kazfan30

iTrader: (18)

Well i have had this convertor in the car for bout 8 months now, and it just never seemed to pull that hard since day 1(1:1 fluid couple)...Now ive been to the track a few times with a cam only setup, and tonight with my new heads and powerbond pulley. I feel like being a H/C car i should surely be in 11's and trapping at least a few more MPH???? Take a look at my best time so far and tell me what you guys think is happening....(And this by no means a bash on Fuddle Convertors, just eliminating possibilities of my cars poor performance due to a faulty one)

60'...1.72(drag radials)
1/8...7.80
1/8mph...88.99
1/4...12.23
1/4mph...111.86

similar setups tonight, and even less mods....mid-high 11's at 113-117 A4's

408WS6

iTrader: (1)

My fuddle is doing the same thing. Actually, I'm not sure whether its the convertor yet or the transmission. But I'm going to try a different fluid and see what happens...

ls1408cp

iTrader: (37)

figure out what rpm you go though the traps and figure out how efficent the converter is

Humvee z28

interesting, my car with just mac midlengths, LM catback, tune, 3400/2.1 fuddle converter, and 3.73 gears was running consistent low 12.4s at 109 full weight. maybe it could be a tuning issue...

CAT3

iTrader: (9)

Well if you trapping at 5600rpms, and using a 26" tire thats putting about 4.25% TC Slip, which is very good. Not sure what your actual rpms are, and tire used though. FWIW mine is slipping 24%
Have you done any tuning? Yes I see RWTD in your sig, but if your not logging anything they tunes they email could be off by a lot.

ultraz

iTrader: (4)

looks like your 60's are great, Id look at other factors in the tranny or possibly another Ls1 specific tuner.

kazfan30

iTrader: (18)

Hmmm, well i thought the car made really decent power when i was cam only..375/358,(locked, so slippage was not a factor on dyno)but not had car tuned since heads and pulley install. Just cant figure out why im only trapping 111 My friends at track told me it look like the car ran strong out of the whole but bout the 1/8 or so it just kinda a slow pull.....like its not gaining too fast??? Hence maybe a convertor slippage issue....tranny seems fine so i dont think its that

s346k

iTrader: (4)

what was your 1/8 trap on that 111 run?

CAT3

iTrader: (9)

Tuning could very well be your issue. Can you look ^ and give me more info, wt, tire size etc? Thanks.

408WS6

iTrader: (1)

Sorry to hijack, but I have a question: if you calculate the efficiency like this, how do you know for sure its the torque convertor and not the transmission slipping? The reason I want to know is I am having similar problems...

CAT3

iTrader: (9)

I really dont know. Other than a trans would feel sloppy, watching the rpms climb but not mph....feeling like there is no pulling....or going up hill, throw it in second from stop and see if it slips (mine I can put right into 3rd since its man valve body).

jimmyblue

iTrader: (11)

Look at engine RPM, input shaft RPM and output shaft
RPM along with Trans Current Gear and you can see
everything you need to know about slip.

Trap slip RPM is not the whole story by a long shot.
You care not only about the peak efficiency (which
is what manufacturers like to advertise) but about
how much of gear is spent at what efficiency (like
area under the curve, TQ/HP). If you get to 96%
efficient at the traps but you spent most of the
distance at sub-90% you lost plenty of energy
over the distance.

Slip RPM can't be taken as the true efficiency if
the converter is still multiplying torque (as is the
case with higher stalls, further into the RPM band).
You have to look at something like locked / unlocked
dyno curves, probably on a MPH basis as well as RPM
(since output speed and input speed both matter to
the coupling).

Back to the converter vs transmission slip question,
take your (input/output) RPM ratio and compare it to
the nominal gear ratio for Trans Current Gear. Dead-on
means no slip in the box.

If you look at the attached pic, this is two TCI
converters (my old SF 3000/2.2, somebody else's
SSF 3500/2.5) against my current Fuddle 3500/2.0
converter. Couple of things worth noting. One is,
the lower stall TCI is significantly more efficient
across a broader useful band, because it's coupled
up earlier. Second is, the Fuddle and the TCI are
within a point of each other (two different cars, so
can't call this a dead match, and even on my car
the TCI3000 and Fuddle are on opposite sides of
a stock -> long tubes swap) but there is a big
difference in where the coupling comes in which I
figure is the STR; a high STR will tend to swing from
big multiplication to hard locked up across a shorter
RPM band while the low STR will transition more
smoothly and multiply further out past the nominal
stall point. This was my preference in spec'ing a
lower STR. So I'm not too bent out of shape about
the 80%-range numbers down low because I think
there is still torque multiplication going on there
(only the dyno will tell, and I've never been). Yet
another point is, if you're using a converter to play
with the powerband, make sure your powerband is a
match to the converter you think you wanted. You can
see the "trajectory" on the higher-stall TCI and the
Fuddle is not topped out and will keep delivering more
but my car is still stock heads, cam and low shiftpoints
so I am not taking advantage of the best the converter
can deliver; I picked one that would make sense for
where I plan to go, not where I am today. And until
I push out the real powerband and set up the trans
to stay with it, I won't be seeing all of the efficiency
there is to be had.

chrs1313

iTrader: (24)

something is definitely up that mph is really down

MNR-0

Best bet is to get a friend who has HPT and log it at full tilt to see what is going on. You will worry yourself sick second guessing everything and end up thinking worst possible cases.