I was one of the first guys with a rotary to use the Tial, I had alot of comunication with them over the bov, they were originally shipping it with a spring that cracked around 26 inhg, then they came with a lighter one that was about 18 in hg, I ended up have to make my own, that cracked at 9inhg, I forwarded them my spring info, and thats apparently what their new spring is based on..
One thing I have found with my car, is that in order to make the Tial work properly, and to get rid of surge, is to setup the closed throttle idle properly, a working back valve is a must with a tial, alot of guys with stand alone ems's skip the bac valve install, some ems's don't support it either, the wolf bac valve control is super shitty, and the microtech has to be pre configured hardware wise to use it, I have the haltech, which does allow bac valve control, but it has to be setup right, in the hitman and haltech manual it talks about setting the minimum idle on the throttle plate, and using the bac for idle up when a/c , or alternator load, drags the idle down, people without bac valve have to set the idle up a little higher than normal to compensate for alternator and a/c loading at idle, so that when the lights and electric fans come on, the motor doesn't stumble down and die.
Its that little bit that the throttle plates are open that delays and weakens the vaccuum signal enough to make the tial not open fast enough, its a very large valve with alot of surface area, and it needs a good signal to crack early enough..
I strayed from the Hitman/haltech and pretty much took out the minimum idle stop on the throttle plates, got rid of the throttle delay pot thats on the throttle body(its a spring loaded plunger with a diaphragm that sucks through a small orifice that makes the car throttle down slowly to allow the stock computer to catch up to the changing fueling requirements under deaccel and get the bac valve open...
So now my throttle pretty much just snaps 100% shut, and the bov is now alot more active than it used to be, even in light accelaration when I let off I get the psssshhttt, where as before even with a super light spring I would get the big turkey gobble effect, its important to get the settings right in the haltech for the bac valve, the bac valve can be setup so that the haltech controls the motor just like the stock setup, and make it act like it still has the deaccell vac pot, just by playing with the settings...
I use 14 for a ms value. 32 for the steps, and minim open of 25% hot, and 75% hot opening.. The car behaves pretty good with these settings...max

Originally posted by SPOautos
So for you guys with the Tial running the no surge spring, does it have any effect on how much boost the Tial will hold??? I assume not but you never know. I think the problem was just that our cars dont run enough vacume to open the flapper cause its spring tension was to high so this is to help the lower vac engines like ours.

Is that correct???

STEPHEN

Originally posted by carx7

FWIW, I did have a turbo XS type Hbefore my TiAl... and it worked flawlessly.

-Chris

Originally posted by the_glass_man
I'm glad I read this thread before purchasing one. It sounds like it still leaves some room for improvement. I'll guess I'll just go with an HKS instead.

Originally posted by SPOautos
Nah, there really isnt anything wrong with it. When it first came out thier standard spring was to still cause most cars run more vacume than a streetported rotary. When they found out that thier standard spring was causing compressor surge for our cars they came up with a different spring for rotary engines. You just need to tell them its going on a rotary engine so you get the right spring.

Other than that there shouldnt be any problems. I just wanted to make sure the revised spring wasnt causeing any other problems.

STEPHEN