Cold air intake

The air filter canister is now mounted more neatly than this photo shows. This was my first try. What under the hood is done now. I haven't cut, drilled or welded on anything original under the hood (which was a goal) but I bent some of the sheet metal out of the way inside the scoop area in order to get the 4-inch intake pipe through. It will draw through the scoop and look stock from the exterior. I am currently making an adaptor for the stock scoop to take a hose.

Edit: This picture doesn't show the new location of of the fuel filter, either. Had to move it to make way for the filter.
 

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Steve Hoelscher said:
When developing my '80 model DSP racecar I tried several version of a cold air intake. I data logged the intake air temp and found that none of my attempts were very productive. I did build an airbox that sealed the intake trumpets to a feed from the side scoop but the restriction was such that there was no net gain and I removed it.
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Hi Steve,

that is super interesting to me.
Are you saying that when you data logged the intake temp that the temp didn't change much between drawing the air from ths side inlet vs. drawing it from the engine compartment?
 
Ulix said:
Hi Steve,

that is super interesting to me.
Are you saying that when you data logged the intake temp that the temp didn't change much between drawing the air from ths side inlet vs. drawing it from the engine compartment?
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There were two problems:

1) the only source that produced lower intake air temperatures was the side scoop. Sealing to the under side of the deck lid and drawing through the OE venting from above only lowered the intake air temp by a couple of points. This is because the majority of the engine compartment airflow exits through the decklid and then tumbles behind the rear window. Dealing with the setup was painful and not worth the results.

2) The area of the OE side scoop opening isn't particularly large. The grill slows the rate of flow and reduces the total area. There is a slight ram effect but to produce any additional flow from the ram effect requires proper ducting and there isn't really room behind the scoop to do that effectively. Data logging air temps showed lower intake air temps at the plenum but the dyno showed no gain in power and the car's acceleration curve was unchanged. I assumed that the restriction of the scoop and the indirect path to the intake was just too restrictive to produce any net gains. I contemplated switching to a crank trigger so I could remove the distributor (all of the advance was already handled by the ECU) that was blocking the only available path for a second feed from the right side scoop but never tried that. Perhaps a second feed would have solved the limited flow problem. The thing is testing with a true cold air source on the dyno only netted about 1 HP and that was within the standard deviation so I decided it really wasn't worth the effort at this point.

Cold air sources for mid/rear engine cars is always a compromise. Modern cars have sources designed in but adding and effective one on a 30-40 year old design isn't easy. I came up with one for my MR2 that works pretty well. The 1st gen MR2 has one side scoop located on the right side of the car. It 4 times the size of the X1/9's opening and divides its airflow between the engine compartment and the rear trunk. I diverted all of the feed to the rear truck and routed the intake feed there. With the decklid in place the trunk is sealed and the side scoop is the only feed. It makes the same power with the airbox and trunk feed as it does with the airbox open and the stacks open to the atmosphere.

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I kind of think, given your analysis, that we might all be looking for unicorns, that there really is no significant gain in providing the intake source at any specific point available on the car....more so on street cars.
 
carl said:
I kind of think, given your analysis, that we might all be looking for unicorns, that there really is no significant gain in providing the intake source at any specific point available on the car....more so on street cars.
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How about visual gains?
 
In this setup the air drawn in from the under the gas intake is about 10 degrees celcius higher than the outside temperatuur, but 30 to 50 degrees lower than the temperature under the hood. The compartment under the intake is separated from the engine compartment. Air is coming from the side of the hood. Under the hood the temperature may rise to 80 degrees when driving 120 kmh on the highway for 30 minutes or longer.
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carl said:
I kind of think, given your analysis, that we might all be looking for unicorns, that there really is no significant gain in providing the intake source at any specific point available on the car....more so on street cars.
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That's kind of my thoughts. Its a lot of effort for minimal gain. A snorkel would be ideal if you wanted to do that. I would be interested in dynoing with one.

I should point out that all of my efforts were constrained by the rule book that governed the car's preparation. It severely limited what could be done to the body work. As an example, I could not cut the grillwork from the side scoop. I couldn't remove the rain tray. I couldn't make any new holes in any bodywork. etc...
 
Mxgrds said:
Otherwise it tends to stall when stopping
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If you did not recirculate the BOV it stalls? I don't recall, are you running the OEM-stock ECU/AFM arrangement or aftermarket programmable stuff? Must be OEM, otherwise this should not happen.
 
Steve, did you consider "forgetting" to reinstall the dizzy access plate and just happen to have the intake hose poke into the cabin?
 
carl said:
Steve, did you consider "forgetting" to reinstall the dizzy access plate and just happen to have the intake hose poke into the cabin?
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:D

A stripper dancing on the roof of the car in impound would have been less conspicuous.

Every time the X was in impound it drew a crowd, my competitors looking for the answer to the question as to why the car was so fast. They always looked at the motor, which, while completely legal, was very innovative. That said, my car was typically the least powerful of any on grid. It seemed to never occur to anyone that it wasn't the motor that made if fast. ;)
 
Dr.Jeff said:
If you did not recirculate the BOV it stalls? I don't recall, are you running the OEM-stock ECU/AFM arrangement or aftermarket programmable stuff? Must be OEM, otherwise this should not happen.
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Running stock. The problem is the quality of the bov. It doesn’t close completely with normal driving. Without recirculation it draws false air. That causes a dip in rpm when stopping before red light.
 
It seemed to never occur to anyone that it wasn't the motor that made if fast. ;)



That was made abundantly clear to me when I was road racing motorcycles, I was on a 500 Yamaha single and got passed at turn one at Summit point by a very skilled fellow on a 250 Ducati.

It's always easy to blame losing to all the cheater vehicles in your class when it's probably someone with immensely better skills.
 
I'm not quite convinced that the intercooler gets enough air flow from the side duct.

The only way to tell if it's properly cooling is to stick a thermocouple on the inlet and another on the outlet of the intercooler (and possibly one on the core). If there isn't a significant temperature drop, the intercooler is acting more like an interheater! :)

Proper intercooling unlocks more HP! But, I believe water to air is the only way to achieve this and would be ideal for a street machine. Either way, I'm kinda jealous that you have an engine "in" your car.. mine is still on a stand :(



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myronx19 said:
I'm not quite convinced that the intercooler gets enough air flow from the side duct.
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That goes along the lines of this discussion in general; how to get cooler air to vital components.

Just like with the 'cold-air-intake' some well planned ducting, opening up the engine bay's confinements, increased circulation via electric fan(s), isolation of primary heat sources like the exhaust system (i.e. heat shielding), and insulation barriers to reduce heat transfer will all help. In Steve's situation he was limited by the racing rules, but for a street car you are not. So I think with additional thermal management the temps can be reduced enough at strategic locations to actually improve performance, reliability, longevity, etc.

In the case of an intercooler I agree having it tucked away down there makes it difficult to get sufficient air flow to remove the heat. Especially if the left side scoop is being ducted to a cold air intake instead of the intercooler. A fan mounted on the intercooler would definitely help. Perhaps in this case drawing air from under the car (with ducting) is better than none. Combined with additional thermal management described above it will likely reduce the intake air charge sufficiently. This is a situation where the limited size of the engine bay really hurts if you wish to keep everything contained within it (i.e. maintain a stock outside appearance). Ultimately I've decided not to try to do that, so I'm opening things up and mounting the intercooler just outside the bay (laying flat directly above the area circled in green in the last photo) and adding a fan to it. But I won't know how well this actually works until I can test the temps as Myron suggests. Likewise for the air filter; I'll locate it the trunk with a tube directly to the turbo's intake. Basically I will be sacrificing a lot of normal conveniences/functionality in the trade-off to try and achieve better heat control. But understandably not everyone is willing to do that.
 
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myronx19 said:
I'm not quite convinced that the intercooler gets enough air flow from the side duct.

The only way to tell if it's properly cooling is to stick a thermocouple on the inlet and another on the outlet of the intercooler (and possibly one on the core). If there isn't a significant temperature drop, the intercooler is acting more like an interheater! :)

Proper intercooling unlocks more HP! But, I believe water to air is the only way to achieve this and would be ideal for a street machine. Either way, I'm kinda jealous that you have an engine "in" your car.. mine is still on a stand :(



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Coincidence. Just today I measured the effect of the intercooler. I use a double temp meter from aliexpress. I sticked the sensors on the outside of the pipes going in and coming out of the intercooler with some isolation, to avoid measuring to much engine heat. I didn’t want to measure inside the pipes being afraid a sensor might snap off and is sucked in the engine.

The photo shows the temp meter. It’s behind the rear window. The wires on the sensors are only one meter.

Today it was fresh outside. 16 degrees. At normal driving, the fan on the intercooler not switched on, the temperature drops between 7 and 17 degrees. It was more then i expected. Need to do some more measurements. Highway, hot outside, fan on, etc.

On the photo with the green circle, one of the sensors can be seen just right top the green circle.
 
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Well done. I can't quite tell if the top reading says 11.9 or 17.9 (C), but you stated a 7 to 17 degree drop across the IC. For us I believe that would be about a 45 to 63 degree (F) difference. If your ambient temp is 16 C (61 F), and your charge temp at the IC inlet is 18 C (64 F), that would mean you are getting IC outlet temps below ambient? I think I'm missing something because that isn't possible without adding an external coolant like spraying nitrous onto the IC. Regardless it sounds like you are getting the charge temp close to ambient which is a good goal.

Also I did not realize you already have a fan on the IC. Is it controlled with a temp sensor or manually? I have not decided how to control the fan that will be on mine. The ambient temps here are over 100 F (38 C) a great portion of the year, so I might just connect it to run whenever the engine is running. That could help to avoid heat sink before it creeps up.
Thanks for sharing your results.
 
Nice, yes - even Aliexpress gauges will be sufficient to monitor. I would go into the air though, as this is the instantaneous measurement of the air temps - not the after effects of heat soak (of the tubes) - plus the tubes insulate the temperature to a certain degree, assuming silicone and plastic tanks of the intercooler. Also, since the probe is in free air, a lot of what you're measuring is ambient temps as well, not intercooler performance.

Your delta should be massive when under boost. The intercooler gets hot when under boost, the air passing through it cools it down for the next boost event (not really during boost as air is passing through the cooler very quickly).

I'm no expert, but I HIGHLY recommend reading Maximum Boost by Corky Bell. It's a great book. After all, we want more power!!! :)


Here's a quick video just to show how quickly the boost temp gets on the inlet side. It's rapid, and this guy is using a water to air - this is in C, we're talking over 100 degrees C almost instantaneously! He has a 70C delta between inlet and outlet. That's not bad! :)

gauge on the left is inlet temp in C, and the right display is outlet temp in C.

 
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