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SVT power output

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  • SVT power output

    I took my car to an engine tuner on my side of the country to check some possible engine management programming issues, and to see what kind of horsepower and torque the car made at the wheels. The first run produced 129 hp, and had to be aborted at 6000 rpm because the air/fuel ratio was 15:1 and the exhaust gas temperature was 1500 degrees, so we feared that engine damage could result. This is with a new SVT Zetec motor, plus the Kent camshaft upgrade, both purchased from Caterham USA (car had 1000 miles on it at the time). The last run was done 9 hours later, and produced about 147 hp, with the following engine changes: custom PCM reprogram, vct eliminator, and adjustable cam gears. I have the following questions:
    What is the typical drive train loss from crank hp to wheel hp as a percentage for the Caterham?
    Has anyone else dyno'ed their SVT motor, with or without the Kent cams, and would you post your dyno run?
    Is the drop in torque and hp from 2700-3700 rpm normal?
    Why is my motor only making this much power?
    Why would the stock PCM allow the car to run so lean?
    The motor was represented to me as a 180 hp motor in stock trim, and 200 hp with the Kent cams. The SVT motor, as built by Ford, produces 170 hp at the crank when installed in an SVT Focus. Assuming a 15 or 20% drive train loss, I am as much as 50 hp down from those numbers. I emailed Kent cams for their input, and they said they made the cams to Caterham USA's specs, and couldn't help me. I've also included a chart sent to me by Caterham USA when I was considering whether or not to buy the cam upgrade. Clearly, it's much different. My tuner said this chart does not look like a Zetec motor's power curve. Anyone have any thoughts on this engine chart? The car was purchased as a turn key car, so I didn't assemble any of it (if I had, it probably wouldn't run at all).
    Attached Files
    Last edited by athens7; June 16, 2008, 02:53 PM.
    Brad
    2013 Boss 302 Mustang
    2005 SV Roadsport (gone but not forgotten)

  • #2
    I am by no mans an expert....but it might be within reason, considering all the variables. AFAIK the same car on the same dyno may be a couple percent different and the same car on different dynos easily 10-15% off. This anyway is not a precise science even with optimal ECU map setup, since air temperatures, humidity, altitude, tire pressure, tire type, oil viscosity, alternator load, coolant pump, intake and exhaust configuration etc. all may play a role.

    I think 15-20% drive train loss are a typical number but I have heard of 20-25%, too.

    Gert

    Comment


    • #3
      Well you asked so here goes-

      My first engine was a stock Zetec with VCT on the exhaust only, using the stock wiring harness and stock computer.

      I had the car on a chassis dyno once, just for kicks.

      Before the dyno run I had figured out that the stock Zetec air intake location fed only hot air to the engine. I took a thermometer with remote probe, put the probe inside the throttle body and compared the ambient vs. intake air temps. The intake was about 30آ؛ F higher than ambient. This was done on a relatively cool evening ~70آ؛ F so on hot days it might be even worse.

      I made a state of the art cold air intake from a lightweight, high tech honeycomb material. (cardboard and duct tape) to force the intake air to come only thru the rear louvers.

      Results from the chassis dyno:

      ~112 HP at the rear wheels with the hot air.
      ~ 127 HP with the cold air intake.

      This on the same dyno a few minutes apart.

      On these dyno runs the engine got quite a bit hotter than it does in normal driving, hot enough to cause the Jet Hot coating on my headers to blister. I did have a header wrap on them to try and keep footwell temps down. We stopped the testing at this point. Since then I do without the header wrap.

      The Focus SVT engine came out a few months after I had my car running and it seemed a decent route to upgrade for not too many $.

      I bought one from a car that had been damaged in transport on the way to the dealer (hail storm). It had almost 0 time on it.

      My plan was to not use the stock intake but use Jenveys to get the intake outside the bonnet for the colder air.

      It bolts right in, the only thing I had to do custom was fettle the Jenvey intake manifold (made for a stock Zetec) to line up with the much larger intakes on the SVT engine and cut the hole in the bonnet.

      While the engine has intake VCT and I have a computer that can control the VCT (Pectel T6 ), so far I have the intake cam locked with a VCT eliminator and adjustable cam gears. When I started this there wasn't any cam map available and no clear info on what was required to control the solenoid. I have this now.

      Because I had no fuel map, car went on a dyno right after installation.

      When I bought the VCT eliminator I was advised to set the cam timing using the alignment plate, drive the car, (runs terrible) then move the cam 5آ؛ one way, if performance improves that is the correct way. After the first 5آ؛ it was much improved and I took it to the dyno figuring we could do some work with it then. (exhaust is at Zero)

      After getting a fuel map setup using a wideband lambda the dyno shop measured 180 HP at the rear wheels. This was a DIFFERNT Chassis dyno so it is not a direct comparison. They were also not able to maintain traction so the 180 HP could be a bit more.

      This shop did not have the abilty to make a graph so I have only the max HP.

      We didn't have more time to do cam timing changes so I left it at this setting for the time being. Worked fine.

      A few months later I took the car to a local drag strip.

      Previous runs a this same strip with the stock engine:

      Hot air intake: ~15.7 seconds
      Cold air intake ~15.5 seconds maybe better

      SVT engine (stock cams) and different tires - tires NOT optimal as too much wheel spin. I don't rev it up and drop the clutch, just drive off the line - they put water down to do burnouts which makes the first few feet slippery.

      Cam timing 5آ؛ from 'zero' 14.7 seconds
      Cam timing advanced to 10آ؛ 14 seconds flat --- I have 20 degrees more to go!!!!???

      I made several passes to get the above numbers not just one run.

      Drag strip closed early so no chance to advance cam more and test.

      This is where I am at now, I need to get back to a dyno and spend time on the cam timing and or implement my VCT.

      The drag strip was LACR (now closed) which is at 2700 feet above sea level, the typical correction factor is to subtract .5 seconds to estimate sea level ET.

      With slicks, practice, and more cam advance (the guy that sold me the VCT eliminator says to advance if fully) I might get to ~13 seconds in the 1/4 mile at sea level.

      Notes:

      HP loss thru the drive train: I have not found a good answer. I've seen estimates of 10% to 25% loss. One ECU maker http://www.sdsefi.com/ points out that the high end loss means a lot of energy is being turned to heat. If you have a 500 hp engine losing 15% or 75 hp that much HP loss would melt the transmission. I understand that the engine is not always making max HP and there are lots of other issues.

      What I have not been able to find are results from someone that has done the testing on an engine dyno and then measured the same engine in a car on a chassis dyno.

      When you go to a chassis dyno for tuning, the point is to come off with more HP than you went on with. The difference needs to be significant as it can very from one run to the next.

      Chassis dynos are not all the same and results can vary widely.

      Using weight and ETs to calculate HP: There are several calculators on the interent where you can plug in your 1/4 mile time and weight to calculate HP and vice versa.

      Using one of these, stock engine, ~125 HP at the wheels and car weight (with driver) my ETs should be much quicker than the ~15.5 seconds.

      The same with the SVT engine results.

      I had some ETs from a Corvette Z06 that ran the same night I did, the weight HP etc are well published for the Corvette. The ET calcualtor was within .1 second of what he was turning. I have no idea why this is unless it's the lack of aerodynamics in the Seven.

      I did run the car with both the full windscreen and Brooklands. No significant difference in ETs.

      Most of the factors Gert mentions in his post were beyond my control.

      Pectel T6 - while these are excelent ECUs I cannot recommend them. My ECU is perhaps 8 to 10 years old and is more advanced than most of the current competition. However, there is very limited support for the T6 without spending big bucks.

      Doug
      Last edited by Doug Liedblad; October 22, 2007, 11:23 PM.

      Comment


      • #4
        Doug-
        If I understand your post correctly, with an SVT motor with a cold air intake (not dual stage?), vct eliminator, adjustable cam gears, and a custom PCM tune, you're getting in the neighborhood of 180 hp at the rear wheels. Your research would seem to indicate that the SVT's hot air intake costs 10-15 hp, so maybe 165 hp at the rear wheels with the stock unit? Cody from Caterham USA has emailed me, and suggested that the hole in the torque curve could be due to ignition timing. Does anyone know the proper timing for the 7? I'm using the MSD ignition that came with the car. I know overly advanced timing can cause a car to run lean. While dynos vary from unit to unit, it still seems like my 129 hp vs your 180hp is too much variance to attribute simply to dyno variances.
        Brad
        2013 Boss 302 Mustang
        2005 SV Roadsport (gone but not forgotten)

        Comment


        • #5
          Your understanding is correct. Keep in mind that my testing is very limited and is only a first approximation. YMMV.

          The SVT engine I bought did not have a complete intake system. At the time I did not think I could make it fit the standard body width so didn't try. I believe Caterham USA has worked this out, maybe a cold air intake too.

          Besides, I wanted throttle bodies as they look cool.

          I don't think overly advanced timing will make it run lean but it will cause pre ignition.

          Attached is my basic ignition map with no correction factors. I did not create this but got it from other Zetec users. It is being used on several cars in the same HP range.

          I don't know what kind of power to expect from the stock SVT setup. It is supposed to be 170ish in the Focus.

          Doug
          Attached Files
          Last edited by Doug Liedblad; October 22, 2007, 12:37 PM.

          Comment


          • #6
            my current setup is what doug's original was. what i hope to do is fiberglass and intake setup that doesn't run backwards. i want to essentialy reverse it so it points to teh front, lose teh accordian section, and make a splitter that will take air ove rthe radiator to a box that has the K&N cone filter and essentially ram the air to the stock throttle body.

            Doug, thank you for posting your experience.
            2002 SV zetec/sierra; yellow over green

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