Need to tell guy what to restall to

[turbo6man]

Hi, I was told that for my setup with the stealth 70mm turbo (big shaft standard bearings) I would need a 3400 to 3600 stall. Well I had a convertor made from a guy I know locally. It is a 9.5" convertor in a T.H.350, and I have the car up and running and tuned to 18PSI boost the data logs show the following:
with transbrake and tps at 42% and 3.7 psi boost= stalls to 3800rpm
with transbrake and tps at 82% and 9.4 psi boost= stalls to 4100rpm
with transbrake and tps at 84% and 11.1 psi boost= stalls to 4800rpm
with transbrake and tps at 81% and 12.9 psi boost= stalls to 5000rpm
when driving and I stab it and boost goes to 10psi the rpms are never below 4800 rpm in any gear.

How much should I tell him to tighten it up? I am thinking on the transbrake at 12 psi boost I would want to be at around 3500 rpm. What do you think?

Some additional info (can be found in sig but related to this post)
At 15psi boost ran 11.7 at 117 with 1.64 60'
28x11.50-15 hoosier quicktime pro
3.50 gear ratio
Have not weighed yet but it should be around 3200 LBS.
Is a hybrid 1963 chevyII
Thanks for any info, James

 

[Dusty Bradford]

What rpm will you be shifting at?

Turn the boost up where you plan to race it. Make some passes and see what the rpm drops to at the gear change. If it only drops 400 rpm you could stand to tighten it 400 rpm.

 

[turbo6man]

Hey thanks for the reply I have been shifting it at 5800 to 6000. I must confess I am not exactly sure where to shift it, but it really pulls great to there
The roller cam specs are:
ATR Model No. RP309H Hydraulic roller
Advertised duration: Intake 276 degrees/ Exhaust 272 degrees
Duration @ .050 lift: Intake 214 degrees/ Exhaust 210 degrees
Lift with 1.55 rockers: Intake .515/ Exhaust .504
Lobe Seperation: 109 degrees
Overlap: 56 degrees
Notes say "Smooth idle/ for modified engines"

I was thinking when I read the logs I would be around 3600 on a boosted launch so when I saw it was more like 5000 i thought something was wrong.

On the 15psi logs I have the rpm's drop about the same: shifting at 6000 from 1-2 as 2-3 and it is about a 620rpm drop per shift.

I plan on slowly turning up the boost to about the 27ish range but I was thinking the converter was way off already and I was wasting power in the converter and due to the free restall it would be better to get it closer now, but that is an un educated assumption and I would like to hear more of what you have to say about it. Thanks again

 

[bison]

Its hard to say based on those numbers since you will be running way more than 13psi boost. Actually with with transbrake and tps at 42% and 3.7 psi boost= stalls to 3800rpm you are not too far off at low boost and it should come up fast based on that but you are going to blow through it really bad up top when you crank it up. In reality you need a complete different set of internals in that converter. The pump and stator combo in there does not seem anywhere near correct for a small ci turbocharged engine. Id let Dusty spec you a 9.5" PTC after you figure out how hard your going to run it. Id want to see a combo like that flash stall to 5100-5200 at full boost (which should be 25-30psi) . Id be shifting around 5700. Based on what i see in your post at 13psi at 16-17+psi you will see zero drop at the shift. Keep in mind if you order a converter for 15psi boost you will blow through it with 30psi or the other way around if you run 15 psi with a converter spec'd for 30 psi your engine will likely be pulled below the power band on ratio changes

 

[turbo6man]

OK I will turn up the boost some more and then re-evaluate the data logs from there. Thanks for the information. I really do appreciate it.

 

[Dusty Bradford]

Hey thanks for the reply I have been shifting it at 5800 to 6000. I must confess I am not exactly sure where to shift it, but it really pulls great to there
The roller cam specs are:
ATR Model No. RP309H Hydraulic roller
Advertised duration: Intake 276 degrees/ Exhaust 272 degrees
Duration @ .050 lift: Intake 214 degrees/ Exhaust 210 degrees
Lift with 1.55 rockers: Intake .515/ Exhaust .504
Lobe Seperation: 109 degrees
Overlap: 56 degrees
Notes say "Smooth idle/ for modified engines"

I was thinking when I read the logs I would be around 3600 on a boosted launch so when I saw it was more like 5000 i thought something was wrong.

On the 15psi logs I have the rpm's drop about the same: shifting at 6000 from 1-2 as 2-3 and it is about a 620rpm drop per shift.

I plan on slowly turning up the boost to about the 27ish range but I was thinking the converter was way off already and I was wasting power in the converter and due to the free restall it would be better to get it closer now, but that is an un educated assumption and I would like to hear more of what you have to say about it. Thanks again

Looks like your shifting in the right place. 5800 is good.

The converter is definately on the loose side and will get looser with more power applied to it. Like Bison said, if you get a converter that is perfect for 15psi, it can get loose at 30 psi due to the power applied to it.

 

[turbo6man]

Thanks guys, and Dusty I sent you a PM :biggrin: