Rear Undertray Extractor Design Question
#1
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I'm installing an intercooler in the bottom portion of the front bumper, between the inlet of the bumper and bottom of the radiator. It's occupying some of the space of the factory undertray now, thus I have to build a new one. It's like an upside-down v-mount, sort of. Sav did it a long time ago, I dunno how well it worked for him though.
Here's a drawing of what it looks like, and my guess at what the undertray should look like.
I'm not the best at predicting how airflow works, so I wanted to get the expert opinions here on if this extracotr/undertray will work, or what I can change to make it work better? I basically found some pics of how some race cars do hood extractors, and used that design but upside down since it's on the bottom of the car. I labeled some of the points and pieces to make discussion easier.
Thoughts? Do I even need Sheet Metal 3 if the splitter is there? Or would it worthless? Would moving point "D" further down improve airflow through the intercooler?
Here's a drawing of what it looks like, and my guess at what the undertray should look like.
I'm not the best at predicting how airflow works, so I wanted to get the expert opinions here on if this extracotr/undertray will work, or what I can change to make it work better? I basically found some pics of how some race cars do hood extractors, and used that design but upside down since it's on the bottom of the car. I labeled some of the points and pieces to make discussion easier.
Thoughts? Do I even need Sheet Metal 3 if the splitter is there? Or would it worthless? Would moving point "D" further down improve airflow through the intercooler?
![](https://www.miataturbo.net/attachments/race-prep-75/143639-rear-undertray-extractor-design-question-undertray%2520design_zps6dpjktpg.png?dateline=1436119521)
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Well I figured having a duct of some type on the bottom was better than nothing. Right? Like when people do hood vents vs just cutting a hole in the hood, the use an actual vent/scoop depending if it's an inlet or outlet.
But I've never made a vent thus this thread!
But I've never made a vent thus this thread!
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No, the intercooler placement in general. Are you following through with the compound, and need 2 ICs?
I think you will need the diverter BTW. The frontal area of the lower IC will be essentially zero. You will be relying solely on the pressure differnce between the area in front of the radiator and under the car to induce flow. The diverter on the other hand allows you to use the vehicle forward velocity times the apeture area with an efficiency factor for you core flow. According to Corky, you will want ~2:1 ratio or better core flow to charge flow.
Anyway, if you are compounding, sweet. So am I. I think you move a little more quickly than I do though.
I think you will need the diverter BTW. The frontal area of the lower IC will be essentially zero. You will be relying solely on the pressure differnce between the area in front of the radiator and under the car to induce flow. The diverter on the other hand allows you to use the vehicle forward velocity times the apeture area with an efficiency factor for you core flow. According to Corky, you will want ~2:1 ratio or better core flow to charge flow.
Anyway, if you are compounding, sweet. So am I. I think you move a little more quickly than I do though.
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No, the intercooler placement in general. Are you following through with the compound, and need 2 ICs?
I think you will need the diverter BTW. The frontal area of the lower IC will be essentially zero. You will be relying solely on the pressure differnce between the area in front of the radiator and under the car to induce flow. The diverter on the other hand allows you to use the vehicle forward velocity times the apeture area with an efficiency factor for you core flow. According to Corky, you will want ~2:1 ratio or better core flow to charge flow.
Anyway, if you are compounding, sweet. So am I. I think you move a little more quickly than I do though.
I think you will need the diverter BTW. The frontal area of the lower IC will be essentially zero. You will be relying solely on the pressure differnce between the area in front of the radiator and under the car to induce flow. The diverter on the other hand allows you to use the vehicle forward velocity times the apeture area with an efficiency factor for you core flow. According to Corky, you will want ~2:1 ratio or better core flow to charge flow.
Anyway, if you are compounding, sweet. So am I. I think you move a little more quickly than I do though.
As for the piece you're talking about, I'll test it with and without that, making that piece will be easy. You're probably right, but that piece also steals air from the radiator too hence why I'm gonna try it without that piece first.
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What's a traditional high flowing IC core? Mine is an ebay 20x12x3 bar/plate intercooler. I ran this same type with the GT3271 at 28 PSI and it was fine, so I thought it would work with the SC. But AITs are way worse with the blower than they ever were with a turbo.
I've seen track cars run V-mounts and say that works well, but I don't want to cut the front end up to do that.
I'm here, tell me what works. I want my AITs 30-40 above ambient at 30 PSI after ~11 seconds of WOT.
EDIT: Also I believe most track cars don't race on pump gas. This is a street car and it runs on 93 Octane, so I can't accept high AITs and not worry about it because I have E85, or any other high-octane race fuel.
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step #1 is replacing the egay mediocrity with something proper. I think it was Jason that did a test a long time ago and figured out that a tube/fin (I believe he tested one from TDR) and also I think brain messed with one of those ebay delta-fins and both reported WAY more airflow to the radiator using that vs your typical bar/plate.
Second: while the MSM rad you're using is better than the stocker, it is nowhere near something like TSE's crossflow. Those two things alone should get you what you need. The last would be good ducting. If it holds up on a turbo track car on a 110* track, it should hold up for you.
Third: if airflow to the rad is not as important for you, get a precision or something else with a proper core. Those are about as efficient as it gets for heat exchange
Traditional as in normal, what all of us use, intercooler in front of radiator. Nothing weird
PS: you're not gonna see 30* over amb on a blower at 30psi for 11sec of wot. period (without spraying down the house with w/m/etc). one can only dream.
Second: while the MSM rad you're using is better than the stocker, it is nowhere near something like TSE's crossflow. Those two things alone should get you what you need. The last would be good ducting. If it holds up on a turbo track car on a 110* track, it should hold up for you.
Third: if airflow to the rad is not as important for you, get a precision or something else with a proper core. Those are about as efficient as it gets for heat exchange
Traditional as in normal, what all of us use, intercooler in front of radiator. Nothing weird
PS: you're not gonna see 30* over amb on a blower at 30psi for 11sec of wot. period (without spraying down the house with w/m/etc). one can only dream.
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step #1 is replacing the egay mediocrity with something proper. I think it was Jason that did a test a long time ago and figured out that a tube/fin (I believe he tested one from TDR) and also I think brain messed with one of those ebay delta-fins and both reported WAY more airflow to the radiator using that vs your typical bar/plate.
Second: while the MSM rad you're using is better than the stocker, it is nowhere near something like TSE's crossflow. Those two things alone should get you what you need. The last would be good ducting. If it holds up on a turbo track car on a 110* track, it should hold up for you.
Traditional as in normal, what all of us use, intercooler in front of radiator. Nothing weird
PS: you're not gonna see 30* over amb on a blower at 30psi for 11sec of wot. period. one can only dream
Second: while the MSM rad you're using is better than the stocker, it is nowhere near something like TSE's crossflow. Those two things alone should get you what you need. The last would be good ducting. If it holds up on a turbo track car on a 110* track, it should hold up for you.
Traditional as in normal, what all of us use, intercooler in front of radiator. Nothing weird
PS: you're not gonna see 30* over amb on a blower at 30psi for 11sec of wot. period. one can only dream
AITs are what I want lower. What intercooler brands or types do these awesome proven track guys run? I've seen a ton of people run ebay bar/plate intercoolers, but hey if there's something A LOT better I'm in. What is it? What do you run?
Hell, what AITs are these proven track setups seeing? And at what power level?
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here's the most recent discussion I participated in
https://www.miataturbo.net/build-thr...5/#post1211634
check out those few pages
I'm not a track guy, but having messed with a ton of heat exchangers I've never seen one stay within 30* of ambient at 30psi for an 11 second pull, and that was on a turbo, I'm guessing a blower is way worse.
https://www.miataturbo.net/build-thr...5/#post1211634
check out those few pages
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It vented under the radiator. Airflow was inadequate, IATs were extremely high. I ended up using the same principles, but flipped, so that the IC sat further back and airflow was ducted above it to the top of the radiator.
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here's the most recent discussion I participated in
https://www.miataturbo.net/build-thr...5/#post1211634
check out those few pages
I'm not a track guy, but having messed with a ton of heat exchangers I've never seen one stay within 30* of ambient at 30psi for an 11 second pull, and that was on a turbo, I'm guessing a blower is way worse.
https://www.miataturbo.net/build-thr...5/#post1211634
check out those few pages
I'm not a track guy, but having messed with a ton of heat exchangers I've never seen one stay within 30* of ambient at 30psi for an 11 second pull, and that was on a turbo, I'm guessing a blower is way worse.
Ok I have a tube/fin IC and the inside of it looks like the one in your last pic (godspeed) regarding fin density. It's not as bad as the ebay tube/fin you have in your pic but it's certainly not like the precision or Treadstone. Hmm.
And yeah it looks like getting a very-effective intercooler with high boost isn't really that easy. I'm emailed a few different track guys and more than one told me they didn't even CARE what their air temps were because of E85.... It just wasn't a problem.
Still I want to get them as low as possible. Looks like I need to do some reading on IC cores and figure out who has or can make one the size I need with a better core.
Still, anybody that actually has a 300+whp car and tracks it, what are your AITs?