Pretty much, convertor slips alot more with a higher stall speed. Everytime you accelerate, the engine will spin a little higher. It is only when more throttle is applied that the convertor begins to come into it's efficiency range. A hi stall car will use more fuel, make more heat and be a general pain to drive in traffic at normal city driving speed. Even at 100km/h our na will unlock the convertor and revs will jump from 2500rpm to a slipping 3000rpm with only slight throttle movement. It is only when it goes over 120km/h with it unlocked that the convertor is actually giving near full drive. I have had hi stalls's in many cars over the years, they are a great thing, but not in a everyday sort of car.
Section AT, page 187 of the fsm. Spec is 2450 to 2650rpm. Most will only hold the brake until around 2600 at the most. Don't forget, stall speed is a product of engine torque, the more torque you create down low, the higher the stall speed. Some stock convertors may go to 2800rpm, other may only go to 2000rpm, if the torque isn't there, the convertor will transmit drive earlier.
for a fast launch and good 1/4 mile times in an auto the two things you really need are a hi stall, and a valve body modification. The Yellow Z could build and hold 16 PSI at the start line (3500rpm) Edit + a good cooler which I believe you already have.
Did you monitor trans temps with your convertor pex? Ours runs rather warm even with a huge derale cooler and like your yellow zed, our convertor isn't very well matched either. You trap speed beore and after hi stall reflect it could have gone afair bit quicker than it would of with a properly matched convertor. Before I go to willowbank again, I will fit a standard tt convertor to the na and I will almost guarantee it will pick up around 5mph, it will still be slow but it's consistency means I can accuratley gauge mods.
I never got a chance to put the gauge in before I sold the car. Still, it made the car great around town, not many RWD cars could touch it up to 100 km/h
Only way to get An auto off the line quickly is with a trans brake fitted, allowing first and reverse to be selected at the same time. when you have the desired revs and boost you want flick the switch and hang on for some brutal launches. Valve body mod is good for quick changes and a large cooler fitted to cope with all the heat your generating. Some sticky tyres and your there.
Maybe I should never have mentioned the drag strip.... it was merely what reminded me of what I had been thinking about a while back. We have a 3L V6. It should, by nature, pull pretty hard even without the assistance of turbos. Or should it? Since the VG30DETT engine is designed to be turbocharged is it going to be less efficient when not under boost than an VG30DE? My rookie understanding says my thinking is correct and an NA will be better off than a FI engine when not under boost. It is this small range that I was looking for ways to improve the power and response of. Most of the advice has been to just get it into boost as soon as possible, and fair enough. I guess the best answer to my question was higher compression pistons.
don't forget advancing the timing a few degrees in the low end of the map as mentioned, makes a noticeable difference
Aaah yes, tuning Which will help everywhere too. Certainly more feasible for me personally than changing pistons.
Generally speaking, the desired stall speed of a converter should be around 50-700 RPM below the engine RPM at peak torque. this means we generally are getting stally's that are not even in the peak area
Can you explain that for me please? If i'm reading it the right way, your saying the auto cams are better for lower rpm, but worse off in higher rpm? I've been trying to figure it out, as I thought manual cams were always looked at as better..
The yellow Z could hold 4000rpm with the assist of the handbrake Benny_C has seen it Tyre fryer on launch though Kieren, the DETT has lower compression than the DE, so less air in the cylinders will mean less power
If you want to get all technical, the TT has a larger combustion chamber than the NA. Amount of air and CR are practically unrelated, more related to displacement. More air does = more power though.
