possible to build boost without load on engine?
 

with a stock s4 turbo(ported wategate) and tmic converted to fmic and 2 inch piping.......say i was at the drag strip and i wanted to build boost at the line...can it be done?? i have a manifold to turbo exhaust leak getting fixed real soon and i know im loosing boost so that is why i dont know...

Fix the leak first.

It's possible - some people can do it, and I understand a ball bearing turbo makes it a lot easier to build boost in neutral, but most cars can't build a significant amount of boost in neutral.

Now, if you're hardcore, you could go with an antilag system. It retards the timing significantly, such that the exhaust port is open (or opening) as the spark fires. This makes very little power, but dumps burning fuel down the exhaust manifold, which will spool the turbo beautifully in neutral. However, it does *really* nasty things to the life of the turbo, and is more for rally cars & dedicated drag cars.

-=Russ=-

gasket is in hand...just waiting on better weather :) ill stay away from the antilag system...lol its a DD and wanted to know if it could be done..

Short answer? No. You can build boost in neutral by hitting WOT and letting it rev, but it'll only be there shortly as it revs and then drop off, and you can't build it by holding any specific rpm. You can get a two-stage setup that sets a rev limiter at a lower RPM than normal, and this backfiring/etc through your exhaust will get the turbo spooled up a lot more than you could manage holding it at the specific rpm, but this wreaks havoc on your turbo (Ask Jrat!)

i see ... so its only gonna get short bursts...at high rpm's for a second or two but nuthin to help launch

Nope, not without a two-step.

http://www.tekniqauto.com/CDN/tsport/tsport.htm

Scroll down to Flat Shift.

^^ thats interesting... pricey but interesting....

324.00 canadian isn't too bad! This would be bad on the drivetrain though. Full boost launch would be harsh!

thats not to bad for what your geting.

Or you could get an auto and preload the torque converter, which puts a load on the engine. Not really worth it on a DD, though.
Edit, just looked at the flat shift thing. Isn't that the same principal behind two-staging?

^^
Kinda, but what about keeping full boost between shifts?

That's exactly what that T-Sport device does, hence the name Flat Shift...

A two-step wired off your clutch switch would accomplish the same thing.

Getting a two step setup on a rotary is a little more dificult than on a piston engine because of the two separate ignition systems (leading and trailing). If you have a standalone then it becomes much easier, as it controls both leading and trailing.

1: two step (ems pretty much required for this one)
2: the "factory" two step
both will build boost effectively with no load.

3rd option: Launch from a higher RPM and slip the clutch

Why would you WANT to do this?
The bitch is hard enough as it is to get the damn thing to hook-up from a standing start.
Are you using racing slicks?
If not, you don't need it, and making MORE power out of the hole is probably going to smoke the tires.

Back when I was doing this seriously, I was launching at 5,000RPM on 225 / 50 / 16 Nitto NT-555R drag radials.
The car was only making 250 at the wheels.


-Ted

just curious ted, what kind of times were you doing with that setup?


I assumed that the OP has slicks or at least ET streets...

if not, you don't need boost off the launch.

LSD or open??

With the nasty camber in the rear, I managed a 2.1xx.
When it did that, I was surprised it got out of the hole that quick.

This is with the stock Turbo II LSD back there.


-Ted