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Thread: 1989 SC needs to run mid 12s

  1. #31
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    We got most of this stuff from the local dump

  2. #32
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    Well we had a great time at the track this weekend, making seven total passes. We are going to need to add some power to get our 12 second time slip.

    Ambient temps were in the high 70s and humidity was pretty low, it was great weather for racing. On the first pass we had a large slug of silicon that clogged the outlet on the fuel cell and caused the car to fall on its face at the line and crawl down the track. The remaining passes of the night went fairly well except for the third one where I wasn't sure I hit second gear, these 5 speeds feel a little different on the shift than a mustang's T-5. The car ran three passes consistently right at 14.35 @ 93 mph with 1.95 60 ft times and eighth mile times of around 9.10. I was happy with it given this is a stock engine in a gutted car.

    The boost gauge said 12 psi peak, AF ratio was around 11.7 to 1 on the wide band with 93 octane pump gas with 10-15% ethanol. I thought that was a little rich so I splashed a little E85 into the tank and we were at 12.2:1 for the last several passes. That is a little lean in my opinion but the car neither slowed down or sped up so i made no more adjustments after that.

    Car weighed 3,120 lbs with me in it and 2,910 with me out of it. Obviously my estimate of weight loss was a little ambitious but we feel there is some more ground to be gained here because we still have some things we can remove.

    First order of business, I think the 2.73 gears are killing the car, as it seems like it may bog a little at launch and then spin the tires when it recovers. I think we'll be better off with 3.08s and a slightly lower launch rpm.
    Last edited by Broncojohnny; 08-02-2016 at 03:01 PM.

  3. #33
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    Quote Originally Posted by Broncojohnny View Post
    Well we had a great time at the track this weekend, making seven total passes. We are going to need to add some power to get our 12 second time slip.


    First order of business, I think the 2.73 gears are killing the car, as it seems like it may bog a little at launch and then spin the tires when it recovers. I think we'll be better off with 3.08s and a slightly lower launch rpm.
    3.08's launched at 3500 should do nicely. You will trap in 3rd at 5500rpm if you timing is on.

  4. #34
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    Quote Originally Posted by Ira R. View Post
    3.08's launched at 3500 should do nicely. You will trap in 3rd at 5500rpm if you timing is on.
    Sounds about right, we are thinking about a 28 spline aluminum center section from a Mark VIII along with the aluminum lower control arms. From what I have read they come with an open 3.07 diff, of course to me that means we plug in a mini spool.....

  5. #35
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    Considering that you are almost 1000# lighter than the rest of us it should be a lot quicker than that. But IDK.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  6. #36
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    Quote Originally Posted by XR7 Dave View Post
    Considering that you are almost 1000# lighter than the rest of us it should be a lot quicker than that. But IDK.
    I was thinking this at the track. The car does seem to be falling off on the top end for some reason although the mph gained in the second half doesn't seem completely unreasonable. The AFR stays steady and there is no obvious evidence of detonation but the knock sensor is still hooked up and functional so that is a possibility. Could this just be because of the 2.73s and the fall off between 2 and 3rd gear?

    Mechanically we are using the complete 95 longblock, the 89 mass air meter and the 89 stick shift computer. I have the 95 mass air meter and computer in my parts bin if they might work better.

    Here are two of the better passes:

    timeslips.pdf
    Last edited by Broncojohnny; 08-03-2016 at 10:02 AM.

  7. #37
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    You can't use the 95 computer and it's not better anyway. Most likely it's on the knock sensor pretty hard. Rather than try to lean it out, put a gallon or two of race fuel in it remove the knock sensor and tape it away from the motor. You can also try removing the ACT sensor and exposing it to atmosphere rather than the engine. But make sure you have enough octane before you try this. The gears are not your problem at all.
    Quote Originally Posted by Miller View Post
    Ya thats why i tape mine down. People think its bc i dont have a moonroof seal (which is true) but its really to keep my roof from ripping off .
    Email me here.

  8. #38
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    Quote Originally Posted by XR7 Dave View Post
    You can't use the 95 computer and it's not better anyway. Most likely it's on the knock sensor pretty hard. Rather than try to lean it out, put a gallon or two of race fuel in it remove the knock sensor and tape it away from the motor. You can also try removing the ACT sensor and exposing it to atmosphere rather than the engine. But make sure you have enough octane before you try this. The gears are not your problem at all.
    Well Dave is usually right when it comes to this and I'm the last person to contradict him. I am however going to second his suggestion that you add fuel and lose the knock sensor. We have found over the years that the amount of timing being pulled at the top end will kill all the power in j ust about any engine. I can't think of one of any of the quicker cars around here who still have it hooked up. Not for years now.

    Also, hanging the ACT sensor out the top of the hood is an old trick.... but a good one!

  9. #39
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    Quote Originally Posted by Ira R. View Post
    I can't think of one of any of the quicker cars around here who still have it hooked up. Not for years now.
    I used to be one of the fastest and my knock sensor has been disabled, turned off through the Moates quarterhorse, for many years now.

    Add a 100 wet shot of nitrous and you can gain a full second in the 1/4, I did.
    Last edited by nickleman60; 08-03-2016 at 07:43 PM.
    SCCOA Member #2406
    '94 SC AUTO - $$$$ Pit
    http://www.sccoa.com/forums/garage_v..._vehicle&id=19

  10. #40
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    Quote Originally Posted by Broncojohnny View Post
    Looks like I have rounded up a whole 1995 car with complete engine so we will back in business soon. Our first race was rained out so we have more time to get this thing back together.

    I am estimating that we have about 1300 lbs out of the car so far. Since these pictures were taken, I got a new plasma cutter and put it through its paces on things like the crash bars in the doors. We have also removed all of the tar sound deadener and remains of the carpet and installed a single racing seat.
    I think your estimate of 1300LBs is a bit optimistic even if you removed all of the glass except for the front windshield AND cut the window frames off the doors after you skinned them (no glass = no reason for a window frame).

    Please put it on some corner scales are prove me wrong.

  11. #41
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    The exhaust can be killing it, Stock SC motors dont react well to no back pressure in my experience..And should definitely be much faster as all have said. You may be getting a good AFR but something is not right. Can you log any of this? Gearing isnt the issue for sure either. Stock SC motor at that weight would fry the tires
    They don't call me "SLOWPOKE" for nothin!
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  12. #42
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    Quote Originally Posted by S4gunn View Post
    I think your estimate of 1300LBs is a bit optimistic even if you removed all of the glass except for the front windshield AND cut the window frames off the doors after you skinned them (no glass = no reason for a window frame).

    Please put it on some corner scales are prove me wrong.
    If you care to read the thread you will see that I already proved myself wrong. But thanks for playing.

  13. #43
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    Quote Originally Posted by XR7 Dave View Post
    You can't use the 95 computer and it's not better anyway. Most likely it's on the knock sensor pretty hard. Rather than try to lean it out, put a gallon or two of race fuel in it remove the knock sensor and tape it away from the motor. You can also try removing the ACT sensor and exposing it to atmosphere rather than the engine. But make sure you have enough octane before you try this. The gears are not your problem at all.
    Thanks Dave for the input. After reading some of the other posts, the knock sensor is going to be unhooked.

    In your experience, roughly how much octane do we need to run with the knock sensor unplugged and the ACT dangling? Would 100 octane unleaded do it?

  14. #44
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    Looks like this Saturday night we are taking her to the track again. Nothing has changed since our last outing but we will be adding an adjustable fuel pressure regulator and cranking the fuel pressure to try and get us to the 8 to 8.5:1 AF ratio we'll need at wide open throttle to run E85. If we can get that we are going to unplug the knock sensor and dangle the ACT sensor to ambient.

    We have managed to pick up the entire IRS out of a Mark VIII Lincoln and will be adding the aluminum lower arms and center section with 3.07 gears to our car. We are going to add a mini spool to the open diff before putting it in. Also, purely by accident we managed to get a set of BBK shorty headers for a 3.8L. These came on a car we are parting out. We'll be adding those over the winter when we have time to rework the exhaust.

  15. #45
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    Our last journey to the track didn't work out so well. We unplugged the knock sensor, dangled the ACT and jacked up the fuel pressure. I never could get the AF ratio to a comfortable reading on the gauge with the E85. I was a little spooked and didn't want to run with it lean so we switched to 104 octane unleaded. Because we had raised the fuel pressure she was pig rich at 10.5:1 and ran a string of high 14s. I finally leaned it out to around 11:1 AF on the last pass and she ran 14.30. We were out of time at that point in the day and couldn't make more passes.

    January 14th is our first race this year and the plan is to get her back up to the 12:1 AF ratio that we ran last year and leave the knock and ACT sensors unplugged. We'll either be running 100 or 104 octane unlead.

    New parts are:
    Mark VIII control arms and a 3.07 center section with mini spool
    BBK headers for a V6 Mustang
    2.5" down pipe
    94/95 Mass air meter
    Last edited by Broncojohnny; 01-03-2017 at 12:04 PM.

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