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01-10-2007, 01:20 PM | #55 |
Drives: Nissan NX2000 Join Date: Nov 2006
Location: Canada
Posts: 12
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Right, but it is important to know what final drive is and how a transmission works.
According to chinocharles, the engine's power goes through 4th gear, the speed is multiplied by 0.9xx and that's it. This is not correct. The power goes through the clutch to the input shaft, then through a gearset to the output shaft. This gearset is different for every gear. The output shaft then travels through the differential, which reduces the engine's speed once again. Most final drives are in the 4:1 range. So if your first gear ratio is 3:1 and the final drive ratio is 4:1, the wheels are actually travelling 1/12 the speed of the engine. If your fourth gear is 0.9:1 and the final drive is 4:1, the engine is still travelling 3.6 times faster than the wheels. The assumption that you have to dyno in the gear closest to 1:1 is false, since the power is going through a final drive, the wheel speed will never be close to the engine speed. If your dyno guy is telling you this, he is wrong. Just because you own and operate a dyno does not mean you know the science behind how a dyno works. At a dyno I went to, the operator did not even know the fundamental relationship between horsepower, torque and RPM which is HP=(Tq*RPM)/5252. |
01-10-2007, 01:20 PM | #56 |
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I will definitely be going back to the dyno to retest the header. Right now my car is stock, as I have the header off to save me some work when I do go back. If the pulley is delivered before the dyno is fixed, I will be testing that too.
Since the dyno was just reading heavy, I am looking at the graphs now and thinking that if you reduce the numbers by about 25% it should be somewhat accurate. Knowing that, the header does so little on its own that I don't see much of a point in testing the car with the stock header and pulley. Whatever the pulley does with the Megan header on is going to be on par with what it does with the stock header, and that saves me having to put the car on the lift twice. |
01-10-2007, 01:25 PM | #57 | |
Drives: Nissan NX2000 Join Date: Nov 2006
Location: Canada
Posts: 12
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Quote:
I am not the typical Yaris owner. I have been involved with cars for more than two decades. I race Nissan NX2000s, I build our motors which make 270hp from 2160cc. Before that I was a race mechanic on a Formula BMW that my brother raced. I just happen to be an environmentally responsible consumer, and consequently have an interest in Yarii. I'm on this site to find out about what is available for this car and what others have done. Heres a pic of my racecar |
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01-10-2007, 01:32 PM | #58 | |
l33t3st Asshole
Drives: MY07 Yaris Liftback Join Date: Nov 2006
Location: Epcot
Posts: 588
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Quote:
wouldn't it make more sense to just buy a header that makes real power instead of trying to cover an open wound with a bandaid? you're claiming 10hp from a pulley right? |
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01-10-2007, 01:34 PM | #59 | ||
Drives: Polar White Hatch Join Date: Nov 2006
Location: chicago
Posts: 407
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A quick google search.
http://www.awe-tuning.com/pages/faq/...ain.cfm?FAQ=22 Quote:
Quote:
There is dozens more hits that back up that being close to 1:1 is important.
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01-10-2007, 01:37 PM | #60 | |
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Quote:
When did I say that? Let me make the font bigger so you can read it. My dyno tech told me that we need to test the car in a gear with a ratio as close to 1:1 as possible. I don't even know enough about engines to say what you quoted me as saying, so please, don't put words in my mouth. I edited the rest out because acrbill was nice enough to quote those pages for me. I knew I had read articles online backing up my tech's statements, but I couldn't find them again, so thank you Bill. |
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01-10-2007, 01:41 PM | #61 | |
Drives: Polar White Hatch Join Date: Nov 2006
Location: chicago
Posts: 407
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Quote:
Your obviously full of shit, and you thought you could come onto a site and pull the wool over our eyes with your supreme knowledge of all things automotive. What you failed to realize is that we are not little kids enamored with pictures of "race cars". Do everyone a favor and buy a Honda Fit.
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01-10-2007, 01:44 PM | #62 | |
Drives: Nissan NX2000 Join Date: Nov 2006
Location: Canada
Posts: 12
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Quote:
Here, check out the flat earth society's webpage: http://www.alaska.net/~clund/e_djubl...rthsociety.htm |
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01-10-2007, 01:45 PM | #63 | |
Drives: Nissan NX2000 Join Date: Nov 2006
Location: Canada
Posts: 12
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Quote:
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01-10-2007, 01:47 PM | #64 |
Break'em off some.
Drives: 07 Yaris LB, 04 Cobra Join Date: Jan 2007
Location: So Cal, OC
Posts: 854
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01-10-2007, 01:51 PM | #65 | |
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Quote:
I don't see that as a huge tradeoff considering... 1) This is still an N/A car, and the 2.5" diameter piping on the Megan header will probably do more for the car with forced induction. 3) After 5600 RPM I'm gaining more than what I'm losing in the rest of the powerband. Sure, my lofty hopes got shot down a tad. Lesson learned... when dealing with low displacement econoengines, don't expect much from simple bolt-ons. 10 HP from the pulley... I'm not that dumb, haha. Judging from what I've seen from the dyno results from other cars, I think 2-3 HP is a good estimate. Considering the piece is a tad over a hundred bucks and you see that 2-3 HP from 0 to 6500 RPM, I'm happy NST decided to make it. |
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01-10-2007, 01:53 PM | #66 |
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+8 to the first person that finds out the final drive ratio for the NCP91.
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01-10-2007, 02:08 PM | #67 |
Break'em off some.
Drives: 07 Yaris LB, 04 Cobra Join Date: Jan 2007
Location: So Cal, OC
Posts: 854
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Here are the transmission ratios for the 5MT
Manual five-speed transmission with shift lever on floor, 3.545:1 first gear ratio, 1.904:1 second gear ratio, 1.31:1 third gear ratio, 0.969:1 fourth gear ratio, 0.815:1 fifth gear ratio 3.25:1 reverse gear ratio manual Final drive ratio, 3.941:1 |
01-10-2007, 02:10 PM | #68 |
Drives: Polar White Hatch Join Date: Nov 2006
Location: chicago
Posts: 407
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tree'd
1st-3.545:1 2nd-1.904:1 3rd-1.31:1 4th-0.969:1 5th-0.815:1 final drive-3.722:1 reverse-3.25:1
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01-10-2007, 02:14 PM | #69 | |
Break'em off some.
Drives: 07 Yaris LB, 04 Cobra Join Date: Jan 2007
Location: So Cal, OC
Posts: 854
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Quote:
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01-10-2007, 02:17 PM | #70 |
Break'em off some.
Drives: 07 Yaris LB, 04 Cobra Join Date: Jan 2007
Location: So Cal, OC
Posts: 854
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Not saying you are wrong, but we found different final drive #s. I got mine off some canadian site. Where did you get yours? Just want to clear it up so we aren't posting misinformation.
We could figure it out mathamatically I guess but I'm too lazy, and don't have a car to veryify it yet :) |
01-10-2007, 02:18 PM | #71 |
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largeorangefont, +8. I don't know what the points means either... you'll have to ask Bigsky2. I got it from him.
To get an idea of how widely these ratios vary, a Cadillac STS-V's final drive ratio is 2.56:1. I wanted to assume most cars had a final drive ratio near 4, but that would obviously be wrong. Now that we know this, fastnx... what the hell was your original arguement? It seemed like you were trying to say that the idea behind a dyno is to get the engine speed to match wheel speed, but there is no gear on a Yaris that comes even close to this. The closest you will come is in fifth when your ratio is 3.212:1. I'm trying to understand where you were coming from. |
01-10-2007, 02:22 PM | #72 | |
Break'em off some.
Drives: 07 Yaris LB, 04 Cobra Join Date: Jan 2007
Location: So Cal, OC
Posts: 854
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Quote:
My mustang has a 3.55 final drive, and a 6 speed transmission and at 80 MPH it is doing 2200 RPM. A Xa I test drove was doing well over 3000 RPM approaching 80 MPH. I will explain more about how a dyno works and how gearing can affect the results after I get some lunch. Last edited by largeorangefont; 01-10-2007 at 05:50 PM. |
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