Converter suggestions

[bobs84ttype]

My current converter is a PTC 10" LU 2800 .
I believe it is operating as designed but it may not be proper for my car.
It is at 2800 With 0/0 vac/boost On foot brake or trans brake I can get to around 4400 and 15 psi boost
Reviewing my last data log
1 to 2 shift I get a 275 rpm drop shifting at 5200
2 to 3 shift I get 175 rpm drop shifting at 5200 .
Right at 5500 rpm the mph is 96 . As I continue the pass the rpms stay steady as mph increases . I used a converter slip calculator the caltularor shows 28% slip
It has been suggested that I look into a 9.5 converter
Any further suggestions?

 

[charlief1]

Did a lot of reading about stall speed and one thing to remember is if the converter is rated for a V8 then it will stall about 3-400 rpm lower on the v6 engines. With the 6262 turbo you have You're at least 200 rpm low but this is something you need to talk over with Dusty or David.

 

[34blazer]

Thanks for bringing this up, Bob, Im going to be in the same boat very soon.

 

[Dusty Bradford]

What turbo size and cam? What et does it run?


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[bobs84ttype]

Hot air 6262 from work turbochargers
Comp cams 206/206 roller
Best et to date. 11.47 114 mph

 

[Nick Micale]

I seriously doubt that your have 28% converter slip with a 275 RPM drop at 1-2 shift, and 175 RPM at the 2-3 shift?

Is your intake still 1984, or have you converted to intercooled?

From my personal experience I have found 2800 RPM at 0 boost is too low in a build like yours, and 3000 to 3100 stall is where I prefer in most modified builds.

I just installed a 62BB billet wheel turbo on a customer's car and it will spool like crazy, a regular 62 will not spool worth a damn with a 2800 stall in my experience.

I never tell an owner the converter stall I pick for their build until after they drive the finished product as they always want too low a stall. I am the one responsible to build the car to meet the owners expectations, and converter selection is very critical in meeting the final goal.

For a performance build at low 11's or better, we do not want or use a LU converter as they suck at high RPM shifts even if the LU is activated.

 

[34blazer]

maybe a datalog would help

 

[bobs84ttype]

 

[bobs84ttype]

raw data 1st to 2nd shift

 

[bobs84ttype]

raw data 2nd to 3rd shift

 

[bobs84ttype]

Nick..... still in the hot air configuration... intake is a champion ported intake

 

[bobs84ttype]

0/0 boost vac at 2800 rpms

 

[bobs84ttype]

4400 rpms and 15 psi boost

 

[Dusty Bradford]

Hot air 6262 from work turbochargers
Comp cams 206/206 roller
Best et to date. 11.47 114 mph

What rpm and tire size at 114mph? I'm just trying to get an idea about slip. At sea level a 2800 0-1 psi stall works very well with a 6262....that's the most common combo now days. If you go looser down low, it just turns into more slip down track.

One thing that's not helping is your shift rpm. That cam needs to shift at 5600 or so. By doing so, your rpm drop is then 400 rpm more than you have now which in turn helps slip. If spool up is really fast, tightening the converter is an option as well.


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[bobs84ttype]

Will try higher rpm shifts and look at data and update

 

[Jerryl]

I am glad Dusty replied to confirm my uneducated suspicion.
I was thinking . . . It looked like Dusty pretty much nailed the converter . . . just need to change shift rpm.

 

[Dusty Bradford]

It's possible it could have some fins laid over from a high rpm trans brake launch which would cause the slip to be high. The closer you launch to true flash stall, the rougher it is on them. Thats a lot of heat going into them at that point. Being able to footbrake 4400 is also suspicious but the 2800 at 0-1psi is dead on so it's hard to say that it's hurt. Some brakes just work that well on these cars. Get some rpm and mph data and share it with me and we can go from there.


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