If I have a 9.5" 2800 stall and a 12" 2800 stall, which is better and why?
02-01-2011, 07:12 PM
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If I have a 9.5" 2800 stall and a 12" 2800 stall, which is better and why? Ive been searching for a straight, easy answer to this but cant find it.
I just used 2800 as an example, I dont have either yet but I want to know if you have 2 converters both rated at the same stall speed and one is a 9.5" diameter and the other a 12", which one should be used and why?
I assume the 9.5" would be lighter. Would that translate to better acceleration, faster revs (love that
), and less rotational mass?
Everyone always talks about how generally a smaller diameter stall equals a higher stall speed but no one talks about the benefits of smaller diameter. Thanks all.
I just used 2800 as an example, I dont have either yet but I want to know if you have 2 converters both rated at the same stall speed and one is a 9.5" diameter and the other a 12", which one should be used and why?
I assume the 9.5" would be lighter. Would that translate to better acceleration, faster revs (love that
), and less rotational mass?Everyone always talks about how generally a smaller diameter stall equals a higher stall speed but no one talks about the benefits of smaller diameter. Thanks all.
02-01-2011, 07:24 PM
#2
You are correct,
9.5" will be lighter which is generally beneficial for all the reasons you listed.
A 12" core is OK for a stock stall to 200-2400 range. Anything above that and it becomes inefficient.
To get more stall out of it, they start giving it quite a bit of negative fin angle and making other changes that kill efficiency.
Where a 9.5" or other smaller diameter converter (11", 10") will work better at higher stalls because you get the stall speed from the smaller diameter, not from building inefficiency into the converter.
I suspect that 2800 rpm is usually better achieved with a 10" or 11" core but current core availability has made the 9.5" a less expensive choice.
9.5" will be lighter which is generally beneficial for all the reasons you listed.
A 12" core is OK for a stock stall to 200-2400 range. Anything above that and it becomes inefficient.
To get more stall out of it, they start giving it quite a bit of negative fin angle and making other changes that kill efficiency.
Where a 9.5" or other smaller diameter converter (11", 10") will work better at higher stalls because you get the stall speed from the smaller diameter, not from building inefficiency into the converter.
I suspect that 2800 rpm is usually better achieved with a 10" or 11" core but current core availability has made the 9.5" a less expensive choice.
02-01-2011, 10:58 PM
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02-01-2011, 11:09 PM
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some stock gm small dia. converters are recycled with a welded ring and are to be avoided.a good designed converter won't slip too much in the upper rpms.my bad.don't buy a converter unless it has a billet front shell.read the sticky on converters.
02-01-2011, 11:11 PM
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02-01-2011, 11:39 PM
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02-02-2011, 12:32 AM
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Why are half of your posts on this site insulting people? State what you do or do not know, or don't, and move on.
I will be up front and honest. The non-billet converters do take care of business when it comes to hard numbers. Being non-billet they may be a tad lighter all else being equal. However, I stand behind the fact that a billet converter is a good choice for a primarily street driven vehicle. By shrinking the converter, you are shrinking the lock up clutch inside the converter. Making the front billet optimizes the clutch surface area.
I will be up front and honest. The non-billet converters do take care of business when it comes to hard numbers. Being non-billet they may be a tad lighter all else being equal. However, I stand behind the fact that a billet converter is a good choice for a primarily street driven vehicle. By shrinking the converter, you are shrinking the lock up clutch inside the converter. Making the front billet optimizes the clutch surface area.
02-02-2011, 12:49 AM
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The greatest portion of my posts are purely tech info based on a huge amount of hands-on experience.
I also don't feel the need to mince words. Don't like it, move on.
02-02-2011, 03:45 AM
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You are THE only sponsor I have ever seen go around and insult or spout off smartass "reading comprehension classes" like you do. You think that being good at what you do makes up for you acting like an ***? You are only making yourself and your business look like complete dogshit.
02-02-2011, 07:57 AM
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Will it dyno higher? I assume you are meaning unlocked? As a locked comparison, yes the weight may make a very slight difference in actual dyno numbers. The problem would be getting exact repeatable results on the same dyno, same car, same day kind of deal. Also, a dyno, like most mechanical devices has a margin of error, so the difference in gain or loss may be lost in that factor alone. People have shown dyno gains with under-drive pulleys which is the same concept, rotating mass. Losing spinning weight through an under-drive pulley and smaller/lighter converter gives the motor a very distinct race car sound as it tends to free rev a lot faster then a stock engine. The revs will rise and fall very quickly with blips of the throttle, where stock engines tend to hang up and feel sluggish. I cant say you could feel this difference while driving. If you are talking about unlocked, there is the big factor of converter efficiency, and that to me plays a way bigger part in an unlocked dyno number then the overall converter's weight. But if efficiency was identical (lets say) and all else was equal except size or weight, then we would be back to the original argument at the top of this paragraph. But no two converters would be identical so its kind of a irrelevant question in that respect.
02-02-2011, 09:11 AM
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Thanks. I guess I'll go ahead and ask, which diameter converter would be better for the 93 in my sig. Its going to be street driven only, and taken care of. Its just really, really sluggish off the line right now.
02-02-2011, 09:23 AM
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Well I wouldnt think it would be too sluggish with the 3.23s but Im not that familiar with LT1s in general. Depnding on what stall size you are considering, I would think that one of the 11 inch budget converters from one of the sponsors may be good for 3k and under speed ratings. What speed were you thinking of going with?
02-02-2011, 09:27 AM
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2600-2800, around there. The Hotcam calls for a 2500 converter. Its not that its really slow off the line, its that it hesitates/surges off idle which really kills the takeoff and is kinda emberassing too. I have been reading, searching, and Ive already asked and others said there hotcam did the same thing until they got a stall. It inly surges until about 1200 rpm. After it gets right above that it feels like you just hit a nitrous button lol. Perfect after that.