transam

Hey fellas, So i have an '86.5 with Ken's chipset 300v and the '87 pressure regulator. Ready to replace the stock injectors. had to recover from Timing/oil/crank gear replacement. Last thing im doing for awhile! What injector rating should i go with? 19/lb or 24/lb? After i get an answer i will call Roger again. Who btw is very knowledgeable and pleasent to talk to on the phone. I just got done reading the post on design II and III's but was lost after awhile. Many thanks in advance

SeanR

You already have 24lb stock, stick with those.

namasgt

But maybe he can take advantage of better/more modern spray pattern. The ones I bought for my S4 were gray colored and I had to use a small saw blade to make an extra groove for the locking clips. I would not use dremel tool its too quick that it would melt the plastic.

jcorenman

The best injector for Ken's chips is whatever Ken tuned his chips for... which I believe was the stock injectors with S4 regulator/dampers. Different injectors-- even with the same static flow rate-- will have different characteristics.

transam

This was the post i was referring to: https://rennlist.com/forums/928-foru...e-ii-info.html

Thankyou SeanR, i wast sure what flow rate they were stock. As for design, I will not be putting in the old needle/pintle style injectors. I would like the better spray pattern. I am going to call Roger and see what he has available.

Don Carter

When I did a recent top end refresh on my 86.5 with Ken's chips and 55psi FPR, I had it in my mind that S3 and S4 injectors were the same. I had a set of rebuilt S4 injectors on the shelf from another project and installed them on the S3. I'd have to say that it doesn't feel very strong. I know the TPS isn't working, but I'm wondering if the sluggishness is due to the S4 injectors. Not looking forward to digging into it again to swap them out.

stolarzj

Stop driving it.. Your running it lean. The S4 injectors are 19lbs and S3 injectors are 24lbs.

I used the 24lb injectors from Ford Motorsports and haven't had an issue with them. They are about the cheapest you will find at under $200 for a set of 8.

Eplebnista

I believe these are the Ford injectors of choice: http://www.blueovalindustries.com/engine/en8810kit.html

This is what I plan to use. IIRC you may need different O-rings and you will have to cut a groove in the top to accommodate the existing fuel rail/injector retaining clips.

These are no longer less than $200, but not a huge jump up from what you would spend to get your existing injectors cleaned etc.

Mike Frye

+1,000,000. You could damage your engine bad. Even running regular gas with that chip set can cause problems. It was tuned for a good running car with all of the mods listed on his website and STOCK injectors using 91 octane gas. Even stock chips would have a problem running 19 lb injectors, but with the more aggressive tuning of Ken's chips you've got no room for error.

The S4 injectors require O-ring changes. The S3 24 lbs are drop-in replacements.

To the OP: I think Ken actually tuned it for the 4-hole spray pattern type that you can get from this link. 'Better atomization' was mentioned in his posts about it. I use them and have had no problems, car runs like a beast.

For injectors, remember that the 928 uses a 'batch fire' technique so it fires the injectors many times making an air/fuel mist above the cylinder that gets sucked in when the time is right. This means you want better atomization and I think the 4 holers are better designed for that.

jcorenman

Again: when you are working with one-size-fits-all chips, and not tuning for a particular car, it is important to match the configuration that the chips were tuned for. Some things matter, some don't.

The LH measures airflow with the MAF, calculates the correct amount of fuel for that airflow, and converts that into milliseconds of injector opening per engine rev. So mods which increase flow, such as an x-pipe, would be mostly compensated for-- more airflow means more fuel to go with it.

Changing injectors is different: The LH has no idea what injector you've actually got in there, it just knows what it was programmed for. And not all 24# injectors are equal.

Ken, on his S300 page, under "recommendations" says "Flowchecked new Ford or cleaned stock injectors (24#)". That's pretty broad, and not particularly helpful-- there are a lot of different Ford injectors.

Some differences between injectors are obvious: Different size, different o-rings, different connectors, 4-hole disc-type versus pintle, slots for the mounting clips, and different "Lb/hr" ratings.

There are also large differences in opening time, initial flow rate, and final steady-state flow rates. So simply saying "Ford 24# injector", you don't know what you've got.

For example: The Ford Motorsports M-9593-A302 is a popular 24# injector, 4-hole disc type in the same package as the stock 19 and 24# pintle injectors. Opening-time is 0.84 ms at 12 volts and 55 psi (and changes with both voltage and pressure). A typical injector pulse-width at idle is around 2.2 ms, and cruising on the highway is around 2.8 ms. So a difference of a tenth of a ms (compared to stock open-time of 0.95ms) is a 3-5% increase in fuel at idle and cruise, not a big deal but still requires resetting the idle mixture (or changing the injector open-time parameter in the LH). But A302's are getting hard to find and expensive.

Ford M-9593-AA302's have been mentioned in other threads, and require that slots be added. They are also 4-hole disc type (plastic body) but the specs are different: Open-time is 0.75ms (12v/55 psi), another 5% increase in fuel at idle/cruise.

The Ford M-9593-LU24a injectors were mentioned above: These are very different, and in the wrong direction. Opening time is 1.25ms (at the same 12v/55psi). That's 40% LESS fuel at idle, and 25% LESS at cruising loads, compared to the A302. The difference at WOT is "only" 10% less fuel, in AFR terms that would be an AFR of 14 versus 12.5, as an example. These would NOT be a good choice for a pre-programmed chip.

And of course Bosch makes a bunch of injectors besides the ones with Ford part numbers. The problem is that while Ford is quite good about publishing spec's, Bosch is not. If you are tuning a particular car that's no problem, just tweak the maps for the parts you've got. But it does make comparing injectors very difficult.

You need to find out from Ken which injectors, exactly, he used for tuning, and then try to get those or something close. You also want to be sure that your MAF is recently calibrated, as MAF's age they read low which means a leaner mixture. And of course make sure the pressure regulator and dampers are swapped for S4's.

SeanR

This is exactly why I suggest staying with the stock ones, too many small variables which can cause bad things if they are not right.

Imo000

I yet to see solid proof that the more modern injectors have any performance advantage over the first generation design.

transam

"Ken, on his S300 page, under "recommendations" says "Flowchecked new Ford or cleaned stock injectors (24#)". That's pretty broad, and not particularly helpful-- there are a lot of different Ford injectors."

I saw this as well. It sounds like you are recommending i ask Ken if the Ford M-9593-AA302's wil work. I appreciate all the info. Oh for the record i had Kevin at Injection Labs recal the Maf. It isnt cheap but he does an A-class job. The car runs strong. it just has the leaky injector deal where it will not re-start after letting it set after driving for a few minutes. Have to wait a half hour then it starts back up.

"To the OP: I think Ken actually tuned it for the 4-hole spray pattern type that you can get from this link. 'Better atomization' was mentioned in his posts about it. I use them and have had no problems, car runs like a beast."

Mike, are you saying you used the exact injectors in the link from Blue oval? I would like the same results you achieved!

transam

SeanR and IMo000, are you suggesting staying with the needle and pintle exact OEM injectors? or the "fat body" type Bosch injector with "disc set up" referred to as the typeII?

SeanR

Common sense would indicate that better atomization will lead to a better, more efficient burn. In turn better performance.