Ben's 914 TURBO Official World Premier, 'cuz it didn't blowd up. Options

[Mueller]

Ben,

yea, I've seen the copper heatsink in the docs of the LM-1...where is your O2 reader mounted? It is "behind" the turbo correct?

James,

My resistors for the injectors do get hot, but they are a good 2 feet from the ECU, I have not checked the ECU components for excess heat, I'll try that next.....yep, ECU is still "open" but there is nothing around it so I don't know how a cover could help......like I mentioned, it starts fine if sitting for a day or so and runs great for about 20 minutes before the VE table resets itself

[lapuwali]

I meant the FETs powering the injectors, which should be mounted directly to the MS board and may get fairly hot. The resistors limiting the current to the low-impedance injector should get hot, and should be mounted far away from the ECU.

Having the cover off means you're exposed to electromagnetic interference from the ignition system. The same thing that causes static on the car radio if you don't run resistor wires and/or plugs can cause havoc with any computer system. Every component on the board, esp. the metallic leads on things like resistors and capacitors, will act like a tiny antenna and pick up the EMF coming off the plug wires. A metallic case will help shield the ECU from this interference.

When you see the reset, you see the VE table is empty (or scrambled)? Hmm. Do you have to re-upload the VE table to get it to work? This is ringing a bell. What *should* happen in a simple processor reset is that it will simply boot again, and copy the config data from FLASH to RAM, and it runs out of RAM. When you edit the tables, it just edits the RAM copy, and when you "save", it's copying the data from RAM back to FLASH. A reboot will literally take milliseconds, so you'd normally have a hiccup while it's booting again, but then it will keep running after it's re-copied the FLASH data to RAM (which will have been erased during the reset). If you see the copy in FLASH going away, then the processor is somehow corrupting or clearing the FLASH. I seem to recall this being a known problem that's been fixed with newer code. I'll have to do some reading on the MS boards to see if I can find this again...

[airsix]

yea, I've seen the copper heatsink in the docs of the LM-1...where is your O2 reader mounted? It is "behind" the turbo correct?

Yep, it's down-stream from the turbo. A good 2 feet behind it. I thought that would be far enough down-stream not to need the heat-sink but it wasn't.

-Ben M.

[Mueller]

Hey Ben...it's me again asking questions (IMG:style_emoticons/default/smile.gif)

what did you do to mate the turbo plumbing to the throttle body?

do you think you are loosing any boost out of the bushings for the throttle shaft?

[airsix]

Hey Ben...it's me again asking questions (IMG:style_emoticons/default/smile.gif)

what did you do to mate the turbo plumbing to the throttle body?

do you think you are loosing any boost out of the bushings for the throttle shaft?

Hi Mike,
I'm not using a stock TB. I pulled one off a turbo Chrysler (it's a Holley) that was sized right - just 2mm larger than stock. It's nice and tight, so no leaks. Nothing fancy on the plumbing. Just tubing and a rubber coupler at each end. Made a little 'T' midway between turbo and TB for the BO valve, which is just attached with clamps and a stubby piece of hose.

I'm using the stock runners, but I modifed the plenum. I cut and reformed my plenum to point the TB straight up (stock 1.7 points to the driver's side). I did that so it was easier to plumb from the turbo to the TB. I also made a flange for the new TB and welded it to the plemum in place of the stock 'cone'(over the top of it actually).

-Ben M.

[Mueller]

when you ran your LM-1 for setting up your tables, did you data log all the inputs or just RPM, MAP and the O2?

thanks for the info....you da man (IMG:style_emoticons/default/smile.gif) (IMG:style_emoticons/default/beerchug.gif)

[airsix]

Definitely not the man, but thanks.
When tuning with the LM-1 I only datalog rpm and mixture. I don't have it set up to log throttle possition and map. I'm too lazy. I can also data-log from the ECU to capture temps/TPS/MAP/RPM/timing/injector-dwell. Then I just eyeball it against the LM1's rpm/mixture log. If I wasn't so lazy I'd integrate them but at this point there's not a need. Mixtures are good and the car runs great.
I had all my tuning done (except on-boost enrichment) before adding the turbo. So, when I added the turbo it was real easy to add enrichment on the possitive side of MAP. That part was a piece of cake actually because the only thing I had to change from my NA map was add boost retard on the ignition table and add boost enrichment on the possitive side of the MAP table. Everything else stayed the same and it runs great.

So, you getting close? Sounds like it.

-Ben M.

[Brad Smith]

Next up, twin turbo?
Run a turbo off of each side... Cyls 1,3 & 2,4

have a look at the sizing and the firing order before deciding this is a good idea ...

Yup. If you were doing a twin turbo you would want to pair the front as one pair and the rear as another. The turbo will respond better if the pulses are even.

Brad

[Brad Smith]

I'd do an intercooler first, and just lay it across the top of the engine, or across the front of the engine bay.  Perhaps do a GT-style all-mesh engine lid to help with temps.  If you look at a number of the "across the top of the engine" OEM intercoolers (2nd gen RX-7 turbo, turbo Soobs), they have a scoop to get air in, but no where for the air to GO afterwards.  Measurements on the RX-7 setup showed the scoop could basically be closed off with no real difference.  Airflow would be nice, but just the intercooler itself will help.  Ducting more air into the upper engine bay is (and should be) something to do, anyway, and can be done w/o ugly scoops visible from the outside.  Adding one would cost much less than $300.  There are lots of junkyard intercoolers out there, from any number of Japanese turbo setups.  Some are pretty small, too.  If you wanted to get quite fancy, you could try to obtain (or even fabricate) a water/air intercooler.  Build a watertight box around a regular air/air intercooler, and circulate the water with an electric pump to a small radiator (oil cooler type) mounted more into the airflow.  One possible place for it is directly in front of the engine, below the front shelf.  You'd catch under car airflow (which is considerable), yet be in front of all of the exhaust heat, and no having to carve up a trunk or run really long hoses.

Water or alcohol injection always seemed like a drag-racing hack to me, and I think is mostly suitable if you're running really high boost for short spurts. An intercooler will improve VE some, and should allow a modest boost increase.  12psi with good VE should give you 150hp or so, which I'd think would be plenty from an elderly 1.7.

This is wisdom. Listen to him. Being an RX-7 guy, I can tell you that the scoop does almost nothing- it's actually located in a low pressure area, so the low pressure is trying to suck air out, while the direction of airflow is trying to push it in. Not much airflow through the doggone thing.

Note that, based on some tests done of airflow and cooling capacity, one of the best intercoolers that can be had cheaply is from a turbo Supra. Not so great for that big six when they pass about 400 hp, but great for the stock levels of the Supra and a little beyond. You aren't planning on over 300 hp are you? They're cheap and relatively easy to find. They also are not monsterous in size, and they're easy to plumb and mount.

Put on the "GT style" engine lid (that is what it's called, right? The one with twice as much grill area) and stick it in the front corner out of the way. Use an electric fan that comes on under boost. (Use a pressure sensor to trigger a relay- or just forget the electric fan. It doesn't take as much airflow as you think... you aren't cooling the whole engine, just the intake charge. A dinky little electric fan that some cars use on the air conditining (like the late 80's RX-7 for example) should do nicely.

Here's a Supra intercooler auction on ebay:

http://cgi.ebay.com/ebaymotors/ws/eBayISAP...&category=46096

Note that this is the Mk III Supra that I'm talking about, not the later model ones. Current bid is $41. They commonly sell for $100 to $200.

Here is a website comparing flow numbers for various intercoolers from production vehicles, and compared against 1 Spearco core.

http://www.gusmahon.org/html/cooler%20test.htm

Note that the Supra core fared VERY well, as it didn't have much restriction internally OR for cooling air through the core.

Cheap intercooler tubing? http://home.earthlink.net/~turbogus2/cooler.html

Note that the author of this website is deceased. (go to the main page for info on that.) Many of you may have seen the "mean mini" sub-13-second minivan- this is the page for that guy.

Good luck, and I hope this is helpful.

[soloracer]

I've seen video clips of that mini van. Pretty impressive to watch a soccor mom van from the 80's taking down a newer style camaro. Too bad about Gus though. Doesn't seem right sometimes the way things go.

On the intercooler side I bought 2 Porsche 944 Turbo intercoolers. I'm not sure of their flow rates as compared to those in the charts Brian posted but they are a sturdy bar and plate unit and I believe they are good for 400 hp each as well. They are shipped more like a brick than a tile so their mounting positions would be different. Some RX7 guys have used them as well. I'm thinking of welding these two together and having custom end plates made. I just have to find a good place to mount them now. I'm thinking somewhere in the rear trunk and have the air "dragged" through them as opposed to front mount where it is rammed through. The exit venting would be either out between the tail lights or the trunk floor. Here is a pic of one sitting on the floor underneath my car. Don't use the tires for size comparison - they're a little bigger than stock.... (IMG:style_emoticons/default/wink.gif)

[Brad Smith]

Nice pic... makes me feel like singing...

"I like big butts and I cannot lie..."

oops, I mean rapping. (IMG:style_emoticons/default/biggrin.gif)

What flares are on there?

[airsix]

Here is a website comparing flow numbers for various intercoolers from production vehicles, and compared against 1 Spearco core.

http://www.gusmahon.org/html/cooler%20test.htm

Note that the Supra core fared VERY well, as it didn't have much restriction internally OR for cooling air through the core.

Cool. Thanks for posting this info. I've got the little Eclipse/Tallon IC that he tested. (not on my car yet)

-Ben M.

[Mueller]

doing "research" for some odd reason (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) and thought I'd ask if you installed the IC yet???

[iamchappy]

Then theres my idea for the intercooler using fans and a fresh air source.

[iamchappy]

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[iamchappy]

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[iamchappy]

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[airsix]

QUOTE (Mueller @ Apr 15 2005, 04:29 PM)

doing "research" for some odd reason (IMG:http://www.914world.com/bbs2/html/emoticons/rolleyes.gif) and thought I'd ask if you installed the IC yet???

Hey look. A thread back from the dead.

Nope, no IC yet. I've been totally consumed by other non-914 projects since November. Hopefully sometime this summer I'll get around to it. Keep us posted on your project. Looks VERY interesting.

-Ben M.