US Manifold vs MEVI dyno results
01-09-2003, 10:49 AM
#41
Originally posted by Y2KevSE
So you're interested in the VI? :nod What changed your mind?
So you're interested in the VI? :nod What changed your mind?
its getting a VSLD tranny in two weeks 
yes it is currently a 5spd 
01-09-2003, 11:43 AM
#43
Originally posted by Ramius83
BTW, where and how much did you find a VLSD ??
BTW, where and how much did you find a VLSD ??
01-09-2003, 11:49 AM
#44
Originally posted by SteVTEC
I'm just presenting the other side of the story so that people understand what they're losing before spending $650 on the MEVI. Maybe they're like me where you can never get your car up to higher speeds, and that $650 would be much better spent on other mods ;-)
I'm just presenting the other side of the story so that people understand what they're losing before spending $650 on the MEVI. Maybe they're like me where you can never get your car up to higher speeds, and that $650 would be much better spent on other mods ;-)
02-21-2004, 06:17 PM
#45
Originally Posted by SteVTEC
j_bryan, thanks for the writeup! More data 
Nothing. Unless you're above 5500rpm, the MEVI is actually going to HURT your performance.
Nothing. Unless you're above 5500rpm, the MEVI is actually going to HURT your performance.
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Am I missing something? Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
02-21-2004, 06:32 PM
#46
Donating Maxima.org Member
Join Date: Dec 2002
Posts: 2,749
Originally Posted by Spaniard
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Am I missing something? Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
You brought this year old thread back why exactly?
Eric
02-21-2004, 06:48 PM
#47
Originally Posted by 99Maxima5sp
You brought this year old thread back why exactly?
Eric
Eric
Because of the question that occurred to me as I was reading this old thread...
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
02-21-2004, 07:14 PM
#48
Originally Posted by Spaniard
Because of the question that occurred to me as I was reading this old thread...
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
Of course there's a benefit to staying in the lower gears. The gear ratios are lower (or higher depending upon if you are talking numerically or size-wise). Think about First gear compared to 5th gear. Your engine has the same HP and Torque whether you are in first gear or 5th gear, but you accelerate (that is, your velocity changes at a greater rate) in 1st gear than it does in 5th gear because of the torque multiplication through the transmission.
02-21-2004, 07:18 PM
#49
Originally Posted by Spaniard
Because of the question that occurred to me as I was reading this old thread...
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... Is there a benefit to staying in lower gears (e.g. 3rd gear up to 7000 RPM) vs absolutely staying in the torque-ey-est part of the RPM range? It does feel like the car pulls harder in 3rd up to 6000 even though the dyno says I get more power by shifting into 4th gear and dropping down to 4000 RPM. Maybe theres something beneficial to lower gearing and higher RPMs??? Something tells me theres a piece to this that I havent learned about...
A VQ with MEVI, mod for mod, will not pull as hard period as an USIM because it's peak twisting force is reduced. But because the MEVI'd VQ can pull for longer in the RPM range and will do more work over time in a given gear it will be faster in all out racing...
You would have to be making MUCH MORE TORQUE than a MEVI'd engine to be able to get away with short shifting at 5500 RPM...MUCH more torque...Which goes beyond the realm of N/A mods...
02-21-2004, 07:33 PM
#50
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Yup, it's because of gearing as Neal stated. Here's a quick example.
Take a stock 4th gen at 80 mph in 3rd gear. At this point you're at about 5500 rpm and well into the downward slope of the torque curve. Shifting to 4th at this point would put you back in the meatier part of the torque curve, but since it's a higher gear ratio your overall torque at the wheels is still less and it's not quite time to shift yet.
80mph/3rd: 5500rpm, 151 wtq x 1.272 (3rd) x 3.82 (final) = 733.7 wtq
80mph/4th: 4100rpm, 168 wtq x 0.954 (4th) x 3.82 (final) = 612.2 wtq
Even though you have more crank torque in 4th at that point, you still have more overall wheel torque in 3rd due to gearing, so it's not time to shift yet.
As it turns out, the optimal 3-4 shift point on a stock 4g is about 90 mph and roughly 6100 rpm.
The MEVI hold the torque curve a lot flatter ala Honda VTEC style, so the torque curve never drops enough to require shifting to the next gear before redline. Optimal shift points on the MEVI are just before the rev-limiter kicks in.
Take a stock 4th gen at 80 mph in 3rd gear. At this point you're at about 5500 rpm and well into the downward slope of the torque curve. Shifting to 4th at this point would put you back in the meatier part of the torque curve, but since it's a higher gear ratio your overall torque at the wheels is still less and it's not quite time to shift yet.
80mph/3rd: 5500rpm, 151 wtq x 1.272 (3rd) x 3.82 (final) = 733.7 wtq
80mph/4th: 4100rpm, 168 wtq x 0.954 (4th) x 3.82 (final) = 612.2 wtq
Even though you have more crank torque in 4th at that point, you still have more overall wheel torque in 3rd due to gearing, so it's not time to shift yet.
As it turns out, the optimal 3-4 shift point on a stock 4g is about 90 mph and roughly 6100 rpm.The MEVI hold the torque curve a lot flatter ala Honda VTEC style, so the torque curve never drops enough to require shifting to the next gear before redline. Optimal shift points on the MEVI are just before the rev-limiter kicks in.
02-21-2004, 07:36 PM
#51
Not DAVEB the parts guy
Join Date: Aug 2000
Posts: 8,555
[QUOTE=Spaniard]Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve... [QUOTE]
Yes, that is why it's mandatory to have the extended redline of the JWT ECU when you have the MEVI. The extra 500-700rpms allows you to stay in the correct portion of the powerband. With the JWT ECU, you also get back ALL the HP/TQ you lost with the MEVI. When I shift at 7000rpms I land into 2nd at ~4800rpms and 3rd at 5000rpms. It's a blast.
Dave
Yes, that is why it's mandatory to have the extended redline of the JWT ECU when you have the MEVI. The extra 500-700rpms allows you to stay in the correct portion of the powerband. With the JWT ECU, you also get back ALL the HP/TQ you lost with the MEVI. When I shift at 7000rpms I land into 2nd at ~4800rpms and 3rd at 5000rpms. It's a blast.
Dave
02-21-2004, 08:08 PM
#52
[QUOTE=Dave B][QUOTE=Spaniard]Looking at this plot, it seems to me that you would have a faster car if you just stayed in the midrange- that is shifted at 5500 RPM and rode the higher (red) curve...
Yes, that is why it's mandatory to have the extended redline of the JWT ECU when you have the MEVI. The extra 500-700rpms allows you to stay in the correct portion of the powerband. With the JWT ECU, you also get back ALL the HP/TQ you lost with the MEVI. When I shift at 7000rpms I land into 2nd at ~4800rpms and 3rd at 5000rpms. It's a blast.
Dave
I ordered my JWT ECU last week. Looking forward to getting the most out of my MEVI.
Yes, that is why it's mandatory to have the extended redline of the JWT ECU when you have the MEVI. The extra 500-700rpms allows you to stay in the correct portion of the powerband. With the JWT ECU, you also get back ALL the HP/TQ you lost with the MEVI. When I shift at 7000rpms I land into 2nd at ~4800rpms and 3rd at 5000rpms. It's a blast.
Dave
02-21-2004, 09:09 PM
#53
Originally Posted by SteVTEC
80mph/3rd: 5500rpm, 151 wtq x 1.272 (3rd) x 3.82 (final) = 733.7 wtq
80mph/4th: 4100rpm, 168 wtq x 0.954 (4th) x 3.82 (final) = 612.2 wtq
Even though you have more crank torque in 4th at that point, you still have more overall wheel torque in 3rd due to gearing, so it's not time to shift yet.
As it turns out, the optimal 3-4 shift point on a stock 4g is about 90 mph and roughly 6100 rpm.
02-22-2004, 06:44 AM
#54
Well if you have an auto you know when first gear chnaged at redline it comes back to 4000 rpms in secodn gear that is almost right back into MEVI range and second gear it is even higher. I think this would benifit autos alot.
02-22-2004, 05:42 PM
#55
dam, this is very depressing. Well, now i definitely have to get an ECU. I felt weaker but i always thought my driving got worst or something. But its not as bad as everyone says it is. i've had VI for likst 2 months but for past week car feels weaker...not sure if VI just settled, bad ecu's, knock finally dieing on me...
all i hope is that with increase low end power from jWT ecu (not rev limit), i stay as strong as stock manifold if not a little stronger, then i also have potential to be WAY faster as i increase rpm
all i hope is that with increase low end power from jWT ecu (not rev limit), i stay as strong as stock manifold if not a little stronger, then i also have potential to be WAY faster as i increase rpm
02-22-2004, 06:18 PM
#56
So will someone answer me this. I've always had this question in my head, but no one has ever addressed it very clearly:
Will a MEVI w/ a JWT ECU (including raised rev limiter) allow you to have the same numbers as stock PLUS added power? It just seems to me that I've heard back and forth that even with an upgraded ECU there's still loss of power somewhere in the powerband...is this true?
Because I wouldn't want to get a MEVI if I was going to lose any more than a couple WHP anywhere in the powerband...And I'm talking NA, not boosted at all.
Will a MEVI w/ a JWT ECU (including raised rev limiter) allow you to have the same numbers as stock PLUS added power? It just seems to me that I've heard back and forth that even with an upgraded ECU there's still loss of power somewhere in the powerband...is this true?
Because I wouldn't want to get a MEVI if I was going to lose any more than a couple WHP anywhere in the powerband...And I'm talking NA, not boosted at all.
02-22-2004, 06:44 PM
#57
Not DAVEB the parts guy
Join Date: Aug 2000
Posts: 8,555
IMO, you should never get the MEVI unless you plan to get the JWT ECU. Like many of us have already proven at the track, the MEVI alone gives you the same performance as the USIM because of the loss in mid range power (-10fwhp/fwtq from 3500-5000rpms) overcomes the gain in power from 5500-6500rpms. You gain more peak power and a ton more power after 5500rpms with the MEVI, but the extra upper rpm power isn't enough to overcome the small loss of power in the mid range. I know I just repeated myself, but a lot of people have a hard time understanding what's going here. Once you add the JWT ECU, all the mid range power that was lost is restored and then some plus your rev limiter is a extended and allows you to accelerate in the correct portion of the powerband.
If I were to do it again, I would have gotten the JWT ECU first because it improves performance without the MEVI. The MEVI by itself only improves performance after 60mph and the car is slower from 0-60mph. Once the JWT ECU is added the car is quicker at ALL portions of the race.
The MEVI/JWT ECU setup drives exactly like the USIM around town. Once the rpms swing past 5000rpms, the USIM looks silly.
Dave
If I were to do it again, I would have gotten the JWT ECU first because it improves performance without the MEVI. The MEVI by itself only improves performance after 60mph and the car is slower from 0-60mph. Once the JWT ECU is added the car is quicker at ALL portions of the race.
The MEVI/JWT ECU setup drives exactly like the USIM around town. Once the rpms swing past 5000rpms, the USIM looks silly.
Dave
02-22-2004, 07:02 PM
#58
Originally Posted by Dave B
The MEVI/JWT ECU setup drives exactly like the USIM around town. Once the rpms swing past 5000rpms, the USIM looks silly.
Dave
Dave
02-23-2004, 07:04 AM
#62
Moderator who thinks he is better than us with his I30
iTrader: (8)
Join Date: May 2002
Posts: 9,335
Originally Posted by deezo
Guys don't laugh at me but when it gets warm I'm going to give my VI another go. That damn Harlan switch ****ed me off something good last year.
02-23-2004, 07:13 AM
#63
Originally Posted by I30tMikeD
Good to hear....don't let that harlan get ya down. Go with the summit, $50 and your golden.
I already have the Summit switch and didn't have it hooked up to the ECU. I had it hooked up to the coil pack so I thought it didn't work. I'm done with Harlan though.
And get that ECU back from Cheston, he obviously is not going to take is car to technosquare.....it's been 2-3 months already!
02-23-2004, 07:19 AM
#64
Moderator who thinks he is better than us with his I30
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Join Date: May 2002
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Originally Posted by deezo
I already have the Summit switch and had didn't have it hooked up to the ECU. I had it hooked up to the coil pack so I thought it didn't work. I'm done with Harlan though.
I've got nothing against Cheston except that he doesn't read the messages you need him to read. He pops in and jets outta here without any updates.
I've got nothing against Cheston except that he doesn't read the messages you need him to read. He pops in and jets outta here without any updates.
It's not a slam against Cheston, but sometimes things that are important to you are not others top priority. Can't blame him for having other things going on......You have tried to help the maxima community which get my respect, but at some point you just have to do it for yourself. Go with JWT.
02-23-2004, 07:30 AM
#65
Originally Posted by I30tMikeD
It's not a slam against Cheston, but sometimes things that are important to you are not others top priority. Can't blame him for having other things going on......You have tried to help the maxima community which get my respect, but at some point you just have to do it for yourself. Go with JWT.
02-23-2004, 07:36 AM
#66
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Originally Posted by Tatanko
Ahh, thank you for clearing that up Dave So the car is normal til you hit 5500 RPM's...then it's like the NA equivelant of a smaller shot of nitrous? 
So the car is normal til you hit 5500 RPM's...then it's like the NA equivelant of a smaller shot of nitrous? 
That would be like a Honda DOHC VTEC where you very little torque until 6000 rpm when suddenly it switches over and you start hauling butt. This isn't like that. Look at the torque curves. It's smooth (no "kick-in"), but just much less of a drop-off at high-revs.
02-23-2004, 08:09 AM
#68
Originally Posted by SprintMax
ok so which one of you N/A guys wants to sell me your VI for cheap 
rule of thumb.. if uncle sprinty hasn't bought it yet.. its not because he is broke... its because details are sketchy
rule of thumb.. if uncle sprinty hasn't bought it yet.. its not because he is broke... its because details are sketchy
Uncle Sprinty now has a VI and is N/A so its ok for the masses to go out and purchase one
02-23-2004, 08:44 AM
#70
Originally Posted by deezo
Guys don't laugh at me but when it gets warm I'm going to give my VI another go. That damn Harlan switch ****ed me off something good last year.
if you need some help pm/email/call me.. I'll help if I can.
I have removed my MEVI for a short time while I am getting stuff in order. I need that summit switch
02-23-2004, 08:59 AM
#71
Originally Posted by bags533
if you need some help pm/email/call me.. I'll help if I can.
I have removed my MEVI for a short time while I am getting stuff in order. I need that summit switch
I have removed my MEVI for a short time while I am getting stuff in order. I need that summit switch
02-23-2004, 09:17 AM
#72
Originally Posted by SteVTEC
That would be like a Honda DOHC VTEC where you very little torque until 6000 rpm when suddenly it switches over and you start hauling butt. This isn't like that. Look at the torque curves. It's smooth (no "kick-in"), but just much less of a drop-off at high-revs.
02-23-2004, 09:22 AM
#73
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Originally Posted by Tatanko
So basically, all the power of the VQ, in a longer powerband? Like...so you don't have to shift as early to keep the power up?
With the USIM the torque curve drops off so sharply after 5000 rpm that the optimal shift points are actually before redline after the 1-2. If you hold each gear to redline the engine is wheezing and you're losing time.
1-2: redline (6550)
2-3: 6200-6300
3-4: 6100
4-5: 5800
With the MEVI there is hardly any torque curve drop-off and hence no need to shift before redline. Actually, the "optimal" shift point for the MEVI is well beyond the stock redline. That's why it's tough to truly gain any 1/4 mile performance with the MEVI and the stock 6550 redline - it needs more revs to play with. That's where the JWT ECU and the 7200 rpm limiter comes in. It's like those two mods were made for each other.
02-23-2004, 09:30 AM
#74
Originally Posted by SteVTEC
1-2: redline (6550)
2-3: 6200-6300
3-4: 6100
4-5: 5800
Since I am running with lower profile tires (50 aspect as opposed to 60 stock)
Would this impact my shift points - Im thinking yes; and if so, would it raise my optimal shift points? Again I am thinking yes...
Thanks mucho..
02-23-2004, 12:57 PM
#75
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Originally Posted by Spaniard
Hiya SteVTEC, I was hoping you could help with a conceptual question...:
Since I am running with lower profile tires (50 aspect as opposed to 60 stock)
Would this impact my shift points - Im thinking yes; and if so, would it raise my optimal shift points? Again I am thinking yes...
Thanks mucho..
Since I am running with lower profile tires (50 aspect as opposed to 60 stock)
Would this impact my shift points - Im thinking yes; and if so, would it raise my optimal shift points? Again I am thinking yes...
Thanks mucho..
02-23-2004, 06:14 PM
#77
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
It's the characteristic bumpy torque curve of the 4g VQ. The intake manifold has resonance peaks and valleys every 500-600 rpm or so. 3400 rpm is the biggest peak and just after that is the biggest valley, and then it flattens out after 4000 rpm. Keven97SE had a really good explanation of this once, but I haven't seen him post in ages. Search for "resonance peak" and Keven97SE and you'll probably find it.
02-23-2004, 06:17 PM
#78
vicodin ... gift of life
Join Date: Apr 2002
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Posts: 5,401
Originally Posted by SteVTEC
It's the characteristic bumpy torque curve of the 4g VQ. The intake manifold has resonance peaks and valleys every 500-600 rpm or so. 3400 rpm is the biggest peak and just after that is the biggest valley, and then it flattens out after 4000 rpm. Keven97SE had a really good explanation of this once, but I haven't seen him post in ages. Search for "resonance peak" and Keven97SE and you'll probably find it.
oh ok, thanks. I asked because I got my first dyno last weekend and I was wondering what the heck that was. No one else there could explain it.
02-23-2004, 08:50 PM
#79
Originally Posted by SteVTEC
I just checked that in the cartest software and with a stock dyno and going from 205/60/15's to 205/55/15's the shift points would still be at the same points.
Changing tire size has nothing to do with how the engine makes its power. It doesn't change the power curve characteristics at all. any change in tire size would not affect the optimal shift points. you could put go-kart tires on the max or put 35" super swampers on it and the shift points would remain the same. Only the speed at which you reach those shift points would change.
02-23-2004, 09:27 PM
#80
Dyno plot says I have the most area under the Administrator curve
Join Date: Jul 2001
Posts: 7,060
Originally Posted by Nealoc187
Changing tire size has nothing to do with how the engine makes its power. It doesn't change the power curve characteristics at all. any change in tire size would not affect the optimal shift points. you could put go-kart tires on the max or put 35" super swampers on it and the shift points would remain the same. Only the speed at which you reach those shift points would change.