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Subaru Crew - Modifications II

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Comments

  • locke2clocke2c Posts: 5,038
    a car I'm paying for will be stock, yes. modding a paid off car would be fine, especially one that isn't worth a great deal.

    -Colin
  • ateixeiraateixeira Posts: 72,587
    So you think I should go a group buy for a Greddy turbo for the Miata? It's cheap - $1080 last time I checked.

    I probably won't. Not worth the effort for the low boost setup I'd be willing to invest in.

    -juice
  • kenskens Posts: 5,869
    Colin -- I thought you had taken the Impreza to the dealer and they had, at least temporarily, fixed the coolant loss. I guess it would kind of suck if the dealer tore down the engine, saw the porting and told you they wouldn't charge it to warranty!

    juice -- I'm sure it's not outrageously expensive to buy a snorkus. ;-)

    Ken
  • locke2clocke2c Posts: 5,038
    Ken-- I wasn't loosing coolant when I brought it into the dealer... I think. Can't remember for sure although I guess the posts from early this year are here on Edmunds if I cared to dig.

    Topping the coolant did temporarily resolve the overheating, I remember that for sure.

    -Colin
  • lilbluewgn02lilbluewgn02 PAPosts: 1,087
    If you're interested, I can put you in touch with a Subie guy here in Florida, that also has a turbo Miata. LMK
    Serge
  • ateixeiraateixeira Posts: 72,587
    True, Ken. I probably won't bother. In fact I'll probably keep Sandy for at least another year or two.

    When the 2004 Forester Turbo comes out, demand will be high at first, so I'll wait for prices to settle. I may also wait and see what the 2005 Legacy twin turbo looks like.

    Miata.net has a great Garage section, lots of folks share their turbo experiences there. It's just a thought. I probably wouldn't.

    I found a high mileage '99 Miata locally, under $10 grand. Thought about selling mine privately, I could probably get $7 grand, and pay the difference to get one 6 years newer, with 24 more horses and a glass rear window.

    But mine's fine, reliable as a Seiko. I think if I sell it, I'll regret it, it'll be "the one that got away".

    -juice
  • idahodougidahodoug Posts: 537
    "I dunno, I just feel like I have to customize whatever I own to my liking. But I probably ought to leave the engines alone - not enough experience to fix whatever I screw up."

    Juice,

    I do a lot of mods to every car I buy. But I don't mess with the powertrain at all, except to put synthetics into it, saving my money for things that will make the car safer and more enjoyable for my particular tastes. I do this because I tend to buy a vehicle that already has a powertrain that meets my needs in terms of power and features, then tailor the car to my tastes with this firm foundation.

    This approach produces a vehicle I liked from the start that now meets my every need without any warrantee or durability issues no matter how hard I push it. I typically add quality lights, stereos, upgraded tires, winter rims, and the like. Call me a wuss, but I don't have the cajones to modify a modern powertrain - especially one under warranty. It's amazing how many younger owners - especially Subie owners - are making fairly energetic mods to their powertrains. But it also makes me wince when I see a lowered 2 year old Civic with clearly modified powertrain already blowing smoke out the exhaust. This person has likely taken a vehicle whose engine would have lasted 200k miles and messed with something that took it outside the mfrs cooling system capacity or similar fatal error. I shake my head and wonder "Did he drop $400 on headers, then $1400 on wheels and tires and decide to put off the oil changes for lack of money while trying to keep up with the payments?" Or was it simply a matter of abusing the vehicle with the slight performance mods?

    It's a reasonable assumption that the manufacturer of today's vehicles has balanced the engine's power, cooling system and brakes in such a way that an abusive owner can be accomodated as long as they're maintaining fluids. But when you extract additional power (more heat) from the engine, it may be that you're stressing the cooling system more easily - leading to blown gaskets, etc. So, ironically the modded engine should be babied in order to avoid exceeding the durability of unmodded parts while the stock vehicle can be driven hard without worry.

    Of course, this all assumes the modding owner spent all his money on 'go-fast' stuff and did not also switch to synthetics and early fluid changes, or a larger radiator. Which I think is typical.

    IdahoDoug
  • ateixeiraateixeira Posts: 72,587
    I doubt they're skipping oil changes, but I see your point.

    What they are doing is putting unexpected stress on the rest of the powertrain. Stock pistons and drive shafts are not forged, usually "R" or "STi" models' are.

    They're also increasing unsprung weight dramatically when they go from 14" steelies to 17" alloys, no matter the price they'll weigh more.

    -juice
  • kenskens Posts: 5,869
    juice,

    Yes, so many potential choices coming up, it's going to be hard to decide! One thing for certain for me though, my next purchase will not be a first model year vehicle.

    Ken
  • ateixeiraateixeira Posts: 72,587
    Really?

    I guess you go an early first-year Forester. Mine was made a few months later, probably after a couple of running changes in production.

    I've been to the dealer once in 4 years and 2 months, that's it. If only all cars could be so dependable.

    In fact, sometimes I think it would be dumb to sell it. Maybe I'm lucky and I got a "keeper", one of those that will join the 1/4 million mile club. I still have all the OE bearings and even brake pads!

    -juice
  • lucien2lucien2 Posts: 2,984
    As you know, my mods are fairly tame. I do think the uprated exhaust helps the car without compromising reliability, and I also think the minor things like swaybar and tower brace are helpful. But I really don't feel any desire at all to mess with cams or turbos and the like. I will probably uprate things like clutch and flywheel when the OEM stuff quits, but that's about it.
  • ateixeiraateixeira Posts: 72,587
    Yeah, cat-backs don't really touch anything that would affect reliability, unless the exhaust itself isn't SS and rusts.

    Bracing won't either, unless it's very poorly designed. Though I have heard of some massive sway bars on Miatas end up damaging the car where the end links bolt up.

    ACT or the Clutchmasters Stage I from Ludespeed? ;-)

    -juice
  • lucien2lucien2 Posts: 2,984
    Stage 1, since bugbomb's ACT slips a lot.
  • ateixeiraateixeira Posts: 72,587
    I remember him telling he got one, it slips, eh? Funny side note: his g/f bought it for him for his b-day, I told him she was a keeper! :-)

    paisan had an ACT I think, maybe on his old car.

    -juice
  • idahodougidahodoug Posts: 537
    Juice/Lucien,

    There's a perfectly good example of a misnomer "the uprated exhaust helps the car without compromising reliability". How do you know this? Did you put a temp probe into your exhaust manifold before the mod and run it hard, then duplicate this after the mod?

    You see, the manufacturers DO these kinds of things. They KNOW what the exhaust manifold temp is while running the car unreasonably hard on a test track at 110 air temps. Then they decide to put in an upgraded exhaust manifold gasket, or a heat shield to protect nearby electronic components, etc etc.

    With your uprated exhaust that changes the flow and pressure characteristics in the exhaust manifold and the entire exhaust - what's happened to peak temps? Have you increased the peak temps by 45 degrees and therefore exceeded the max temp range of a couple nearby sensors? Or wiring? Or shortened the life of the oxygen sensor? Is the exhaust pipe's hottest spot now a couple feet back from stock next to where it passes by the transmission casing? Who knows?

    I make this point not to belittle anyone, but you have to understand the complex interplays of the automotive engineering and design process to see how seemingly little changes can have a dramatic affect.

    Perhaps what you say is true - there is no real flow change and therefore no real alteration. Of course if this is true, you haven't changed the vehicle's performance a whit, but it's a possibility.

    The truth of the matter is that the engine is a system and you simply cannot make a change to it and get measurable output changes without losing something in the process. Witness Juice's comment on the swaybars. A seemingly "free" performance upgrade like stiffer sway bars, right? Well, sway bars transmit torque forces measuring in the 1000s of ft-lbs and the aftermarket makers didn't realize the Miata's sway bar system (there's that word) was designed to handle only a certain amount of ft-lbs which they blindly exceeded. Damage to the system (chassis/swaybar mounts) resulted.

    Comprende'?

    IdahoDoug
  • ateixeiraateixeira Posts: 72,587
    Doug: a high-flow exhaust would likely run cooler, if you think about it.

    I doubt Subaru chose their exhaust based on heat measures, most likely weight and cost were bigger factors. And noise, that's the big one, you tend to get louder with aftermarket cat-backs.

    Also, any half-decent custom-fit exhaust is tuned and tested by the 3rd party manufacturer.

    In the case of the Miata, the folks that sell those fat sways also sell something that reinforces the connection to the end link. Buyers may cut corners and get bad results, but they did cut corners.

    -juice
  • locke2clocke2c Posts: 5,038
    Doug,

    I respectfully submit that you're overstating the dangers of an exhaust system, especially when that "system" is a simple muffler replacement, just a tad.

    Most likely they just increase noise, yes. Most definitely they are not hurting anything.

    -Colin
  • paisanpaisan Posts: 21,181
    The clutch I had was, I got it from Primitive Racing. It was a 6-puck copper clutch and man did it stick hard!

    -mike
  • paisanpaisan Posts: 21,181
    Ok folks quick question on brands of guages.

    I'm looking at VDO and Autometer not sure which are considered better/accurite etc.

    -mike
  • locke2clocke2c Posts: 5,038
    VDO has been around longer, but I wouldn't be afraid to use either of them. I have used both in the past, but don't currently have a car with VDO gauges. The '69 Camaro has Autometer.

    -Colin
  • paisanpaisan Posts: 21,181
    ones @ summit racing for the SVX so I'm probably gonna go with them. Just need to figure out which threads I need on the sending units for the oil pressure and the ATF plug.

    -mike
  • lucien2lucien2 Posts: 2,984
    The exhaust is a stainless steel cat-back measuring 2.25" and made by Brullen. This mod was undertaken only after determining from several reliable sources and my own research that this system worked well on this powertrain with no adverse short or, for that matter, medium term effects. This sytem was dyno tested extensively by the manufacturer and by customers, and shows a consistent ~10hp gain at revs over 5K, with no appreciable loss in torque at low revs (unlike 2.5" or turbo-spec systems). Noise increase is the biggest appreciable, quantifiable drawback. Which is ok with me. I have NOT done anything about headers or, obviously, cams, because of known problems with these areas. I have not gotten 17" rims because only rims with a +53mm offset work properly in BD Legacy rear suspensions, and I don't have the dough for Prodrives.

    I have uprated the swaybar from 15mm to 18mm, a slight increase that is plenty for this car's geometry. It is not the huge jump Juice referred to in his Miata post, and I have spent over $500 in supervised track time to ensure I have the training to understand the changes in my vehicle's handling characteristics. I would further submit to you that a change in tire compounds can have a profound effect on the loads a stock setup must endure (going from RE92 to PP S-03s for instance), and that a 3mm change in bar rate is not a problem. But just in case I switched out the stock plastic mounts for metal ones with hardened bushings.
  • Mike - have you checked out this site:

    http://www.egauges.com/index.htm


    bit

  • paisanpaisan Posts: 21,181
    Thanks for the replies. I like the VDO Analog Guages, but I'm thinking of getting some Digital ones that would match the Climate Control system Guage that the SVX already has. A little more $ but probably worth it.

    -mike
  • idahodougidahodoug Posts: 537
    Colin,

    He said "exhaust", not "muffler" and that appears to be the case here.

    On the changes wrought by an exhaust. Again, I think you need to know a bit about flow, backpressure and temps to understand that things can be dramatically changed. None of us know what temp changes would occur and where, but I can virtually guarantee this: If you took an infrared photograph of the underside of the car in stock form under heavy use there would be very hot spots here and there. If you took the same photographs of his car, you will find these hot spots in different locations since the point of the exhaust was to change the airflow. Where are they now? How hot are they? What's getting extra heat?

    Look under your car and you'll find myriad little aluminum heat shields on wire bundles, the floor in places, drivetrain components, etc that Subaru put there after tracking down the proper locations.

    The stock exhaust may have provided the correct backpressure to reduce flow through the cat through a restriction just after it through careful research. This would ensure proper cat temps and operations. Because of this, the flow might have been very fast in the header area and the headers were relatively cool. The manufacturers have concerns like peak exhaust system temps to prevent the car igniting grass or other things it may be parked atop of. They do infrared analysis, they embed dozens of sensors in the exhaust and drive it thousands of miles because this is a huge liability.

    Now put on a low restriction exhaust where the back pressure is managed in the header area by cylinder pulses because there's less total system backpressure. Perhaps due to an unfortunate choice of bends or tube diameter there are certain RPMs at which a slow flow exists due to a standing wave of pressure, and perhaps a very hot spot is next to the transmission. This causes the transmission temp overall to rise 35 degrees but next to the pipe there's a 100 degree rise. And there's a solenoid with a pliable seal that hardens after 12,000 miles and no longer provides a smooth 1-2 shift. Totally speculative on my part and I have absolutely no evidence to support such a situation exists under your car. None.

    But since the hot spots have moved - where are they now? And how hot are they?

    Not to create a doomsday scenario here, but I can tell you with virtual certainty that the exhaust manufacturer did not have the budget to do the same testing as Subaru did. Subaru designed one exhaust and researched it well. Call them and ask them at what location in the exhaust system does the peak temp occur. In direct opposition to the contention that they carefully research this stuff, last year a big article in a 4WD magazine covering the installation of a popular aftermarket exhaust got this result: Zero. Zero power, zero MPG. All they got was a "throaty sound" and in a nod to preserving their ad revenue from this large company, they made much ado about the great sound and did not address the accompanying dyno/fuel flow charts at all. I'm not saying that's the case with your exhaust, just that buyers tend to assume these folks are out there with $350,000 worth of testing regimens for each model and it simply isn't true. Dyno improvements I believe. But the whole point of my little diatribe here is - at what cost? What else in a carefully balanced system has been changed? As important to knowing these changes happened, is accepting that we don't know what the changes are.

    I am not against modifications per se, just trying to get you to understand that they can have hidden and not-so-hidden consequences. I don't have all the answers, but it's important to realize that neither do the aftermarket vendors.

    IdahoDoug
  • lucien2lucien2 Posts: 2,984
    loud and clear. I was trying to respond by demostrating that I have thought this through, researched the potential consequences through the manufacturer but also a broad base of customers and, lastly, those involved in competition who have put these systems through various punishments. That is also why I took pains to tell you what I have not or will not do, precisely because I have put all this time into the research.

    I think it is great that a popular 4X4 exhaust manufacter was debunked by a magazine. Anyone who buys anything based on ads or solely a manufacturer claim gets what he or she deserves. In my case, the paramaters of my system were exhaustively tested (heh heh) by a niche magazine. The results were that a 2.25" is the ideal size for getting hp without...ya know what? I understand your point, but I spent 6 months researching this mod and I don't want to spend anymore surf-time detailing it all over again.
  • locke2clocke2c Posts: 5,038
    Doug,

    I don't feel the need to toot my own horn but let me just say that yes, I do have a working concept of how exhaust gas temperature works. That knowledge leads me to take issue with the following statement:

    Perhaps due to an unfortunate choice of bends or tube diameter there are certain RPMs at which a slow flow exists due to a standing wave of pressure, and perhaps a very hot spot is next to the transmission. This causes the transmission temp overall to rise 35 degrees but next to the pipe there's a 100 degree rise. And there's a solenoid with a pliable seal that hardens after 12,000 miles and no longer provides a smooth 1-2 shift.

    1. standing wave in the exhaust? maybe if you stay really steady at one rpm, say cruise control on absolutely flat ground. I can't see a "very" hot spot being generated at any point in the exhaust downstream due to a standing wave or any other factor. the exhaust is at most 1600 degrees exiting the exhaust port and it cools *very* quickly from there, especially after the catalysts.
    (pigs flying)

    2. air, especially moving air under a car, is not a very good medium for convection. I just don't see the transmission being heated 35 degrees by being next to an exhaust hot spot I don't even think could happen.
    (flying pigs take over the town)

    modern cars are complicated, yes, but not in this sort of crazy way. exhaust temperatures simply don't vary this much via modifications.

    respectfully,
    -Colin
  • jfljfl Posts: 1,356
    mike, what gauges are you thinking of going digital with?

    My personal opinion is this: I don't tell time by reading the numbers, I look at the relative position of the hands. Same with rpm and engine temp, are they in the "red".

    I remember hearing of racers who positioned their gauges so that 12 o'clock was the optimum position for the hands. They could tell at a quick glance what was happening.

    My $0.02.

    Jim

    BTW - Ages ago I purchased a digital tuner because it was so d*mn hard to find a specific radio station. Just so you know I'm not totally anti-digital. 8~)
  • idahodougidahodoug Posts: 537
    I think you guys are both correct and there's no better way to research a mod than to talk with the racers who use and abuse them. And I sincerely agree that good old fashioned research went into Lucien's mods - time well spent obviously.

    As to exhaust temps and the scenario I posited, the pigs flying comment seems to imply that these are hard numbers and a factual scenario I put forward. I thought I'd made it clear I had no numbers on this and that it was an illustration to make my point based on past experience. I have seen the data points on vehicle component and exhaust temps, and I have seen them change exactly as I outlined due to changes in exhaust routing and other seemingly minor changes. Years ago, I was Worldwide Powertrain Planner at General Motors HQ and we had enough resources at our disposal to certify our own EPA emissions, MPG, etc. That exhaust temps and hotspots vary and can be moved around is not new news in my world, and I wanted to bring this to the discussion as a caution.

    Did Lucien's mod create an undesirable increase in heat somewhere that may shorten a component life? Dunno. You'd have to measure the heat before/after. Can we say the manufacturer's stock exhaust was free of undesirable heat buildup? I'd say 99.999% yes. Can we say the mod did not create a hot spot that will show up later? No, and that's my point.

    My original point was to exercise caution in modifying vehicles too much from stock without expecting consequences. I think that point was made and I do not want to blow a lot of bandwidth on it as Lucien mentioned, since there seems to be limited interest. I appreciate both of your replies, BTW.

    IdahoDoug
  • locke2clocke2c Posts: 5,038
    doug--

    the "pigs flying" bit was my take on the chances of this happening. if you can park over grass without setting it on fire, the non-stock exhaust probably isn't doing squat to anything under the car either including the transmission.

    -Colin
    ps, planner = engineer? I wouldn't think so, you don't sound like one. no offense to you or engineers! ;-)
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