Had Steve order me a 9.5" 4500 stall over the winter to replace my 8yr old no name brand 10" 3500. Old stall had a neutral fin angle angle and was able to get me a best 60 foot of 1.61 with an 11.30 @ 121+. The BTE has a -150 fin angle and only flashed to around 4k.

First impression was that the car drove well and is as streetable as the 10". gas mileage is worse but it was terrible to begin with.

Made 4 passes, the results are as follows:

MPH....113 / 114 / 115 / 114
ET.....11.73 / 11.86 / 11.73 / 11.79
60`....1.65/1.74/1.66/1.65

As you can see my mph was off 4-6 and the et was off 3-4 tenths in similar weather.

Looks like my old stall is going back in.

Any ideas for the drastic change? Is it too loose for my heavy car? I did notice it did not pull my head off like with the old stall in high gear.

Thanks

Looks like its too loose...do you get a free adjustment with that converter?

How are you determining the converter flash? Playback tach? Data acquisition? You say similar weather, how are you recording/tracking weather conditions? Anything else changed on the car? What's the most recent timeslip info you have with the old converter (1 week ago, 1 year ago)? Assuming nothing else has caused the engine performance to drop off I would say the converter setup was simply missed. I would expect a looser converter to give up a little efficieny but you've given up performance at both ends of the track. DO you know whether the car was dead hooking? Your 60' times look .04 slower than the old converter. Tires OK? If the 60' times were the same as the old converter then I would agree with Bob. I run an 8" ATI converter in mine and while it's a little too loose for everday street driving it's fine for a street/strip deal. Have you talked to the guy that spec'd/built the converter? I weighed my car yesterday at Commerce and it weighed exactly 3730lbs with me in the driver's seat (I weigh 200lbs). It's a little lighter than yours but not significantly. In 4,250' air it ran 11.04@120.7. For reference, my converter brake stalls to 4,900-5,100 depending on weather and flashes to 5,300 as verified with my playback tach.

Chris, I'm sure I'm one of the many who've been watching your progress. I'm glad you got it back out there but disappointed it didn't improve for you. More proof that the right converter is critical. I hope they will adjust it for you. I hear that some of the best racers will pull a converter several times before it's adjusted to their liking.

By the way, thanks again for the CD! smile.gif

Rod

Ken,

I have never heard of anyone being able to brake stall that high, I hate to steal the thread but do you have some sort of special prop valve or something directed toward the rear brakes? I supposedly have a stall of somewhere near 3200-3600 but I don't know how to measure for sure given I can't dead hook and don't have a transbrake, and the last trip to the dynojet was just a useless mess, and I'm hoping the disclaimer on the company about HP numbers and high performance converters on dyno's were right, because even when the converter grabbed, the numbers were off by 30hp & 30tq compared to my baseline dyno with a stock 12" loaner just to get the car home.
I really wish these things were easier to change because most everyone who I meet says I should muster 120mph out of my combo as is, but its not. Granted, they may not understand the impact of having a car that is well over 4000lbs with driver when saying how fast they think I should be going..

I have one of those custom 9.5" units too, and I wonder about it. Not a BTE, but another company. The guy who did my cam swap also runs a 9.5" unit, but I am unsure from which company, and he said he goes about his converters from a slight positive fin angle for down low mush then wants it set up to grab at a certain RPM appropriate for the torque curve of the engine. I should ask him which company is making his 9.5" (7 or 8 second blown car, full interior and drives on the street..).
I was looking at a BTE converter to possibly replace mine if I am still scratching my head at the end of the summer looking for the mismatched part, but now...

Sorry for partially hijacking the thread. A converter change is a major operation for me, so it just drives me nuts that this is what I might need to be playing with to get that 120 goal..

Matt

What info did you provide to BTE? HP estimate? Obviously your times, but did you have an accurate weight, density altitude etc?

I've ordered about a half a dozen converters over the last few years and as I acquire more and more infomation (ET's, dataloging driveshaft/engine RPM, and chassis dyno #'s), the closer they seem to get.

I also have a BTE steel stator 9.5" +200 (as tight as they can make a 9.5") and they hit it within 100 RPM on the transbrake N/A! I wanted 4700 and I think it goes 4760! It slips 3% at the top end N/A. It is a bit looser than I want on the nitrous so I am going to try one of their new 11" promod nitrous/turbo converters.

Phone BTE and see if they will restall it for free or really cheap!

Hey madmarv, a converter change isn't THAT big of an operation! ;) I've ran three different converters in a 24 hour period and I changed them solo LOL.

a converter change is like a 2-3 hour job depending on the car, some cars are more of a pain because of the exhaust/header situation.

Before you kill the new converter you might want to do a little more investigation.

Do you know what your RPM was through the traps before & after the converter change? If the RPM was the same and the MPH is now lower than the converter is probably the cause, but if the RPM tracks right for the MPH than maybe there is an engine issue . . .

Just a thought

Originally posted by MadMarv:
Ken,

I have never heard of anyone being able to brake stall that high...
Matt That's transbrake, not footbrake smile.gif I always check my stall speed using the brake before every race. It's a good indication of how much power the car is making. I've seen it very by as much as 400 rpm from good to really bad air (like yesterday).

66 283 are you doing it on jackstands? I have no idea how you can do it in 2-3 hours.. I could if the car was high enough up off the ground..

I can remove or reinstall my engine quicker than I can do a torque converter.. That also explains the 3 6gal containers of what I call "mixed automotive waste" and need to find out what the heck to do with it..

Matt

I can also R&R a converter by myself in two to three hours easily. I don't take the trans completely out (to take the trans out completely, I have to remove the starter and passenger side header for the bellhousing to clear the header collectors...there too narrow for the bellhousing to fit through), rather drop it down a little and slide it back in the car as far as possible which happens to stop against the driveshaft loop. This is just enough to slide the converter in and out.

disconnect points...
- cooler lines
- driveshaft
- dipstick
- flexplate/converter bolts
- exhaust X-pipe
- trans crossmember
- shifter cable linkage
- speedo cable
- bellhousing bolts

Originally posted by kjett:
How are you determining the converter flash? Playback tach? Data acquisition?

No playback tach...roll at 10 mph in 3rd and mash it. Unscientific but that`s all I got

You say similar weather, how are you recording/tracking weather conditions?

The weather network / checking out other guys weather stations when I can. I do know that yesterday was a decent day weather-wise and in similar conditions I would run about 11.45 @118 I would think.

Anything else changed on the car?
Nothing else changed

What's the most recent timeslip info you have with the old converter (1 week ago, 1 year ago)?
Last Sept. Went 11.36@120.

Assuming nothing else has caused the engine performance to drop off I would say the converter setup was simply missed. I would expect a looser converter to give up a little efficieny but you've given up performance at both ends of the track. DO you know whether the car was dead hooking?
No. It was spinning a bit from what I was told.

Your 60' times look .04 slower than the old converter. Tires OK?
Probably have less than 40 runs on them..

If the 60' times were the same as the old converter then I would agree with Bob.

Well, 1.61 was a best ever. I usually run 1.61 - 1.65 so it was not terribly off..

I run an 8" ATI converter in mine and while it's a little too loose for everday street driving it's fine for a street/strip deal. Have you talked to the guy that spec'd/built the converter? I weighed my car yesterday at Commerce and it weighed exactly 3730lbs with me in the driver's seat (I weigh 200lbs). It's a little lighter than yours but not significantly. In 4,250' air it ran 11.04@120.7. For reference, my converter brake stalls to 4,900-5,100 depending on weather and flashes to 5,300 as verified with my playback tach.

Bottom line is I have never run slower et`s / mph. I was initially skeptical when I was told of the -150 fin angle but then what the hell do I know? I also think that the stall I was given is not specifically tailored to my car and is an off the shelf unit as I now see it marketed as their 9.5 SuperBracket. Perhaps the fact it is one size fits all hurt the performance. I must mention though that I gave all the specs for my ride and this was not a crap shoot. That said, I do not have a data recorder or playback tach so my info will be not as good as the serious bracket racers but I believe it was enough to get something better. For the record: This is not a slam against Steve Oldani or BTE. I think he/they are nice guys and were willing to help answer any and all questions I asked. graemlins/thumbsup.gif

Originally posted by Eric68:
Before you kill the new converter you might want to do a little more investigation.

Do you know what your RPM was through the traps before & after the converter change? If the RPM was the same and the MPH is now lower than the converter is probably the cause, but if the RPM tracks right for the MPH than maybe there is an engine issue . . .

Just a thought I was going through the traps at about 6500 as I was last year.

Originally posted by MadMarv:
66 283 are you doing it on jackstands? I have no idea how you can do it in 2-3 hours.. I could if the car was high enough up off the ground..

I can remove or reinstall my engine quicker than I can do a torque converter.. That also explains the 3 6gal containers of what I call "mixed automotive waste" and need to find out what the heck to do with it..

Matt Madmarv, yes I do mine on jackstands with no impact tools. I get the car reasonably high and thrash away. Mine is more of pain because I have stock floor and a CSI tranny/flexplate shield which takes all of the gap between the tranny and the floor. I can get it out in less than an hour solo, takes longer to get it back in through the headers and all w/o gravity to help.

Unlike Todd, I can't move my tranny back more than an inch before it has to come down so I have to take it right out to swap converters. By the time you do it 5 or 6 times you will get your time down! LOL

ttt

Chris, got your email and am pretty surprised at hearing this. It has run into a late night with a bunch of incoming calls, so I will call you tomorrow as soon as I get home from work. Yes, we will certainly not let you drive a slug, lol. Once we can go over some things I will call BTE to see about a tweak on it. They are always more than decent to work with. Thanks for the heads-up!

I know this idea sucks, but it sounds to me like you are going to have to re-install your old converter and make sure the car returns to it's previous performance level.
I had to do the same thing once when I borrowed a Hughes 8" Super Stock converter that was supposed to be a soft hit real efficient deal. All it got me was more tire spin at the start, more rpm at the finish line....on the order of 500rpm and a loss of about 2 mph.

Sometimes I think converters are even a mystery to the manufacturers who build them.

My Nova is a full exh car and it takes a good 3 hours just to get the thing out!

On the lighter side, before you crawl under the car, take two new quarts of ATF.....squirt one under the car in a nice big puddle where you have to lay, and pour the other one all over yourself.......makes it real easy to slide under and out from under the car!

Best of luck man!

Ron

Everyone makes a bad convertor every once in a while even the real good makers. Unfortunately it looks like you got a bad one.