cutout= loss of low end torque
11-04-2007, 09:44 AM
#21
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Here is another example where a cut-out helps. This is a friends dyno tune, he had lid & cut-out ONLY:
....PLEASE TELL ME WHERE THE TORQUE DOWN LOW SUX!
Peace,
Craig.
....PLEASE TELL ME WHERE THE TORQUE DOWN LOW SUX!
Peace,
Craig.
11-10-2007, 03:39 AM
#22
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My cut out made me slower at the track by 2 tenths of a second until i got my car dyno tuned for it at mti and it gave me 5rwhp and 8 rwtq over when my cutout was closed.
11-12-2007, 12:41 PM
#23
Article this month in carcraft or hot rod, forgot which, about how open headers with short collectors give up low and mirange power compared to longer collectors, which act in a similar manner to your ypipes straight 3 inch section. just a thought. open headers are more for show anyway unless you got crap exhaust
11-12-2007, 01:27 PM
#24
I don't think anyone is saying it kills low-end, but it will certainly have an effect on it. The loss of backpressure means you will be allowing a lot more air to pass through the cylinder at lower rpm's when it might be better to have more pressure to keep it in there. On some setups, this can hurt performance. Whether or not it is 1hp or 10hp down low is completely dependent upon the setup.
11-12-2007, 02:32 PM
#25
Tech Resident
Funny, I run slower with it open. My low end took a big hit with it open. I even have mpg loss because of the low end loss. It pushes the torque curve up higher, and that means you'll make less torque way down low. Do you understand that? It may make more torque at WOT on a dyno, but the curve is PUSHED UP. That means upon normal driving when you're not seeing rpm's over 2500, you're going to make less power down low.
Again, my car is .2 slower with the cutout open. I lose 1 mpg with the cutout open. Why? Because I have a stock stall, it's a daily driver and I'm almost completely in the very low rpm's where the cutout hurts performance. I keep it open because I like the noise, not the feel.
Again, my car is .2 slower with the cutout open. I lose 1 mpg with the cutout open. Why? Because I have a stock stall, it's a daily driver and I'm almost completely in the very low rpm's where the cutout hurts performance. I keep it open because I like the noise, not the feel.
But, nothing sounds meaner.
11-12-2007, 03:24 PM
#28
Funny, I run slower with it open. My low end took a big hit with it open. I even have mpg loss because of the low end loss. It pushes the torque curve up higher, and that means you'll make less torque way down low. Do you understand that? It may make more torque at WOT on a dyno, but the curve is PUSHED UP. That means upon normal driving when you're not seeing rpm's over 2500, you're going to make less power down low.
Again, my car is .2 slower with the cutout open. I lose 1 mpg with the cutout open. Why? Because I have a stock stall, it's a daily driver and I'm almost completely in the very low rpm's where the cutout hurts performance. I keep it open because I like the noise, not the feel.
Again, my car is .2 slower with the cutout open. I lose 1 mpg with the cutout open. Why? Because I have a stock stall, it's a daily driver and I'm almost completely in the very low rpm's where the cutout hurts performance. I keep it open because I like the noise, not the feel.
cutout works did back to back runs at the track and dropped my et by .2 and mph when up by 2 mph...try it at the track and you will see...
bottom line cutout works at the track...if you are driving around town keep it closed...hense the whole reason for getting one...the flexibility of it...
11-12-2007, 03:32 PM
#29
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I dunno, I certainly took a hit in the low end. I'd rather drive around with it closed as the car is a bit stronger and more reactive.
I had TTP do back to back dyno pull, 2 closed, 2 open, with the cutout closed I made 10rwtq more than open at top (uncorrected numbers only), on bottom obviously the torque was more with it closed.
This is on B&B triflow and flp longtubes, cam.
I had TTP do back to back dyno pull, 2 closed, 2 open, with the cutout closed I made 10rwtq more than open at top (uncorrected numbers only), on bottom obviously the torque was more with it closed.
This is on B&B triflow and flp longtubes, cam.
11-12-2007, 04:02 PM
#30
Tech Resident
Everyone should. Almost everyone on this site daily drives their car. Around-town performance is extremely important.
Says who? I care way more about around town manners than WOT performance. I rarely go WOT. I drive it around town all the time.
Actually, a cam would probably cause a decent loss in horsepower around town. That's why big cams suck in daily drivers and very few people go big - people care more about around-town performance.
Are you insane? I did go to the track, twice, to see what the cutout would do. It was an average GAIN ON MY ET of .2. My car was significantly slower with the cutout open. Where did you gain your .2 and 2 mph? On a stock exhaust system? I have a Corsa catback that flows very well. The cutout hurt me.
Not in my case. When I ran the car, it had stock 2.73's. It killed me off the line. The cutout's only going to help once I start turning serious RPM's and off a launch with such a high gear like a 2.73, it killed me off the line. This amounted to a significant hurt on my ET.
It ain't rocket science - a cutout over a good catback will push your torque curve up, hurting your low end horsepower. If you have a tall gear like a 2.73, it's gonna hurt you off the line. I've proven this to myself with 5 track runs over the course of 2 days. The cutout hurt.
Says who? I care way more about around town manners than WOT performance. I rarely go WOT. I drive it around town all the time.
It ain't rocket science - a cutout over a good catback will push your torque curve up, hurting your low end horsepower. If you have a tall gear like a 2.73, it's gonna hurt you off the line. I've proven this to myself with 5 track runs over the course of 2 days. The cutout hurt.
11-12-2007, 04:07 PM
#31
TECH Fanatic
11-12-2007, 04:25 PM
#32
Cutouts have always helped me. Had one on my 95 Z28, 99 Z28 and now the SS. I trapped over 1 mph higher at the track with it open. My exhaust flows very well too. Around town I don't notice the difference anyway. Choco you must have one sensitive ***.
11-12-2007, 04:42 PM
#33
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i just put cutouts on my car today and it dont really feel much different but i agree with that one guy it feels a bit slower on the bottem but feels a bit stonger on the top end. i dont know maybe my 4.10 gear is messin with me lol
11-12-2007, 04:49 PM
#34
that dyno graph is cute, really. BUT as previously mentioned, the loss of torque occurs in the daily driving range (for an stock-stalled not cammed a4 that's about 500 to 2000 rpm, less for an m6). this graph STARTS at 2k rpms...therefore proving nothing about what we've been discussing here.
11-12-2007, 05:44 PM
#35
Tech Resident
As much of the SOTP feel changed, it changed even more at the track. Cutout open = slower ET's every time.
11-12-2007, 05:46 PM
#36
Tech Resident
that dyno graph is cute, really. BUT as previously mentioned, the loss of torque occurs in the daily driving range (for an stock-stalled not cammed a4 that's about 500 to 2000 rpm, less for an m6). this graph STARTS at 2k rpms...therefore proving nothing about what we've been discussing here.
It's great that he posted up a dyno chart, but what is it compared to? For all we know, it could make 10 hp more at 2,000 rpm's with the cutout closed. He just posted up a random *** graph with absolutely no benchmark to compare it to, which is why his argument is pure bullshit and the numbers mean nothing at all.
11-12-2007, 08:19 PM
#37
Slower Et's for you, not for me. All of my previous Fbodys and my recent one ran faster with the cutout open vs. closed. I notice nothing on the street just putting around. Only thing I notice is the sound, and pissing people off on the street with a loud car is fun (not that pissing people off as any relevance to this discussion, haha). At the track I want the most power. I open the cutout for that. I could care less about 5 ft/lbs of torque lost at 2000 RPM. I am never in that range after I take off anyway. The RPMS are always way up when running down the track. People have posted an increase in track times and power numbers with them open. I am a firm believer that cutouts are beneficial.
11-13-2007, 10:49 AM
#38
yes i do agree with you the gain over a good catback already installed wont be much but over a stock exhaust...or in your case losing 2mph or 2 tenths...
yes around town you might see a loss in torque, but then again why get an electric cutout if you are always going to leave it open...just use it at the track...
whats next a lid or maybe skinnies also hurt your ets too because for some reason your p.o.s. cant run so it must be true for everyone else...you are in the minority and your ingorance proves that with each post...
My offer is still on the table if you got the ***** to take it...any amount of money...or better yet if you are wrong never post on this site again...i think people would rather see that more than anything...
11-13-2007, 12:06 PM
#40
Not in my case. When I ran the car, it had stock 2.73's. It killed me off the line. The cutout's only going to help once I start turning serious RPM's and off a launch with such a high gear like a 2.73, it killed me off the line. This amounted to a significant hurt on my ET.
It ain't rocket science - a cutout over a good catback will push your torque curve up, hurting your low end horsepower. If you have a tall gear like a 2.73, it's gonna hurt you off the line. I've proven this to myself with 5 track runs over the course of 2 days. The cutout hurt.
It ain't rocket science - a cutout over a good catback will push your torque curve up, hurting your low end horsepower. If you have a tall gear like a 2.73, it's gonna hurt you off the line. I've proven this to myself with 5 track runs over the course of 2 days. The cutout hurt.
Galen