft-lbs PEAK TORQUE GAIN, with maximum gains of +19 HP at redline!!"

That should make about 220+ at the crank, right? I'm not misreading this, correct?

Sorry if I sound like I'm in disbelief, but coming from Hondas where extra HP isn't always so readily accessable, adding 50ish hp for less than 3 grand is AWESOME.

Regarding heads, how much of a PITA is it to install them? I imagine it's a bit more complicated than a OHC design.
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Old 02-01-2001, 04:29 PM   #6
ColinL
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Oh, right. Given that part list I would say that 30HP is entirely believable. The EJ25 is significantly detuned in stock configuration compared to most any Honda engine. (not all, but most.) There is simply a whole lot of power Subaru has left at the table...

Now will this 220HP naturally aspirated be the same as a 5psi turbo making about the same 220HP? No. It will have better throttle response, but won't make much if any more power below ~3500rpm, whereas the turbo will be at 5psi early-- perhaps 2200rpm.

You really should do some searching and see what others have already done.
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Old 02-01-2001, 04:36 PM   #7
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Cool

Guys, just clarify, when it comes HP, 2+2 does not equal 4.

If you install the cams, and only the cams, you'll see the 14HP at the wheels, as the dyno chart shows.
If you remove the cams and add an intake, which was dynoed at 8HP, you'll see an increase in HP in the range of 8HP.
However, add the cams and intake together and you WILL NOT see an increase of 22HP.
You just cannot add HP numbers individually.
As an example, my car has intake, power pulley, borla headers, mid pipe and stromung exhaust. Trey estimates that the car is making 192HP and 190lbs of torque. All together accounts for an increase of 27HP. If I add the cams, the car will not make any more than 200-202HP.

Cheers,
Marco (whishing I were wrong)

[This message has been edited by Marco (edited February 01, 2001).]
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Old 02-01-2001, 04:38 PM   #8
ColinL
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And as far as how hard the cam install is... Here is my story. Could I install a second set faster? Sure. Would I look forward to pulling cylinder heads again? No way. But could I do that faster too the next time-- sure.

EDIT:

Marco, your assertions seem to be in direct opposition to Trey's statements on the street cam page:
Quote:
Dyno testing, comparing a stock 2.5L Impreza with and without camshafts, has shown a +14 PEAK HP GAIN to the wheels and +13 ft-lbs PEAK TORQUE GAIN, with maximum gains of +19 HP at redline!! These gains were seen when comparing otherwise unmodified, stock cars. More gains are possible if your vehicle is modified with upgraded intake and exhaust systems.
Now as a general rule, I would agree that directly adding the HP gain of various mods is unwise. This is a symbiotic relationship though, the cams can make even more power (a little more) if given a better "team" to work with.

[This message has been edited by ColinL (edited February 01, 2001).]
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Old 02-01-2001, 04:41 PM   #9
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Colin, thanks for the info.

Marco, I have you covered on the 2+2!=4. However, Cobb states on their site that the results they display for cams is for a stock engine, and that a modified one should respond even better.

Anyhow, I really appreciate the replies. I'm not planning on doing any mods soon, but I like knowing what is out there.

Thanks again.
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Old 02-01-2001, 05:09 PM   #10
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Marco wasn't saying that you wouldn't see ANY gain by combining multiple mods, he was saying that you couldn't just add the two individual numbers and come up with your peak gain. It would probably be somewhere inbetween the stock and combined numbers. And, in rare cases higher if the two mods are that closely linked.

In addition, you should keep in mind that butt-dyno is not the same as real HP. Most bolt-ons aren't going to give you a lot more additional HP, but they will make better use of, and make more accessible, the HP you do have.

Engine/tranny mounts would be a perfect example of this. You aren't adding any HP to the engine, but you are adding HP to the wheels by reducing loss in the drivetrain.
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Old 02-01-2001, 05:12 PM   #11
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Colin-

Never said anything about the cams not being dyno-proven. We all have seen the many results.

However, different people have received different dyno results on the bolt-on front. Admittedly, they've done so with different dyno systems and any one of an infinite number of variables can be screwing with the results, but it's still really strange to see someone get no HP (Cobb) and someone get 15+ hp (Shiv.) Obviously there are differences, but we really lack any hard evidence.

I hope to make a trip down to Florida this summer for some headers (and maybe a temporary turbo) testing with Tom Coleman of Ludespeed...and maybe we'll throw in a couple of variables that some tuners have ignored. All TBD.
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