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Thread: AC reinstalled on my 91 SC along with a couple more upgrades....

  1. #1
    Join Date
    Apr 2002
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    St. Charles, MO
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    AC reinstalled on my 91 SC along with a couple more upgrades....

    Switched from a MP FMIC with AC deleted to a traditional FMIC with full width Griffin radiator, full width condenser and OEM style fan....all for a 97 Thunderbird. To make room for the new IC tube routing, the battery was relocated to the trunk. While the car was apart, the stock timing chain was also upgraded to a double roller billet set from SCU. Good thing because Dave found that my chain tensioner was broken and cam sprocket was badly worn. All the old braided stainless rubber fuel lines that were leaking gas fumes in my garage, were replaced with new PTFE braided stainless lines.

    After getting the car on the dyno (aka Dream Crusher) we found that air charge temps are much lower (120 F max) and boost is down significantly. Even with my smaller blower pulley (3.375") the most boost it will make now is 19.5 PSI. With the old MP setup it used to make 22 PSI on the large pulley (3.500"), and about 23.5 with the smaller pulley so it's down about 2.5 psi and 30 rwhp on pump gas tune and 4 psi on race tune. Since there are no boost leaks and only about a 2 psi pressure drop on the new inter-cooler, we are assuming the drop in boost is because because of greater inter cooler efficiency but not really sure. It still pulled 450 rwhp on pump gas tune with no corrections for the 80 degree weather and previous stumbles and misfires are gone.

    Car is much more pleasant to drive with cold AC blowing and car not overheating. Planning to overdrive the blower another 6.3 % on pump gas tune and 10% on race tune to get the boost and power back up to normal levels. Here is a video and a few pictures of new stuff. Big THANKS to David Dalke at SCU inc for a job well done.



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    David
    Last edited by David Neibert; 07-08-2020 at 04:14 PM.
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  2. #2
    Join Date
    Sep 2004
    Location
    Herrin Illinois
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    Looks great David. Your going to enjoy the ptfe lines man lol. Im in the middle of redoing my exhaust right now. My rborla resonater cam apart inside. My car with a 3.5 blower pulley and no overdrive only makes around 18 tops right now but i figure while im breaking the new 4.2 in its probably better anyway lol.
    member #2488
    2016 shootout Best of show award
    2015 Carlisle Best of show modified, 1st place 92 93 SC and Celebrity's choice award winner.
    2014 Shootout Best of show 1st award winner
    2014 Comp cams VIP Car craft street machine nationals
    http://www.sccoa.com/forums/garage.p...e_view&id=7152

  3. #3
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    Nov 2016
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    Outstanding build! Thanks for the update.
    Creighton

  4. #4
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    Apr 2002
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    Parts to spin the 2.3 Whipple a little faster have arrived.

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    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  5. #5
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    Aug 2004
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    KSRQ
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    Glad to hear you caught that cheap piece of plastic before it broke! Some guys have all the luck

    Another great looking job by Dave, and the car sounds as good as ever. What a great idea for moving cooler air through the system!
    Last edited by Ira R.; 07-11-2020 at 11:20 PM.

  6. #6
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    Quote Originally Posted by Ira R. View Post
    Glad to hear you caught that cheap piece of plastic before it broke! Some guys have all the luck

    Another great looking job by Dave, and the car sounds as good as ever. What a great idea for moving cooler air through the system!
    Yes I'm very lucky the timing chain didn't break. Dave said it's the worst he has seen and couldn't believe it was still running. Here are a few pictures.


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    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  7. #7
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    Apr 2002
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    St. Charles, MO
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    21,155
    Removed the UD pulley set and installed 10% OD crank pulley and stock size WP and ALT pulleys and switched supercharger pulley from 3.375" to 3.500". This increased overdrive by 6.3% and should get it back to about the same power it was making with the MP FMIC on the pump gas tune. I'll swap to the 3.375 pulley if using the race gas tune. Here is how it looks now with pulleys reconfigured for street tune. Haven't had a chance to measure how much more boost it's making, but it feels a little stronger.

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    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  8. #8
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    Sep 2004
    Location
    Herrin Illinois
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    Me too

    Quote Originally Posted by David Neibert View Post
    Yes I'm very lucky the timing chain didn't break. Dave said it's the worst he has seen and couldn't believe it was still running. Here are a few pictures.


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    Thats exactly what happened to my current motor before i got it and rebuilt it. Mine has one of the double rollers as well.
    Last edited by davec73; 07-20-2020 at 06:16 PM.
    member #2488
    2016 shootout Best of show award
    2015 Carlisle Best of show modified, 1st place 92 93 SC and Celebrity's choice award winner.
    2014 Shootout Best of show 1st award winner
    2014 Comp cams VIP Car craft street machine nationals
    http://www.sccoa.com/forums/garage.p...e_view&id=7152

  9. #9
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    I am curious about this tensioner failures. Is valve floating or bouncing of re limiters causing this? Looks like some sort of abuse is in play here. Were these Chinese replacement parts or OE?

  10. #10
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    Quote Originally Posted by ricardoa1 View Post
    I am curious about this tensioner failures. Is valve floating or bouncing of re limiters causing this? Looks like some sort of abuse is in play here. Were these Chinese replacement parts or OE?
    Ricardo,

    I'm told it's because of high rpm, which in this case means routinely exceeding 6000 rpm. The timing set shown in pictures was all new parts that were included in the 4.2 engine build that SCU did for me in 2009. I don't think SCU had a double roller timing set at that time and the only option was Morana. I have seen a lot of problems with them, so I'm sure I would have insisted on the stock timing chain especially since failures were pretty much unheard of. Anyhow, I exceeded 6000 rpms pretty much every time I drove the car and when racing it my shift point was 6500 and the rev limiter was 6800. If doing a burnout I would usually hit the rev limiter at least once. So I'm surprised it lasted as long as it did.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  11. #11
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    Boston, MA
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    Ok just trying to get an idea how pressing it is and it’s root, I know your is pushed hard, but on my car I sometimes forget I can go past 6000. The redline is at 5500 or so on my car and I for some silly reason short shift it. Maybe cause I would be breaking the speed limits by then so I shift up. I don’t think I hit the rev limiter before. It’s pretty high up, I have valve float way before the rev limiter. My car is done about 6,300 so I tend not to push it that high unless on the dyno, the shift light is around there 6300 to 6500 i don’t see it light up often. The car feels like it’s about to explode that high up, the Coyote I can do 7500 and it’s pretty smooth, they break oil pump gears when hitting rev limiters. I set it at 8000 to prevent it.

    I’ll put it on my wish list. But more back burner wish list.
    Last edited by ricardoa1; 07-16-2020 at 10:42 PM.

  12. #12
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    Quote Originally Posted by ricardoa1 View Post
    Ok just trying to get an idea how pressing it is and itís root, I know your is pushed hard, but on my car I sometimes forget I can go past 6000. The redline is at 5500 or so on my car and I for some silly reason short shift it. Maybe cause I would be breaking the speed limits by then so I shift up. I donít think I hit the rev limiter before. Itís pretty high up, I have valve float way before the rev limiter. My car is done about 6,300 so I tend not to push it that high unless on the dyno, the shift light is around there 6300 to 6500 i donít see it light up often. The car feels like itís about to explode that high up, the Coyote I can do 7500 and itís pretty smooth, they break oil pump gears when hitting rev limiters. I set it at 8000 to prevent it.

    Iíll put it on my wish list. But more back burner wish list.
    Ricardo,

    I wasn't planning to do anything with the timing chain on this round of upgrades, until seeing a post Dave Dalke made about several recent timing chain failures on SC motors of similar power level. Very glad that I did, because I'd be fixing a lot more stuff if the chain broke. Now I'm a little more mindful of RPM, but I don't imagine my driving habits will change much, so I'm not bothering to change the shift light settings.

    David
    1991 SC AOD 4.2..2.3 Whipple..........10.910 @ 125.61
    2016 SRT Challenger Hellcat.............10.597 @ 135.78

    My Garage

  13. #13
    Join Date
    Jul 2005
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    Mississauga
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    Dave;
    I am glad you got a better result from your tensioner failure than I did.
    I ended up on the side of the road with a dead car and ultimately had to rebuild (thanks, Dave) my whole engine.
    Alan

  14. #14
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    At what rpm should the factory setup be a concern?

  15. #15
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    I've broken 2 of the tensioners, first one bent all the valves and well the second found after removing engine to be replaced.
    SCCoA Member#: 2515
    1990 SC AOD 2.1L Kenne Bell
    11.676 @ 121.35 mph
    506hp/478tq
    My Garage

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