Thread: SC silencer fix?

Was talkin to my friend the other day who has a sc/ss cobalt and he told me they have a mod where u pull the blower off and fill in some pockets that act as silencers for epa reasons. He said they followed instructions from a gtp site as its a mod for the m90 as well. I guess you use quick steel and after that the air becomes super sonic and the effect is a nice sound and supposedly u pick up a couple tenths. I did a search on here and didn't come across anything. Anyone know anything about this??

Well i dont like doing mods without research first, gimme some info on what benifits come with porting the blower and what if any supporting mods are needed. Also this is my daily driver so do u send a ported unit out and then take a core or how does that work?

Well i have the off road 3" DP and zzp pwr log goin in this weekend, next mods were to be a pcm probably from overkill and a 3.4 pulley. possible mods maybe next month im considering rockers and tb. Didnt really plan on doin an intercooler, do u think porting would be benificial with those mods?

here is what he was talking about for sealing the silencer slits:



it makes it louder at a lower boost level, but its not any louder at full boost.

like i was saying before though, the throttle body wont help out all that much at your minimal mod level. the rockers would though. that would be a good choice for a next mod after doing the exhaust.

rockers are full of all kinds of win. they add more lift to your cam thus moving more air around in the motor thus making more power. they pull pretty good on the top end

Originally Posted by blowfishRus6

rockers are full of all kinds of win. they add more lift to your cam thus moving more air around in the motor thus making more power. they pull pretty good on the top end

What kind would u reccommend?

i love my roller rockers. they quited down the valve train and they seem to pick up rpms good no matter where im at. i can hit it low in second and it picks up pretty good. and pull hard in the 4500 and up range.

i cant speak on the stock modified rockers.

Well I would assume the stock modified give the same gain if the ratio is the same. Anyone running the stock modified?

Also wondered back to my origional question here so blocking off those silencer ports, that have any gain in pwr or no?

Originally Posted by LSXHP

Well I would assume the stock modified give the same gain if the ratio is the same. Anyone running the stock modified?

the stock modified wont perform as well as roller rockers because of the fact that they arent roller rockers, but with rollers you pay more and need to change valve springs if you go over 1.8:1.

Originally Posted by LSXHP

Also wondered back to my origional question here so blocking off those silencer ports, that have any gain in pwr or no?

zero gain in power. sound gain only.

Originally Posted by LSXHP

Well I would assume the stock modified give the same gain if the ratio is the same. Anyone running the stock modified?

It wouldn't be as efficient as the roller rockers...

Originally Posted by LSXHP

Also wondered back to my origional question here so blocking off those silencer ports, that have any gain in pwr or no?

Blocking off the ports gives you no gain in power, just sound...it is when you hog out the "V" and the inlet of the blower is where you gain your power at.

Damnit Nick I swear...LOL

Originally Posted by Bio248

the stock modified wont perform as well as roller rockers because of the fact that they arent roller rockers, but with rollers you pay more and need to change valve springs if you go over 1.8:1.



zero gain in power. sound gain only.

The stock modified rockers from ZZP do not require different vavle train parts, they say they work fine with all the stock stuff and there 1.9:1.
What is the stock ratio 1.5 or 1.6?

As for the blower I guess I wont bother with those ports then....unless I decide to just have it ported...

Originally Posted by LSXHP

The stock modified rockers from ZZP do not require different vavle train parts, they say they work fine with all the stock stuff and there 1.9:1.
What is the stock ratio 1.5 or 1.6?

As for the blower I guess I wont bother with those ports then....unless I decide to just have it ported...

i agree. i run modified stock rockers on my car with stock valve springs. rollers you will need higher strength ones. the stock ratio is 1.6.

Originally Posted by Bio248

the stock modified wont perform as well as roller rockers because of the fact that they arent roller rockers, but with rollers you pay more and need to change valve springs if you go over 1.8:1.

He comes from the LSX world where roller rockers aren't all that. Like I've been trying to tell you guys... Rollers are pretty much a waste. If you bother to look at how the tip on the stamped contacts the valve tip as it goes through its motion, you understand this.

LSXHP, go for L76 springs (from the G8 GT engine, you can get them cheap at your local dealer) with 1.9 modified stock rockers. The L76 springs are better than stocks, but not harsh on the valve train like aftermarket springs nor are they prone to failure like comp cams springs.

again ill say i love my rollers

if there such a waste why do people, even when keeping the same ration, go to rollers with motor builds?

they consume less energy, usally lighter, thus a free'er reving valve train.

in no way are they a waste especially when your gonna pay close to the same price.

Originally Posted by blowfishRus6

again ill say i love my rollers

Have you had a car without rollers just modified stock 1.8s? I love my 1.9s too. Not a very empirical comparison.

Originally Posted by blowfishRus6

if there such a waste why do people, even when keeping the same ration, go to rollers with motor builds?

Not knowing better? Bragging rights? On some engines it can make a difference if the stock setup used a really horrible rocker design. Ours, like the LSx engines, is very good so you see little to no gains. There are a lot of dyno runs out there testing on LSx engines that use roller vs modified stock, same ratio. There is no difference within the acceptable margin for error of that dyno.

Originally Posted by blowfishRus6

they consume less energy, usally lighter, thus a free'er reving valve train.

In theory, it's good. But like I said the stock setup was designed to achieve this anyway without the added complexity (and cost) of a roller tip. They're just something fancy that the vendors can charge more for that people seem to want.