sweet!

 

Does your car idle rough with those cams cause your cam gears are set to 0/0. Just wondering cause I'm about to get them. Hopefully wake this huge *** turbo I got up.

 

No. I used to have a lope but went away with the turbo upgrade. Dont ask me why cuz I dont know.

 

I am in the subs. Brandon, Riverview

 

The lope is due to cam overlap and low engine vacuum.. adding a restriction at idle (a heavy aftermarket turbo compared to stock) was probably enough to increase your vacuum level at idle.. stable idle means stable air drawn through the MAF and less prone to surging until your trims go out of range and reset.

 

good answer and makes sense. =)

 

What turbo does TT use in their kit?

I was hoping to get my car tuned here on the east coast before i ship it out west but it has to go tomorrow.. I was hoping for 410-420 on 93 and 450+ on c16, this is with my RNR turbo kit and a gt30..

the 420 was on pump?

 

420 is on pump. The TT kit is biult to their specs. I think it is a 50 trim though. I think it was designed for a compromise of awesome spool and top end. With this turbo, I can run 28psi or so on race fuel and be around 500awhp.

 

I'm glad to hear that big turbos don't lope on 272s. I think my gt35r .70 a/r will be large enough to eliminate loping I think I am one of the only turds running stock cams with a huge turbo. Not for long though!

 

It isn't always the case.. but happens often enough.. In some cases with the stock maf you may find the engine speed surging up and down because of the mass of the larger turbo..

 

Well if it was the MAF you think it would already do it then and it doesn't so I am hopeful that the cams won't pose a problem. I mean if anything the cams would allow more air in relieving said pressure from the larger turbo around the maf.

 

one way or another you need cams. Whatever the outcome...it will be a positive one anyway. =)

 

Yes and no... adding cams means hurting idle vacuum, if you have no trouble now, but you reduce your idle vacuum, you may find that a big turbo may not adequately draw air through the MAF sensor..

Its a double edged sword.. since theres probably a balance of how much and how easy the air is drawn through the turbo.. a little too large and it can't draw the air through, so you get poor idle, or surging.. and smaller turbos end up with lopey idle from cams.. its a catch-22 that generally evens itself out with bigger cams and turbos, but keep in mind that it isn't always the case.

Typically you'll need to raise your idle RPM to 1000-1200 no matter what, that usually eliminates most problems, occasionally the ECU will complain that idle is too high and throw a CEL..

There are several sorely needed features for working with the stock ECU, either as a standalone module, or as a firmware revision of the UTEC, and that is Tip-in fuel compensation, and adjustable stepper motor control/bias to intercept/alter engine speed without altering the BISS settings (though you always need to set your base idle speed in open loop first)

 

Actually, a larger turbo presents less of a restriction. I suspect any change in idle quality to be due to different tuning.

 

If you add mass to the impeller, until it starts spinning at a high enough rate, its a restriction.. That was my whole point.. Its obviously less of a restriction once its moving air.. but if its barely spinning it may not be moving fast enough for allow adequate air to be drawn through it.. The stock turbo always seems to have a slight positive airflow through the upper intercooler, but my experience has been once the turbos get larger, that positive airflow isn't as high.. so you have the intake vacuum working against it, and not enough exhaust pressure to spin the turbo at idle.. generally raising idle speed gets around it.