my car is UNBELIEVABLY slow of the start but once i get up to 25-30 i can gas it and your head will be thrown back into the seat... WHATS THE DEAL i need this fixed if i am going to be racing anyone. i've got a lot of new parts also

Blue Streak Cap and Rotor
Fuel Filter
Plugs/Wires *accel and ac delco*
Hypertech Chip
New K&n with 3" intake
basically all the mods listed on my sig
NO muffler though *could that really slow me down of the start?*

 

no answers huh

 

with no muffler you proabbly arent getting enough back pressure, and the reason it seems to through you back once you are moving, is because it gears down and takes off...

 

you're gonna be needing some torque to get you off the line, reason a complete exhaust system is necessary. with some big v8, if you were running a single exhaust (like we all have) w/o a muffler you might be ok, cause the pipes would give enough restriction to provide the low end torque you need, however with a six that really doesn't need to breath out nearly as much gas i'd be thinking that you're probably overdoing it, and should get a nice muffler to put on....no muffler = good excuse to buy that flowmaster you've alwayz wanted.

 

Agreed; with no muffler to lower backpressure, your exhaust gasses are probably building up in the pipe, and choking the engine.

Also go over everything in the major tuneup list, including all the cleaning and adjustments; if you think you've done a major tuneup, then give your new parts a check-over.

 

i knew that had to be a problem, i'll do that in about too months since i have to finish the body and am trying to get a ws6 ram air hood.
Things iv'e done to the car, for tune up has been alot
New gear oil, synthetic
Change Oil every 2,000, synthetic
K&n Intake
New tranny fluid/ filter
Flushed coolant... blah blah blah
Two things i need to redo is timing and minum air, haven't had the time lately working on the body of the car. Should be putting on a used door pretty soon. Thanks for the replies

 

ahh... more backpressure nonsense.

You want your car to be faster? Automatic, right?

I'll bet you anything you want, you'll get move much faster with a ~2400 stall convertor. You're making more power with no muffler (AND LESS BACKPRESSURE) the problem is, the powerband is shifted higher, and you have less torque down low (but much more slightly higher up - hence the 'throw your neck back' once the rpms get up)

With a higher stall convertor, you will rev higher into your powerband, before the tranny 'catches' and you take off. If backpressure were such a good thing, why do all the REALLY fast guys at the track run open headers? :lala:

Also, a bump in timing will help you out, as well... push her up to around 12-14 BTDC - and watch for detonation!

 

Hey- I never said he wanted backpressure.

I told him to put a muffler on to reduce backpressure, to increase the scavanging effect.

 

From a muffler? He's running no muffler now, isn't he? I can't see how you can place anything in the way of the airflow, and increase the flow through it. ANY muffler will create backpressure - it's just a matter of how much.

 

You'd think so, right? But that's where exhaust engineering comes in, and how places like Flowmaster and Dynomax are in business. A performance muffler increases the scavenging effect. A stock muffler won't.

For open pipes to work, they have to be as short as possible to the engine to prevent the buildup of exhaust gas. I ran with no muffler while I waited for my first Dynomax system to come in the mail; the car was a dog.

But 1986CamaroSC, you never "want" backpressure. You said he needs some; the truth is, he's got way too much right now.

If you've got Excel on your computer, go here for one of the "classic" charts: http://www.mattrandolph.com/wrx/Muff...o-shootout.xls

If you don't have Excel, google.com can help, http://216.239.33.104/search?q=cache...hl=en&ie=UTF-8 click here for a messy excel-converted page</a>.

 

chart helps out alot, bassani doesn't make a catback for our cars do they? because just a muffler wont reap the benefits of a full catback.

 

I don't know if Bassani has a catback for our cars... I'd doubt it, though.

I've already redone the entire exhaust from the manifolds, through the turbo, the downpipe, no cat, then stock from the back of the 'cat pipe' back. Won't be a problem to run a 3" mandrel bent setup back, into a custom bassani, and out....

Check the 'Free Gloves with a Dynomax' post to see some quarter mile numbers and such with various mufflers.

 

Oh yeah - Tom... actually, places like Dynomax and Flowmaster are in business because while the mufflers DO flow better than stock (headers scavenge, mufflers don't - they just don't *block* the exhaust as badly as stock), 90% of people buy them for the sound. Why does everyone want exhaust clips? Because on a street driven car, most don't care how much hp they free up - only that they have freed up some, and it now sounds MUCH better.

 

The best comparison is to test each change to the vehicle individually, and not off of someone elses chart claims. Those charts are generally from a motor and drivetrain setup entirely different than what you are running. It is determined solely off of your cam profile whether you are running a lowend torque motor or a topend race motor. Top end performance will suffer from ANY restriction.

Here's the catch- On a street car such as ours, we run an extremely long catback system. In the length of this exhaust system, gasses will cool and slow down causing restriction. This is why you dont want too big OR too small (too small will not flow adequately of course) of an exhaust pipe diameter. And, you don't want an exhaust that is too long and not properly balanced. Often when you just cut off the muffler (in the case of our third gens with the muffler all the way in the rear) The exhaust will lose "heat" form the large muffler chamber. At low rpm's(when exhaust gasses are slow) they will cool and restrict slightly.same thing happens when you remove the cat entirely, the heat of the cat (whether it a high flow or stock) will keep the exhaust hotter going to the rear of the car and promote better flow over a distance.

Are motors are not a large enough displacemant to ever worry about this muffler performing better than that muffler. There is not a muffler on the market that will not work well on any 3L motor at any performance level.

 

Doward, that link you posted ( http://www.boyleworks.com/ta400/psp/exhaust.html ) has one problem regarding this discussion. Unless I read the tests wrong, they compared cat-back systems to open headers.

Sure open headers will give you more power, but it doesn't help here, because to get that on our cars, you'd have to remove the whole exhaust system - all the pipes - except for the manifolds. And then you'd cook everything under the hood, get pulled over daily, and probably fall asleep at the wheel from all the carbon monoxide pouring into the passenger area.