Shorties or Long tube
08-12-2006, 06:57 PM
#31
Hence my response above: To run open exhaust CORRECTLY (like the Pro's do) You need MAD GEAR to make up for the loss in low-end power. Your buddy, with like 4.56's and his stock exhaust vs. his updated exhaust and the taller gears SHOULD be faster with the better flowing exhaust. BUT, I'm sure he doesn't have 4.56's does he?
Proper gearing is CRUCIAL to take advantage of your powerband.........but really is only relevant on a strip-only car. You cannot expect to run 5.xx gears on the street and it be drivable, hell, even 4.56's probably suck on a street car. SO, there is the compromise, which is why 3.73's are so popular.
Its all relative. Back-pressure on a very much street-oriented car, with moderate or stock gearing can be beneficial due to low-end torque production.
Free flowing exhaust is a better thing on a very much track-oriented car because, with proper gear for the power output, the car will be faster with the open exhaust.
Jay Allen, of Camshaft Innovations has run an 11.56 in his full-weight 90 notch with a stock '93 cobra longblock, longtubes, 3.73's, Systemax II intake and one of his cams. The heads were stock GT40's with upgraded valve springs and setup for running stud-mount rockers. No port work, nada. So, you want to talk going fast with stock parts, he's definitely done it.
Now, as soon as you start upgrading the induction package and making the engine a more efficient pump......well, then upgraded exhaust will almost become a necessity in order to make optimal power.
Proper gearing is CRUCIAL to take advantage of your powerband.........but really is only relevant on a strip-only car. You cannot expect to run 5.xx gears on the street and it be drivable, hell, even 4.56's probably suck on a street car. SO, there is the compromise, which is why 3.73's are so popular.
Its all relative. Back-pressure on a very much street-oriented car, with moderate or stock gearing can be beneficial due to low-end torque production.
Free flowing exhaust is a better thing on a very much track-oriented car because, with proper gear for the power output, the car will be faster with the open exhaust.
Jay Allen, of Camshaft Innovations has run an 11.56 in his full-weight 90 notch with a stock '93 cobra longblock, longtubes, 3.73's, Systemax II intake and one of his cams. The heads were stock GT40's with upgraded valve springs and setup for running stud-mount rockers. No port work, nada. So, you want to talk going fast with stock parts, he's definitely done it.
Now, as soon as you start upgrading the induction package and making the engine a more efficient pump......well, then upgraded exhaust will almost become a necessity in order to make optimal power.
08-12-2006, 07:03 PM
#32
CMOC Veteran
Join Date: Oct 2004
Location: Drummondville,Québec
Posts: 272
Originally Posted by bombdigitty
lol..It isnt all about quater mile times....
I dont think this car will ever see a track. I dont want to twist her. Im going more for look and sound. I dont have to etest the car so i went long tubes.
I dont think this car will ever see a track. I dont want to twist her. Im going more for look and sound. I dont have to etest the car so i went long tubes.
08-12-2006, 07:08 PM
#33
true, it means very little. how about some physics then? on a basically stock motor what is important for excavating the exhaust fumes from the combustion chamber is exhaust velocity. when you bolt up a huge set of headers to a stock motor you're gonna lose all the velocity, the combustion chamber won't empty as fast, at least not until the upper rpms when it's producing more exhaust fumes increasing the pressure and the velocity. keep in mind that in the upper rpm range it's not excavating any faster than it would with the stockers, it's doing it about the same. the stockers however are emptying the chamber faster at the low rpms giving you better performance. also, having the bigger exhaust can lead to burnt valves because they aren't getting rid of all the hot gasses.
if you don't believe me do some research, there have been tons of back to back dyno tests proving that in a car making less than 300HP aftermarket headers don't help, and can even hurt performance compared to ported stockers...
if you don't believe me do some research, there have been tons of back to back dyno tests proving that in a car making less than 300HP aftermarket headers don't help, and can even hurt performance compared to ported stockers...
08-12-2006, 07:28 PM
#34
CMOC Veteran
Join Date: Dec 2004
Location: Lidsville, Ontario, Canada
Posts: 407
I have track results from my old 89 LX Notch to back up what Scones said.
It was a bone stock 89 top to bottom longblock, with the usual bolt ons, pullies, a 65mm TB, Cone filter, bored out stock MAF, timing bumped, 3.73s, 2.95 T5, alum DS, headers were stock ones with the welds on the inside hogged out [did this when I did my new clutch], stock H pipe, and straight pipes from the stock H out the back to dynomax stainless tails.. [it sounded nice]. Slicks and skinnies. Car ran 13.11 @ 102.74 MPH and was doing low 1.7s for 60s. Lots of 13.1s all day and ran 102 all day.
I added, full rear suspension with Baseline Suspension adjustable uppers, Pro3i lowers with weight jackers, mac shorites [equals], pacesetter off road X, and a Magnaflow cat back. I was really.. gearing up exhaust wise for the AFR 165s, and intake and cxrap that was to follow.
Anyways same weather conditions, I took the LX back, hoping to squeak into the 12s with my new found tracion and the 15 or so HP I surely would get from the exhaust. Wrong. Car bested a 13.199 and went 102 MPH once and rest of the day was 101 MPH car running 13.20-13.30s @ 101.xx MPH. Prior to the aftermakret exhaust, I was able to cut 1.7s all day leaving between 4500-5000, and with the traction stuff and exhaust, I got ONE 1.79 60 [it got me the 13.19999999] and I had to leave at almost 6000 RPM out of anger.
The car seriously did go slower with the larger exhaust. There have been dryno tests on the past that show no gains switching to a larger header than stock on a STOCK longblock.. on a stocker there is about 15 HP to be had by a better cat back.. It threw both Mike [Scones] and I for a loop, because it "felt" faster when I added the better exhaust parts due to the lack of low end, you could literally feel the motor come on around 3500 and start to pull.. so I thought.. "wow, not a bad gain there.." till I actuall got some times for it on slicks.
IF you are planning big mods like heads/intake/rockers or cam/ etc then by all means buy headers/exhaust then... OR, of you have a power adder... on a stock motor then headers will make huge diffs.. but unless... then the factory headers and even H pipe if its on decent shape is plenty for a 225 HP engine lol..
This was my experience anyways.
It was a bone stock 89 top to bottom longblock, with the usual bolt ons, pullies, a 65mm TB, Cone filter, bored out stock MAF, timing bumped, 3.73s, 2.95 T5, alum DS, headers were stock ones with the welds on the inside hogged out [did this when I did my new clutch], stock H pipe, and straight pipes from the stock H out the back to dynomax stainless tails.. [it sounded nice]. Slicks and skinnies. Car ran 13.11 @ 102.74 MPH and was doing low 1.7s for 60s. Lots of 13.1s all day and ran 102 all day.
I added, full rear suspension with Baseline Suspension adjustable uppers, Pro3i lowers with weight jackers, mac shorites [equals], pacesetter off road X, and a Magnaflow cat back. I was really.. gearing up exhaust wise for the AFR 165s, and intake and cxrap that was to follow.
Anyways same weather conditions, I took the LX back, hoping to squeak into the 12s with my new found tracion and the 15 or so HP I surely would get from the exhaust. Wrong. Car bested a 13.199 and went 102 MPH once and rest of the day was 101 MPH car running 13.20-13.30s @ 101.xx MPH. Prior to the aftermakret exhaust, I was able to cut 1.7s all day leaving between 4500-5000, and with the traction stuff and exhaust, I got ONE 1.79 60 [it got me the 13.19999999] and I had to leave at almost 6000 RPM out of anger.
The car seriously did go slower with the larger exhaust. There have been dryno tests on the past that show no gains switching to a larger header than stock on a STOCK longblock.. on a stocker there is about 15 HP to be had by a better cat back.. It threw both Mike [Scones] and I for a loop, because it "felt" faster when I added the better exhaust parts due to the lack of low end, you could literally feel the motor come on around 3500 and start to pull.. so I thought.. "wow, not a bad gain there.." till I actuall got some times for it on slicks.
IF you are planning big mods like heads/intake/rockers or cam/ etc then by all means buy headers/exhaust then... OR, of you have a power adder... on a stock motor then headers will make huge diffs.. but unless... then the factory headers and even H pipe if its on decent shape is plenty for a 225 HP engine lol..
This was my experience anyways.
08-12-2006, 07:49 PM
#35
A proper set of stepped long-tubes will create more air flow and velocity (due to scavanging) than the stockers. BUT, most aftermarket longtubes aren't stepped. And the stepped ones are much more money.
Velocity is relative to pipe diameter. If you replace your stockers with a set of longtubes with the same diameter of pipe, you aren't decreasing the velocity, because the diameter of the tube that the exhaust is exiting through has remained the same. What you MAY do is increase flow, by the better scavanging characteristics the longtubes have over the shorties, even if not stepped. Thing is, nobody puts a 1 1/2" set of longtubes on their car to compare. Its always like 1 5/8ths and 1 3/4's, which will decrease velocity, since the diameter of the pipe has increased.
Back-pressure would hurt velocity, so, having the stock 4-cat H-pipe isn't helping you by providing increased velocity; the size of the pipe that the exhaust is flowing through is doing that. An off-road H-pipe of the same diameter, would increase flow and maintain better velocity.
Its all relative. Upgrade the pump, and then all of the above changes as well.
Velocity is relative to pipe diameter. If you replace your stockers with a set of longtubes with the same diameter of pipe, you aren't decreasing the velocity, because the diameter of the tube that the exhaust is exiting through has remained the same. What you MAY do is increase flow, by the better scavanging characteristics the longtubes have over the shorties, even if not stepped. Thing is, nobody puts a 1 1/2" set of longtubes on their car to compare. Its always like 1 5/8ths and 1 3/4's, which will decrease velocity, since the diameter of the pipe has increased.
Back-pressure would hurt velocity, so, having the stock 4-cat H-pipe isn't helping you by providing increased velocity; the size of the pipe that the exhaust is flowing through is doing that. An off-road H-pipe of the same diameter, would increase flow and maintain better velocity.
Its all relative. Upgrade the pump, and then all of the above changes as well.
08-12-2006, 07:59 PM
#36
See, that was easy wasn't it?-question answered, pure and simple. you guys could go on forever with this...........seems this site is getting more and more like another site we won't mention..............mine's bigger than yours is.........
08-12-2006, 10:18 PM
#39
Isn't arguing technical theory in a civil manner what the 5.0 Tech forum is all about?
BTW, Overkill - I agree with your last statement whole heartedly. Too bad they don't make 1 1/2 inch long tubes....that'd be neat.
BTW, Overkill - I agree with your last statement whole heartedly. Too bad they don't make 1 1/2 inch long tubes....that'd be neat.
08-12-2006, 11:13 PM
#40
CMOC Rookie
Join Date: Oct 2004
Location: Newcastle, Ontario
Posts: 328
Originally Posted by Stang Illusions 5.0L
considering long tubes are a MUCH better flow then shorties am I not right or what?
Here's a question. What flows more? My 1 3/4 shorties or 1 5/8's long tubes? I have bigger primaries but the LT shoudl have better welocity becaus eof the individual runners.
I bet my shorties flow more and make more horsepower.....but then again we now have to look at an engine entire combo.
