Technical converter Question
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Technical converter Question What factor determines shift extension in a converter? Stall or STR?
Ex-- same stall, more STR= more shift extension
Or-- same STR, more stall= more shift extension
Thanks!
Ex-- same stall, more STR= more shift extension
Or-- same STR, more stall= more shift extension
Thanks!
Re: Technical converter Question Actually, STR generally makes a bigger difference on how much shift extension you have and stall speed has more to do with at what rpm it occurs; however, converter holding capacity (size) has a bit to do with it too.
For example:
10" 3500 stall with low STR: 4600 shift extension
10" 3500 stall with high STR: 4200 shift extension
9.5" 3500 stall with low STR: 5000 shift extension
9.5" 3500 stall with high STR: 4600 shift extension
These are generalities. Pump to turbine clearance, stator configuration, and pump blade angles change the amount of shift extension as much as they can stall speed. If a converter has real snappy throttle response, it's a pretty good sign it has a high STR and lower shift extension.
A Vig 3600 (stalls 4300) and a Yank Pro Thruster 4400 both have similar stall speeds and STRs. The Vig has snappier throttle response. It also has about a 5200 rpm shift extension where the YPT4400 is more around 5800 rpms. This is one of the reasons why the Pro Thruster is so deadly from a roll. Its stator design, multiplies torque for a much longer time than any other converter on the market.
For example:
10" 3500 stall with low STR: 4600 shift extension
10" 3500 stall with high STR: 4200 shift extension
9.5" 3500 stall with low STR: 5000 shift extension
9.5" 3500 stall with high STR: 4600 shift extension
These are generalities. Pump to turbine clearance, stator configuration, and pump blade angles change the amount of shift extension as much as they can stall speed. If a converter has real snappy throttle response, it's a pretty good sign it has a high STR and lower shift extension.
A Vig 3600 (stalls 4300) and a Yank Pro Thruster 4400 both have similar stall speeds and STRs. The Vig has snappier throttle response. It also has about a 5200 rpm shift extension where the YPT4400 is more around 5800 rpms. This is one of the reasons why the Pro Thruster is so deadly from a roll. Its stator design, multiplies torque for a much longer time than any other converter on the market.
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2013 Corvette Grand Sport A6 LME forged 416, Greg Good ported TFS 255 LS3 heads, 222/242 .629"/.604" 121LSA Pat G blower cam, ARH 1 7/8" headers, ESC Novi 1500 Supercharger w/8 rib direct drive conversion, 747rwhp/709rwtq on 93 octane, 801rwhp/735rwtq on race fuel, 10.1 @ 147.25mph 1/4 mile, 174.7mph Half Mile.
2016 Corvette Z51 M7 Magnuson Heartbeat 2300 supercharger, TSP LT headers, Pat G tuned, 667rwhp, 662rwtq, 191mph TX Mile.
2009.5 Pontiac G8 GT 6.0L, A6, AFR 230v2 heads. 506rwhp/442rwtq. 11.413 @ 121.29mph 1/4 mile, 168.7mph TX Mile
2000 Pewter Ram Air Trans Am M6 heads/cam 508 rwhp/445 rwtq SAE, 183.092 TX Mile
2022 Cadillac Escalade 6.2L A10 S&B CAI, Corsa catback.
2023 Corvette 3LT Z51 soon to be modified.
Custom LSX tuning in person or via email press here.
Re: Technical converter Question Partrick:
Your example of the Vig 3600 and YTP 4000 shows exactly why STR has a less factor. You can design an efficient higher STR converter with a long shift extension if you start from scratch with the right design.
To illustrate why stall is king lets first at two of Yank's converter with nearly identical STR and housing size: the ST 3500 and YTP 4200. The YTP has a shift extension that is 500 rpm greater. The difference is all due to stall. Next, compare the ST 3500 with STR of 2.5 and the SY 3500 with a 1.6 STR and you'll see the shift extensions are nearly identical despite a 50% difference in STR (although the housing size is not constant in this example).
I agree that if you hold stall constant, a different stator can change the amount of shift extension. But if you are looking to buy what's on the market, a general rule of thumb for shift extension and power froma roll is too look at Stall first and STR secondary.
Your example of the Vig 3600 and YTP 4000 shows exactly why STR has a less factor. You can design an efficient higher STR converter with a long shift extension if you start from scratch with the right design.
To illustrate why stall is king lets first at two of Yank's converter with nearly identical STR and housing size: the ST 3500 and YTP 4200. The YTP has a shift extension that is 500 rpm greater. The difference is all due to stall. Next, compare the ST 3500 with STR of 2.5 and the SY 3500 with a 1.6 STR and you'll see the shift extensions are nearly identical despite a 50% difference in STR (although the housing size is not constant in this example).
I agree that if you hold stall constant, a different stator can change the amount of shift extension. But if you are looking to buy what's on the market, a general rule of thumb for shift extension and power froma roll is too look at Stall first and STR secondary.
