Poor peformance after mods, help - Page 2 - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


2000-2005 Discuss your 2000-2005 Bonneville SE, SLE, and SSEi Please use General Chat for non-mechanical issues, and Performance and Brainstorming for improvements.

Reply
 
 
 
Thread Tools Search this Thread
Old 08-18-2004, 01:27 PM   #11
Senior Member
True Car Nut
 
Join Date: May 2003
Posts: 7,262
Thanks: 0
Thanked 0 Times in 0 Posts
ssesc93 is on a distinguished road
Default

if all else fails, show your mods the pic of your avatar, that should get them to act right
ssesc93 is offline   Reply With Quote
Old 08-27-2004, 04:39 PM   #12
Senior Member
Certified GM nut
 
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Thanks: 0
Thanked 0 Times in 0 Posts
DrJay is on a distinguished road
Default

Quote:
Originally Posted by Foghorn
Quote:
Originally Posted by DrJay
No engine works better with backpressure. Read that twice if you need to. Backpressure only makes the engine work harder to get the exhaust out.
I think that statement is only true if you put it in the proper context - less backpressure works best at WOT runs such as 1/4 mile acceleration.

Quote:
Originally Posted by DrJay
What you're experiencing when you make your exhaust too large is a combination of two things. One is that (as most of you may know) the exhaust from one cylinder actually pulls exhaust from the next.
Cylinder scavenging is an important component in achieving volumetric efficiency. At low rpm, or part throttle, if there is little or low backpressure, you're not going to exhaust suffiently well enough because of low volicity. By using the pulse and pressure difference of other cylinders, the velocity can be maximised therefore allowing more complete exhaust of spent gas front the cylinder and a better intake charge - this accomplishes better volumetric efficiency and gives better throttle response.

Since most of us drive our cars under a variety of load conditions, it'* neither correct to say you need a lot of backpressure nor to say backpressure is your enemy. If you want only to maximise the performance of your car for one driving conditon, like WOT, then you could optimise the exhaust for that condition only whereby you'd want little backpressure. On the other hand, if you rarely went WOT and wanted better drivability and throttle response around town, then you'll need backpressure but you'll suffer at the track.

Like many things, backpressure is a comprise condition in response to a variety of demands we put on the engine to respond under loads.

Hope this makes sense...

Cheers,
Man, I thought I killed this thread till I mentioned it in another one and got motivated to read it again. Strange I don't get emails sometimes.

Blah ok, well I'm saving my typing fingers for the other thread ("Give your supercharger what it wants" : good debate so far, join in) so I'll make a quick comment and suggest some 'good reading' for the time being.

I'd really suggest people go to google.com type in "Backpressure myth" and see what they come up with. Here is an exampleto get you started:

http://www.uucmotorwerks.com/html_pr...torquemyth.htm
DrJay is offline   Reply With Quote
Old 09-02-2004, 10:45 PM   #13
Senior Member
Certified GM nut
 
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Thanks: 0
Thanked 0 Times in 0 Posts
DrJay is on a distinguished road
Default

Two sausages are cooking in a pan. One says, "Man its hot in here!" The other one says, "AHHH A TALKING SAUSAGE!!"
DrJay is offline   Reply With Quote
Old 09-10-2004, 01:21 AM   #14
Senior Member
Posts like a Camaro
 
Join Date: May 2004
Location: Columbia, MO
Posts: 963
Thanks: 0
Thanked 0 Times in 0 Posts
BonEvilSSEi is on a distinguished road
Default

Nitrous is kinda like a hot chick with an STD you really wanna hit it but youre afraid of the consequences!
BonEvilSSEi is offline   Reply With Quote
Old 09-10-2004, 01:25 AM   #15
Senior Member
Posts like a Camaro
 
Join Date: May 2004
Location: Columbia, MO
Posts: 963
Thanks: 0
Thanked 0 Times in 0 Posts
BonEvilSSEi is on a distinguished road
Default

LOL...anyways back on topic...When I got my 2.5inch cat back on my 95 SSEi I immediately noticed a lot less off the line punch but at the time the only other mod I had was a K&N cone stuck on the end of my intake mani...(bad idea I dont suggest it) and after I got the rest of my mods the car feels better than ever before...so what does that meen...buck up the 75 bucks and get a pulley!
BonEvilSSEi is offline   Reply With Quote
Old 09-10-2004, 08:51 PM   #16
Senior Member
Certified GM nut
 
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Thanks: 0
Thanked 0 Times in 0 Posts
DrJay is on a distinguished road
Default

haha yeah the smaller pulley is well worth it I'd say. Between it and the filter its like I put another engine in the trunk.

Has anyone looked into the backpressure thing any? The octane thing is done (I think) so I'd like to hash this out if anyone is into it....if not oh well
DrJay is offline   Reply With Quote
Old 09-10-2004, 09:01 PM   #17
Senior Member
Posts like a Camaro
 
Join Date: May 2004
Location: Columbia, MO
Posts: 963
Thanks: 0
Thanked 0 Times in 0 Posts
BonEvilSSEi is on a distinguished road
Default

Quote:
Originally Posted by DrJay
haha yeah the smaller pulley is well worth it I'd say. Between it and the filter its like I put another engine in the trunk.

Has anyone looked into the backpressure thing any? The octane thing is done (I think) so I'd like to hash this out if anyone is into it....if not oh well

LOL DrJay are you a lawyer???....cause you sure like to debate!!!
BonEvilSSEi is offline   Reply With Quote
Old 09-10-2004, 09:05 PM   #18
Senior Member
Certified GM nut
 
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Thanks: 0
Thanked 0 Times in 0 Posts
DrJay is on a distinguished road
Default

I've been told I should be

My deal isn't so much with debates, which I do enjoy...If I'm right! haha
I've just been doing a lot of research and come across a few myths that I feel people should be aware of. At least I believe they are, if I'm wrong I'm wrong but with that I realize that it will take nothing less than a debate to convince people. Hell the octane thing took 6 pages to quell.
DrJay is offline   Reply With Quote
Old 09-10-2004, 09:13 PM   #19
Senior Member
Posts like a Camaro
 
Join Date: May 2004
Location: Columbia, MO
Posts: 963
Thanks: 0
Thanked 0 Times in 0 Posts
BonEvilSSEi is on a distinguished road
Default

Quote:
Originally Posted by DrJay
I've been told I should be

My deal isn't so much with debates, which I do enjoy...If I'm right! haha
I've just been doing a lot of research and come across a few myths that I feel people should be aware of. At least I believe they are, if I'm wrong I'm wrong but with that I realize that it will take nothing less than a debate to convince people. Hell the octane thing took 6 pages to quell.
Ah maby then you should join up with the Discovery channel and those Mythbusters guys LOL
But I do agree sometimes it takes a good debate to squash the myths....by the way ill never use anything but 91+ octane in my cars......I dont care if I can get away with it or not!
BonEvilSSEi is offline   Reply With Quote
Old 09-10-2004, 09:15 PM   #20
Senior Member
Certified GM nut
 
Join Date: Feb 2003
Location: Georgia
Posts: 2,095
Thanks: 0
Thanked 0 Times in 0 Posts
DrJay is on a distinguished road
Default

Heey I'm not out to convince anyone to use less...but if any of your buddies start talking about how you'll destroy your engine with it you can say "If your sensors are in proper working order, no you won't....BUT <insert personal paranoid thoughts here>... haha :P
DrJay is offline   Reply With Quote
 
 
Reply

Related Topics
Thread Thread Starter Forum Replies Last Post
Poor, Poor GTP!(now with before pics) sse1990 Lounge 22 07-07-2004 01:19 PM
Look at my poor poor trunk, what's wrong with this? TaylorD General GM Chat 19 03-20-2004 08:54 PM
that poor poor neon...like i care! SSEimatt93 Lounge 4 10-22-2003 03:48 PM
poor poor civic LOL SSEimatt93 General GM Chat 6 05-12-2003 11:05 AM
Poor Poor Hollywood :( Tamara 1992-1999 3 11-17-2002 07:28 PM


Thread Tools Search this Thread
Search this Thread:

Advanced Search

Posting Rules
You may not post new threads
You may not post replies
You may not post attachments
You may not edit your posts

BB code is On
Smilies are On
[IMG] code is On
HTML code is Off
Trackbacks are Off
Pingbacks are Off
Refbacks are Off



All times are GMT -4. The time now is 11:39 PM.


We are a participant in the Amazon Services LLC Associates Program, an affiliate advertising program designed to provide a means for us to earn fees by linking to Amazon.com and affiliated sites.