Who has hard data, E.T,MPH,RPM, Converter slippage and combo? I need real world info

[Dusty Bradford]

Dusty the converter should be delivered on Monday.......yeah agree you originally spec'd the converter to be 3000 stall and its only 2600 @ 0psi anoth 400-500 rpm sounds good. Now thats going to make it looser up top correct? its already slipping at 14% or are there other adjustments that can be made to increase the stall and improve the slippage up top? Also as you say more rpm helps it couple well I think my engine is done around 5600 I dont think I can turn it much higher so this is where my concern is....if my rpms are 5600 at only 107mph which is what it did last week whats gonna happen if the slip% stays where it is and I turn up the wick.....at 117-120mph my rpms are gonna be through the roof if it will even pull that high? This is what the car ran with my old converter...11.7-11.5 @116-118

Everything is ok with your converter. We were looking for something that would cause more slip up top than normal but found nothing. If we raise stall you will most likely also see some extra slip depending on the shift rpm. If it was shifting early, holding the shift out longer can offset this slip. For example if we raise stall speed 400 rpm but you raise the shift point by 400 rpm you will have better spool without getting more slip. The other option for less than 10% slip without raising the shift point and still seeing 3000 stall is the 9.5 non lock.

 

[Dusty Bradford]

I'm running a similar combo with the same converter at the same power level and seeing the same thing. So the solution seems to be either to raise the power level which will raise the flash stall, or get the converter tweaked. I guess we could turn up the boost more out of the hole to get it through the coupling stage and then turn it back down to current levels afterwards. Maybe this is what Dusty meant by pouring the power on? I'd hate to get the converter adjusted since I know it would work better with a little more power, but I'd like it to work better at current levels. Tried leaving with more rpm and the initial hit is hard, but the coupling still drags it down and hurts the 60ft. Running 25lbs of boost or so, similar to Paul, so it seems like I'd have to raise the boost to 30lbs or so after the hit to shorten the coupling time.

Does this sound about right?

Yes you are correct. If you want the converter to perform better at lower power levels it could be loosened. Just remember when you turn the boost back up you will have more slip.

This is what I discussed in another thread. A converter is spec'd by the overall et goal. If the power is turned down, it will get tighter. A converter performs according to the torque applied to it. Turbo cars are just like nitrous cars. A nitrous converter can't be optimized for n/a then also be optimum for a 250 shot of nitrous. Just like a turbo converter can't be optimized for 16psi then also be optimum for 25psi. Stall speed changes according to the power applied to it.

 

[pacecarta]

Stall speed changes according to the power applied to it.

you stated this before ("pour on the power") and now i see you basically saying the same that more power applied will change it
i agree more power will change it ..but in my case and murphs if i had my target boost lower i would agree -raise the boost
if you look at what i posted there is no other way to get MORE POWER than what is there with the converter as is
its at WOT , the boost was there at the couple (23.8 psi there is upwards of 650hp) ... its building to the target and still building boost after the couple yet remains flat for 1/2 sec . i could target higher but that wont change the hang time

to qoute scottie ..im givin er all she got captain

 

[Dusty Bradford]

Most cars I tune will see a short flat spot in the rpm when the converter fully couples. 1/2 is what I would consider short. I have saw some that remain flat for 2 or 3 seconds in which case the car really responds to more power at that point in the run. If the rpm drop on the gear change is over 1200 rpm I loosen the converter to help the flat spot. If the car has really low slip% it can also be loosened. If the slip is % 6-8 and the flat spot is short the converter is working ideally. I then go back and look at my tune up prior to and during the flat spot. Is the timing ramping out to fast, is the a/f ratio optimized, can the boost be brought in sooner, can the launch boost be raised so it reaches target boost sooner.

I tuned a car last weekend that had an rpm dip when the converter coupled. It would flash then drop 400 rpm and it was at full boost when this happened. It had never did it before but the track was the best I have ever been on. In his case he needed a looser converter because the track conditions had changed where the car needed more rpm. Even with the dip I was able to raise launch rpm 400 and 3 psi boost and the car went the best 60' it had ever been.