Intake manifold bolts, BAT reductions

I love data and science. My educational background includes a healthy dose of it, specifically the analysis of research methodology to determine the value/applicability of various studies. Having said this, I suspect the reduction of BATs due to SS or other fasteners with less thermal conductivity with be minimal, at best. The gasket itself has much greater surface area to facilitate or prevent heat transfer. Further, a minimal BATs reduction will likely have an immeasurably small impact on actual power output, less than the margin of error measurement window. For instance, it'll probably be imperceptible with VDyno or even an actual dyno. That's my hypothesis, anyways. I'd love to see what you find, though.

 

IMO, people over focus on total power output and not enough on things that cannot be captured on a dyno.

I guess its a case of X will get you Y. With Y being imperceptible but larger than zero. Now we know.

The fuel rail setup should be interesting, as the fuel is being pressurized quite a bit in between the proposed measurement points. I think the prevailing idea is that fuel can/does cook off at the pump after shutdown, which sets a baseline for the expected temperatures entering the area.

 

So what benefit are you suggesting exists, potentially? I glanced through the other thread, and it seemed to be focused primarily on heat transfer, not anything else. Did I miss it? If so, what is it, and how will you operationalize it and control for extraneous variables??

 

Potentially exist for the intake, or the fuel rail?

For the intake the benefits would be the same as seen with the phenolic gasket. For the fuel rail its up in the air if reducing the temperature at the pump or rail would be beneficial to fuel flow and slowing/stopping fuel boiling off after shutdown.

I would be open to ideas about controlling variables. I dont intend to put my car on a dyno in a temperature/pressure/humidity controlled wind tunnel each time, so the options are limited.

 

TL;DR Scientific Experimentation Philosophy and its Application - Skip if It's Not Your Cup of Tea

I hear what your're saying, but to me those are less a matter of benefits, and more a matter of effects. A benefit for the IM, for instance, would be "because X material transfers Y less heat from the head into the IM, we see a difference in Z of such and such amount (which could be lower BATs, for instance, or anything else that has is a positive, measureable outcome). Are BATs the only variable that could be deemed thusly? No. But for most people, they're the first thing that comes to mind regarding keeping your IM cooler. Why would you want your IM cooler if not for BATs being lower? And if you spray methanol, like me, it's a completely moot point.

For the fuel rail/system, potential benefits are even more elusive. The only thing I can think of is the fuel boiling in the HPFP is sometimes associated with accumulation in the HPFP that can need cleaned out, or can clog up the spill valve. Flow increase cannot be a benefit for the fuel system because the limiting factor is the DIs themselves. I'd surmise you wouldn't see a drop of even 1 IDC under controlled circumstances, but I'd love to be proven wrong. We all know the relationship of a pressurized system on the boiling point of a liquid. When running a Speed WOT and seeing 1700-1900 actual psi, fuel boiling is not an issue at all.

In other words, a benefit addresses a known problem in an influential manner, or has an outcome of performance increase. And as a pragmatist, if a "problem" really isn't a big deal (for instance, different IM fasteners only making a 3 degree difference in BATs at best (completely arbitrary #), then there's really no point in swapping fasteners for other pragmatists, like myself. For a "performance increase" if we're only talking about a few degrees, then there's really no point because it doesn't manifest is statistically significant and accurately measureable outcome, you know?

 

You are suggesting that time and effort should only be invested into projects that have a known, and substantial beneficial outcome? That completely ignores knowledge that we don't know that we don't know. Which is where we are right now with the complete lack of information as to what temperatures are present, in the fuel line, relative to the engine.

 

TL;DR What's the point?

It depends on what you're testing. I mean, let's put this in perspective: you're not trying to cure cancer.

I can philosophize all day long. Literally. I know all about epistemology and have studied it extensively. I <3 esoteric and abstract concepts for the sake of thought experiments, if nothing else.

But with regard to modding, I'm a pragmatist. I see no potential benefit to your tests. Could one arise? Perhaps, like I said above. But heat transfer of bolts? C'mon. I certainly love data, but based upon surface area alone, are you going to construct a repeatable experiment that produces statistically significant results on multiple cars in multiple climates with multiple setups?

And what is the point of knowing the temperature of fuel in a 1700-1900psi system? The scientific method starts by attempting to test a hypothesis. What's your hypothesis? And what conclusions would proving or disproving your hypothesis potentially lead you into? Or if you're strictly gathering data, why? You must have some idea of some potential outcome that Speed owners would care about, or else you wouldn't do it.

 

No one seems too keen to assist in the multiple climates and setups arena. So thats kind of a dead end.

Is the fuel temperature above the temperature of the engine coolant/oil? If so, by how much? How much does the fuel rail temperature rise from idle (~400 PSI) after consistent operation at ~1700 PSI? I don't know, so I am gathering data to provide insight.

At this point, with the amount of DGAF I see, I dont really see the point in sharing much of the data.

 

It's not that I don't care. Ask anyone around here; heck, check out my threads: I LOVE data. But data always has a purpose for me.

Look, I'm not trying to give you a hard time. My question is genuine: why does fuel rail temperature matter? I've already provided the only conceivable reason I can think of: its bearing on the accumulation of sticky death in the fuel pump. But if you're going to test that hypothesis, you've got a ton of dis- / reassembly work ahead of you. Not to mention the sticky death issue has already been solved.

I'd LOVE to hear another reason why you want to know about fuel temps inside the rail. Seriously. But saying why it matters, or even why it could matter, is fundamental; otherwise, what's the point? That's the disconnect I'm having. Make sense? I don't understand why you're planning on doing what you're suggesting. You say "to provide insight." Insight into what phenomenon/phenomena that relate to fuel temps?

 

It would be interesting to see if eliminating temperature delta could stabilize fuel pressure a bit.

 

There ya go; now we're talking. My point wasn't to nitpick, but to have objective questions we're trying to find data about, or at least data that could be related to it. Another question naturally follows: what would be the effect(s) of stabilizing fuel pressure? Would this increase HPFP internals or HPRV longevity? Would this mean a higher average flow rate? Etc...

 

I've seen/read that a temperature delta across a fuel rail can be significant enough to affect performance. The hottest section of the rail presumably limiting via flow rate, or knock. If we keep the entire fuel system cooler we could potentially increase fuel density, increase knock threshold, and probably reduce long term failure rates.

If the fuel in the rail (technically metal of the rail, not the fuel itself) is only 10 deg F above ambient with a 5 deg F delta then there is no point in further investigation. If its 100-150 deg F above ambient with a 50 deg F delta, then maybe its worth looking into further.

We wont know the potential scale until we have data to review.

 

Pump housing is roughly 25 to 45 degrees below ECT at all times. Passenger side of the rail is roughly 5 degrees hotter than the pump housing. Delta cross the fuel rail immediately after shutdown is 5 degrees. While driving it is ~10 degrees F, at most 17 degrees across.

Assume ECT is between 180 and 192 at all times.

 

Interesting data points. In situations like traffic, the radiator fan doesn't even turn on until 216 or 217, so we know there are conditions during which we see much higher ECT, especially where I am, in TX.

 

Agreed that 216 is when the fans normally turn on. Do you believe that the temperature delta across the fuel rail will be dramatically different at high temperatures?

 

Fuel pumps through the very short rail at such a rapid rate and such high pressure (especially @ WOT) that I believe rail temperature has a very minimal impact on fuel temperature.

 

217 switch on

I finally got around to reading your thread. It was great seeing you at the BBQ as well.

 

Injectors see the flame front, so temperatures can be high. They only get cooled by the water jacket in the head (minimal contact) and the fuel leaving them, which will be hotter during cruise (longer time in the rail) and cooler just after a WOT or other high flow pull. The temperature of the fuel does go up after shutdown, as can be seen during a normal PRV test. How high it goes depends on the ambient and engine temperatures, obviously.

Injector / fuel temps could be a factor in long cruise blowups on completely stock tunes but that would be tough to prove.

I can all but guarantee that fuel does cook off in the pump, vaporizing and pushing liquid fuel back into the tank. I can just about prove this too, as I did a similar test for black death many moons ago and came up with a set of circumstances that shows evidence that such a thing is actually happening; I can elaborate more if you like.

Ultimately, chasing lower manifold temps to the point of lower bats is a fools game IMO, since the temps drop rapidly during a WOT pull and equalize within a second, 1.5 at the most. If this is truly a serious concern, the easiest thing to do is probably swap to a plastic manifold; next easiest thing to do would be to have the manifold ceramic coated, and after that probably develop a heat shield out of ptfe or something that would go in where the MAP sensor is installed with the goal of blocking the *radiant* heat from the manifold itself, though that seems somewhat wasteful on time and money to me.