| Re: Transmission question |
Subject: Re: Transmission question by BeachBum on 2009/1/1 16:13:57 Quote:
My comment to Dan, was I just didn't want him loosening up his converter based "soley" on my recommendation. There are other factors including driveability that I hadn't talked about and he needs to understand them before he makes a final decision. As with most things in life, its a give and take.... make your car faster, but lose a little daily driveability manners is a common one. :angry1: A 3500-4000 is loose on accelerating.... best way to describe is listen to it. Go to the dragstrip and listen to some of the racecars as they pull up in the lanes. Yours wouldn't be that bad considering most of those are running 4500+ converters.... but you get a understanding of the "mushiness" of your pedal as you pull from a stop. This of course is not good for gas mileage.... it'll knock a few off. That slippage builds heat, thus you want to run a good transmission cooler "always" when running an aftermarket converter. This slippage is more prevelant when cruising at highway speeds as well, with a mild un-locked converter, you might cruise at 70 mph at 2500 rpm, whereas a high stall un-locked converter might be slipping to 2800 rpm at that same 70 mph speed. Easy way to solve this is run a lock-up converter, which adds a little weight and reportdly can hurt et on the dragstrip if not locked, albeit, I have never seen it, I believe it. A lock-up will do just that, lock-up the converter and all of the sudden you drop to 2200 rpm at that same 70 mph. (As a note, I personally never lock-up the converter at wot... its too hard on most, but some run a multi-clutch converter that will allow it, this is reportdly worth a tenth or so if they do and a 1-2 of mph improvement) If you do loosen up your converter substantially, you want to make sure whoever is doing it knows what they are doing. Simply put, typically when you loosen up the converter, you're also loosing efficiency on the top, meaning you could lose mph on the top through wot slippage. A racer in a high 9 second car recently reported a 2 mph trap difference between the same rated stall converters from different manufacturers. Just saying.... there can be a difference from manufacturer to manufacturer, so buyer beware. You also want to have confidence in the manufacturer hitting the stall you're going after.... a "lot" of people will buy a 3600 rpm converter, that doesn't actually stall to 3600 rpm.... the manufacturer missed. (Angle of the stator) But, typically if you give good accurate information on your racecar as to the cam/heads/gearing, etc... to an experienced manufacturer they'll come close. You might want to pose your question to some of the guys on lstech.com or ls1.com..... there are a lot more of those guys running 3500+ rpm converters and can perhaps verbalize it well for you, or one might even be local to you and offer a test drive. Corky's set-up is pretty neat, a 7000+ rpm solid rollerd 355, fairly tame cam too..... yet, he runs in the 10's with a 3.07 gear and a loose converter. Thats pretty stout ! |
