How true this is in this case. Axel never fails to impress.
Let’s understand that intake spacers have already been tested and shown to work.
Let’s also understand that intake spacers reduce the intake surface temperature. Thus changing the environment inside the intake manifold that your fresh air travels through.
Let’s also not act like air temperature can’t be effected by the surface area of the material it passes over and is effected by the boundary layer. This is the entire idea of an intercooler. It cools or heats the air as it passes throughout the intercooler. The more surface area and temperature differences the more potential for heat transfer. It’s the entire concept. Surface area aside telling me the air isn’t in the intake long enough to effectively effect the variables of heat and flow can be said about an intercooler as the air very quickly passes through that. A intercooler is designed to alter temperature and while a intake isn’t designed as inter cooler or inner heater isn’t to say the intake doesn’t do that as a byproduct.
Also keeping In mind that spacers also help with turbulence and flow. Now the heat radiating off the manifold will heat up the air adjacent to it, which is within that boundary layer. The more heat that’s radiated (higher IM temp), the more excited the air around the boundary layer gets due to the slight pressure change. This will cause additional turbulence in the boundary layer and increase it’s size, effectively choking the runner a small amount. We know velocity is king for torque, so one could argue this is okay at certain (low) air speeds, but once you start flowing enough air, that’s when the choke down starts to hurt.
Intake spacers do several things to help performance. The big rub comes when your try to put the exact number on the effects they have. The percentage will change as the temperature changes and with a ton of variables there is no curve to say this or that is the exact amount of power or gain. The gains from spacers can be seen in the drastically reduced intake temperature and consistent acceleration with less heat soak.
In the end your reducing heat and the effects of heat transfer. And that’s always a good thing
I’m not questioning it. I believe the gains in most situations you put the car in are too small to reliably measure even for JHM. I went through the AZ thread linked to earlier and the data presented is inconclusive at best.
IF we can manage to indirectly, but reliably, measure the amount of heat being transferred (which will have to involve insulating the top of the manifold I suppose) we would have by far the most accurate number for temperature gains possible.
The problem is the counter-intuitiveness of it really. One manifold feels cold, the other feels hot, so the gains must be substantial. The specific heat capacity of the manifold material is lower than that of air. At full throttle there is a lot of air mass passing through. Every few seconds an entire manifold mass worth of air goes through. So you can transfer quite a lot of heat without that heat affecting intake temperatures to a large degree.
[quote=justincredible]Let’s also not act like air temperature can’t be effected by the surface area of the material it passes over and is effected by the boundary layer. This is the entire idea of an intercooler.
[/quote]
Did you miss the part where I talk of intercoolers in the very first post?
Anyway, I will gather data and come back to it. It’ll be a couple of weeks.
explain yourself. You can’t just drop a comment like that and not back it up. You call EVERYTHING inconclusive when it doesn’t agree with you. I have already pointed this out…it’s because you’re an engineer. It’s in your nature to question things. Granted, however you need to wake up man…we’re talking about accelerating in our cars. For fun. We’re not building a bridge that will be used to transport yellow cake. There’s a point where you have to recognize that NO test is perfect and you need to use what is available to you. If you can’t, you’ll always be stuck in your textbooks. While everyone else is accelerating faster in their cars.
To show the forum part of their testing, JHM posted acceleration in RPMs per second using a vagcom log on the same stretch of road both with the spacers and without. You can actually see the RPMs per second data falls off quicker without spacers. It’s very minor…something like 3-15 RPMs per second difference. For perspective, my car gained around 80 RPM/second with tune downpipes and bolt ons and exhaust on that platform, if my memory serves. That was around 40 hp…so you’re talking the effective difference of maybe 6-7 hp MAX. Not a GAIN of 6 or 7 hp…but the REDUCED LOSS of 6-7 hp. This is key to understanding the product because you keep talking ‘gains’ when the point is to preserve power while accelerating, not add it.
[quote]The problem is the counter-intuitiveness of it really. One manifold feels cold, the other feels hot, so the gains must be substantial.
[/quote]
See this is all in your head. Show me ANYWHERE that someone has said
a) there are ‘gains’
b) those ‘gains’ are substantial
You will find that nobody did. We are preventing losses here. The runner length torque bump is nominal. JHM mentions this and says that is nearly immeasurable in any demonstrable fashion. They instead focused on the ability of the car to make repeated acceleration runs with and without intake spacers on the same stretch of road in the same conditions. The car with spacers accelerated better, to the tune of about 3-15 RPM per second, starting at the lower end of that range when both cars ran their first runs, and moving to the bigger end when they made their 3rd, 4th, 5th runs.
I think you’re arguing with yourself here. You’re entirely missing the mark.
Here is JHM’s log spreadsheet that they posted 7 years ago. Euroswagr copied that post in a new thread here yesterday.
The key is 4200-6500 RPM. The B67 S4 is best shifted at about 6500 when all motor. When you change gears going full chat, this is the range you’ll find yourself in.
In the first run, both cars were similar. 522 spacers vs. 519 without. 3 RPM/second difference. Nominal.
On the second runs, the delta starts to show up. 524 vs 512. 12 RPM/second difference. Getting bigger and this is measurable. The key is that the spacers car hasn’t really lost anything from run 1. The no-spacers car however has dropped the equivalent of about 3-4 hp
On the final run the delta is biggest (makes sense). 520 vs 501. 19 RPM/second, and maybe 5-7 hp. The JHM car is down barely at all from the original run. The no spacers car has dropped from 519 to 501.
JC is the type of guy that can’t see outside of his box. If it doesn’t make sense on paper or a computer program, then it isn’t possible. Forget the fact that he is controlling all of the equations and variables he wants to use to fit his argument.
All this talk about spacers has me excited! JHM intake manifold and spacers are going on tonight!
but didn’t you read the post by the guy with no performance testing and no credentials…he said they probably don’t work because his volvo intake manifold wasn’t that hot!
I’d need to know the volume of the manifold for the first one. Anyone want to fill theirs with water and check?
The second is too difficult to accurately calculate because surface area is a total unknown, hence why I suggest the best way forward would be to calculate exactly how much energy is being transferred (need mass and delta T measurements) and then apply that number to the mass of air and the heat capacity of air both of which are known.
So that’s my suggestion. I’ll fix a K-type thermocouple to the manifold (will try out a few different spots) and another to the head as close to the manifold as possible. We’ll do idle tests, running tests, and the rate at which the temperature of the head and manifold converge once the engine is turned off with no airflow through the manifold or over it.
Can we at least agree on the fact that whatever heating effect a warmer manifold has on the air, the effect will be largest at low rpm and smallest at high rpm?
And that whatever the delta T between the spacered manifold and the regular setup is, the change in air temperature will be only a fraction of that difference?
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Even if you know the rate of energy transfer while the engine is off it would be inaccurate, too many draws on the engine while running the heads cooling lines oil outside air inside air ambient conditions all play a factor while the engine is running even the amount humidity in the air could effect your results. You know as well as I know there is only one way to get an answer here that will hold any merit air temps before manifold and air temps after. The concept is simple. Not rocket science.
Even if you did get a result you would only have what the potential heat transfer could be to the air in the manifold with out the surface area you would have know proof of how they actually interact.
I don’t have any number results for the intake spacers but I can tell you this…
A while back when I was running the JHM tune and spacers I did the NYC RS4 run. After driving for about an hour and a half we all stopped at a check point, me and another RS4 owner opened our hoods side by side and felt each other’s IMs… mine was completely cold to the touch and his was warm/closer to hot.
It does make a significant difference in that aspect and I can’t imagine it not helping in engine performance.
Compared to so many things for this car it’s relatively cheap and almost a why not mod.
I’d just like to point out this wasn’t invented or used for the first time in our application.
FORD Racing sells a GT-40/Cobra Intake Manifold Phenolic Spacer Kit designed to reduce heat transference between the the upper and lower intake manifold to lower inlet air temperature to increase horsepower and allow for increased timing with less detonation. It’s been around since the late 80’s, still available to buy today…
I saw ArthurPE’s name above, brought back old memories…
Beyond Ford Racing, Trick Flow also sells them for the 5.0 crowd…
Lots of testing shown in MMFF back in the day. Great point I think this is just something the hard core guys that have really been around race cars for a long time know about and have already seen the testing. It’s been successful and successfully tested now for years. It’s almost like these guys that are new to the scene don’t know car history or modification history. You almost have a situation where the newer guys who don’t know cars or car history actually move backwards.
Everyone had a good weekend?
Because there’s more than one variable? If they posted full VCDS logs along with the rpm/second numbers maybe we would have something to analyze in depth. The differences are also quite small in absolute terms so I’d like to see data from a much greater number of pulls for statistical relevance. There is a margin of error and variability inherent in this type of testing.
I’d also like to know how the testing was done precisely. Did they heatsoak the car after each pull for a fixed amount of time or did they do them in very short succession? At high engine loads you’d be cooling down a hot manifold during the actual run because of the sheer amount of cool air going through it. Depending on how you test it performance could increase or decrease in subsequent runs!
An actual temperature probe on the manifold would also go a long way to understanding exactly what goes on.
[quote]I have already pointed this out…it’s because you’re an engineer. It’s in your nature to question things. Granted, however you need to wake up man…we’re talking about accelerating in our cars. For fun. We’re not building a bridge that will be used to transport yellow cake. There’s a point where you have to recognize that NO test is perfect and you need to use what is available to you.
[/quote]
I am not an engineer, which I think I’ve pointed out before. I do question things, which is generally a good thing for the sake of understanding and making progress as far as I’m concerned.
[quote]Show me ANYWHERE that someone has said
a) there are ‘gains’
b) those ‘gains’ are substantial
[/quote]
Well, I said that any ‘gains’ there were would not be substantial. This thread ensued. So I am assuming that people don’t agree with my statements which implies they do think your points a) and b) are true.
Furthermore, someone posted after this:
[quote]mine was completely cold to the touch and his was warm/closer to hot.
It does make a significant difference in that aspect and I can’t imagine it not helping in engine performance.
[/quote]
That’s what I meant with intuitiveness being an issue in matters like these. Reality can be extremely counter-intuitive sometimes. That doesn’t mean that it is in this case, of course.
We need multiple measurements in multiple scenarios (some with the engine running, some not) to get a somewhat accurate idea of how much conduction goes on. It’s not going to be perfect, but a hell of a lot better than what we have right now.
We can do without the (impossible to calculate) surface area. We need to find out the conductivity, measure the actual delta T between head and manifold and log the amount of air going through the manifold.
The difference between expected temperature change and actual will show what is being transferred to the air. There’s nowhere else it can go in any big amount.
Even if the end result would be that spacers might be worthwhile after all, we’ll have a MUCH better understanding of the exact changes the air undergoes inside the manifold. If everyone kept following the contemporary line of thought without questioning we’d still be in caves.
it’s a comment on your mindset, not what it says on your business card. You’ve confirmed engineering was your education path in the past so I’m not sure why you say you aren’t.
[quote=JCViggen]Well, I said that any ‘gains’ there were would not be substantial. This thread ensued. So I am assuming that people don’t agree with my statements which implies they do think your points a) and b) are true.
[/quote]
sorry…because people don’t agree with you that spacers ‘do nothing’ per your thesis, you assume the forum in general now believes the spacers make ‘gains’ and ‘substantial gains’ at that? Even though everyone has told you they bought these to prevent losses, as minor as that may be since they help? Your assumptions are pretty piss-poor. Try to pay attention when people are helping you.
I really don’t understand guys like this…I’ve said it half a dozen times already
NO ONE believes these add 20hp, but we know from actual experience with OUR cars that these spacers prevent a LOSS.
In my book preventing power loss is just as important as adding power, same reason guys upgrade cooling systems and intercoolers. No one ever said an upgraded intercooler will provide you 20hp, but it will help you lower IAT and either push a little more boost or prevent a loss from the higher IAT your old intercooler provided.
We aren’t telling you to buy these JC, we are simply disagreeing with you statement that these spacers “do nothing”…because it’s pretty obvious that is wrong.
I dont know half as much as some of the members on here. With that said after reading this thread i decided to hand touch my car friday night before the new IM and spacers went on. I drove 30 minutes in traffic to my buddies house. WAITED 30 mins with hood open to get engine as cool as possible to work on. EVEN AFTER leaving the hood open for half hour after driving i couldnt keep my kind on IM for more than 5 seconds.
Saturday i drove the car from my buddies house. I drove the piss out of it for 25 mins (love the new intake manifold pulls strong up top). I got home and popped the hood INSTANTLY touched it. I could keep my hand on the intake manifold and had NO NEED to pull my hand off of it.
So with that said, in my mind as others have stated. This probably doesnt net me shit. Maybe 3 or 4 hp. BUT this is me just thinking, when the engine becomes heat soaked and you loose power because of heat soak this would cause me to NOT LOSE AS MUCH HP which technically is giving me gains when the engine is heat soaked.
If im off tell me BUT you cant sit here and tell me they do nothing. That just doesnt make sense.
[quote=“sakimano,post:56,topic:7232”]
Where did I say that, good sir? I definitely said the effect was not zero. Just that has to be very small to the point that 250 bucks is a lot of money for the expected improvements over stock.
And for every example of someone selling phenolic spacers or a race car using them, there are many more which don’t use them. Most cars used in competitions don’t use phenolic spacers. Most manufacturers don’t use them either. Couple weeks ago I saw a relatively modern Ferrari engine in bits, nice big aluminium intake manifold and all. Nothing there to act as a heat barrier. It would cost Ferrari peanuts to include, or even make the manifold out of a different material if heat transfer to the air was an actual concern.
Heck, Aluminium is a poor design choice in general if you believe there is a significant amount of heat being transferred to the air to the point performance degrades. Still most cars both cheap and expensive use them. Some are using plastic (vastly superior heat transfer properties!) on their cheaper models and then fit an Aluminium one to the more expensive ones… shooting themselves in the foot supposedly.
Anyway, I’ve got a plane to catch. With some luck the stuff we need to gather data will be waiting for me in Belgium along with the car parts that have been piling up in my parents’ flat.
What formula are you planning on using? I can’t fathom how you would be able to tie any pertinent data results back to the manifold unless you actually use the the manifolds physical interaction with the air. Imagine I have a cube of aluminum and a sheet of aluminum I apply the exact same amount. Of energy to both the place both in a chamber of air the exact same amount of air. They will absorbe all the energy differently and releas it differently the air will again react Differently even tho they have the same mass. For you to say you can accurately predict how the air will react to the manifold with out knowing how it is physically interacting with the air you are a wizard.