Nealoc187

iTrader: (23)

I've noticed this the few times I've gotten on it in the last 2 weeks. Above about an indicated 6700 or 6800 the car starts bucking a little bit, acceleration cuts out and back in in rapid succession and I can actually hear my intake tone changing in concert with the slight lurching. This has just started within the last 2 weeks and only happens above 6700 or 6800RPM. I've never experienced valve float before, but something tells me that's what this is. Perhaps my 140K mile valve springs have just about had it.

So, the real questions. First and most importantly, is our motor and interference motor. Namely am I going to bend valves and ruin my pistons and sleeves here.

Second, how involved is the installation of valvesprings on the VQ.

Nismo87SE

You haven't been doing any high speed runs deep into the redline by any chance have you? If so you can/will kill the engine completely I did the samething 3 years ago and the damage wasn't pretty. All valves are bent #2 exhaust valve broke at the stem, the rocker was destroyed and the piston had a nice hole in it .

HitManSE

iTrader: (1)

Neal if I were in your shoes, id save up a little bit of cash. Ill post tomorrow eactly how involved (labor time) the valve springs are gonna be. If you find that you got a few extra $ laying around and the involvemt is quite a bit, just get the JWT cams as well as some springs, lightweight valves, ect... and do the eitire job all at one time. Looks like you gonna be into it atleast $2k if that is the route you choose to go. I say just live with it and dont race til you fet the cash for the job and do it right if the involvment it too many hrs. Ill post tomorrow how long you should expect the job to be.

SR20DEN

iTrader: (7)

I would say they are floating for sure.The VQ is more than likely an interference motor so you don't want to let them float too much or you will cause damage. On a newer VQ30 the float doesn't happen till about 7500 and it sounds quite nasty. You probably dont even want to know what all you have to go through to change them.

HitManSE

iTrader: (1)

You ever heard a bigblock float its valves w/o an exhaust on? Now that sounds nasty Unless you have taken apart and cylinder head and slapped it back on with a good outcome I would stay away from doing this job myself.

ZuMBLe

iTrader: (1)

And I have my JWT ECU coming!! OH NO!

SR20DEN

iTrader: (7)

Changing the springs themselves is the easy part. But to actually get to them is the hard part. It's like trying to walk through a maze and the exit door is on the other side of a glass wall in front of you. You can see it but must walk several miles out of your way to get to it.

IceY2K1

iTrader: (3)

PLEASE please get a dyno. Otherwise, you're going to throw away lots of money on BS you probably don't need. It could be soOOO many other things.

Plus, I need that info for an argument I've been having with a co-worker.

HitManSE

iTrader: (1)

Yes I know, you see the damn thing, Its right there and looks sooo easy to remove. Then you realize WTF this sucks, I have to do all that to get to those. The really hard part it keeping all the small things organized, there is only like a hundred things you have to keep track of and they must go back in with a certain order or nothings is gonna work. Its a very time consuming job and unless you have had a few under your belt I dont thing some1 should attempt this. You are gonna need more tools then you think.

MardiGrasMax

iTrader: (14)

IMHO, it would be easier and cheeper to just get a low milage used VQ from a newer model and swap the whole motor. Been their, done that!

Sprint

iTrader: (10)

selfish

SR20DEN

iTrader: (7)

I30tMikeD

iTrader: (8)

Ohh, this is not good news.

HitManSE

iTrader: (1)

Do as he sez Neal. I just got the labor time and its a solid 20.0 hrs. That means your lookin at a good $1K in labor (thats if the rate is $50/hr thats just an example). You can get the cams, springs, ect... but the motor still has apprx 145K miles on it and kinda tired at that mileage. I personally would get a the lower mileage motor with like 30-40K miles on it (if you can find one with that mileage). It will still eventually start to float the valves due to the fact that the stock valves are not meant to rev over 6600rpms. Your best bet at this point would be to get another VQ30DE and obviously do a compression check to start off with be4 any install. This would be the best time to build that motor since it is already out of the car. This will be costly but as you already know you gotta pay to play. Its gonna take quite a bit of time but just run on your motor as is until the other 1 is complete. You should take it easy on your motor from this point on and try not to go above 6K just to make sure it lasts for the time being. Sooo I guess the rest is up to you, goodluck man.

Nealoc187

iTrader: (23)

What about getting a spare set of low mileage heads and swapping those? Would that be an easier prospect than changing the valvesprings on my current heads? My ability isn't a concern, I'm confident between myself and guys I know I can handle the install, it's the downtime and money that worries me. My winter beater died a few months ago.

Mardigras how long did your motor swap take you back when you did it?


SR20DEN I believe I recall you mentioning something about valvespring shims to help stave off float. I assume that this would require the disassembly of the heads anyways so it's probably a moot point but I thought I'd ask.

This might be a blessing in disguise afterall, maybe by the end of the summer I'll have a built set of heads on my VQ

HitManSE

iTrader: (1)

Getting low-mileage heads would be eaiser to do then the springs would. That way its just the heads that come off and just slap on a new pair. Ive alread stated what I think about the stock valves in my last most. If you do get a set of low-mileage heads as you know it would be smarter to just build those head with thougher springs, lighter valves, polished ports, cams you know the whole 9 yrds.
If everything goes perfectly the downtime should be no longer then 2days and thats still kinda pushing it. It is possible to complete in 1 day but id rather take my time and do something correctly then do it twice you know what I mean.

The motor swap itself shouldnt take as long as R&R the vlaves would.
I know for a fact the whole motor taken out, completly disassembled, reassembled, and re installed is a 29.9hr job in the Labor book. The car will be down for a minimum of two days, and thats if you guys are working on the car most if the time so it will be more downtime then that obviously. If you want exact labor times for anything just post them all here and Ill give you the times on monday, im off til then though. Same goes for the torque spec if you dont already know them.

Nealoc187

iTrader: (23)

Even though I've had only 2 days to think about it, I'm kindof leaning towards the idea of getting a spare set of heads and doing a little bit of work on them. Perhaps milling them down to raise compression, and cleaning them up, and sending the cams off to ISKY or Crower or someone to be reground. May as well do the springs while I'm in there. Not sure if this would require an ECU reprogram, but if it did, I'd send my ECU back to JWT and go even higher on the rev limiter and probably raise the idle a bit.

A-Ron Max

Does this mean that having a 7k redline w/the JWT ecu is dangerous? I don't redline to 7k very often, but w/the VI it feels almost nescessary, my engine only has 62k miles on it, but i'd still be concerned if I could cause any potential damage.

Nealoc187

iTrader: (23)

I haven't heard of anyone else having trouble. I've probably got the highest mileage car out of the MEVI/JWT crew so it might just be old age arthritis for my motor. Time for some surgery.

SR20DEN

iTrader: (7)

Yes it would help but I failed to mention the excessive labor involved in actually getting to them.


Milling the heads will also retard the cam timing which will remove some top end power and raise your EGT slightly. Get some adjustable cam gears if you do this. And I would suggest Crower as your best bet for regrinds. That's who I was planning to use before I heard of the JWT cams.
If you get a second set of heads don't skimp out and still use the stock springs. Crane probably makes a spring that will fit. You could even contract them to make you some +1mm lightweight or better valves. I know they already make them for several Jap motors including the SR20DE.
On the ECU front you may as well leave it alone unless they give you a super deal on a new progam AND you can have them custom tune your car at their facility. To me it sounds as if you should start looking into a standalone system such as a learnable TEC-III or perhaps a MOTEC. Electromotive and MOTEC both have facilites with 45 mins of my house so if any of them did you wrong I could go crack some skulls if need be.

HitManSE

iTrader: (1)

Well If your not gonna go with the whole motor idea, a second best is to get the spare heads and built them up to the task to take revs over 7K. As SR stated, your best bet with a regrind is gonna be crower unless you go straight up JWT but that is you call to make. Crane does make some of the best springs, I dont know if a double spring is needed (probably not, but I always go overkill ) The lighter valves will definetly help in the upper rpms. I would also if not port atleast polish he heads. If you do decide you do decide to go ported, I would go no more then just getting ride of the rough edges (if any that is) that are in the ports and do minimal porting. If the heads are made to flow too much then you low-end power will suffer a bit. Thats why I personally would just grind rough edges and polish it up, you get a increase top-end w/o effecting the lowend. I have not opened up the VQ so I dont know what kind of lifter are in there, upgraded lifters would be a good match for the rest of the upgrades as well. When I say the whole 9yrds I mean that and everything around it as well. Everything else from this point on is your call, like I said if you need any labor times or specs just ask. Looks like the fastest all motor max is gonna be runnin just as fast(if not faster )as some of the S/C guys

Nismo87SE

You could drop some serious $$ and have the combustion chamber redesigned to gain compression too along with headwork. For the ECU unless you have access to a consult and do timing sweeps on a dyno, it is a shot in the dark unless you can drive to JWT that is . If you have any contacts/friends at a nissan dealer, use whatever means at your disposal to get that CONSULT . With the CONSULT I believe you can adjust the timing from 13-17*BTDC if stock is 15*BTDC +/- 2*. The se-r guys did this when JWT first came out with cams and found that the cams make more topend power with less timing, but more midrange with more timing.

Nealoc187

iTrader: (23)

I was under the impression changes made to the timing with the CONSULT revert back to default once you unhook the car from the CONSULT. Is this not the case?

SR20DEN

iTrader: (7)

For any ECU before 2000 that should be the case. The older ones were not programmable. Look under your hood at the settings and it will say timing is 15º BTDC and it can't be changed.

luckee2bhere

iTrader: (1)

sounds like some $$$$$ is going into the fastest NA Max...good luck with everything Neal...

with 95k miles and a limited budget I wonder if I should invest in MEVI and ECU like I had planned. I definitely don't think I could handle putting money into the Max like it sounds like you are going to have to do. I plan on selling my car when I graduate school at stock specs so this kind of work might be out of my league.

I30tMikeD

iTrader: (8)

Do the age of the valve springs really make a difference on whether the valves float or not? I really don't want to run into this problem with the JWT ECU. I have 100K.

HitManSE

iTrader: (1)

Not really, but it doesnt help thats 4 sure. You cam make a motor with less the 10K on it float the valves if you rev it high enough. Look at all those M3's blowing their motors latley. They are revving them to nearly 9K, the valves are floating and the blocks are being destroyed. If your engine is not prepped to take hi-rpm abuse then revving over the stock redline is not really the best idea.

SR20DEN

iTrader: (7)

Yeah those new M motors stretch rods at 9k. Not recommended to take them past the redline for any reason. The VQ35 has been proven to handle over 9k in stock form though.

luckee2bhere

iTrader: (1)

I revved my car to about 9k RPM when I first got it. Redline 3rd..slammed 2nd...ouch! Sound made me want to

HitManSE

iTrader: (1)

Ouch! youd think you would atleast do it the more popular way. Redline 2nd and jam it on 1st tryin to go into 3rd. (like some people have ) The new 6th gen max seems to have a weird shifter problem as well, seems that going into 3rd you sometimes find 5th. That would suck goin down the 1/4 hoping for a gooe ET, you lauch perfectly, hit second with perfect timing and slap it into 5th to cruize your way to a 17sec ET

I30tMikeD

iTrader: (8)

What seems odd is that Neal said they seemed to start floating at around 6700 rpm's which is just barly past redline. I would think Nissan would design the springs to be strong enough to go at least 5K past fuel shut off. That makes me think it may just be worn out springs(if that is posssible, I am no expert on this).
If he was going to float his valves I thought it would have been at his 7200 rev limiter.


Shifting from 2nd to 5th at the track.....that's what I did the first 3 times I ran the 1/4 mile

Nealoc187

iTrader: (23)

Update

Now I'm not so sure what's going on. I was feeling daring last night so I went out and made some runs through the gears. In all I went through 7200 in 2nd probably 20 times, through 7200 in 3rd 15 times, and through redline in 4th 5 times. Out of all these blasts through redline, only ONCE did I experience what I described in my first post. WTF. Now I don't know what to do. I think I may still build a set of heads anyways just to make some more power and stave off float if indeed that is what I'm occasionally experiencing. I think I need to get it on a dyno.

Keven97SE

You sure you're not running into fuel delivery (pump, injector, or regulator) issues? Sounds more like a fuel issue to me, but then again I've never experienced valve float.

IceY2K1

iTrader: (3)

Get a dyno!!

HitManSE

iTrader: (1)

I30tMikeD: The age will effect it but it all depends on how far past the redline the motor is revved. Neal go get a dyno, but id still build the heads if I were you.

Dreizehn

iTrader: (4)

JWT has springs for our cars?

Has anyone found lighter valves? I am taking my heads into the shop here in the next couple days just to see what they could do. If someone already makes valves, I might get those for the job.

IceY2K1

iTrader: (3)

Honestly, he doesn't know if it's valve float, a fuel delivery issue, a hole in the JWT ECU map, or what.

I just feel like he's running around in circles and going to throw away lots of money by ASSuming it's tired valve springs.

I'm not saying a dyno will tell all, just that would be MY choice as a FIRST step in his situation.

Good luck Neal!

Nealoc187

iTrader: (23)

I've already thrown away lots of money on this car. What's another grand. It's only money I'll dyno once I get my new exhaust hopefully this friday.

knock on wood.

IceY2K1

iTrader: (3)

I hope you can repeat the "valve float" you think you are experiencing on the dyno.

Make SURE you get the wideband 02 graph also.

Nealoc187

iTrader: (23)

After my testing last night I'm not sure I'll be able to. I was planning on the wideband anyway because I want to compare the JWT to my stock ECU.