Gauging interest: 3.4L Phenolic Spacer Kits

[96 Runner]

All -

Phenolic spacer kits are a huge hit with the Nissan crowd right now because they produce results. In a nutshell, phenolic spacers thermally isolate critical parts from one another, reducing temps and increasing power. An example of these parts would be the throttle body from the intake manifold, or the intake manifold (or supercharger) from the intake plenum.

In my quest to make safer power, I often find myself researching what others have done. I've been watching the Nissan enthusiasts (mainly with the VQ35 and VE30 crowd) and I've seen a lot of rave reviews about phenolic spacers on those engines. They just plain work. So why not get something going for the 5VZFE (and maybe some other engines too)?

I shot an email out to Aaron over at Nissan Works to chat about the kits he offers and if he'd ever be interested in producing a kit for us Toyota guys. As with any good businessman, Aaron said if the interest was there that he would seriously take a look at producing the kits for us. Take a look at what he's doing currently: http://www.nissanworks.com/Phenolic_Spacers.html

If this is something you would consider purchasing for your rig, please respond in this thread. Aaron said he would join UY once I sent him the link and pop in to check things out and answer questions. Pricing would be somewhere in the $150 to $290 range (roughly).

He is going to need a guinea pig vehicle or two out of North Carolina to help with R & D if there is enough interest. Keep that in mind.

What do you say guys?

(Example) Maxima SE kit with coolant bypass mod:
http://www.nissanworks.com/images/Maxima-Phenolic-Spacer-Kit.jpg

[96 Runner]

Bump! C'mon guys, whaddya say?

[MTL_4runner]

I can't say it would do much for me up here. It's a good idea especially for the S/C'd guys. I think for $150 you could get some takers, but $300 sounds a bit steep for that. I wonder how much the phenolic sheets cost because I have access to a waterjet and might be able to try it out first for a few folks.

[mastacox]

It's a cool idea, and I might be interested some time in the future. Only thing that worries me is that the only thermal path for the supercharger is into the block (and air blowing around it). If you block that off any heat generated by compressing the air will have nowhere to go... course the air probably isn't heating up that much anyway with 6-10psi of compression, I'll have to do some calcs. Also, the throttle body is dependent on cooling with engine coolant, would you block these off to try and keep your TB as cool as possible once it's "thermally isolated" from the lower intake and supercharger?

EDIT: Also, how thick would the spacers be? Quarter or half an inch? It might be tough to find a bolt that will replace the "long supercharger bolt."

[96 Runner]

Also, the throttle body is dependent on cooling with engine coolant, would you block these off to try and keep your TB as cool as possible once it's "thermally isolated" from the lower intake and supercharger?

EDIT: Also, how thick would the spacers be? Quarter or half an inch? It might be tough to find a bolt that will replace the "long supercharger bolt."


Brian -

Good point about the TB. That's why the coolant bypass mod is done too :). I did the CBM this past weekend and I am happy to report that there are no ill effects. No idle problems, no driveability problems, nada. I don't have any data to support if it did anything for me, but from an observational/common sense standpoint if one removes an internal heated liquid source, the temp should drop. I recommend the CBM. If anyone wants to do it, all you need is a $0.97 5/16" brass splicer from Lowe's. The lines fit right together. I plugged off the coolant inlet/outlet of the TB with some hose and golf T's.

As for how thick the spacers would be, I am willing to bet the R&D testing would have to determine that. Hood clearance, bolt length, and performance results would all be taken into account. From what I can tell, 5/16" seems to be the thickness of choice on other V6 engines. Yeah, that long SC'r bolt will make things interesting!

[MTL_4runner]

Also, the throttle body is dependent on cooling with engine coolant, would you block these off to try and keep your TB as cool as possible once it's "thermally isolated" from the lower intake and supercharger?



The coolant in the TB is more for preventing ice buildup in winter than it is for cooling in summer.
Doing the CBM in a place that sees subzero temps regularly could actually be dangerous.

[mastacox]

The coolant in the TB is more for preventing ice buildup in winter than it is for cooling in summer.
Doing the CBM in a place that sees subzero temps regularly could actually be dangerous.


Yeah, I was just thinking that actually the coolant is to heat up the TB not cool it... in which case I can't do the TB bypass because Los Alamos gets down to freezing a lot. Heck, it snowed a little a froze overnight just a few days ago. Also seeing as how this is the snowboarding rig, it will be seeing sub zero temps a lot.

My plan for keeping the intake cool is an 8 or 10 inch electric fan mounted in the hood scoop blowing air on to the supercharger's body. I plan to add it when I go with the main electric fan and 60 amp variable controller.

[MTL_4runner]

Yeah, I was just thinking that actually the coolant is to heat up the TB not cool it... in which case I can't do the TB bypass because Los Alamos gets down to freezing a lot. Heck, it snowed a little a froze overnight just a few days ago. Also seeing as how this is the snowboarding rig, it will be seeing sub zero temps a lot.

I was thinking.....which is always dangerous but anyway...

You could just run a 1/4 turn ball valve on the coolant line going to the TB so during the summer you get the cooling you need and in the winter your TB won't ice up. The key would be knowing when to switch over but I think it would be pretty easy and accessible so it wouldn't really be a big deal.

Something like this valve for a toilet would work:
http://img.alibaba.com/photo/50479144/1_4_Turn_Straight_Supply_Stop.jpg

[96 Runner]

Jamie -

That's exactly the route I was going to take. It's a great idea and I just might do it in the future. As you know, even in Phoenix the temps can get in the 20's (for a couple days/year :) ) and I also go north sometimes - it would be great to simply have a valve to make the switch back to stock...hmmm...

[mastacox]

! EUREKA !

I was doing a bunch of calculating to try and decide if thermally isolating a supercharger would be a good idea, and I inadvertently stumbled upon a very important observation!!!

So a huge question many people have been asking is "why do our supercharged engines seem to ping worse at higher altitudes?" Some people deny it happens, others like me have seen the effect first hand; I think I just discovered the answer, and it lies in how a gas's temperature rises with pressure! The temperature rise for an adiabatic compressor is defined as:

T2 = T1 * Rc^((k-1)/k)

Where T2 is the compressor discharge temp (CDT), T1 is the intake temp (IAT), Rc is the compression ratio, and k is the ratio of specific heats for air (1.4 for our case).

So the compression ratio (Rc) is defined as the absolute output pressure divided by the absolute inlet pressure. At sea level the intake pressure is 14.7 psi, and so the output pressure for a 6psi pulley would be 20.7 psi, yielding a compression ratio of 1.41. So on a 70 degree day, a 6 psi supercharger will increase the air temperature to 124.4 degrees Fahrenheit. On a 100 degree day with a 9psi pulley, the CDT jumps to 181.8 F.

Now, what happens where I live, at 7500 ft? Well, the compression ratio actually CHANGES. Since the air is thinner at altitude, atmospheric pressure is at about 11.12 psi, far less than at sea level. So, the effective compression ratio increases if we assume the supercharger is still putting out 6psi (which it might not be, but that's another thing for another time); for 6psi of boost with 11.12 psi ambient pressure, the compression ratio is about 1.54 - a 10% increase. This means that on a 70 degree day at 7500 feet, the CDT is 139.5 Fahrenheit, already significantly higher than at sea level with similar conditions... and with a 9psi pulley and an 85 degree day, the CDT jumps to 185 F, higher than a 100 degree day at sea level.

This may explain why it is that our engines ping worse at altitude- because the compression ratio and therefore CDT actually increases with altitude... At least it's more of a scientific explanation than I've seen out of anyone else yet.

[MTL_4runner]

Now, what happens where I live, at 7500 ft? Well, the compression ratio actually CHANGES. Since the air is thinner at altitude, atmospheric pressure is at about 11.12 psi, far less than at sea level. So, the effective compression ratio increases if we assume the supercharger is still putting out 6psi (which it might not be, but that's another thing for another time); for 6psi of boost with 11.12 psi ambient pressure, the compression ratio is about 1.54 - a 10% increase. This means that on a 70 degree day at 7500 feet, the CDT is 139.5 Fahrenheit, already significantly higher than at sea level with similar conditions... and with a 9psi pulley and an 85 degree day, the CDT jumps to 185 F, higher than a 100 degree day at sea level.


Brian, the assumption that the outlet pressure on the compressor would be 6 psi at both altitudes given the same RPM is obviously not correct (as you mentioned). If you think about it, the compressor can't magically get more efficient at higher altitudes (ie it doesn't mechanically change from producing 1.41 to 1.54 somehow......any more than an engine's compression ratio would change either). You'd have to take the same compression ratio and empirically get the outlet pressure at altitude given the absolute inlet pressure, then do the temp math to give you an apples to apples comparison. Any increase in temp at altitude would be due to the differences in efficiency of compressing different inlet pressures to the same outlet pressure (which is what your numbers of going from 1.41 to 1.54 show). You did basically prove it is less efficient to make boost at altitude (which is true and the inefficiency shows up in the form of additional heat) so if you're going for more power (for example both people trying for 6 psi), this would definately hurt you in your quest (ie you'd hit the limits of useable boost much faster than people at sea level).

[mastacox]

If you think about it, the compressor can't magically get more efficient at higher altitudes (ie it doesn't mechanically change from producing 1.41 to 1.54 somehow......any more than an engine's compression ratio would change either).


Yeah unfortunately everything falls down if you assume that the supercharger's boost drops linearly with air density... Since the air density at 7500 ft is 75.6% that of sea level, if a supercharger puts out 6 psi at sea level then it only puts out 4.5 psi at 7500 ft. This makes the compression ratios equal (which of course makes sense for a fixed-speed supercharger) and thus the CDT becomes essentially equal as well... back to square one :shake:

Sea level / 6 psi boost / 70 deg. day -> CDT of 124.41 F
7550 ft / 4.5 psi boost / 70 deg. day -> CDT of 124.43 F

[mastacox]

Anyway back on topic...

If you thermally isolate the supercharger, it still might not be all that "cool." Even on a "perfect" 70 degree day at sea level with a stock 6 psi pulley, your CDT can be as high as 124 F at full boost. On a 100 degree day at sea level, that temperature could be as high as 181 F. Driving up a large hill going out of San Diego for example, I can see how you would be running at high boost for long periods of time, and your supercharger would heat up pretty fast.

Still, you obviously aren't running at full boost for long periods of time so it could be you might see a net effect if you've been cruising for a while and then floor it. Also, keeping the IAT as cool as possible helps drastically reduce your CDT's (and EGT's obviously), so spacing the TB would be a definite plus. I'd be interested to see some infrared thermometer temperature readings on the supercharger's body with and without the phenolic spacers.

How hot does the lower intake where the supercharger bolts on actually get? Hotter than the engine coolant temp? I have touched my supercharger after some long stints of driving, and it didn't strike me as being "really" hot...

[MTL_4runner]

back to square one :shake:


Not completely, what you did was to show that the effect of compressing a lower density air charge vs a higher density charge to the same outlet pressure results in more heat. Thus someone at sea level (inlet 14.7 psi) trying to make say 6 psi will have cooler air outlet temps than someone at 7500 ft (inlet 11.12 psi) trying to make the same amount of boost.

[MTL_4runner]

Still, you obviously aren't running at full boost for long periods of time so it could be you might see a net effect if you've been cruising for a while and then floor it. Also, keeping the IAT as cool as possible helps drastically reduce your CDT's (and EGT's obviously), so spacing the TB would be a definite plus. I'd be interested to see some infrared thermometer temperature readings on the supercharger's body with and without the phenolic spacers.


You made a very good point here...

It is the phenomenon of heat soak and thermal gradients. Were the dyno runs done after the engine had been running a long time or were several runs done first and then one final run or was the first run the best since the intake had yet to have time to completely heat soak?

You can calculate the gradient across the supercharger using the following formula:
Te - [(R/RT) x ΔT] = HL

Te = engine temperature, degrees Fahrenheit
ΔT = (engine temperature) - (supercharger temperature)
R = cumulative R-values of all materials starting from the engine
RT = R-value of the total assembly
HL = heat loss, degrees Fahrenheit

R value is just the reciprocal of thermal conductivity
R = 1/C , where C in the thermal conductivity

The snag with using the above formula is that in addition to the engine, the S/C also inputs heat into the system....

So the question becomes, is isolating the Supercharger a good thing (ie would it make the S/C hotter or does it actually cause more heat to be drawn into the compressed air charge)? Ideally you'd want to have the S/C get cooler not hotter so will further isolating it from the engine be a benefit or a detriment? I think Brian's suggestion for using an IR thermometer is a good one and should be done on a dyno after the motor has fully heat soaked the assemblies.

[96 Runner]

Another interesting question (which could be mathematically figured out I'm sure) is how much volume is added with a phenolic spacer kit, and how that might have an effect? Thoughts?

[MTL_4runner]

I just noticed something on their dyno sheet.....

http://www.nissanworks.com/images/VQ35DE-Phenolic-Spacers-Dyno.gif

Anyone come out with 1HP gain not 10HP when you do the math? (214 HP stock vs 215 HP spacers).
I see they just picked out an RPM where you get the highest HP differential not the peak HP difference.
Marketing dept should get a :spank: for that, but the torque still looks decent though.

[mastacox]

Another interesting question (which could be mathematically figured out I'm sure) is how much volume is added with a phenolic spacer kit, and how that might have an effect? Thoughts?


Volume where, in the intake? The small amount of added volume wouldn't have any effect IMO.

[MTL_4runner]

Volume where, in the intake? The small amount of added volume wouldn't have any effect IMO.


I'd agree, the added volume for the TB/intake would be negligible IMHO.
The benefit if any of the mod is clearly the thermal gradient it creates.

[mastacox]

http://www.nissanworks.com/images/VQ35DE-Phenolic-Spacers-Dyno.gif

Using the provided Dyno sheet, we can deduce a couple of things:

1) Any increase in horsepower due to the phenolic spacer by design should be because the vehicle's upper intake is cooler than it would be normally, and therefore the IAT is lower and the incoming air is denser. For the maximum claimed gain of 10 hp at 4300rpm (stock horsepower is about 175 judging by the sheet at that rpm range) you would need a 5% increase in air density; assuming the intake is normally at 150F which could be a tad low, this would mean an approximate IAT drop of 30 degrees, which at least seems to be within the realm of possibility. If the intake is cool to start with, or the entire engine bay has heat-soaked, the effect will be less prominent.

2) The longer the air is in the intake, the less time it has to heat up. Because of this, the higher your engine RPM the lower the effect, as seen by the fact that the "gain" is only 1 Hp at the peak. But this brings up the question of whether the short intake really heats up the air that much anyway... hard to say really.

3) The fact that the largest gains occur in a power-band from about 3800rpm to 5100rpm tells me there may be something else at work here. It might be explained by the fact that the intake had heated up some, and air flowing through it had to cool it down before maximum gains could be achieved (seems doubtful if the power-band is the same for every run). Alternatively, maybe the intake charge isn't cooling at all but instead the intake's resonant frequency is changed by the spacer, and in that specific band the engine is able to take in a little bit more air (a stretch, but seems possible in that it may be similar to exhaust scavenging). If this was the case, it would actually mean that the increase in volume was the culprit; I know, I have already changed my mind on how the volume increase affects things... In any case, something doesn't quite add up in my eyes.

[blink]

I ran a phenolic spacer on my taco a year back and the difference was pretty big. It had gone from being able to touch the the s/c for a few seconds and having to pull my hand away to "cool to the touch". Also, you have to take into consideration that when the bypass valve is open its recirculating the air, so s/c air temps are going to rise with some of the recirculation air being heated again.

[MTL_4runner]

I ran a phenolic spacer on my taco a year back and the difference was pretty big. It had gone from being able to touch the the s/c for a few seconds and having to pull my hand away to "cool to the touch". Also, you have to take into consideration that when the bypass valve is open its recirculating the air, so s/c air temps are going to rise with some of the recirculation air being heated again.


If this is true then I would be very interested in seeing a before and after run with a S/C'd motor and using an IR thermometer to take readings on the S/C itself. It sounds like the engine is adding heat to the S/C rather than removing it so in that case the phenolic spacer would be a good idea.

[Stevo3]

Sounds like it definetly could be useful, But I think the hardest part on the install would be changing out those 2 threads on the front and rear of the manifold to make them longer for the spacer, the 2 that take the nuts.

[blink]

Actually i used 1/4 material and those threads were just fine... it was the rest of the bolts that were trouble.... :)