It’s the “off-season” here in Chicago right now, so I’m just planning mods at this point and every now and again I get the idea that I need a bigger ‘verter <img src="gr_grin.gif" border="0"> <img src="graemlins/burnout.gif" border="0" alt="[Burnout]" />

I’ve got an SY3500 right now and I like how relatively easy it is to launch on DRs on the street or track. But sometimes I think I want a little more from a roll, but I don’t need the super high STRs that the TP series has, so the SY4000 seems like an upgrade I should consider. Install won’t cost anything as the trans is coming out to be replaced in the spring anyway, so that’s why I’m thinking that might be a good time to upgrade if I’m ever going to.

So, how do you guys like the SY4000? I’m not looking for record breaking 60 foots here, and I know it’s only going to launch a little harder than my SY3500, but it’s from a roll improvements that I’m looking for here. Plus, with the new cam going in I think it might be a good idea to get my shift extension up and 500 rpm more stall should help that...

 

[quote]Originally posted by RPM WS6:
<strong>
I'm not looking for record breaking 60 foots here, and I know it's only going to launch a little harder than my SY3500, but its from a roll improvements that I'm looking for here. Plus, with the new cam going in I think it might be a good idea to get my shift extension up and 500 rpm more stall should help that...</strong><hr></blockquote>

you meet the criteria well for an upgrade; it will work well for you. Let me add, however, it does launch harder than the SY3500. The higher stall and slightly higher STR combine to put a significant bump in low end torque to the wheels off the line. It will still not be as hard a hit as a YTP, but the SY4000 can put up some good 60' numbers. Check out the gains:

http://www.converter.cc/super_yank_dyno_overlay.htm

The extra midrange will really help on the 1-2 upshift.

 

Ragtop, thanks for the link. That chart is very interesting and makes me wonder. Why does the SY4000 drop of so much more then the SY3500 above 5000rpm? Is it less efficient? Would it actually hurt trap speeds and/or high rpm performance much over the SY3500?

By looking at the sheet, it would give me more right after the upshift, but then it would drop off getting towards the top of that gear? <img src="images/icons/confused.gif" border="0">

I'd hate to loose 5000+ rpm performance just to gain pre-4500rpm performance...

 

It is a less efficent than the SY3500.

Gain depends on how fast you start from and your gears. The chart is based upon converter output shaft speed, not engine speed. After the 2 - 3 upshift, you drop to 3600 - 3800 rpm; an area where the SY4000 provides extra power. If you start at a speed where the car will not downshift to 2nd, then the output speed could drop down to 3200 or so. On the other hand, if you start from high in 3rd gear, the SY 3500 would have an advantage.

BTW, the output shaft speed drops even more on the 1-2 upshift.


The extra shift extension will also keep you in your cam's power range too.

 

I’ve got about one or two more months to think about it, so we’ll see what happens...

Thanks for the words of wisdom <img src="gr_stretch.gif" border="0">