Minimum stall

[Mike T]

My new transmission requires a N/L converter and I currently have a Hughes 3 k L/U that will stall on the foot brake at around 2465 @ 1-2 psi with a GTQ70 (just starts to boost @ 2250). I know that the turbo is a little big but it really seems to spool decent and has a steady hard pull that I just don't want to give up. I don't want to loosen it up too much because the car has a small cam. It seems that the minimum recommended stall for the GTQ is a 3600 but since mine appears to be starting to spool ok with such a tight converter would I be able to get away with an additional 400 stall (3400) and have a decent 60 foot and minimal slippage up top ? I am looking to purchase a converter soon.

TIA
Mike

 

[Dusty Bradford]

You should be able to send it back and have them loosen it 400 rpm.


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[Mike T]

It was a second hand purchase and after receiving it I looked up the Hughes # 21-30 L (9 inch I think) and found that it was not recommended for turbo applications. Also it doesn't have anti-balloon plates. It's a nice driving converter but I need a N/L now and my first baseline dyno was 450whp so I need a little room to grow. Given the above info would a 3400 be close for my combo or am I off ?

 

[Dusty Bradford]

What are your goals? Your not using much of that turbo at even 500hp. Are you looking to run 9's?

If it doesn't have anti balloon plates your probably better off buying another converter by the time you pay to restall it and have it beefed up with anti balloon plates.

A 3000-3200 stall will make a big difference in it. Your only around 2400-2500 now so another 400-600 will be very noticeable. Final stall speed and converter selection will depend on what your ultimate goal is.


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[Mike T]

Low 10's would be the goal and about as far as I would want to take the stock crank in this motor. The 450 was on pump gas only and a few guys have said with alcohol the car should make 600+ even with the small cam. I have a few of the parts in place like the large IC & turbo for when I build a larger motor later.

 

[Dusty Bradford]

That's definitely a combo for a 9.5 non lock. You can sell yours if you know someone interested or trade it in. Value won't be very high though.


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[Mike T]

So maybe even a true stall of 3200? I'm surprised that the advertised stall & the true stall is so for off on my converter. Is this much of a difference common?

 

[Buick Mark]

The higher the torque produced the higher the stall rpm.

 

[Jerryl]

I bet the 3k rating is at 5psi.
Just tested my 3200 protorque. 2550/0, 3200/5

 

[Dusty Bradford]

So maybe even a true stall of 3200? I'm surprised that the advertised stall & the true stall is so for off on my converter. Is this much of a difference common?

Yes it's very common. Majority of the converter companies are used to dealing with V8's. Your converter will probably stall 3200 or so behind a healthy small block so when you call and ask for a 3200, they build this converter. The V6 off of boost makes very little torque compared to the V8 so it stalls much lower than advertised.

This is also why you may see someone say they have a 3800-4000 stall. I can promise you if you see a Buick with 4000 stall at 0-1psi, it's terrible to drive and extremely inefficient. In my opinion stall at 5psi or even 10psi is useless in determining how a converter will spool a given turbo. If any of these engines make boost around 3000-3200 rpm, they will spool a turbo. Even a 274ci with an 88mm will only see 3200-3300 before making boost.

 

[charlief1]

I'm not a transmission guy but from what I've read from Dusty, Lonnie, and several other smart members on here, a converter will spool 300 to 400 RPM's less on a V6 VS it's rated stall speed. If I'm wrong I'm sure Dusty or someone else will correct me here. That seems to be one of the things no one seams to realize.

 

[we4Mateo]

I'm not a transmission guy but from what I've read from Dusty, Lonnie, and several other smart members on here, a converter will spool 300 to 400 RPM's less on a V6 VS it's rated stall speed. If I'm wrong I'm sure Dusty or someone else will correct me here. That seems to be one of the things no one seams to realize.

My Vig is 500rpm below the rated stall at 0-1psi so pretty much spot on there.

 

[qws2000]

Mike, don't mean to steal your thread, but you got me thinking.... I have a stroker motor with an aggressive Cam and fully ported race heads, with that stroker do have to change stall???? I have 9.5 N/L 3400 or 3200....

 

[Dusty Bradford]

Mike, don't mean to steal your thread, but you got me thinking.... I have a stroker motor with an aggressive Cam and fully ported race heads, with that stroker do have to change stall???? I have 9.5 N/L 3400 or 3200....

A stroker will raise the stall speed from the stock stroke due to the extra torque.

Another thing people don't understand is turbo size effects stall speed. You can have a TA-49 with a converter that stalls 2600 rpm at 0-1#, change to a q-trim 66 and it may take 3000 rpm to build 1# of boost.

Stall speed is just a number. As long as your turbo spools quick enough to suit you it doesn't matter if its 2400 or 3000 rpm. What matters is what it flashes to at the power level you intend to run at.


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[20psiofevil]

Low 10's would be the goal and about as far as I would want to take the stock crank in this motor. The 450 was on pump gas only and a few guys have said with alcohol the car should make 600+ even with the small cam. I have a few of the parts in place like the large IC & turbo for when I build a larger motor later.

Man your sig is screaming for a 6262 turbo! Just like my sig is screaming for a 70q lol. What ar you running on that turbo?

 

[Mike T]

Man your sig is screaming for a 6262 turbo! Just like my sig is screaming for a 70q lol. What ar you running on that turbo?

The car has not been down the track with the new motor but with the current tune and straight 93 I think 11.70 at about 115 would be a fair guess. I try to be on the conservative side of what to expect out of the car and most of my projected estimates have been fairly close so far. I know 11.70 sounds weak for some of the parts that I have but I want to start with a solid foundation and creep up on low 10's.