Converter choice (another thread!)

[Quickstop [UK]]

I was wondering if you guys had any input into my converter purchase as I am about to pull the trigger. Here goes...

After logging my TC earlier this summer and seeing it was slipping and not stalling where I would like it, I have been scouring the web for options and have settled on Circle D as my next manufacturer.

I have ported RPM vortecs, a 415 cam and a GT35R. On a previous log, the truck started spooling at 2400rpm. When I boosted it, I was holding 25 psi at the line and it was only 80% stalled at 4800 rpm :tdown: I reckon the stall was around 5k rpm. Not good. The truck should have been way, way faster. No sooner than it started to pull but the gears changed and I ran out of RPM. So, I want a known brand converter and I have not read one bad thing about them. I've been browsing for months. Here are my thoughts.

Pro III 258 mm 1B Convetter
I was thinking of getting a 10 1/4" converter from Circle D which stalls at 2500-2700 rpm. It is billet, triple disc and full lockup can be applied at any point. Basically it's a strong SOB! It is a little bit looser than the spool value of the turbo but should be really tight beyond that. I know the truck pulls well when it's tight because when I locked up the TCC at 5mph, it felt like night and day. Soft and spongy vs. a real shove in the back. So this is my top choice.

Pro III 258mm 1C Converter
I was also getting advice from e95 Ty on here seeing as he has a Circle D in his truck (Matt - I hope you're reading this!). His stall was supposed to be 9.5" (245mm) converter and 3200 stall but Matt says he has seen it as high as 3600 or so. Apparently, the 10.25" converter will be a bit tighter than the smaller diameter converter and it has been suggested that I go for a 3000 stall they sell, one stage up from the 1B above. They were worried the 2500 stall above would be too tight.

The thing is, Matt needs the looser stall to spool his enormous turbo whereas I have come to realise my GT35R only really needs about 2600-2800 rpm to get going.

I am very wary of being too high. I don't want to be too loose again and I guess it's a toss up between these two converters. It's a $500 round trip from the UK for my "free" restall so I would like to get this right.

I am strongly leaning on the 1B converter:

• It matches the turbo's spool value very well
• Tight is right
• 2500-2700 rpm will probably give a little once the turbo spools placing me bang in the 3k bracket anyway
• The 80e only has a 2.48 1st gear so it is a lot more susceptible to a loose converter and a poor launch.

But...

• I don't want it to be like a 20G/12cm housing with a stock converter and not spool.

I guess I could always spool it with a NOS shot? Right

What do you guys think? I'm almost at the point of saying - screw it, get the 1B and if it is too tight, just leave it for now. Chris has said he'll honour a free restall for 2 years because of my being in the UK. Now THAT is customer service.

So... what do you think?

 

[atkonkler]

Re: Converter choice (another thread!)

Woah nelly, I have a 20g now and ported and polished the inlet. It's gotta be close to a 12cm housing now and runs Like a scalded dog out of the hole on a 8-10lb boost launch. It's like 0999sy said don't believe everything people say. Try it out and prove people wrong or learn from it. My truck is stock with stock t.c. and a 20g/10cm ported and polished. We took a lot of metal off when we port matched it. Go with what you think is right and be a pioneer instead of a follower! IMO, let me know how it goes!

 

[randy merritt]

Re: Converter choice (another thread!)

Mark,
My convertor is a Precision Industries triple disk lockup that has a rated stall of 2800 rpm. If I really hold it on the line for a little, it will stop revving at 3000 rpm max, and about 10 psi of boost. I am sure I could get more boost off the line, but I haven't tried holding it for any length of time. As you know, I have a similar build (turbo, heads, etc), but I am still running a 4L60.

 

[lt1sy]

Re: Converter choice (another thread!)

id use a yank or prescision for sure nice tight convertors for boost.

 

[MadMike]

Re: Converter choice (another thread!)

i have a real GT35 i think .84a/r, 80e, 2800 yank, stock cam and I think it is about right to a little tight, but i'm not making the power i wanted at 370hp/480tq at the wheels. If i was making like 475/575 it might be right on for me, but my gut says i should go a little looser. I do like a more GT style setup and working the triple digits than just straight drag racing.... but the reality is most street driving is straight line so maybe a little on the loose side is better.

Any way.... yes to the big billet thriple disk, but if you want to get the best answer you need to talk to your about power levels, shift points, peak power rpm, etc.... I'm to lazy to look back at your posts...

The dude at Yank was pretty nice, we ran thru some simple numbers and landed on what i wanted. I of course was talking to about 100hp more than what i ended up with.... so pretty spot on. And the re-stall once for free... shipping might make it prohibative for you, but if your not having that type of conversation answers will be everywhere....

I voted 3000, bc i think you cam has an even higher peak power rpm...

 

[Aeroking]

Re: Converter choice (another thread!)

id use a yank or prescision for sure nice tight convertors for boost.

x2

 

[TeeTopZ]

Re: Converter choice (another thread!)

Woah nelly, I have a 20g now and ported and polished the inlet. It's gotta be close to a 12cm housing now and runs Like a scalded dog out of the hole on a 8-10lb boost launch. It's like 0999sy said don't believe everything people say. Try it out and prove people wrong or learn from it. My truck is stock with stock t.c. and a 20g/10cm ported and polished. We took a lot of metal off when we port matched it. Go with what you think is right and be a pioneer instead of a follower! IMO, let me know how it goes!

Your build is not the same. He has a 4L80e which has a much taller first gear ratio than the stock 700r4. He needs more stall to get a launch.

I have a billet 10" precision vigilante lockup in my Camaro, and it definitely is a right converter. I have read that over 3000 stall the yank is better though

 

[Quickstop [UK]]

Re: Converter choice (another thread!)

Wow - I didn't get the emails when I subscribed to the thread so only just saw the responses and also the poll!

Thanks guys - I would have been more responsive if I knew there was such good participation

I have gone with the 2500-2700 converter so should have it in a couple of weeks. I only have a trans rebuild and a TC rebuild and the install in front of me. :rotf:

I'll let you all know what develops out of the performance. I am kind of resigned to having to either get another TC or get this one restalled. So much back and forth and with being across the pond, it adds up fast :tdown:

I am pretty optimistic though. The turbo won't be fully spooled at 2700 rpm (logs say it somes on at 2400) but it will be on its way. I'll have more of 1st gear to power me up to speed than if I had been sitting at 3200 I hope. I also hope the cam does make more power at a higher rpm - this converter should be tight enough to propel the truck forward rather than just spin the tc and make the fluid hot. I'll post some pics of the converter and the logs when it hits the road, hopefully early 2014 :tup:

 

[It's just a six]

Re: Converter choice (another thread!)

It seems that most times w/our Sy/Ty's seem to get more stall than what is advertised. That is why I chose the 2500-2700. I am thinking it will stall higher than that. More like 3000, if your Ty is running good.

I have the stock converter, stock engine & I seen my stock converter brake stall to 3025 when I data logged it.

My friends stock Sy w/a 20G laggy turbo would brake stall to 2200, & would take forever to get there.

He then installed those original TCS "Rusty" (the guys name) 9/11 3000 stall converter, it would then brake stall to 3400 RPM, too high, not good for a stock engine IMO, best it ran was 13.6 @ a 3000 ft altitude track.

Just saying, our engines seem to go over advertise stalls.

Good luck on your new converter.:tup:

 

[Quickstop [UK]]

Re: Converter choice (another thread!)

My friend had the same experience with a 3000 Hughes converter and a 20G. It was too loose. I agree. 15 psi :woot: Slow launch, not so :woot:

In my limited experience and understanding, the stall will climb as the torque increases which happens with boost. So if your TC can't handle the torque then the stall will climb and rather than the torque being applied to the wheels, it turns the TC round and makes the fluid hot, not transferring the power to the ground. It probably feels good but I want to see the rpm climbing at a constant rate after the turbo spools i.e. with the converter stalled.

My previous converter would have 25 psi at the line but be a slow launch - clearly a very loose stall. I hope that this 2500-2700 will be tight throughout so I can put the power down.

What would be awesome would be if a torque converter came with a torque/power curve map that showed stall vs torque at a given rpm so you could match it to a specific build instead of the guesswork we have to endure; like the way a turbo has a compressor map. It's the same thing - turbine/rotor/stator etc. I wonder why the industry doesn't provide that. :2cents:

 

[Damian]

Re: Converter choice (another thread!)

I have the B&M Holeshot 2400 stall with my GT37 and I get 10psi off the line, full boost (18psi) by 3000. I like it pretty good. I haven't logged it in quite some time but it works good for me.

 

[e95 Ty]

Re: Converter choice (another thread!)

I swear half you guys don't read before you post. For the second time in this thread, (he has a built 4L80e)! Not a 700/4L60. So you guys running the stock transmissions really can't give good input cuz you have a completely different trans.....

Mark, go with the Circle D. If your worried it will be too loose than go with the tighter one.

Remember a 2500rpm stall on one persons build could be 3000+ on someone else's.
But again what do I know.....

 

[Quickstop [UK]]

Re: Converter choice (another thread!)

Thanks Matt,

Like you mentioned in PM, you don't necessarily get it right on the first go so I am fully expecting that I will need to send it back for a restall. I just hope that it's not so far off that it is undriveable (har har - my Ty? Driveable? :rotf.

Maybe I'll get lucky but that doesn't happen in my experience

 

[It's just a six]

Re: Converter choice (another thread!)

With you having a taller first gear in the 4L80E, you will most likely stall higher than if you still had a 700R4.:2cents:

My 20G turbo w/a 12 CM turbine housing spools pretty good/quickly w/my stock T.C. I figure a 2600 stall converter would be better for my app though.