Whose 727 street/strip converters are you using?
#2709518
10/23/19 01:24 PM
10/23/19 01:24 PM
|
Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
OP
Taking time off to work on my car
|
OP
Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
|
I have the same Dynamic 9.5" that I bought in '99(?) and it's still in good shape given how little my car's been running over the years. However, it was spec'd for the car when it was making maybe 550 HP and running very low 11s. The converter still seemed to work well w/ the 50+ HP increase that put the car into the mid 10s, so I was happy. However, the new engine is an easy 100+ HP more than the converter was spec'd for originally in '99. It's still going to be my baseline when the car is back together, but at some point I a$$ume it's either going to need to be re-configured for the new engine... or perhaps I'll want (need?) to change to another converter. So, as my subject line states, whose 727 street/strip converters are you using?
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: BradH]
#2709549
10/23/19 02:58 PM
10/23/19 02:58 PM
|
Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
|
master
Joined: Oct 2007
Posts: 4,206
New York
|
The question is "how much torque does the new engine make at the observed stall speed?" It may have less than the original engine (later intake closing = lower CCP) and will stall lower despite the higher peak power.
If the stall torque is higher, the stall speed will increase (duh) by the ratio of (new torque ÷ old torque)^.5 RPM = K × (T^.5) Just using easy numbers: Stall now 3,500, new torque 550, old torque 500 (550 ÷ 500)^,5 = 1.0488, × 3,500 = 3,671 RPM new stall Stall now 3,500, new torque 600, old torque 500 Same math = 3,834 RPM new stall
Whether this helps or hurts launch...?
Boffin Emeritus
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: polyspheric]
#2709564
10/23/19 03:35 PM
10/23/19 03:35 PM
|
Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
OP
Taking time off to work on my car
|
OP
Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
|
The question is "how much torque does the new engine make at the observed stall speed?" It may have less than the original engine (later intake closing = lower CCP) and will stall lower despite the higher peak power.
If the stall torque is higher, the stall speed will increase (duh) by the ratio of (new torque ÷ old torque)^.5 RPM = K × (T^.5) Just using easy numbers: Stall now 3,500, new torque 550, old torque 500 (550 ÷ 500)^,5 = 1.0488, × 3,500 = 3,671 RPM new stall Stall now 3,500, new torque 600, old torque 500 Same math = 3,834 RPM new stall
Whether this helps or hurts launch...? Converter flashed to ~4500 from 2000 launch w/ old engine combination, so I highlighted the #s at 4500 for comparison. Your formula shows about a 4600 stall w/ additional torque.
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: BradH]
#2709577
10/23/19 04:26 PM
10/23/19 04:26 PM
|
Joined: Mar 2009
Posts: 2,458 Sydney,Australia
tex013
top fuel
|
top fuel
Joined: Mar 2009
Posts: 2,458
Sydney,Australia
|
Brad , I ran a similar Dynamic/Lupo to you for years stalled around 48/4900 . This was with both 440 and 505 footbraking . Now with transbrake I have a A1 Performance 8" unit , stalled at 5800 with original 505 and 440 . When I went TF270 head stall went to 6000 , but car went 0.25 faster so the heads obviously helped the motor HP wise. Drives fine daily . Even drove to a race in Mildura on the other side of the state - 12 1/4 hours on the highway no dramas . Tis was 2 weeks ago .
Tex
New best ET 10.259@129.65 . New best MPH 130.32 Finally fitted a solid cam, stepped it up a bit more 3690lbs through the mufflers New World block 3780lbs 10.278@130.80 . Wowser 10.253@130.24 footbraking from 1500rpm Power by Tex's Automotive
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: tex013]
#2709590
10/23/19 05:14 PM
10/23/19 05:14 PM
|
Joined: Jan 2003
Posts: 8,021 Tulsa OK
Bad340fish
master
|
master
Joined: Jan 2003
Posts: 8,021
Tulsa OK
|
I have loads of street miles on a Turbo Action 8" 4500 when I had my 727. My 904 had a 8" 4800 until the snout broke but that is getting repaired. The 4500 behind the 727 flashed to about 5500 and the 4800 with the 904 flashes to 6400. I did 5 drag weeks with the 727 converter and 1 with the 904, car weight on the road for drag week is around 4000ish.
The street manners of them don't bother me at all.
68 Barracuda Formula S 340
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: BradH]
#2709606
10/23/19 06:29 PM
10/23/19 06:29 PM
|
Joined: Oct 2007
Posts: 4,206 New York
polyspheric
master
|
master
Joined: Oct 2007
Posts: 4,206
New York
|
That's not "my formula", it's the one the transmission and converter manufacturers use.
Boffin Emeritus
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: BradH]
#2709664
10/23/19 09:37 PM
10/23/19 09:37 PM
|
Joined: Jan 2003
Posts: 1,807 North Dakota
Azzkikrcuda
top fuel
|
top fuel
Joined: Jan 2003
Posts: 1,807
North Dakota
|
Turbo Action or PTC, never had any issues with either one.
The only Carbs I care about are under the hood!
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: calrobb2000]
#2709705
10/24/19 06:29 AM
10/24/19 06:29 AM
|
Joined: Jan 2003
Posts: 15,439 Val-haul-ass... eventually
BradH
OP
Taking time off to work on my car
|
OP
Taking time off to work on my car
Joined: Jan 2003
Posts: 15,439
Val-haul-ass... eventually
|
hi ,
the dynamic worked good for 20 years and you want to know where to get a converter ?
My Dynamic has worked very well so far. My friend's sucked. Nobody hits 100%, and converter tech & good builders can change over 20 years. If the new engine and the old converter aren't a good match, I'd like to know what other people's experiences have been.
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: BradH]
#2709733
10/24/19 09:16 AM
10/24/19 09:16 AM
|
Joined: Aug 2011
Posts: 2,853 Pattison Texas
CSK
master
|
master
Joined: Aug 2011
Posts: 2,853
Pattison Texas
|
For my A518 I had PATC custom build mine, told them my engine combo & they nailed it, so far so good, 3500miles of abuse .
1968 Charger COLD A/C Hilborn EFI 512ci 9.7 compression, Stealth heads, 4.10 gear A518 ODtrans 4100lb,10.93 full street car trim 2020 T/A 392 Stock 11.79 @ 114.5
|
|
|
Re: Whose 727 street/strip converters are you using?
[Re: Dragula]
#2709926
10/25/19 07:39 AM
10/25/19 07:39 AM
|
Joined: Aug 2004
Posts: 214 Hamburg / Germany
Den300
enthusiast
|
enthusiast
Joined: Aug 2004
Posts: 214
Hamburg / Germany
|
FTI - great Service! Switched from a 9.5" PTC with 3200 stall to a 9.5" FTI with 3500 stall. Day and night difference! Much better.
Hamburg/Germany
69 Chrysler 300 446cui Dual Quad 12.64 @ 110.7
|
|
|
|
|