Nitrous + Converter

Discussion in 'Race 400/430/455' started by Buicks4Speed, Oct 31, 2002.

  1. Buicks4Speed

    Buicks4Speed Advanced Member

    :puzzled: I Just got back from running in the Wild Street Race at Rockingham and my nitrous is still blowing right through my converter. I trans brake at 3400 and the Nitrous is set to come on at 3600. My 9" competition converter flashes to 5800-6000 before tightening up and only drops to 6200 from 6800 when shifting my glide to high gear. Even when short shifted the rpms won't drop below 6000. I'm not using all the torque the nitrous is making. I figure anything much past 5000 and I'll be giving up e.t.
    I run a Art Carr 9" with a "F" stator and 45 degrees of fin angle. A "C" stator is the tightest stater Art Carr makes next to a steel stater, and 50 degrees is as tight as they will go on the fin angle. I was told if I had a "P" stator they would have alot of room to work but its an "F" so it doesn't look good. I have already sent the converter off once and they adjusted the fin angle to 45 degrees. The converter is rated at a 3200-3500 stall. I can't hold it on the brakes past 3000rpm. Anyone setting up a converter for nitrous and want to get full benefits make sure its REAL TIGHT! Buicks make LOTS:blast: of torque, don't waste it.
    I talked to Coan who makes a good competition converters told me they could make a 9" so tight that it would stall my car out when I put it in gear. Of course it runs $979 on sale w/ a steel stator. It could just be you get what you pay for. I still paid $700 for the Art Carr unit but its wasted money if it doesn't work how I need it.
    I ran 5.70 at 123 this weekend on a 210 hp shot. With the converter right I hope to run 5.50's at 126.
    I don't have enough money to spend it twice so I figure neither does anyone else not to mention the hasle of taking out converters on shipping them off.
    This is not the same converter that I stood the car up with and being that its in a 11 second street car there's no getting it back so I'm trying to get this one to work at least as good if not better than my last one :gt: That's why you change things to make them better, right?
    I'll be taking the converter back out to have it set up as tight as it will go and I will keep the board posted. I Have been real happy with Art Carr's 9" converters and I still have hope It just didn't work out of the box like it was suppose to. Thats just racing I guess.:TU:

    SRRAY iT aND LET iT FLY!!!:stmad: :stmad: :stmad:
  2. GS Kubisch

    GS Kubisch THE "CUT-UP" BUICK

    My buddy is going through the same deal('87 Firebird w/ 572 and glide)
    He went 8.7's in the spring,changed the plate in favor of the fogger.......
    now the car won't move w/o smoking the tires.....he's hitting it w/ 325 on the starting and thinks the converter is too loose.
    I think he should start w/ 150/200 and work up to it,or make some suspension adjustments.
    He frustrates me because he won't back off the nitrous just to get started.

    Anyway...keep after it,you can pave the way for me when/if I get the nerve to spray my clunker.
    Good luck and keep us posted.
  3. Buick

    Buick Ramin Ansari

    Hi Rick.

    Coan is about a 45 minute drive from the house. I had my trans and convertor done by them and I'm very pleased, though I run a much milder combo than your beast. I feel I spent my money well with them.

    I dealt with Art at Coan and recommend talking with him. I asked a bunch of questions on the phone and in person and he dealt with me as if I were as important as their regular NHRA customers. He knew what had let go inside my trans even before I brought it to him. He was also able to describe the internal components and construction of my 10 year old convertor from another manufacturer before they even cut it open. That impressed me.

    It would suck a big one if you dropped a grand and still had 6000 stall though! Maybe others here can also help you decide.

    Good luck.

  4. cray1801

    cray1801 Too much is just right.

    Rick, I did get your call last week, sorry I could not make the race. I was in LA at a wedding :rolleyes: . I did speak with a guy in Fuquay-Varina that said he saw you run.

    My project is coming along however. I need to find a engine dyno within a couple of weeks, got any suggestions? I've got one possibility, a guy I met in Rockingham on the 19th. He's located in Concord, close to Charlotte. I also met a couple of Buick racers Tom Rix and another guy named Jay both Buick racers (nice guys).

    Looking forward to you getting that converter situation resolved. I've got to see that thing run, any more races before it gets too cold?
  5. alan

    alan High-tech Dinosaur

    I bought a "tight" 9" converter from Coan for my turbocharged 455. I haven't spent much time sorting things out but on the shifts the engine RPM didn't drop much at all and stayed above 5000. I also tried short-shifting to no avail. I have a 10" that I'm trying for now, but if you find something that works well with a lot of torque I'd like to know!

    Brewers in Sharpsburg has a little test and tune day (we call it the Christmas Nationals!) that coinsides with our Christmas brunch at work. It will be on 12-13-02 this year. (Friday the 13th!)
  6. Stage Zero

    Stage Zero Active Member


    OUTRAGEOUS Well-Known Member

    I have an Earick racing conv. in my street '71. it is a 9''. I compared it to a "off the shelf 10'' My results: 2.5 tenths quicker + 2mph quicker. my short times were the same between the two converters. The Earick converters do not have that "looseness" you typically feel while driving on the street. it's a VERY heavy duty well- built piece. Gary Paine (GREAT SCAT) runs one & had similar results as well. Brian Earick would be happy to help you! Hope this helps!:beer Randy
  8. Buicks4Speed

    Buicks4Speed Advanced Member

    power rating

    Earick Only rates there 9" at 600+ ft lbs of torque and I figure I'm making closer to 900+ at 5500 rpm. I don't think it will be much better than the Art Carr unit I have. I'm sure both Art Carr and Earick converters are excellent pieces but I think I've exceeded there operation range. :spank:
    I will be talking to Art himself today and I will let you know what he has to say. I want to know if they changed they design of converters when they went to the billet housing. I feel my old style converter was much tighter than my new one that was suppose to be matched to it.:Do No:

    Coan guarentees me they can make a 9" that will be plenty tight enough. They also recommended a steel stator for the torque level I say I'm at.

    Alan, If the weathers right and I've got my converter back from Art Carr I'll try to be there. Have you sent back your converter to have it adjusted at all? Where exactly is your Coan unit on the TIGHT scale? What stator are you running? Do you know what you conveter flash stalls to? If you short shift what do your rpms drop to, Ball park figures? :Smarty: How fast have you been so far?
  9. alan

    alan High-tech Dinosaur

    I'm running a different one for now so I haven't sent it back yet.

    I've had the converter out of the car for a few years now, and I don't even remember which stator it has! If I can find the sales reciept I'll let you know (there may be numbers on the converter that will tell, I'll look and see.)

    I told them what I was running and it was supposed to be set up tight, but I don't know if that's tight for the combo or tight for a 9"!

    I should have said stays around 5000 and as I remember the RPMS didn't drop on the shift (may have a little, but that was before I installed a datalogger)
  10. Quickt

    Quickt Member

    Rick you might want to check out a Neil Chance Pro-Mod converter. You can get it in a bolt together so stall changes are a easy. They make converters for 2000 HP not a cookie cutter converter like a Coan or a Carr. We have a local guy running one has a 3450lb car and runs a 350 shot of the juice car runs 5.51@129 with a slip % of around 5%. They are popular in the Hi HP turbo cars as well. Check it out.

  11. GS69350

    GS69350 Buick NUT

    5.51 @ 129? Thats 1/8 or 1/4?? I'd imagine a 5 second quarter being at 200 + ?

    Dan (with a modest 250 hp 350 : ))
  12. Quickt

    Quickt Member

    Yep thats an 1/8 mile time.
  13. Buicks4Speed

    Buicks4Speed Advanced Member


    My converter is at Art Carr as we speak and I'm suppose to call them back in about 30 min. to see what the verdict is on my converter. If they can't tell me they can tighten it up 1200 or more rpm I'll be looking at other converters but I have to give them a chance since I already have my money in this converter.:Do No: :gt:
  14. Dennis Halladay

    Dennis Halladay Well-Known Member

    Neal Chance is the converter of choice for most of the very fast heads up cars arround here. Several mid to high 7 second cars in that class at over 180mph, I think they have aprox. 2800lb. minimum weight. I would definately give a call to Neal Chance to ask questions even on your current converter. There is a locking TH400 being made but I don't know how much power it will take and the price is pretty serious. I think it is precision, Jack Cotton handles them. I talked to Jack about one before I put a switch pitch in mine to save money. I did only break one switch pitch in three years and was serviced well when it did break. I am guessing you are 100-150 HP and torque more than I was, I dynoed 814hp 826 torque and found a bit more power later figuring aprox 900-900 at the end.
  15. Buicks4Speed

    Buicks4Speed Advanced Member

    Neil Chance

    I'd LOVE to have a Neil Chance converter :Brow: but I've got to see what I can do with Art Carr since He's already got my money. It is a "full tight" 9" converter and it won't be going back in my car. Hopefully we can work something out to get a 10" in exchange. How come you try to go forward and buy something better and it turns into a big mess!:af: All I can say is they must have gone to a different core with the billet plate since my last 9" was at least 800 rpm tighter than this one. All well. :Do No: :af:
  16. Buicks4Speed

    Buicks4Speed Advanced Member

    Art Carr is replacing my 9" with a 10". It was possibly going to be here Fri so I could make it to the track Sun and try it out but, Of Coarse, the weather was perfect so, of coarse, it didn't show up. :af: And I work next weekend.
  17. Buick

    Buick Ramin Ansari

    Here's an interesting question, and I'm sure there's a reasonable explaination. In general smaller diameter convertors are higher stall. If that's the case, why wouldn't or couldn't a convertor vendor build a larger diameter bullet-proof race convertor as an additional way to get lower stall for the customer???:puzzled:
  18. Buicks4Speed

    Buicks4Speed Advanced Member

    Things to consider

    An efficient small converter will flash stall easier and lock up just as tight at higher rpm plus its less rotational weight. There so many variables that change how a converter will stall, it is hard to determine exactly what you need in size or stall. A 1000 hp small block will not take the same converter a 1000hp big block. It all depends on what rpm you make your power at , plus weight, gearing, tire size, ect. In my case they just underestimated the the mass amount of low end torque of a Buick on nitrous. Sure my 9" converter eventually tightened up at 6500 but it was all about done by then. Hopefully this weekend I'll get to try out the new competetion 10" I got. I'm crossing my fingers.
  19. StrokedBuick

    StrokedBuick Got Cubic Inch??


    What backspacing and size rims do you run to have those 10.5's?

    did you have to do any modifications to fit them inside the wheels wells?
  20. Buicks4Speed

    Buicks4Speed Advanced Member

    The fit

    I run a 10" rim with a 5.5" backspacing running a 29.5x10.5 M/T. The top wheel well lip is trimmed and the inner wheel well is pounded as needed for clearance. The 28x10.5 M/T fit really easy but I opted for the 29.5 (actually 30") instead of a gear change but the 28s' still cut a 1.32 60ft. I also had a 29.5x10.5W but that was pretty TIGHT being it was a 11.2" wide tire.:shock:

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