What difference does converter diameter make

I'm looking at getting new converter and I was wondering what effects a smaller diameter converter has?I had a 10 inch 3800 stall tci super street fighter behind my 514 and took out the sprag.So I was thinking of using a 9 inch with a similar stall,but didn't know what would the difference would be.

A smaller diameter usually means less weight.
This relates to a higher stall speed and quicker rpms.

a smaller convertor will not handle as much power as a larger one...
more HP more stall and less HP lower stall, a high Hp engine will blow right thru a small diameter convertor

lots more stuff to a converter than diameter..................

lots more stuff to a converter than diameter..................


Jon,you got that right..Lets see... engine size, comprssion, camshaft, cyl heads, intake, fuel system, trans, gear ratios( trans & rear), weight, rpm range, etc.,etc..... That's just what I thought of off the top of my head. Call a reputable converter manufacture & talk with them. They can help you make the right choice.. :)

I was planing to call and give them all the specs.I was just wondering why the different diameters?

so they can sell you a 10" then a 9" then say you realy should have a 8" only to find out later the 10" was best for you.o......and they just got you for a couple of grand for the lesson.

Exactly! I'm just trying to be a little more informed when I buy my next converter.

Ratpoison, since we have no ifo on your combo, I will give a very broad answer. If you 514 is relatively mild, I will guess that an 8" converter could work for you. If it is a stouter engine, then a 9" will probably work better. When I was running my 557 before we ported the heads, I was using an 8" converter in a 2800 lb. Super Gas car(strut/ladder bar). Car ran a best of 9.20@144mph (9.20@144mph). I was turning 6000 rpms in the 1/8 & 6800 rpms in the 1/4. We then ported the heads,changed intake,cam,etc. & my 557 went to turning 6800 in the 1/8 with the 8" converter.The new HP didn't like the 8" converter. I have been running a 9" converter ever since.
As far as a converter ccompany trying to sell you one size converter & then selling you a differnt size converter because the first one was wrong size... Well I would say that you better look for a different company because they don't know their a$$ from a hole in the wall. Talk to a reputable company & give them good HONEST info about your set up & they will get you pretty close if not dead on. :)

so they can sell you a 10" then a 9" then say you realy should have a 8" only to find out later the 10" was best for you.o......and they just got you for a couple of grand for the lesson.
You get one from Lenny there is a 99% chance it will be spot on, if it falls in the 1% I can bet you 100% it will get taken care of...............

i run a 9.5" from the best out there
http://i206.photobucket.com/albums/bb173/nbjuljetta02/Cameron.gif

A heavy car (3000lb) with lots of hp(850 + is probably gonna need a 9" or better.

Now here is my spill for quality. I have been running a ptc (performance torque converters) 8" with a sprag and aluminum stator for the past 8 years it has not made a pass at less than 5.70 1/8 mile.

This converter was originally built for a 466 with dove heads but has worked fine with a 466 with tfs streets 5.51 best , 533 with scj's 5.26 best and a 562 p-51 5.12 best.

It has not been sent in one time until last week, it finally broke the sprag , stator and a few fins in the turbine , but they are fixing it and up grading it to steel stator and spragless , getting rid of the prehistoric parts :D

It has not been sent in one time until last week, it finally broke the sprag , stator and a few fins in the turbine , but they are fixing it and up grading it to steel stator and spragless , getting rid of the prehistoric parts :D

Could you keep us updated on this, ET wise......curious to see if it can still run the number...

Thanks.

Could you keep us updated on this, ET wise......curious to see if it can still run the number...

Thanks.

Yes no problem. They said it would only lose 1mph in the quarter.

Thing to keep in mind here the car went several passes at 138 mph in the teens, the 5.12 was at 134 2 passes before It broke.

I am not sure if the drop in mph was from the tune or the converter because I put the fuel to it on the 5.12 pass and the egt's were in the 970-990 degree temp range so I know it was rich .

I got a hole in my tire and put a new set of Mickey Thompson tires on the car (old tires had over 60 passes on them) it appeared to dead hook from the video , not sure if that is what broke the converter or not.

Could you keep us updated on this, ET wise......curious to see if it can still run the number...

Thanks.

I went spragless this year. I haven't seen a difference. I do think a spragless converter likes to be spun up higher from what I have seen. :)

Ok guy's here's my set up.Stock 514 frrp.roller cam crate motor rated at 625hp at 6250 rpm and 600 ft.lbs. torque at 4250 rpm. It's in a 1970 Mach 1 that weighs 3400 lbs. with me in it.I use a c6 with a full manual vb. with every thing else in the tranny is stock.This goes to a 9 inch rear with 3.70 gears and a Detroit locker and 31 spline axles to 28 by 11 inch hoosier quick time pros..I had called tci and told them what I had and told them this would be a street and strip car,and I was looking at their super street fighter converter.Who ever I talked to on the phone agreed it would be a good choice.Now the car did run well but,I always felt I was leaving something on the table.It ran a best of 7.025 at 105 mph.on the 1/8 mile.Then One day I launch it in 2nd.gear by accident and the car has been slowing down ever since.The last time out the best pass was 7.48 at 99mph.The 60 foots have slowed from 1.50 to 1.78.I talked to Frank Merkl and he thought it was the converter. Now I'm the kind of guy that wants to know why,I like to learn why you use this part or that part.Just being told to use it isn't enough I like to know why. Just trying to learn more about converters.

It all depends on who you talk to.I use to have 514 in my car weighed 3050,called kenny at ptc he recomended a 9 inch and it ran well.My friend just put a 514 in his 3050pd car nearlly identical combos he called and talked to lane at ptc he recomended an 8 inch and it runs well also.But so far slower than my setup was.I currently run a 572 in my car weighing in at 2850 and have had a 10inch spragless from ptc in it then switched to a 10inch ati sprag converter and they run identical all the way down the race track.

Thanks guys I was just given a 9 inch converter with what is suppose to be a similar stall 3800 rpm.I think I'll try it and see next summer.

Did you have a Super Street Fighter or an Ultimate Street Fighter? I have an Ultimate Street Fighter that they rated at 3800 rpm and they said the SSF was rated at 3500 rpm stall. Kinda got me worried now as the motor I plan to build over winter will be around same hp, but I am taking my converter down to Midwest Converter to have the stall raised to 4500 I am sure they will tell me of any problems though. TCI told me the SSF was only rated to 600 hp that was reason I went with the Ultimate as it is rated to 850 and SFI approved for nitrous. I dont plan to run nitrous but figured if I ever did it was there.

Yes it's the super street fighter,with the anti ballooning plate.They told me it was a 3800 stall but I should be able to push it to over 4000 with my combination.But they never said anything about how much hp. or torque the converter was good for.

I wonder why they didnt say anything to you about hp rating? I called TCI directly though maybe difference idk :confused:.When I called Jegs they seemed kinda clueless so that is the reason I called them directly. TCI gave me the part# and I ordered it through jegs as it was about $40 cheaper that way.

Ya I did the same thing.I called tci first and then ordered it through summit instead.I told the guy what I had you know weight,gears,tire size trans. and all the motor specs.and I told him it would see more street driving than track.Then I told him that I was thinking of the super street fighter and he said it should work ok.

I guess it depends on each techs experiences. I call comp helpline and tech suggested a cam after getting the suggested cam and a year of trying to tune it I called them back and was quite mad at the performance vs. the old cam the tech I talked to second time said what I had found out the hard way, that I had a better cam to begin with. Racers should be selling racing parts not people who have no experience.

I guess it depends on each techs experiences. I call comp helpline and tech suggested a cam after getting the suggested cam and a year of trying to tune it I called them back and was quite mad at the performance vs. the old cam the tech I talked to second time said what I had found out the hard way, that I had a better cam to begin with. Racers should be selling racing parts not people who have no experience.

Burned by the infamous "phone jockey" / so called expert....:rolleyes:

So who do you trust?Half of the company's use call centers these days,and all the phone guy knows is what info is in front of them.They don't know what it means just that they're told that it suppose to work.But most of all they're told to sell what they can.I know this because we have three of these center's here in town.And family members have worked at them.These center's range from cell phones to road side assistance and none require any prev.experience.