from what size exhaust post cutout? I can see it making a big differnce if he is runningsmaller than 2.5" and with a 35r. But still, it cant be more than 15-20hp depending on the size post cat.

 

the difference is the boost pressure will be different. example, with the 2.5 system and its additional back pressure from the cutout system and boost controller set to say 18 psi you will spool in x amount of time and the turbo will hit however hard. now you open the dump you are now changing the flow characteristics and now the turbo spools faster, hits harder, and isboosting to 28 psi, awp rods will be bent here. yes the boost level changes with the dump tube open. we tuned donsupremes car to run at 17 psi normally and with the cutout it is hitting 26 psi. which he can handle cause i tossed in scat rods, and a bosch 033 in tank pump. he also had a unitronic (best software ever) bt 660 file with there respective injectors. this set up would be terrible for ryan. he dosent have a fraction of the hardware and based on my experience his rods are probably rusted (jk ryan....had to get you back).

 

oh also i didnt answer your question he has a 2.75 opening to a 3 inch. trust me we found out the difference as soon as it hit 30psi and started detonating. there is no cat in his system.

 

ok, im on drugs for my back and they are now kicking in. So bare with me and im not trying to sound condicending or like an ***

He has a 2.75 turbo back and a 3" dump... correct? Now your telling me he gains 9psi just by opening the dump regaurdless of boost control? Thats not right. Also your talking 35r which at 19psi can bend any stock rod. So your totally losing me on this. If this is the case, what is used for boost control?

But yes, spool will be faster and more power will be made with less restriction on a 2.75 => 3" dump on a 35r, but a 2.75" is more than enough exhaust to not hinder any turbo up to a 3071r or even 3076r and going to a 3" dump will give minium gain. So im having a hard time believing your explaination

 

he has a crappy exhaust set up. it goes from a 3inch down pipe to the cut out section, after that it flares down to a 2.75 with a muffler on the end. believe it or not im telling you this is how it works on this car. with that dump open it is raising boost considerably. we are using a turbosmart boost controller. whenever you change a turbo's flow dynamics it changes boost pressure. you have to adjust the boost controller accordingly. manual boost controllers are passive and cannot tell the difference from turbocharger flow dynamics.

do an experiment, disconnect your catback, i guarentee you see a change in charge pressure.

also a i agree, the 35r comes on very aggressive and can bend rods, but alot of speed psychos out there take this chance daily. i know he has gone over 19 on stock bottom but rarely. now with the drop in scat rods he is constantly passing this mark with no problems. actually this same guy is setting up a drag race day at capital raceway in the audizine regional forums. i will try to get him to chyme in here. but believe me i rode with him for 3 hours to h20 and watched this in action.

 

i seedonsupremepost on vortex all the time.

 

well idk if your farmiliar with his set up but this is how this car is running. and i dont see how on any car there would be no difference in boost by changing a component such as exhaust.
i swear i am not trying to sound like a *** hear i want to let you know i think you are really knowledgeable in tt or 1.8t tuning, and never usually have to post stuff hear cause you are quick to give the correct answer. but have you ever installed or personally had experience with cut outs? or highly tuned cars? I think the way you are thinking is based more or less on any car with the stock boost controller hooked up and just a off the shelf chip. most highly tuned cars are no longer running alot of sensors or dont have some of the protection features that off the shelf chip upgrades give. custom tuned software specifically from unitronic is very aggresive and usually throws alot of stuff out the door. if donsupreme's car had a MAF onit, he prolly wouldnt even have a cel.

 

I can see it making a spoolfaster and more overall power, but boost is regulated by the pressure in the charge pipe going through vac line to the wastegate and altered by a boost controller inbetween. Im not seeing how changing the exhaust size or length of the exhaust will change how the boost is regulated. But your right, i havent delt with a cutout let alone on a highly tuned car.

Are you guys usuing a turbosmart mbc or their ebc?

 

its the mbc. im sure you know how a boost controller works, so know that why wouldnt it change? it being the boost of course. it is still set to to bleed out x amount of psi. so you change everything else then the mbc has to be changed.

 

With a ball and spring mbc, the pressure needed to move the ball up to get to the other side of the mbc to then reach the wastegate takes force. So i know that wouldnt change, but a bleed/gated valve might be the problem. So im betting if you move to a ball and spring mbc (ceramic ball for faster spool) or a ebc you wouldnt have any dramtic spikes like you seem to have with a bleed valve. Plus im only a fan of bleed valves on a stock turbo, and nothing else.

from Boostvalve.com






How does it work?





Alright. So, why is it better than a "bleeder"?



A bleeder valve is open all the time. Bleed valves work by fooling the waste gate into only seeing some of the boost pressure. The rest of the pressure is vented off, sometimes completely wasted by blowing out an open hose. Just like an air leak in any other hose this wasted air can cause problems with modern computerized engine controls. Additionally this causes the waste gate to open before maximum boost whichcan create turbo lag.

So again, dump the bleed and go with a ball and spring or a full ebc and im sure you wont have problems anymore