vetracer

I need to replace my injectors and want to install the Ford SVO (Bosch) injectors. Does anyone know the part # for the injectors that work best in a fairly stock 350 TPI? I've heard 24Lb injectors is what I want.

scorp508

The Ford SVO drop right in. In fact I just put a set in my engine yesterday. The only difference is that they are more like a GM 26# injector so you will have to compensate with fuel pressure or programming changes.

vetracer

Do you think there is any advantage to using the SVO (Bosch) injectors? the last thing I want to do is put them in and have the car run like crap. I have an AFPR already, but am I opening the door for more driveability/idle quality issues? I have heard that the Bosch injectors do a better job of atomizing the fuel, but don't know if this is true. I have also heard that they are cheaper, is this why they are so popular? my cost thru GM is a whopping $73 per injector, or $584 a set and my parts guy says that GM shows it to be a Bosch part. Ford parts guy says a set of 8 24lb injectors (light blue in color, I guess this is how they are identified) is $260 I'm totally confused about what to do.
:confused:


[Modified by vetracer, 4:37 PM 11/4/2002]

gbody5

I had the 24# SVO injectors put in mine with no computer changes at all, car runs great. Got them through Summit. Looking in their catalog right now it has what I belive to be the same injector listed under their Ford Racing Injector kit as part number FMS-M9593A302 $219.95

It states that these are designed for race applications and must be used with recalibrated Hi-Flo Mass Air Sensors. Of course, that is going into a Ford 302, not a TPI 350.

I could probably do some tuning on mine and maybe optimize the performance of these larger injectors, but I get no trouble codes, easy starting and great throttle response as is with stock prom.

vetracer

Thanks for the response. I hope my results are as good as yours. With my 52mm TB, cold air induction kit, and descreened MAF maybe I will be able to make use of the additional fuel.

XtremeVette

so whats the concensus....cause now I too am confused? lol

anybody else running these injectors without any changes to their car?

gbody5

The stock injectors are 21lb/hr are they not? 24lb is not that much more and it is my understanding that the ECM will simply compensate by changing the injector pulse width to maintain proper A/F.

As I recall another advantage is the disk design instead of pintle design, which has a better spray pattern. The only changes I have are T/B bypass, open lid filter (K&N), frisbee, and some aftermarket mufflers that are supposed to be better flowing than stock. Nothing major that would constitute the 'need' for bigger injectors.

My mechanic put a scan tool on it when he did the change, said everything looked fine. :chevy

ELEVENS

I've recently been through the same excercise, and here's what was learned:

It's possible that the 24# SVO injectors will supply too much fuel for your ECU to compensate for, unless you can lower the rail pressure. The reason is that Ford rates the flow of their injectors at 39 pounds of rail pressure, Bosch rates them at 44 pounds. Late 350 TPI cars have 22# Bosch injectors. The Bosch have a pintle design, which provides an excellent spray pattern, and excellent atomization. The Bosch's are quick to respond (low latency), and can operate at much higher pressures than the SVO's. They are the best, and you will pay dearly for them. TPiS sells a balanced set of 8 for around 450. These are my favorite. I was told by someone who I trust that the Accels are junk - stay away from them.
The SVO's cost about $219 from Summit. The are a disk design, and shoot a pencil-like stream of fuel, resulting in poor atomization.

I recently bought the SVO's, because of the cheap price. I just couldn't see how something twice the cost cost really be worth it. IF I HAD ANOTHER CHANCE, I'D BITE THE BULLET AND GET THE BEST-BOSCH. Admittedly, the SVO's really haven't had a lot of tuning time yet, but after setting the injector constant (in the chip) so that the same amount of fuel is being delivered (BLM's and Integrator values are normal- 128), I'm seeing a tip-in hesitation, even with the accel. enrichment set to the moon, and the transition after a period of steady throttle seems too fat - it takes a few seconds to clear up. Like I said, I haven't given the SVO's a fair chance, and I am trying to tune in 35 degree weather, but so far, I'm not "sold" on the Ford parts. Then, on the other hand, there's an awful lot of happy SVO injector guys out there, so.... who knows?!
My advice would be, if you can afford it, get a set of balanced Bosch injectors. You cannot go wrong with what the General uses. Alternately, maybe you can find a used set - I just sold mine on this forum for around $200.
Good luck vetracer!

Nathan Plemons

I think you'll be happy with the SVO injectors. In the case of the LT1 it came with 24's stock, so going to SVO 24's isn't that big of a deal. All it does for you basically is gives you a larger injector to play with because of the rated fuel pressure difference noted above. My old injectors were not bad, but I got a good price on the SVO's so I bought them. I didn't notice any change in driveability at all with them and I have a theory on that, I'll mention later.

Currently according to Datamaster my injector duty cycle at WOT is WAY up there. Tomorrow I am going to put in a borrowed set of SVO 36's and see if I can get that duty cycle down. This could be too much injector but I'll find that out tomorrow. It's possible that with the 36's the computer won't be able to cut the pulse width small enough to make it idle without dumping too much fuel. I'll just find out.

Why didn't I notice anything with the 24# SVO's? I'm thinking it has something to do with the type of injection system used in my 92. See 92 and 93 LT1's and I assume all L98's used what is called a "batch fire" fuel injection system. If I understand this system correctly this means that it cannot individually control ONE injector. It must fire every cylinder on a bank at the same time. In such a case every single injector will fire 4 times as often as it would in a sequential fire system, but for just a smaller pulse width. This also means though that while the injectors fire, one intake valve on that bank might be open, all the others are closed. This means that the fuel is just going to puddle on the back of the valve anyway until that valve opens. When that valve finally does open that fuel will dump into the cylinder along with another short burst from the injector. This calibrated dumping seems like a pretty sad system, but apparently it works.

This means though that whenever the valve opens, most of the fuel is just puddled anyway and has effectively a miserable spray pattern anyway so the additional bad spray pattern of the SVO injector might not be so much of a problem.

That's my theory and I could be WAY off on how the batch fire system works, but for now that's my understanding of it. If I'm wrong somebody please correct me.

scorp508

Careful with that one. I think the speed density L98s came with 19# injectors. The reasoning being that a smaller injector operating at a higher rate was more controllable.

ELEVENS

Right on, Scorp. That's why I said "Late” TPI - which would be the 90-91 S-D cars. The original post didn’t specifiy what year. That reminds me of one of my favorite quotes: “Assumption is the Mother of all f*** ups”. Wish I knew who said that one.

ELEVENS

Hi Nathan,

Your description of batch fire corresponds with my understanding of that design. Regarding puddling on the closed valve, I have my own theories, as well. I suspect some puddling does take place, but the more fuel that remains atomized in the port, the better. I also wonder about the event timing at various RPMs. I remeber a post by you stating that you shift your car at pretty high RPM’s. It’s plausable that with higher RPMs, things are happening so fast that the squirted fuel doesn’t even have a chance to hit the back-side of the valve because it had already started to open up. Wouldn’t it be cool to get a little camera in there and play it back in slo-mo? Intriguing stuff!

vetracer

Thanks for all of the responses. Got the SVO #24s after work yesterday and started putting things back together but didn't get it finished last night - man, what a job!

install injectors and fuel rail, hook fuel lines and cold start inj up, then pass side runners won't fit under fuel rail. Remove fuel lines and cold start inj, raise fuel rail, install pass side plenum, reinstall fuel rail and fuel lines, cold start inj, drop bolt holding fuel lines to intake, spend 1 hour looking for bolt lost in front of motor, find and install bolt, find that driver side rear plenum bolt cannot be reached with cold start inj in place, remove cold start injector again, tighten bolt, reinstall cold start injector....Whew! now it's 10:30 and I've got to go to bed.

Sure hope these @!#$ injectors don't give me any trouble - I'll let you guys know the results tomorrow if I finish. I guess I was under the impression that the Bosch injector sold by GM and the Bosch injector sold by Ford were one and the same. After reading this thread it should be clear to everyone that they are not. After all, why would Ford sell them for half of what GM charges?


[Modified by vetracer, 4:14 PM 11/5/2002] :smash:


[Modified by vetracer, 4:15 PM 11/5/2002]