Downpipe

[boostedtsi0069]

Hey guys, well im goin for the first time to the track to see how my baby is doing. Im all stock just hacked maf, bcs restrictor off and momo shift knob(). I have a question, my bolts on the downpipe where they connect to the catalytic are rusted i had to cut the downpipe and was a bit faster but was too loud so i weld it back on, i dont want to cut it off again, but is it safe to disconnect it the downpipe where the o2 housing ends. My oil filter is like right there i dont know if it will burn it up. Also if it aint too much trouble i wanted some opinions on what can i do before sunday to my car so i can get the most power out of her. Im going to do the seafoam thing on saturday but what else. Thanks for your help.

 

[awdtalontsi1992]

Well I personally wouldn't recommend removing the exhaust at the downpipe. The lack of backpressure could actually cause you to loose power. I would recommend just keeping the exhaust on. All those hot gases could cause a overheating problem or could as you said melt the oil filter.

As for power I would recommend a few things. Give your car an fresh oil change. Check the air filter and if it is dirty change it. Run the car down really low on gas and then fill it again with good fresh gas. Check all your vacuum lines to make sure none are cracked and do a boost leak test while you are at it. If you feel up to it you can remove the back seat at the track to save some weight.

 

[boostedtsi0069]

Thanks ill do that. Ill be back monday with the results. Oh and would give rep points but don see the icon.

 

[blackbyrd]

Only mods can leave rep points, it tells you how in rule number 5 at the bottom of each thread.

And no backpressure is not the term you were looking for, awdtalontsi. Nor could it cause you to loose "power"(hp).
"backpressure" is your enemy . Backpressure is resistance/drag inside of a pipe.
When you change pipe diameters you change the velocity of the exhaust gas. Bigger the pipe the less velocity, smaller the pipe the more velocity.
The theory behind the "idea gas velocity", works on the gas pulses out of your head. As gas shoots out one valve and through the pipe it pulls the air behind it, thus creating a vacuum, which would allow the next valves to open easier. Now since it's based on pulse vacuum you have to take into account that it'll make more of a difference at low rpms(torque), as high rpms are a lot more of a constant flow.
And since our turbo is stuck inbetween our head and exhaust it really takes out of the pulse vacuum advantages. IE it makes more of a difference on a N/A. But, the vacuum does effect the internal wastegate operation, and too large of a pipe might cause "boost creep"
It's a struggle to find a happy medium, or idea gas velocity.
Well not really a struggle, plenty of people have been there to tell us what to do.

A lot of us run open downpipe at the tracks. Normally the idea is to run open at the cat, but I've known people to run open at the O2. Just make sure nothings in the way that can get burnt.

http://dsmtuners.com/forums/showthread.php?t=231256&highlight=open+downpipe
http://dsmtuners.com/forums/showthread.php?t=163992&highlight=open+downpipe
http://dsmtuners.com/forums/showthread.php?t=112268&highlight=open+downpipe
http://dsmtuners.com/forums/showthread.php?t=133585&highlight=open+downpipe
Continue searching for "open downpipe" to research more..

Good Luck!

 

[boostedtsi0069]

My friend said that at the track disconnect the bov recirculation hose and cap it and ill run harder because of the extra gas. Is his right, should i try it, i mean ive done it before and it feels faster.

 

[blackbyrd]

I wouldn't on a stock maf. You really need a maf-t or a standalone or something to do that. There's a lot of threads on this.. One of the main FAQ's even : http://www.dsmtuners.com/forums/showthread.php?t=113858

 

[T is for TURBO]

Well I personally wouldn't recommend removing the exhaust at the downpipe. The lack of backpressure could actually cause you to loose power.

Back pressure DOES NOT make our cars loose power....

Read this thread, then when you are done reading it, read it again.
http://www.dsmtuners.com/forums/show...=back+pressure

-Shawn

 

[boostedtsi0069]

I wouldn't on a stock maf. You really need a maf-t or a standalone or something to do that. There's a lot of threads on this.. One of the main FAQ's even : http://www.dsmtuners.com/forums/showthread.php?t=113858

doesnt more fuel mean more power, and dont you get that by taking it off.

 

[PieEyedPiper]

Question 1: No.
Question 2: No, not in any advantageous fashion.

Power isn't about maximizing fuel. It's about the air/fuel ratio. It's all in the tune. If you're not tuned for that extra fuel, and you're not - especially since you only run rich between shifts, just think how hard it would be to tune for an amount of fuel that is never static.
The extra fuel that is being dumped into the cylinders it will slow you down.

 

[oldman]

My friend said that at the track disconnect the bov recirculation hose and cap it and ill run harder because of the extra gas. Is his right, should i try it, i mean ive done it before and it feels faster.

Your friend is an idiot and you shouldn't be listening to him anymore, at least when it comes to modding a car, unless you mis-interpreted what he said.

The biggest issue, besides melting things, is boost creep, if you run with no DP.

 

[blackbyrd]

No it doesn't...
When you vent your BOV to the atmosphere your releasing metered air already introduced in your system. Yes, your car is expecting more air to be there then what actually is, so you end up with more parts per fuel per parts of oxygen. Now remember basic tuning, and the stoich ratio of oxygen to fuel 14.7:1. More fuel does not always mean more power. And in the majority of the cases venting the bov to the atmosphere on a stock maf and bov produces negative results..
http://www.dsmtuners.com/forums/search.php?searchid=2235512
http://www.dsmtuners.com/forums/showthread.php?t=107412&highlight=bov+rich
http://www.dsmtuners.com/forums/search.php?searchid=2235543
http://www.dsmtuners.com/forums/showthread.php?s=&threadid=89000
http://www.dsmtuners.com/forums/showthread.php?t=113858
http://www.dsmtuners.com/forums/search.php?searchid=2235545

EDIT: Too slow, hah.