Phenolic Spacers, and their effectiveness

I'd like to hear people's thoughts and impressions of phenolic spacers.

To be a little more technical:
I understand that the IM can, and does, get quite hot. The heat in the IM will transfer to the intake charge, resulting in less dense air, etc... I've even seen the graphs of IM temp with- and without phenolic spacers, and that temp can be quite dramatic. However, has anyone actually put a temp probe into the IM and measured the effect on the charge itself? I havent busted out any of my heat transfer and fluid dynamics books, but I wonder just how much heat is transfered to the intake charge during the very short period it spends in the intake manifold.

^^ Agree'd as the O.P. said the charts show the difference when comparing the with and without the phenolic spacers. Heat transfer through the metals makes a huge change in air temp which creates less dense air in turns reduces power as the engine heats up so help reduce the IAT by reducing heat transfer and you will maintain optimum performance.

I sold my heat transfer textbook years ago to get some quick cash, but I did some quick googling of equations and made LOTS of assumptions. The resultant math was quite surprising--which makes me think i did it wrong. If anyone else has a textbook, or some time to google, i'd love a math check.

Assumptions:
100F IAT post IC.
18" IM length per cylinder
2.5" diameter per cylinder
Smooth, circular walls
Laminar, fully developed, continuous flow
Engine breathing at 350 cfm (so x1/4 per cylinder)
Constant temp of IM
-152F without spacers (taken from Grimmspeed's website)
-134F with spacers (taken from Grimmspeed's website...but shouldn't it be lower?)

I know thats a LOT of assumptions, but i figured it'd give me a ballpark figure. If (a big IF) I did my math right, there's about a tenth of a degree difference in temp of the air at the heads with and without the spacers.

Fujiwara said:

I think that list of assumptions may be drastically oversimplified.

Click to expand...

Agreed. If i still had access to a COSMOSworks i'd try to model something up.

I'm also contemplating doing a tgv delete, and putting a temp probe where the tgv comes out. I've never seen the part in person, so I don't know how feasible that would be. I also dont know how motivated I would be to take the IM off for the TGV delete, and then again later for phenolic spacers for a before/after comparison.

the laminar flow assumption is almost definitely wrong. changing it to turbulent you will see much higher heat transfer to the intake charge.

melia said:

the laminar flow assumption is almost definitely wrong. changing it to turbulent you will see much higher heat transfer to the intake charge.

Click to expand...

yeah, i thought of that after i did the math. But the heat transfer coefficient is only like 4 times more right? Still sounds like a negligible temperature difference...but there are still some monster assumptions up there, like continuous flow and circular IM piping.

I think the only way to get an accurate result is to model it or test it in the real world.

if you could get the manifold cad drawing i could test it for you with star ccm+

Grinder34 said:

yeah, i thought of that after i did the math. But the heat transfer coefficient is only like 4 times more right? Still sounds like a negligible temperature difference...but there are still some monster assumptions up there, like continuous flow and circular IM piping.

I think the only way to get an accurate result is to model it or test it in the real world.

Click to expand...

No manifold drawing.

You could always simplify it and have it be a tube with a radiused bend. I know intuition can get you in trouble, but i dont think the exact shape of the manifold and TGVs is going to be the major determinant of heat transfer. Maybe just assume surface roughness is really high?

But if you wanted to eliminate the shape-related transfer unknown, you could make the whole interior roughly the profile of the TGV-engine interface like so:



But I think most of the manifold and tgv path is relatively circular. Even at the tops of the tgv it's still circular.

As Grinder asked for here are 2 test results:

I beat these things to death and tested out the temperatures at the TGV's and at the IM runners. I was pretty surprised to see that they on average reduced the TGV and IM temps by 10*! This is WITH thick phenolic spaces on as well (both stock and TIC's). Here are the results.

Stock with Phenolics:
At TGV's inner side is where the temps were measured:

#3 - 145* #4 - 140*
#1 - 141* #2 - 141*

Note: #3 is hottest due to location by turbo.

Intake Manifold @ the runners above flange

#3 - 124* #4 - 111*
#1 - 128* #2 - 119*

TIC's Composite TGV's:
@ TGV's

#3 - 140* #4 - 105*
#1 - 130* #2 - 130*

Intake Manifold:

#3 - 110* #4 - 102*
#1 - 113* #2 - 109*

&

Stock No Spacers:
At TGV's inner side is where the temps were measured:

#3 - 155* #4 - 145*
#1 - 146* #2 - 144*

Intake Manifold @ the runners above flange

#3 - 134* #4 - 120*
#1 - 140* #2 - 129*

TIC's Composite TGV's:
@ TGV's

#3 - 138* #4 - 125*
#1 - 134* #2 - 128*

Intake Manifold:

#3 - 108* #4 - 101*
#1 - 108* #2 - 107*

Is that surface temp or air temp?

I know every bit helps with keeping temps down, but I'm just curious how much thermal energy is really imparted back to the intake charge after the IC.

Also, any thoughts on why #1 and #3 are so hot vs 2 and 4? The metal coolant pipe under the IM?

Time to revive this thread.

So I'm about ready to finally do my engine build and am considering getting a set of 3mm phenolic spacers.

Do you guys feel that this is a worth while upgrade since I already will be reinstalling the intake manifold?

What's the Preferred spacer KS or Grimspeed?

TiC (i think its them) makes a nice set of composite TGVs, albeit at a slightly higher cost.

If i already had the IM out, i'd do one or the other, as it certainly doesnt hurt to have even slightly lower temps there.

Dunno about size or brands though.

Grinder34 said:

TiC (i think its them) makes a nice set of composite TGVs, albeit at a slightly higher cost.

If i already had the IM out, i'd do one or the other, as it certainly doesnt hurt to have even slightly lower temps there.

Dunno about size or brands though.

Click to expand...

I plan on doing the composite TGV housing when I switch from side feed to top feed injectors when I do a turbo upgrade in the future.

If I can turn off the code and keep my pro tune on my ap I will do the tumbler valve delete on the side feeds but I need to look in to the code issue a bit more.

You can usually email your tuner and they can just disable the codes and email you an updated map. Pro-tunes are locked IIRC, so any change must be done by them. But for a simple code disable, I think its usually gratis.

I'd do the phenolic with the composite tgv.
As grinder said, if your map is locked then you can't disable the codes. Your tuner should be able to hook you up.
As for tuning? Some say you should and others no. Log your trims to see if anything is outta whack. You might need a retune.

Grinder34 said:

You can usually email your tuner and they can just disable the codes and email you an updated map. Pro-tunes are locked IIRC, so any change must be done by them. But for a simple code disable, I think its usually gratis.

Click to expand...

The tuner was dan Harmon and he no longer tunes public cars and it's also on a version 1 cob ap so that could be an issue as well blahaha

Alinro guided me here so I will post comment on my experience soon. I'm not an engineer, let alone be a guy who can calculate all the stuff mentioned earlier in this thread
I have installed the 8mm Grimmspeed spacers last week. Haven't driven the car yet due to other modifications in progress, so you'll have to be patient

What I DO know, is this: installing the spacers without eliminating the other 2 'heat sources' will have less effect. IMO if u install the spacers, at least do the throttle body bypass mod as well. Keeping the TB 'cooler' will also reduce heat in the IM. Last but not least, the coolant tank also touches the manifold, thereby transferring heat as well.
I know this will sound stupid, but even if every mod reduces temp with only 1 degree (for example), it already makes 3 in total . So all the little bits help (correct me if i'm wrong, this is purely my vision and I can't proove anything ).
Keep in mind that it's not only transferred heat influencing the IM, it's radiant heat as well. Therefor, a good heat shield or turbo blanket can help keeping the underbonnet temp lower. As I said before, many small things....