Dave B

Just for fun I glanced over Mr. Cranmans dyno of his MEVI with the JWT ECU to determine the shift points:

http://www.vanillaice.com/webmasters/hype/mrc/mrcVI.xls

The dyno run only went to 6800rpms and I don't know if this is where the rev-limiter was hit (I'd hope not) or if the operator let off because the tach was already showing 7000rpms at the time. Anyways, the dyno shows the Max making ~185fwhp from 6000rpms to 6800rpms. That's just insane. There is no point at which the dyno graph begins to fall as it approaches the rev limiter. SO, with the JWT ECU, all shifts should be at 7000rpms. The amount of "average" HP/TQ gained with the MEVI is very significant, more so than I orginally thought. In 2nd gear with the stock manifold assuming you hit the 1-2 shift at 6500rpms, you're accelerating from 4000rpms to 6200rpms. HP at 4000rpms is ~141 and peaks at 177hp and then plummits after 5500rpms which forces a shift at 6200rpm which is 169hp (shifts are based on available torque@rpm/gear ratio/upshift gear ratio). With the VI and JWT ECU (using the 6800rpm Cranman dyno), you get to prolong your shift from 1st until 6800rpms. This means you're entering 2nd ~300rpms higher in the powerband and with more power. With the VI in 2nd gear, you accelerate from 4400rpms to 6800rpms with HP at 158hp at 4400rpms and peaks at 186hp@6200rpms and holds that way until 6800rpms. Not only do you gain a huge amount of power after 5500rpms, but you get to accelerate in the meatier part of the powerband. That additional amount of average HP teamed with the ability to accelerate longer, results in a significantly faster car. In 3rd and 4th gear, things only get better, significantly.

In a nutshell, the stock 6500rpm rev limiter is severely hampering guys with MEVIs. That extra 500rpms of useable rpm means we could be accelerating on a curve that has an extra 15fwhp. I've got to get the JWT soon Dare I say we could honestly use a 7200rpms rev-limiter if the valve train could support it.

All shifts at redline fellas.



Dave

NmexMAX

iTrader: (22)

I was at that Dyno, and I'm not sure, but I think he took it up to ~7250 once. His car is nasty as heck.

I think that's my next mod. JWT ECU

ericdwong

Well maybe if redline is extended to 7000 RPM, the 4.17 gear in the final drive will make the car even faster?

Anybody care to do a car test? Please pretty please?

Mr Cranman

iTrader: (1)

Thank you for analyzing that. I had spent nights looking at that and trying to figure...when the best shift point would actually be for the car. I agree with you...I normally when racing a V-8 or some turbo car that has cranked the boost a little...I will take through redline to about 7K-7.2K (I think that 7.2K is where the rev limitered is on my car or seems to be) Don't take it that high that often. I asked the person doing the dyno to go through the redline...so I don't know if he quit at 7K and I'm off by .2K on my tach. But, whenever racing...if I can make it to a 1/4 mile track...in your opinion...I should drag it out to about 6.8-7K?? That is what I've been doing, and that is the conclusion I had come to. That is why I think the JWT ECU is such a must have with the VI, plus I think it might help plateau the HP gain also.

Just my 2cents,
John

Mr Cranman

iTrader: (1)

Actually that is one thing that I'm interested in is to find out the top speed of the car and how fast we can actually get there with the VIM...But, I think taking it to 7K should produce somewhere in the 150-160 range final gear topspeed. Just my thought. Once I get my Knock sensor replaced...I will probably do another dyno run and also try the hybrid intake to see how that improves the dyno...and just do a High speed test at that time.

-John

XXXL Cracker

iTrader: (3)

It seems the automatic guys like myself, will definitely need to manually shift as opposed to letting the ECU do it for them.

The other questions I have is how the ECU would affect or help us automatic guys. I know with the mods I have now, my car really creates a lot of power in the higher RPM's and I see a benefit from manually shifting without having my VI installed yet.

Any one have any experience with the above scenario?

Dave

Nealoc187

iTrader: (23)

This is more evidence to support my claim that all 4th gen tachs read 200rpm higher than the actual value. Mine is exactly 200 high, Mr Cranmans is, assuming the dyno operator let off at an indicated 7000rpm, etc.

I dont think a 7200rpm redline would be any problem honestly. Most cars can rev significantly higher than their redlines, and the VQ is overbuilt by most measures. That the valvetrain could support 7200rpm would not surprise me in the least.

Mr Cranman- If you make it to a track, rev it out as far as it will go. I have a hunch you will find your rev limiter at an indicated 7200rpm. If so, rev it to there, if you want to get the best times. Now that I've got my MEVI, I go as close to the rev limiter as I can without hitting it, hitting it will hurt your times. I hit it occasionally.

Mr Cranman

iTrader: (1)

I'm thinking that hopefully I'll be the next 4th gen all motor max in the 13's (if not the first, but with the elevation I doubt it)...but don't have a track close enough to get practice. Plus I've never run a 1/4 mile so I think my first runs will be high 14's. But, after I get my replacement differential bearings and replace the 3rd gear synchro...I should be making a road trip in like in a week and a 1/2 to the closest 1/4 mile track to get my times. Hopefully I won't be dissappointed.

-John

BSwithTF

iTrader: (8)

If you have the VIM on an auto, you MUST manually shift to get the full benefit from it. I usually see .3-.4 slower times when I let the car do the shifting. The car just shifts way to soon and that in turn drops you lower in the RPM's to start the next gear.

maximamoose

that is correct!! that is why i love my 5 spd. anyway, when is there going to be an ecu for a 97???

xHypex

iTrader: (1)

My tach actually reads closer to 300 rpms too high. I noticed this when I installed my VI indicator light and my shift light.
-hype

Mr Cranman

iTrader: (1)

I know there are like several guys that use the 95-96 ECU on the 97 with no problem...Or maybe the engine light comes on but not to sure. But I know there are some guys that have done it in the 97's and have gotten good gains.

-John

96sleeper

iTrader: (4)

I got a question for you...you have the JWT ECU and an auto...did they bump up your rev limiter, or is that just for 5 speeds?

XXXL Cracker

iTrader: (3)

Good question, I was wondering that myself....

infinitiblast

iTrader: (2)

Oh yeah this is all fair and good for people who can actually get the jwt ecu...what about us lowly 99's. Someone call up jwt and yell at them for missing us..haha

Nismo87SE

The 98-99 people need to get off their asses and make an adapter harness for a 95-97 ECU. Honda adapter harnesses run around $125-200, so figure around that much for 98-99s.

Nismo87SE

I've run the simulations there is a very slight (1 tenth difference) between a 3.82 vs 4.17 gear. Now if the power peak was around 6400-6500rpm and there was a 7500rpm limiter then a 4.17 gear would help alot.

Nismo87SE

I dunno usually nissan sets the rev limiter about 400-500rpm shy of where valve float begins. If anything for insurance SR20DE valve springs + retainers will easily allow 7500rpm. Can you imagine a MEVI/cammed 4th gen with 7500rpm to play with . Just for kicks I ran a simulation too see what happens if a 4th gen has a MEVI + cams that equal ~ 5% more power (10whp gain). It drops 2 tenths and runs 1.5mph quicker also hitting the rev limiter in 3rd gear at the finish line. After 1 mile the VI + cammed car is 8 wheel lengths ahead!

Mr Cranman

iTrader: (1)

So you think if we had stronger springs and retainers that we wouldn't have to worry about the valve floating possiblity (theoretically)??? Do you think upgrading to VQ30DET springs and retainers would do just as fine as the SR20DE springs and retainers??? Because that might be something I should look into just to prevent wear and tear...or valves dying. I know I probably sound stupid here...but what do you mean by retainer?? I know about the vavles and the valves springs...is the retainer like at the end of the spring that you torque down. Sorry for my stupidity...Never really talked about retainers before. Thanks for your input and clarification.

-John

speedtrip

I know that 2nd gear coming back to 4k rpm is hurting my et. On my dyno I lost hp from 4k to 5k rpm. 3rd gear is not as bad as the motor drops to 4600 rpm. A jwt ecu would help me immensely. I'd wager that it would drop my et by .3 seconds. When I have raced other modded maximas at the track I might pull a bumper by the end of second gear. It's not until third gear when I start to walk away.

Maybe there will be a jwt ecu in my future next year.

farm boy

Yes, the rev limiter is bumped up for automatics.

BSwithTF

iTrader: (8)

Yes, I have the bumped up rev limiter. I usually manually shift up at about 6800 because it takes a little bit for the auto to do it's thing. The added power the ECU adds is really nice too! I feel like a lot of people are forgetting that this thing does more than raises the rev limiter and cuts the speed limiter. IT ADDS POWER. I put my stock ECU on and I felt like I'd dropped anchor. I'll say this: The ECU is worth the money!(if available for your car )

Bags

iTrader: (3)

Time to kick you in the shin ;P

that was uncalled for...lol..making funof us 97 and newer models

and for an auto if we could have a 7200 rpm red line... wow

the 1/2 shift would be insane, being able to hold 2nd that long, getting on the highway would take on new meaning.. and the 2/3 would be much better, use 3rd gear as a passing gear .. and the 3/4 shift I think would drop it right at 5200 rpms.. VI area... but that would only be out at the salt flats

Dave B

I'll definately be happy to gain some extra mid-range punch (maybe break 200fwtq?) along with the extended rev-limiter I think I'm going to get a junkyard ECU (send that one to JWT) so I can go back to stock and sell the JWT a hell of a lot easier. I'll probably buy the ECU as a Christmas present, unless my yearly raise in October is a good one (I'm not counting on it).


Dave

Nealoc187

iTrader: (23)

OK, now that we are seriously talking about ECUs again, I'm planning on getting a spare ECU here in the next week or two to send to JWT.

Does anyone remember Iron Lung's dyno, the 5spd swap still using the auto ECU that was putting down more power than any other bolt on Max we've seen. Does anyone think it would be beneficial to get an auto ECU as opposed to a 5spd ECU? Of course once JWT mods the ECU any gains provided by the use of the auto ECU would go out the window...

96sleeper

iTrader: (4)

That will be the advantage that your car has over mine now then. I have the g-force ecu which didn't raise the rev limiter, even though the mid range torque it added was great. I think when cold weather gets here we will both be pretty happy though. Even if your times are better than mine, as long as we are running some mid-high 14's I will be happy. I have been thinking that after this fall though, I will start in my hunt for 12's, so I will be out of the N/A game.

96SE5Spd

Since no one answered your question I will, The retainer is what holds the valve spring in place, on a push rod engine it looks like a disk with a hole in the middle of it (it probably looks the same in an ohc engine, but I've never taken one apart). Hope this helps,

Ryan