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Old 03-30-2009, 10:08 AM   #1
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Default DIY FAQ Injector discrepency

Listed under the PNP injector list is the:

PNP 89-92 Toyota Supra 7MGE Turbo 430cc black top.

Then listed below that w/ the LOW OHM injectors is:

86-92 Toyota Supra 7MGTE Turbo 430cc black top.

A 7MGE Turbo is a 7MGTE... notice the T, they are the same thing.

I've got a friend who has a built 7MGTE in this '86.5 Supra Turbo and has extra injectors laying around. They are black top.



I sourced and have yet to install 89-92 7MGE 305cc green top Supra N/A injectors, but I could've/still can get some 7MGTE 430's for free. Should I get them? How hard/expensive is wiring in the resistors? Worth the effort?

I'm going to be running EMB (because it came w/ the car) and have a Walbro 190HP FP installed.

I'm such a rookie, sorry if this is a lame post.
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Old 03-30-2009, 10:14 AM   #2
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A question first- you have an EMB, and you noted a Walbro 190-HP. Do you also have an adjustable rising-rate FPR?

If you do, then stick with the lower-capacity injectors. Your car will idle better and your low-load (light-throttle) cruise performance will be more stable.

If not, then it's decision time. My personal opinion is that the 430s are too big for the EMB to drive without making too many sacrifices. Other folks feel differently, and a couple of those have actually run injectors in the 4xx range and have learned to live with them.
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Old 03-30-2009, 10:16 AM   #3
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thanks. probably a reason i never had the part number listed :P
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Old 03-30-2009, 10:19 AM   #4
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Quote:
Originally Posted by Joe Perez View Post
A question first- you have an EMB, and you noted a Walbro 190-HP. Do you also have an adjustable rising-rate FPR?
Not yet but I was under the impression the stock pump wouldn't perform well enough under boost applications (although I've since read lots of build threads where guys are using them) so that's why I upgraded. Also had lots of troubleshooting problems getting the car to idle and thought that was part of the problem but was pleasantly surprised when I found the fuel lines on backwards under the intake!

Anyway, I'm planning to buy a RRFPR. I guess it's the easiest way at this point.
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Old 03-30-2009, 12:54 PM   #5
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Responding to this and your PM in one post.

Quote:
Originally Posted by Project84 via PM
Care to shed some more light on the use of EMB, 305cc injectors, 190HP FP, and RRFPR for me? I just bought a tuning cable and software from GiffTech for the EMB. I also have the boost sensor.

I'm a total newb to modifications this extensive. I bought the car for what I thought was a good deal and I'm just trying to figure out what it needs at this point to run safely and make decent power with what I already have lying around.

My turbo is a T04E w/ .63 A/R, I'm looking to "upgrade" to a smaller turbo (OEM Saab unit) so I won't have so much lag.... but I still have never driven the car w/ its current setup.

I guess my goal is 200+whp.

After a RRFPR will I still need more supporting mods?
The EMB cannot directly reduce injector pulse lengths. It compensates for increased injector size by modifying the AFM/MAF signal. This is in contrast to the EMU, where the injector signals actually pass through the unit, and it can divide down the length of the injector signals without altering the airflow signal. This latter method is far more precise.

As a result, there is a practical limitation to the size of injector you can install on the EMB and still maintain a decent idle. It's not a hard-and-fast rule, simply a matter of degrees. As injector size goes up, the capability for precise and minute adjustment is degraded. Common wisdom holds that injectors in the low to mid 300s are "acceptable".

Now, if you do limit yourself to ~300cc injectors, you won't have enough fuel at stock rail pressure to make your 200+ WHP. At 0.6 BSFC and allowing 90% duty cycle, 305s will max out at around 170 crank HP, which will be maybe 150-155 at the wheels. So those wishing to make big HP with reasonably sized injectors on the EMB have historically needed to use a rising-rate fuel pressure regulator as well, with the EMB acting as a fine-tuning instrument.

Now that's not to say that you can't throw 430cc injectors on the car. People have done it, and it does work. You just have to live with idling at about 11:1 and probably a bit of a rich tip-in accompanied by hesitation on light throttle. It's entirely a matter of what you can live with in the car.


As to the fuel pump. The stock pump works just fine at the 200-250 HP range, assuming that rail pressure is kept stock. The shortfall of the stock pump is that it has trouble maintaining flow at higher than stock pressures, which is the case when running an RRFPR. Years ago, that was pretty much the only way to deal with boost- aftermarket ECUs were profoundly expensive, rather complicated, and a bit scary, so most folks stuck with the tried-and-true RRFPR. It is from this era that the stock pump earned it's bad rep.


When you say that the EMB "came with the car", is it installed in the car already, or just in a box?
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Old 03-30-2009, 01:31 PM   #6
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Was installed w/ a PNP harness, has since been uninstalled while I was troubleshooting the no-start issue. Since the problem ended up being as simple as HOOKING THE FUEL LINES UP CORRECTLY (I didn't make the mistake, the previous owner must've because he sold it as "not running") I doubt the EMB caused any problems. But yes, currently, it's in the trunk, not installed and did come w/ the purchase of the car.
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Old 03-30-2009, 01:59 PM   #7
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If I might also add something... the DIY FAQ is very helpful, and I've read it about 6 times and "remember/learn" something new each time, but none of the links are valid anymore. Braineack, do you have intentions on fixing that? It would be much more helpful and greatly appreciated by all newbs.... myself included.
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Old 03-30-2009, 02:07 PM   #8
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its already been fixed.
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Old 03-30-2009, 03:01 PM   #9
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Quote:
Originally Posted by Braineack View Post
its already been fixed.
I figured I would post this here since we are already on the subject.

After you made the change to the table in the DIY FAQ.. It shifted everything so it is now a major PITA to read.
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Old 03-30-2009, 03:06 PM   #10
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yeah i noticed that too....i need to get html to work again.
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