LS1crazy01

iTrader: (14)

I just wish we had a Dyno sheet of a car with true duals vs. the mufflers on the collectors.

TXZ28LS1

iTrader: (5)

has anybody noticed a performance gain by running a muffler right off the header instead of a y pipe and catback?

LS1crazy01

iTrader: (14)

^ Read my previous post on the first page, I think thats the closest where gonna get. I just wished I dynoed it first.

TA1364

iTrader: (11)

Well I'll have some track times eventually comparing both. I dont want to do it tho untill I get my cam put in. Stock cam would sound terrible with this setup.

BigDB

I still dont like an exhaust with out some sort of crossover or junction. It helps scavange the other side when the odd fire hits on each bank. Escentially u have 2 4cyl engines when u run a pipe off each header and not connected anywhere becasue they arnt feeding off the other sides exhaust pulses.

TA1364

iTrader: (11)

Then how come cars run open headers?

BigDB

cars that run open header and actully make more power than with exhaust use even fire manifolds or have the 4-7 firing order changed. Either one will create a closer pulse sequence in the collector and create a vacumm on the exhaust. A tuned length header only means the primaries are the same length so it will take cyl1 and cyl7 the same amount of time to reach the collector, cyl7 is closer to the exhaust system so if it didnt have a primary that was the same length it would get to the collector at or near the same time as another cylinder causing excessive backpressure and a lose of power. That doesnt solve the odd fire sequence though. Exhaust gasses dont come from an engine as an even flow but in 8 pulses, 1 from each cylinder. If each cylinder fired at 90 deg then it would be as close to an even flow as possible but this is reality and 7 and 4 are odd fire and when that happens it crowds the collect or the exhaust system and disrupts the scavenging effect.

Also open header usally only make more power up top tq wise but hp will be the same or less, since hp is a relation of tq vs rpm if its making less then it was in the lower rpms(as will an open exhaust since its not scavenging off the other bank) then hp wont increase. Open header is for high rpm and race only since the power band is moved way up the range and is narrowwer than with an exhaust. Exhaust lenghth and diameter plays a huge role in powerband and power production. With an exhaust system of some sort the peak number might not be higher but under the curve and drivabilty will be improved.

Another aspect is when u vary collector length u tune the rpm band and range. Most engine dynos are setup with a 18-26in long collector and they make adjustments from there. Escentially tuning the engine for open header and an rpm range can be done before its in a car, the math has been takin into account and hours of R&D have gone to setup the engine correctly.

5_02ls1

iTrader: (20)

i have about 18" of pipe off the header going into the knock off spiral flows"im wanting to say twisters or somthing"same design though.....im running an lm7 with a really mild h/c setup bout 10:1 CR and at idle and lower rpms the car is really quiet...

my old setup was 2 chambers with an x and it was twice as loud...

Z28/2002

iTrader: (27)

After I get a "fly-by" video of the car with the bullets, I'm going to get the one chambers welded on. I'll post the video when it's done

Codprice

i could not stand my car with turndowns. i have the 3" ebay stainless system with just the baffles in the pipe. Once I cut off the turndowns it sounded amazing. I think they bounced all the drone into the car. now it just shoots out the back. It ends at about the axle, no problem with exhaust inside really. but its not a daily either.