To intercool or not to intercool?

It'd make more boost on the engine that flows less.

The SC14 seems to be a popular option for Commodore guys with the 3.8 V6 - might it be too much for a 1.5L?

DaewooOfDeath wrote:

Keith Tanner wrote: I've seen a setup using fuel as an "intercooler" blow a lot of engines. It's always blamed on something else, but statistically it's an outlier. One thing to consider is throttled volume. On a SC setup, your throttle is usually pre-SC. So all the air volume between the supercharger and the intake ports will have an effect. Higher volume adds some lag but more importantly it'll add to idle droop and general poor idle behavior. I'd rather run a methanol injection system with some failsafes in case of a methanol delivery failure. Dunno what an SC14 is, but I know that intake temps on an M45 running 6 psi on a 1.6 engine are over 200F. Not sure how much over, the sensors we were using at the time peaked at 100C.

With what I'm planning to do, the throttle body will actually be about a meter behind the supercharger. Like the picture, but since I'm transverse and interested in making the install as stealthy as possible, mine is going to mount under the powersteering pump, wrap around the bottom of the intake manifold and then attach to the factory throttle body location.

Watch out, putting the tb post-sc means you need a big blowoff valve I've seen them blow the seams on intercoolers with pressure surges. It'll also make a fairly unholy noise. All the time. It's not stealthy.

soooo... I'm gonna have to argue that adding fuel DOES cool the intake charge, though I'm not going to calculate by how much, and therefore I don't know if it is significant.

1. Intake charge temp is air + fuel + whatever else. As long as the fuel or whatever else you are injecting is at a lower temperature than the air, then you are cooling the combination. (i.e. pour a glass of boiling water into a glass of ice water - the result will be neither boiling or ice, but rather lukewarm). I would imagine this could have a significant effect, since the fuel is much more massive than the air.
2. Adding anything not compressible (any liquid) to a combustion chamber effectively raises compression and tendency to detonate. If the goal is to reduce tendency to detonate, adding the fuel or meth or NO2 or water must also be having another effect to more than counteract the bump in compression, which I believe is cooling.
3. old-school tuning. rich runs cooler and lean runs hotter.

I would totally intercool.

http://www.bellintercoolers.com/pages/techFAQ.html#FAQ_1

Keith Tanner wrote:

DaewooOfDeath wrote:

Keith Tanner wrote: I've seen a setup using fuel as an "intercooler" blow a lot of engines. It's always blamed on something else, but statistically it's an outlier. One thing to consider is throttled volume. On a SC setup, your throttle is usually pre-SC. So all the air volume between the supercharger and the intake ports will have an effect. Higher volume adds some lag but more importantly it'll add to idle droop and general poor idle behavior. I'd rather run a methanol injection system with some failsafes in case of a methanol delivery failure. Dunno what an SC14 is, but I know that intake temps on an M45 running 6 psi on a 1.6 engine are over 200F. Not sure how much over, the sensors we were using at the time peaked at 100C.

With what I'm planning to do, the throttle body will actually be about a meter behind the supercharger. Like the picture, but since I'm transverse and interested in making the install as stealthy as possible, mine is going to mount under the powersteering pump, wrap around the bottom of the intake manifold and then attach to the factory throttle body location.

Watch out, putting the tb post-sc means you need a big blowoff valve I've seen them blow the seams on intercoolers with pressure surges. It'll also make a fairly unholy noise. All the time. It's not stealthy.

Good info on the BOV. As for the noise, they come with electronic clutches, like a/c pumps. That's actually why I'm thinking blower over turbo. I'm hoping I can spend my commute with an effectively completely stock engine and only have the crappy gas mileage and higher wear when doing so is actually fun.

rcutclif wrote: soooo... I'm gonna have to argue that adding fuel DOES cool the intake charge, though I'm not going to calculate by how much, and therefore I don't know if it is significant. 1. Intake charge temp is air + fuel + whatever else. As long as the fuel or whatever else you are injecting is at a lower temperature than the air, then you are cooling the combination. (i.e. pour a glass of boiling water into a glass of ice water - the result will be neither boiling or ice, but rather lukewarm). I would imagine this could have a significant effect, since the fuel is much more massive than the air. 2. Adding anything not compressible (any liquid) to a combustion chamber effectively raises compression and tendency to detonate. If the goal is to reduce tendency to detonate, adding the fuel or meth or NO2 or water must also be having another effect to more than counteract the bump in compression, which I believe is cooling. 3. old-school tuning. rich runs cooler and lean runs hotter.

I'm not saying it doesn't cool AT ALL, though i suppose i should have made that more clear before.

I'm just saying that actual cooling is a FAR second to what's actually happening.

I guess none of this really matters without hard data. I know it's out there, this has been the subject of many lengthy discussions.

If this does actually cool a noticeable amount, then why not just run bigger injectors to begin with and run it richer? But, we know that that doesn't keep up. All my turbo cars would not survive without an intercooler with their current tunes. Could i hold them together for a bit without one, adding meth injection and re-tuning? Maybe. At lower power levels.

Rough math using big turbo stuff i found on another discussion about this.

"If your intake tract is 1 cubic foot, and your S366 flows 600cfm, any drop of water/meth will therefore spend a tenth of a second (likely less) in the intake tract."

I'm not a physic major or anything, but it seems unlikely that spraying meth will be able to do all the things it needs to do to cool your IATs by 50% (or more, to match the efficiency of an intercooler) are unlikely to happen within the extremely short period of time it has before it hits the combustion chamber.

Also, the amount of meth/additional fuel/water/whatever you're spraying does not have the volume necessary to counteract the temperature of the air coming through to anywhere near the effect of an intercooler.

DaewooOfDeath wrote: Good info on the BOV. As for the noise, they come with electronic clutches, like a/c pumps. That's actually why I'm thinking blower over turbo. I'm hoping I can spend my commute with an effectively completely stock engine and only have the crappy gas mileage and higher wear when doing so is actually fun.

The problem with that idea is that unless you have some way to bypass it, the SC will really choke the engine of air when not being driven.

I'd consider running it this way: Filter > TB > SC > Air/water IC > Intake manifold. The A/W intercooler will not increase system volume the same way a air/air with plumbing would.