So my MEVI will be arriving today. I don't have the other components that I need to make it work yet, as mainly I'm waiting for the Harlen RPM switch (I just ordered it Wednesday).

After thinking about it, I spend basically the entire quarter mile above 5k RPM except while launching. Any reason I couldn't install the intake manifold, leave it "closed" for day to day driving, and rig it "open" at the track to see if I can get the high end power until I get everything else hooked up?

Loosing power during my launch wouldn't really be a bad thing, as I have problems keeping the front end planted anyways...

 

Ziptie it open. Or you can hook up the vacuum straight to the actuator.

 

Do you think it would improve my times? I guess that was the question I was (poorly) trying to ask.

 

your times should go UP. BUT maybe this is what YOU need to get a good launch. Your TQ is gonna be horrible.

Give it a shot. you may have just solved a launching problem. Try it 2 times and then close it and try it another 2 times

 

Up? Really?

I spend 90% of 2nd gear, and all of 3rd and 4th above 5k RPM while racing...I figured it would be open the vast majority of the time if it was working...

Oh well...we'll know wednesday!

 

I had the VI open at all times for a while. The torque loss isn't that bad! I think you feel the loss more around 3000-4000.

 

If the only thing you're waiting for is the Harlan switch, you could always just wire the solenoid to a switch in the cockpit, on the shifter maybe. Then just manually activate it when you want to. This would save your low-end torque, but still give you the top-end advantage.

It would also get all the wiring done now so all you'd have to do is pop in the Harlan when you get it.

 

IF you hook up the vac to the actuator it will close at wot. I suggest ziptie unless you already have the vac can hooked up.

 

Well, I don't have anything yet. I was going to go shopping/junkyard diving this weekend. However I'm sure I won't have the harlen for at least a week or two...

 

If you can just pick up the solenoid than you can do what I described and have everything in place, VI working when you want it, and car ready for the Harlan. I'd try to find a solenoid and then get cracking.

 

Yeah, I'm not excited about that. I've never been able to find a junk yard around with many (if any) Nissans...

 

Yes up I think. This comes from dynoing with mine open. BUT I did not have a SC and the TQ loss was BAD.

So I do want you to try it

And ya, NO vaccum at WOT ziptie it open

 

I will

 

Doesn't have to be a Nissan.

Almost every car I've found at a junkyard that had Cruise Control on it had a solenoid somewhere. But they all look different, and some only have 2 ports instead of 3, so it takes time and patience to find one.

(3 being 1 in, 1 out, 1 open to atmosphere)

IanS

 

I found that out.

However, I took Deezo/Doug's advice and order a new GM one:

http://forums.maxima.org/showthread....hreadid=208123

Its worth the extra $10 or whatever not to have to deal with the hunting aspect to me.

 

I wouldn't tie open the VI because it will make you much slower. Since you don't have a 7000rpm fuel cut, you're not going to be landing anywhere close to 5000on a redline shift except in 4th. Assuming a 6500rpm shift, you'll land at ~4000 in 2nd and 4500rpm in 3rd. While it doesn't seem like a big deal, it's a HUGE deal. I'd estimate you'd be a solid .3-.4 and 3mph slower with the runners tied open.


Dave

 

What does the MEVI do for the intake????

 

The vacuum switch can be gotten anywhere. Just go to any "newer car" in the junk yard and pull the EVAP purge valve vacuum switch off of it. I took one off of a 93 civic. Poor guy will spend weeks trying to figure out why his CEL is on. Just kidding the car didn't have an engine in it.

 

Well, I don't know. If you watch that video before, I spend all of 3rd and 4th above 5k.

Regardless, I'm going to go to the track wednesday (weather permitting) and I'll play with it.

 

I watched your video and I'm seeing an indicated 4000rpms entering 2nd and ~4700 entering 3rd. As most of us have seen on the dyno, the stock tach is off (reads high) by 200-300rpms depending on gear. I calculated out the true entry rpms on a 6500rpm shift and you're looking at 3800rpm entering 2nd and 4600rpms entering 3rd.

Believe me, I've dynoed with the MEVI and I can tell you if you engage the VI before 5000rpms, it will take motor till about 5400rpms to recover and actually start showing some gains. I engaged my MEVI at 4600rpms because I thought it felt better, but the dyno proved I was completely wrong. Simply engaging the MEVI at 4600 resulted in a max loss of 15fwhp/fwtq at 4600rpms and didn't match the dyno plot of the more effective 5000rpm engagement until 5400rpms. I could only assume the losses of keeping the butteflies open would be far more severe and you wouldn't see ANY kind of useful gain until well after 5000rpm which is of little use. I know there are plots floating around showing a loss of well over 30fwhp in the lowend when keeping the butterflies open.

You want to be able to launch hard, not soft. If you have problems launching hard, then you'll have to invest in tires.

Dave

 

So where do you recommend opening the MEVI up at? if the 5k opening only begins to result gains till 5400 then thats 1000rpms of any gain.

 

I hooked up a LED to my RPM switch this weekend and my tach is off by 300rpm in 2nd gear on my auto. My RPM switch is set to 5200rpm but I don't see the light come on till an indicated 5500-5600. My problem is tha I don't know when to shift out of 2nd now! Is this error exponential?

Dave: What RPMs are you using these days? 5200 still?

 

I've been using 5000 since the beginning, and it has shown on 28 Dyno runs to consistantly be the best choice.

 

Maybe I'll try 5000 rpm also. But you're boosted so that may make a difference.

 

I had the MEVI was I was NA also - 5000 was still best for me.

results may vary, I suppose.

 

Anywhere between 5000-5200 is good. You're right that the MEVI only shows gains for about 1000rpms with the stock 6500rpm fuel cut. It also has a loss of power from 3500-5000rpms and that's why these cars are no quicker in the 1/4 mile with MEVI alone. Not until midway thru 3rd gear is the power utilized. This is because you accelerate in the gears longer. Not until you get a JWT ECU will the full potential of this setup be realized. That 7000rpm limiter and extra power in the midrange mean everything.


Dave

 

The loss in power is no more than 5-10tq....

Don't forget to mention that.

 

I lost:

2-7 fwhp & 2-10fwtq from 3200-3500rpms

2-10 fwhp & 2-15fwtq from 3800-4800rpms

2-6 fwhp & 2-8fwtq from 5000-5400rpms

As you can see, I pretty much lost power from 3200-5400rpms. Check out my homepage for a comparision graph of my dyno numbers before and after MEVI. All the before and after dynos I've seen show nearly the same kinds of losses. I think Nealoc187 suffered the worst losses (upwhere near 20fwtq lost). The good news is the JWT ECU fixes most of the power loss, thank God. Honestly, with just the MEVI, it's like your car doesn't have a y-pipe, but it's able to breath straight to 6500rpms. It's a total trade off.


Dave

 

I think us boosted guys are in a different boat though. Yes I'll lose some power, but its not as drastic as it was for you NA guys.

I think.

I'll know wednesday.

 

Definately give it a shot since it's an easy mod, but do remember the SC causes a loss of power in the lower rpms. Team that with the lack of power with the butterfly valves open (~30 less fwtq/fwhp), you're car might pull off a slightly better 60 foot, but your 330' will suffer regardless. I know you're not in 1st very long nor are you in 2nd very long, but the lack of power at the beginning of a 1/4 mile will make you slow. That 1-2 shift will feel incredibly weak. The initial acceleration means everything.


Dave