How to get 14's with your econobox (posted on EFI Live Lounge)

[DaleMX]

Too much work for me.

 

http://forums.vwvortex.com/zerothread?id=776885

[PUSHER]

I knew it was going to be that car from the title, that article has to have been around for about 3 years now.

[660Z]

Years ago Hot Rod magizine did the same thing to a Cadilac with a 472ci or 500 engine. Can`t remember how fast it went, I think it went 11`s maybe early 12`s but it was down to the frame by the end of it all.

 

If someone did that to an early Z I don`t think they would go much faster, since there`s nothing to them to begin with

 

Mark

[savageskaterkid]

Glorified Gokart

[Challenger]

That was a nice car to start. Id start with a cheaper car. Hmmm...

[Gollum]

I'm not exactly sure that car still classifies as a daily drive. I suspect it's not still legal...

[Careless]

funny article but i couldn't justify doing that when there are tons of other jalopies around town that are horrible to have on the road.

 

but i guess thats what makes it funny

[auxilary]

welcome to 2002

[Gollum]

I was just thinking a fun car to do this with would be the SC400/LS400. I bet it could easily hit 13's.

[savageskaterkid]

Lack of back pressure is killing them I'm sure, my civic's muffler rotted off and there is a diffrence of night and day. No backpressure=sucks off the line.

[Gollum]

Lack of back pressure is killing them I'm sure, my civic's muffler rotted off and there is a diffrence of night and day. No backpressure=sucks off the line.

 

I highly suggest you read this:

 

http://www.uucmotorwerks.com/html_product/sue462/backpressuretorquemyth.htm

 

Your comment is borderline heresy. Backpressure alone doesn't create ANY power what so ever. Backpressure from things like tube sizing, bends, and muffles only hurt power and torque in all RPM. Well designed headers and fuel tuning will give you peak exhaust tuning RPM for a given application.

[savageskaterkid]

I know for a fact that lack of backpressure on a stock car(low end stock car) tends to bog. Mine does, its a civic. Maybe not in a BMW or Mercedes that have much more ECU involvement at any givin time then my EG civic, which doesn't do but so much other then a few preset commands. I doubt the sentra in question's ECU is that up to the challenge of fuel tuning stock. Or a stock manifold being used wouldn't be considered a well designed header, do you consider it a header?

 

Not tryin to bash, but even turbo cars lose power from lack of backpressure with a very nice free flowing exhaust. Its usually a 1 hp, or ft/lb loss off idle, but makes up for it much more up top.

 

Look up in some magazines at downpipe installs with a catback, very little power is lost due to lack of backpressure, but the upper RPM results is worth that 1 or 2 ft/lb

[savageskaterkid]

In a civic that probably came with about 8 ft/lbs of torque(kinda sarcastic) when you drop 1, thats a HUGE deal, and forget A/c off the line without my exhaust, even my gas mileage dropped because I have to give it more throttle to move away from a stop light.

[Gollum]

With correct fuel tuning removing back pressure won't loose low end power, I guarentee it.

 

One of the big reasons why on cars like the newer mustangs (especially the new 3 valve) changing exhaust parts looses low end power is that they've lost all the factory scavenging tuning that was done for the lower RPM. Kenne Bell is a big preacher about how he doesn't change exhaust on a 03/04 cobra, or even the new GT500 until he's WELL beyond 600hp, usually around 800hp. The stock exhaust FLOWS that well. And when I say FLOWS I mean has very LITTLE backpressure. Kenne Bell has research papers on his website showing supercharged mustangs at over 500hp with less than 1.5psi backpressure. That's insanely LOW!!! And by the time you get to 3psi in the exhaust, and then remove backpressure he's gaining HP in ALL RPM.

 

 

Remember, backpressure does nothing in reality. The effects of what's causing the backpressure DOES! A header might create backpressure, but it also might be helping the exhaust pulses line up just right to recieve good torque at a lower RPM. Does that mean backpressure is good? No. It means the backpressure is a result of an exhaust designed for a particular RPM.

 

 

I'm just saying your termonology is wrong IMO. I agree that by cutting off the exhaust they would loose some low RPM power, but with the right tuning I'm sure all the power could be recovered.

 

And backpressure on a turbo car?! You're kidding me right? Please explain how backpressure even MIGHT be good for a turbo car? I can maybe understand under certain muffle designs that a certain amount of backpressure migh be required to get the exhaust pulses to resonate just right through it, but in an open exhaust system on a turbo, you want to eliminate as much backpressure as possible.

 

If backpressure was in any way good, we could just use large pipes and crush bend them. But that's not the case. What people do is use the RIGHT sizes pipes for a given RPM range, and then MANDREL bend them for as little back pressure as possible.

[(goldfish)]

Backpressure is always bad. The exhaust system is very dynamic. One arrangement that is good flowing at one rpm does not mean free flowing at a different rpm. The best way to tell is hook up a pressure gage and measure, it's not always obvious.

[savageskaterkid]

With correct fuel tuning removing back pressure won't loose low end power, I guarentee it.

 

And backpressure on a turbo car?! You're kidding me right? Please explain how backpressure even MIGHT be good for a turbo car? I can maybe understand under certain muffle designs that a certain amount of backpressure migh be required to get the exhaust pulses to resonate just right through it, but in an open exhaust system on a turbo, you want to eliminate as much backpressure as possible.

 

 

 

Correct fuel TUNING, it never in the article that it was TUNED. Is a STOCK sentra correctly tuned to run without an exhaust? I don't think so, or is the STOCK sentra a serious race car too? Maybe the ECU compensates fuel and timing when it relises that the exhaust is gone?

 

Didn't say backpressure was good for a turbo car at all, just said that it can negatively effect it. I'm gonna go find one article in particular where they had a full catback(some overly expensive HKS I think) on an SR-240sx. By putting on a downpipe they made (X) power and (X) torque at (X) RPM, but did loose about 1 or 2 ft/lbs off idle. I think the reasoning might be based on your statement saying that diffrent sized exhausts effect diffrent RPM ranges. Maybe the exhaust was causing it to loose torque at low RPMs because the turbo hasn't starting spoiling up enough to build boost yet(ie. still pulling vaccum)

[Gollum]

When were we ever talking about the article specifically? My first post about the topic was directed at your blanet termonology that me, and others here, didn't agree with.

 

Don't take anything that's been said to you as an attack. I'm just trying to set the record straight, backpressure is never a good thing. Period.

 

EDIT: As per HybridZ rules, I think I should rephrase that. I personally believe that on 99% of vehicles out there backpressure alone is never a good thing.

[savageskaterkid]

When were we ever talking about the article specifically? My first post about the topic was directed at your blanet termonology that me, and others here, didn't agree with.

 

Lack of back pressure is killing them I'm sure, my civic's muffler rotted off and there is a diffrence of night and day. No backpressure=sucks off the line.

 

This is where I was talking about backpressure effecting the car in the article, and you went against that. I highly doubt the stock sentra is going to gain alot of power vs. loss of low end torque to even make it worth the while to chop off the exhaust. Maybe I'll try it on the B15 we got, its just a GXE, but maybe worth a shot, no?

[Gollum]

Your last sentence there was a bit of a blanet statement isn't it? You later deffended your statement that backpressure could be a good thing.

 

I'm willing to drop this right now though, as we're not getting anywhere. Sure, in the article they might have lost some low end power, but who knows for certain.