 2.0 Stock Muffler, Do aftermarket mufflers drop power? |
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| Thack |
 Nov 20 2007, 04:38 PM
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#1
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Member  Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182  |
When I had my 911, a race mechanic told me that most aftermarket mufflers lost power over the stock unit. Is this true with the 914? Any dyno evidence out there?
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Replies(1 - 15)
| Rand |
Nov 20 2007, 04:43 PM
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#2
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Cross Member Group: Members Posts: 7,409 Joined: 8-February 05 From: OR Member No.: 3,573 Region Association: None |
Depends on the muffler. Even some of the cheapo turbo mufflers are very free-flowing and cause no power loss. Then there are other variables too... Engine build, tuning.... Different combos net different results.
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| Thack |
Nov 20 2007, 04:52 PM
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#3
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
I kind of want the stock sound level. Performance is the least on my list of needs. I like reliable, docile streetability.
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| Gint |
Nov 20 2007, 05:16 PM
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#4
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Mike Ginter Group: Admin Posts: 16,075 Joined: 26-December 02 From: Denver CO. Member No.: 20 Region Association: Rocky Mountains  |
Stock muffler on a FI motor is very quiet. Too quiet IMO.
Stock muffler with carbs sounds pretty good and not nearly so quiet, but not loud either. As for the performance difference I can't say. |
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| Cap'n Krusty |
Nov 20 2007, 05:42 PM
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#5
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Cap'n Krusty Group: Members Posts: 10,794 Joined: 24-June 04 From: Santa Maria, CA Member No.: 2,246 Region Association: Central California |
The only 911s to suffer serious power losses with some aftermarket mufflers were the MFI cars. Too little backpressure, allowing the some of the fuel charge to pass right through the combustion chamber. The Cap'n
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| PeeGreen 914 |
Nov 20 2007, 06:53 PM
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#6
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Just when you think you're done...wait, there is more..lol Group: Members Posts: 10,219 Joined: 21-September 06 From: Seattle, WA... actually Everett Member No.: 6,884 Region Association: Pacific Northwest 
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Most of the dyno charts I've seen show that most aftermarket exhausts increase hp over the stock. For the 911's and 914s that is.
I don't think any performance exhaust would decrease hp. If that was the case, why would race cars run straight pipes? |
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| Brando |
Nov 20 2007, 07:02 PM
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#7
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BUY MY SPARE KIDNEY!!! Group: Members Posts: 3,935 Joined: 29-August 04 From: Santa Ana, CA Member No.: 2,648 Region Association: Southern California |
Race cars and our cars stock are 2 different worlds. Race cars run straight pipes because they run at WOT most of the time. Tons of fuel (burnt and unburnt) running straight through. Wild cam profiles, lots of overlap. You run a straight pipe so that expanding gasses going out the muffler draw that next charge of air and fuel into the cylinder. Chances are, on a race car you're running carbs or PEFI - so all the variables are tunable.
Different worlds... |
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| PeeGreen 914 |
Nov 20 2007, 07:14 PM
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#8
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Just when you think you're done...wait, there is more..lol Group: Members Posts: 10,219 Joined: 21-September 06 From: Seattle, WA... actually Everett Member No.: 6,884 Region Association: Pacific Northwest
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But the guy said he was a race mechanic. Now if your just talking about a stock 914 I agree that you need to change certain things to make it all work properly, but in all you should get more hp out of your car with an aftermarket exhaust. No?
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| Bleyseng |
Nov 20 2007, 07:16 PM
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#9
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Aircooled Baby! Group: Members Posts: 13,034 Joined: 27-December 02 From: Seattle, Washington (for now) Member No.: 24 Region Association: Pacific Northwest |
Grassroots Motorsports did a dyno comparison on a warmed up 2056 djet 914.
Stock 914-good hp Bursch-good with +2hp at high rpms Monza- lost hp so its either stock or bursch..... (IMG:style_emoticons/default/chair.gif) |
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| Thack |
Nov 20 2007, 07:21 PM
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#10
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
Performance parts are sold because people buy them thinking they increase power or told that they increase power. The mechanic who told me about exhausts loosing power tunes engines in 911s and GT3s that go to Le Mans and 24/Daytona. I saw his dyno and his shop was full of race cars.
I myself have tested 2-stroke bikes on a dyno where aftermarket silencers decreased HP, yes decreased HP. I was shocked because the manf. was huge in the motocross business. Unless you tune the whole system, sometimes aftermarket parts are a let down. I just wanted to know if it applied to 914s because I haven't seen any charts or info on exhaust parts, stock or otherwise. |
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| PeeGreen 914 |
Nov 20 2007, 07:21 PM
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#11
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Just when you think you're done...wait, there is more..lol Group: Members Posts: 10,219 Joined: 21-September 06 From: Seattle, WA... actually Everett Member No.: 6,884 Region Association: Pacific Northwest
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It would be nice if Dave, Triad, would do a dyno on one of their cars to see what it would do in comparison to a stock exhaust. On my six you can feel a big difference, but I don't know the numbers.
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| PeeGreen 914 |
Nov 20 2007, 07:24 PM
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#12
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Just when you think you're done...wait, there is more..lol Group: Members Posts: 10,219 Joined: 21-September 06 From: Seattle, WA... actually Everett Member No.: 6,884 Region Association: Pacific Northwest
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QUOTE(Thack @ Nov 20 2007, 05:21 PM)  Performance parts are sold because people buy them thinking they increase power or told that they increase power. The mechanic who told me about exhausts loosing power tunes engines in 911s and GT3s that go to Le Mans and 24/Daytona. I saw his dyno and his shop was full of race cars. I myself have tested 2-stroke bikes on a dyno where aftermarket silencers decreased HP, yes decreased HP. I was shocked because the manf. was huge in the motocross business. Unless you tune the whole system, sometimes aftermarket parts are a let down. I just wanted to know if it applied to 914s because I haven't seen any charts or info on exhaust parts, stock or otherwise. Well, I guess your guy would be right in that reguard, but in every case you need to tune the whole car. However, if you do tune the car correctly a stock exhaust is not better than the Triads I have run, but I do tune the car for them. Oh, and the 911's that are in the ALMS do NOT run stock exhausts. |
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| Thack |
Nov 20 2007, 07:29 PM
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#13
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Member Group: Members Posts: 283 Joined: 1-June 05 From: Houston, Tx Member No.: 4,182 |
The mechanic was Sam at AutoTechnik in Houston. A lot of people add mufflers to their stock cars and he tunes street cars too. I have an aftermarket muffler on mine and I don't want to have to tune my engine to damn near race specs. I want a nice stockish output. Street cars spend so much time at low to mid throttle and it seems some of these aftermarket mufflers flow too much for low rpm. That's just seat of the pants testing. I appreciate your inputs. This forum is great.
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| PeeGreen 914 |
Nov 20 2007, 07:37 PM
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#14
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Just when you think you're done...wait, there is more..lol Group: Members Posts: 10,219 Joined: 21-September 06 From: Seattle, WA... actually Everett Member No.: 6,884 Region Association: Pacific Northwest
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What you have should be fine without any tuning unless you have a really extreme exhaust on there. The PO may have just change yours out due to the OE rusting out.
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| rhodyguy |
Nov 21 2007, 09:23 AM
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#15
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Chimp Sanctuary NW. Check it out. Group: Members Posts: 22,081 Joined: 2-March 03 From: Orion's Bell. The BELL! Member No.: 378 Region Association: Galt's Gulch |
bear in mind that most aftermarket exhaust systems are far cheaper than the oem units. i think most people want a racier sound, and are looking to save some money. if they feel they are getting a bit more power that's just a bonus.
k |
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| championgt1 |
Nov 21 2007, 08:44 PM
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#16
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Don't embarrass me Filmore! Group: Members Posts: 2,680 Joined: 3-January 07 From: Tacoma, Washington Member No.: 7,420 Region Association: Pacific Northwest |
QUOTE(rhodyguy @ Nov 21 2007, 07:23 AM) bear in mind that most aftermarket exhaust systems are far cheaper than the oem units. i think most people want a racier sound, and are looking to save some money. if they feel they are getting a bit more power that's just a bonus. k (IMG:style_emoticons/default/agree.gif) Well said, that is basically what it all comes down to. |
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