I'm nearing the time when I'll have to upgrade my stock secondaries to something bigger. Going to run out of fuel real quick with a turbo upgrade!

I've been informed that some Bosch 'white top' pn# 0280150846 http://cgi.ebay.com/ebaymotors/1600c...item3f03bc3f12
will work with some light mods to decrease the upper plastic covered section so it fits in my stock secondary rail and a pintle cap needs to be swapped or something (need more info). I also need a resistor for each injector or an FJO driver (huh? is that like a flyback board?) because these are medium-low z. What that means is they come with 4.5 ohms so sort of the high side of low impedance.

If I could just get away with a couple simple resistors, I'd really prefer that approach. They're not super low impedance like S4 injectors so maybe I can use three on my secondary bank. Would I need to set pulse width modulation in the MS? It's currently set up for high impedance and I'd like to keep it that way and just add the resistors. Possible?

 

Then this eBay ad by fiveomotorsports caught my eye. Looks like these were modified to go right in. Even come with some EV1 connector pigtails and Mazda-looking pintle caps and rubber cushions. http://cgi.ebay.com/ebaymotors/2-Bos...Q5fCarQ5fParts

But then I noticed this seller also has a set of apparently 2000cc Bosch EV1 injectors that appear similar but lower coil resistance of 3.2 ohms and more precisely flow matched; part of his Asphalt series for higher performance. http://cgi.ebay.com/ebaymotors/2-Bos...Q5fCarQ5fParts

What are my options? What have you guys done? I've got a MegaSquirt 2.2 with the classic CPU running in high Z mode. I don't have a flyback board because my stock injectors were high impedance (around 14 ohms). I don't want to deal with a flyback board. Can I just get some resistors and the 4.5 ohm injectors and call it good? Do I need to mess with PWM?

 

keep searching im seen 1600cc in hi-z

 

like I said before 4.5 Ohms for the indy whites is on the upper side of low-z injectors and has been reliable for me sofar using them with the stock drivers.

 

You've got a 3.0 PCB I presume? I've got the 2.2 board, built back in '04. Worked perfectly in high-z mode. Never tested with low z injectors or pulse width modulation.

Sounds like I should get three resistors and keep running in high-z mode. The resistors should protect the 2.2 components as they aren't as robust as 3.0 components.

Now I need to know what resistance I should end up with so I know which resistors to purchase. Since my high-z injectors are 14 ohms, do I need to get myself a 10 ohm resistor for each Bosch Indy white? It'd put me around 14.5 ohms.

10 ohm is easy enough to find. What wattage should I get?

 

Hey Jobro, I'd like to say thanks for recommending the Bosch white injectors and providing a part number 0280150846. It made searching for them a lot easier. I just now ordered a set of three that have been modified to fit an 86-92 RX-7 rail and come with upper and lower o-rings and EV1 connecters with pigtail. They should fit right into my 20B secondary rail.

After some research it turns out I should get three Ohmite resistors 5.0 ohm, 25 watt from digikey part number 825F5R0E-ND. Then I can leave the MS in high z mode and never bother with PWM.

 

BASHES HEAD ON WALL

The Flyback circuit on the V3.0 PCB does not work and has never worked for me.

NO resistors needed.

Stage at 80% duty cycle. With 550cc primary injectors and duty cycle above staging will be ~20-30% to low for no current limiting to be a problem. As duty cycle rises to 60-80% sure they might get hot, but I question the amount of time you can spend burning that quantity of fuel without driving around at 120mph all day

You won't have a problem. Just make sure you have a large number of earths to your ECU. I use about 9 10A rated wires, soldered onto a strap that has 6mm copper conductor.

 

Thank you for listening RE the injectors. As I said I paid $89/each for mine and they have been brilliant.

Until Paul Yaw provides me some hard engineering data injector dynamics is a **** **** hype product in my eyes. (For clarity: High speed images showing spray patterns of each model, quantitative information on droplet size (not fucken its better than most 500cc injectors on the market **** **** bullshit) , details about the modifications he makes to adjust flow rates.)

 

Also Jeff, you really need to free up that turbine housing. If you can get a 1.32 or 1.5 I really suggest you do it.

You now have a big fuel system. If you put in a tank of E85, run it around 0.7-0.78 lambda, 16 degrees timing at 13psi, 10 @ 18psi, you will crack out a BIG power number. I'm talking like 600 no sweat

 

Wait, are you bashing your head because of me or because of you?

I've got the 2.2 PCB so I'm getting resistors because it's known the injector driver section of 2.2 is less robust than 3.0. They're only 5 ohms so not much resistance there.

Yeah, I filled every available open pin in the DB37 with ground wires. Should I route them all to a single thick cable like you did? I heard something about ground loops can be a problem if you don't run your grounds right.

I don't understand staging yet. I haven't tuned that far yet. Last time it ran was in '05 as a bare bones NA. Parts were what I had on hand. It ran well enough to get it around the block but that's about it. No real power, just low end torque up to maybe 5k. It kept wanting to overheat so that issue will be adressed. It also would stall between shifts obviously because it was untuned. The point is it was the first MegaSquirted 20B to run under its own power and that was good enough for phase one.

So primaries should be set to 80% duty cycle and no higher? That's where the secondaries should be staged to come on? Then when they come on, what duty cycle should they both drop to?

 

I read a bunch of that Paul Yaw ID injector stuff until my eyes became dry and bloodshot. I gotta say the only thing I liked about them was the high impedance of the base EV14 injectors. But I'm glad I got some classic EV1 injectors instead. Less costly. Less hype. Proven to work in my application. I even like the color.

They came modded to fit. I paid $111 each for mine which included turning on a lathe and some EV1 pigtails. I'd say that's a good deal. Purchased from fiveomotorsports on eBay.

Test fitting one just now, the small black o-ring goes on first. The bigger green o-ring goes on next so it sits at the top. This configuration seems to fit in the rail better and is snug about the same as stock. Maybe a little tighter (new o-rings).

Oh yeah, spray pattern? These huge injectors are secondaries. Who cares? lol

 

I've got a very early engine. It is #756 and has the smaller castings and supposedly weaker shaft. Everybody says to run them NA or if you do boost them, count on only having around 350 or 400 max.

A bit of recent news I can happily report is this. Apparently you can safely crank up the power to 500 max HP if done extremely carefully. It was GtoRx7 who said this about an early casting engine Carlos at CLR built.

So knowing I have that kind of headroom, I decided to choose a turbo that's big enough to get me to 400HP and spool quickly for more fun driving it. That's why I picked a .96 A/R instead of a 1.1 or higher.

Lots of other parts were sized accordingly for this kind of power. 3" exhaust, not 3.5" or 4". Mufflers were purchased and welding is already complete. GSL-SE gas tank has a slosh cup and baffles. The slosh cup is smaller than S4 but should be big enough for 400HP maybe. I'll keep fuel level above 1/4 tank. The trans can apparently handle 400HP but not 500. The clutch is likely too small. I'll probably have to get a puck.

The engine was ported back when it was going to be NA. Now that it's going turbo I kinda regret porting it. Oh well. Hopefully the fast spooling turbo will give back the low end that porting took away.

 

Hey Jeff,

One thing. You do not need resistors for your secondary injectors. I have the flyback circuit and PWM current limiting disabled on my V3.0 PCB. It does not work for me.

If you use resistors you will have an ugly notch in your VE table where they start working.

When building a V3.0 there is a fair amount of 'redundant' or useless circuitry.

To be realistic, a V2.2 PCB using megasquirt 1 with Kens Zeal LM1815 circuit and a 029y4 of Hires code will have 99% of the power and features of ms2extra when it comes to a rotary vehicle.

 

I mean it, you need more turbine!

The engine will be 10x happier being able to breathe out.

You basically need the biggest turbine housing you can get, if not an additional heavy back cut, or a Q-trim and a large housing ballpark 1.15 or bigger.

Don't worry about the street porting. Its there so just design around it.

 

Well that's just great. I spent all that money on the wrong turbo.

 

You should be able to move it on at your cost, its pretty spot on for a 13B.

 

Ok, thanks.

 

On the plus side limiting yourself to 10psi and 6500rpm will make a very lazy 400rwhp ballpark and it should last forever.

 

That sounds promising.

I really don't need more than 400HP. Others have said parts begin to break with regularity above the 400 mark. Or things get really expensive. Well I guess it's both.

They say the rear diff of 1st gens can handle 400 but you need a big 9 incher for more. Aaron Cake has stated his tranny (same one I'm using) survived up to 400 but popped when he ventured up to like 441HP or something. This was smoothly applied power on the freeway that broke it, not shockloading harsh launches.

Let's see, what else... 400 is attainable with a 3" exhaust. The 3" mufflers and tubing are already paid for and ready to go in. My cooling system is big enough for 400 but not much more than that.

I do have a question about my fuel system. I have a single Walbro 255 and a GSL-SE tank with 5/16" (8mm) send and return hardlines under the car. The tank has a 1/2" pickup and a 5/16" return already plumbed as stock. The fuel pump is external. Will I require a second Walbro for safety into the 400s? I seem to recall a single walbro is ok up to like 300 or so.

 

@ 55psiG and 13.5V at the pump you have 244litres/hour to play with. That is 4000cc/min.

You will be getting close to the limits of a single GS342 with 10psi and 6500rpm. On a 20B you should be up around 430rwhp like that. As soon as you push for your next lump of power you will want to swap the walbro for a bosch 044. But as you know you will also be up for mutiple diffs gearbox's clutches and axles at that time also

This is certainly drive line damaging horsepower.

So you have an SE diff what what gearbox?

 

My fuel pressure is currently at stock levels, using the stock FPR in the secondary rail.

Could I get another walbro and run two in parallel? Is that common on external fuel pump setups? Then 3/8" line size?

Oh, right. I didn't mention driveline specifics yet. Rear axle housing is a large flange S4 LSD unit the previous owner swapped into my S2 '81 S model. Actual year of housing and axle diameters are unknown (could be late modle '83 large flange +small axles or '84-'85 large flange + large axles). I have access to two spare complete LSD rearends.

Gearbox is an S5 NA for now. I have several other S4 NA, S3, S2 and even an S1 plus a couple of early ribcases.

Several upgraded pressure plates from RB race to RB street strip and lots of stock pressure plates. Several clutch discs, but my strongest organic will go in for now. It is an ACT modified street disc. I'll look into puck discs later when it becomes an issue.

Several spare driveshafts.

By the way, the GSL-SE diff is actually weaker than the 12A diff. I have the 12A diff.

 

89-91 Turbo2 gearbox is the go. I will move over to one eventually.

I would personally use a single GENUINE (not poverty spec 2/3 the price 1/2 the flow chinese copies) 044 over twin walbro pumps. You can get 1L surgetanks from efihardware designed for 1st gen RX-7s. They work very well.