Kawowski

I know it is kind of random, but does anyone know the exact flow pattern of coolant flow in the 7th gen Max VQ35DE? I ask because I got my headgaskets replaced under warranty and know that they used the "updated" head gaskets, part number 11044-9N01A and 9N01B.

Does anyone know what the "update" was to the head gaskets?

I saw a write up on a VQ rebuild where they used the VQ35HR head gasket to get better coolant flow. Apparently, the inlet to the heads from the block are blocked off on the new gasket... this allows fluid to come up evenly around each piston and primarily by the hot exhaust valves. With the original design, the coolant would flow up from the block to the heads in the front of the engine and flow rearward. The problem is the coolant would heat up as it made its way to the rear cylinders causing excessive heat in the rear of the engine.

I have also seen pictures of a Murano, which supposedly has the same engine as the Maxima. The old head gaskets were still on and appeared to block the the inlet as mentioned above. But, I wanted to confirm if anyone knew if the Maxima used the same exact head gasket of the Murano.

I tried to explain everything the best I could... but if it doesn't make sense, please read this...

http://www.motoiq.com/magazine_artic...st-3-days.aspx

Just wondering if the 7th gen Maxima uses the old version of head gaskets or the newer ones shown in the article.


I have read a ton on the Maxima's VQ and that it has HR heads on a DE block (thanks SurraTT). I also read an article that showed the difference between the head design of the VHR vs. a DE head. Does anyone know if the HR head has the improvements (air flow and head cooling) noted in the below article on the VHR heads? The article mentions smaller diameter spark plugs for increased coolant flow in the VHR heads... Our Maximas also have the smaller diameter spark plugs. This is what makes me think maybe our heads are actually VHR heads without the VVEL component on the intake cams.

Here is that article... pages 5 and 6
http://www.370z.com/MagazineArticles...akthrough.aspx

I don't know enough about coolant systems to really get the funtioning of them within the block and heads. From my research, it appears you can "block off" certain coolant channels to create the flow you want... but I'm not sure. Is this true?

Thanks... I know that's a lot of questions.

L36

iTrader: (4)

I doubt this applies to this gen of VQ. Even if that was the case your car is not designed for track and you would never have issues with cooling with driving even if its Sahara hot outside.

Kawowski

I figured it wasn't necessary... I was just hoping to start some discussion being the Maxima's engine is pretty unique with a DE block and HR heads. It also differentiates itself from the Altima motor as it has valve timing on the exhaust cams while the Altima does not. I found the articles interesting, but I tend to like to know every little detail about my engine. I also am not convinced that we do not have the VHR heads (without VVEL) because of the pics below. I was hoping someone with definitive knowledge might comment and start a discussion.

Here is a pic of the 7th Gen Maxima's "HR" head (all credit to SurraTT)...



Here is a picture of a stock "DE" head intake port from side angle...




Here is a picture of a stock "VHR" head intake port...



We definitely do not have the DE intake head/port as it is much further forward and much more rough in its finish. Our engine sure looks exactly like the VHR head if you compare the 1st and 3rd pics... it even has the same smooth overall finish with the rough "lines" in the exact same areas as the VHR heads/port. Maybe the rough lines are casting lines.???

The question remains... if we definitely have the HR heads as currently thought or if we have the VHR heads (minus VVEL) shown in this article. I really wish the article compared the HR vs. the VHR heads so we could know for sure.

Again, I know none of this really matters... I just like to research things like this and know every little detail. I'm sure there are others out there that enjoy the same and I hope they find this informative and can add something to the discussion.

Kawowski

Here are the rough "lines" I was talking about above, but highlighted...





You can also compare the "cuts" right behind the valves, rear of the chamber, and see they match the VHR exactly...

Shipwreck

Perhaps we have some sort of VQ35DE variant, like the "Rev-Up." I'm not so gearhead savvy about engines (I'm still learning) but it might explain how Nissan was able to push the Maxima from 255 to 290hp from the 6th to 7th gen.

Either way, it's nice to know we have "cleaner" heads. If I had the tools and the cajones to rip my engine apart, I'd likely consider doing a nice port and polishing.

Shipwreck

I'm going to assume you found this thread as well:

http://my350z.com/forum/other-vehicl...ng-vq35hr.html

Kawowski

Yeah I did... I actually got a ton of info from SurraTT on this forum and others. I PM'd him, but I'm not sure how active he still is and it's only been a few days. I then started researching as much as possible and found other sites/forums. I was especially interested in knowing if the 7th gen has the improved coolant flow pattern as mentioned in the first article because I had my engine torn apart and the short block replaced due to head gaskets and main bearing issues.

http://forums.maxima.org/7th-generation-maxima-2009/662567-engine-knock-head-gaskets-w-pics.html

Then through my research on head gaskets I was led down the path of coolant flow and if the new head gaskets have the improved coolant pattern described in the first article. This then led to me finding the improved cooling abilities in the VHR head described in the second article... and the ball just kept rolling. After reading all of SurraTT's posts I agreed we definitely have at least the HR heads... but wonder if we might have the VHR heads as I described in my earlier post.

And I agree that it's nice to know that we have "cleaner" heads. It probably doesn't even matter with the way I drive, but it makes me feel better anyway.

And thanks for the link... I'm sure it will help someone in the future that may be going down the same path I am now.

Kawowski

I've done some comparisons of the FSMs between the VQ37VHR (2013 Infiniti G37) and our VQ35"DE" and have found that nearly all valve related measurements (height, width, valve angles) are either exactly the same or very close. The few that are different have very small differences. This leads me to believe we have the most advanced VQ heads (minus VVEL) on our DE block!

dr_2010SV

Good work, stuff I would have looked into 20-30 years ago when I was a bit younger building V8's for Bracket racing.
Unless I missed it you don't really mention if these measurements include camshaft profiles B/T the two comparisons mentioned above, like lift, duration, and such?
The .2L displacement increase over the 3.5 alone will get you a relative HP and torque increase (all other things being equal).

Kawowski

Thanks for the +1. The actual measurements for the camshafts are very similar, but because the VHR uses VVEL it can change the valve lift continuously why our heads can only change the valve timing. And yes the additional TQ and HP come primarily from the increased displacement and a small amount from the VVEL. So my guess is the VHR is really just our engine with a bore of the cylinders and the complicated VVEL mechanism. It's nice to know we have the newest heads as far as flow even if we do only have a "DE" engine. As the thread title says though... I prefer to call our engine a VQ Hybrid.

SurraTT

iTrader: (59)

the 7th gen maxima motor has true hr heads.

its the exact same part number for maxima, altima, 350z, g35,

and even the murano, which i just learned. hmm

Child_uv_KoRn

iTrader: (7)

So what you're saying is that 7th gen LIM will bolt to 350Z HR....

Yes, that's relevant info for a swap I'm planning lol

Bificus99

Too bad we can't use all the engine since our cars have a cvt.