60lb injectors on a Radixed 2004

[H2Racer]

For those who don’t recall my last setup, I had 42 lb injectors and a fuel pump voltage booster and they were leaving me a bit lean on top end of the RPM band. Here’s the short history…

 

42 lb injectors WITHOUT the voltage booster I saw this-

1st gear- AFR: 11.0 - 12.6 (with 23.8 ms injector on times)

2nd gear- AFR: 11.0 - 12.7 (with 23.8 ms injector on times)

 

 

42 lb injectors WITH the voltage booster I saw this-

1st gear- 10.9 - 12.1 AFR (with 23.8 ms injector on times)

2nd gear- 11.0 - 12.1 AFR (with 23.8 ms injector on times)

 

Clearly, the voltage booster was helping out a lot but was not able to keep up with the AFR I wanted (11.1 - 11.3).

 

 

Now, the 60lb injectors WITH the voltage booster gave me this-

1st gear- AFR so rich it would miss and not run right at all.

2nd gear- Same.

 

60lb injectors without the fuel pump voltage booster gave me this-

1st gear- AFR 10.9-11.2 (with 13 ms injector on time)

2nd gear- Same.

 

The extra AFR allowed me to run more timing again and not have any fear of burning parts. With the 60’s I have lots of room for growth without having to buy injectors again. I definitely would not recommend these to a novice tuner. You will have a hard time getting these to work right- if you even succeed.

 

Getting the 60’s to run right was a serious challenge. We expended about 15 hours and 18 gallons of gas getting it right. We tried several approaches and ran into issue after issue. If the injectors would idle good- PE was fouling the plugs. If PE was good- part throttle drivability was crap. We tried scaling the VE, scaling the injector constant, scaling the MAF. Nothing worked quite right. This took many hours.

Finally, we put 72’s in the injector constant (because the Motrons are rated at 60 lbs on a 3 bar system), ran several logs of MAFless VE tuning. Got that nailed, then went on the scaling the MAF to make it stop adding fuel. The MAF required targeted scaling based on MAF Frequency logs because it needed more scaling in the lower regions than the upper.

We finally realized (well, I didn’t, but Jimbob did) that the problem was the big injectors were puddling fuel. Puddled fuel is interpreted as a lean condition by the PCM and the logging software makes you think that you have to add fuel when you should have taken fuel away. You end up overshooting and chasing a moving target.

 

These Motron 60’s are idling at 1.8 - 1.9 ms, which is pretty small considering that the 42’s idled in the 4 ms range. That says a lot about the quality and ability of the Motrons.

 

 

To install the 60’s I followed guidance I found here on Silveradoss.com that told me to buy the car type injector plugs (got mine from the sponsor Speartech) get 5/8 longer bolts (the ones I bought from Home Depot were 6mm x 30mm) and some tubing to make a 5/8 spacer for every injector bolt (bought aluminum tubing from Lowe’s). It takes six bolts by the way.

The install of the injectors was fairly easy and straight forward. The only issue or question was about how to splice in the new injector pigtails. I took the truck plugs apart and saw that it was labeled “A” and “B” so I mated the appropriate wire on the harness to the new plug wire labeled “A” and “B”. I left about 3 inches on each pigtail so there was plenty of wire left to return to stock if necessary.

 

 

I firmly believe that the 42's are fine for all the guys with pre-2004 trucks. You guys have a fuel pressure regulator that gains pressure as boost increases. That makes your 42's seem a good deal larger under boost conditions. The 2004 does not build pressure in the same way. I took measures to ensure that flow did not drop off with the voltage booster, but I could not control pressure which must have been falling off at the high RPM region. With the 60's I have so much injector available that a drop in pressure has no effect on my system. I don't know what the 2004 reaches for pressure at wide open throttle or under boost conditions. I do know that I have 58 psi at idle.

I highly recommend consideration of the fuel pump booster for guys trying to stretch the 42's a little farther. You can see how it worked for me above. However, ff you've got 60's on, you had best leave it alone. I expect I'll sell mine since I can't use it any longer.

[BigTex]

A few years back, I changed out the injector pigtails and ran Ford SVO injectors on my 99 truck with a whipple. As far as I know, I was the first guy to swap out injectors like that and to remove that whipple piggyback computer and program it for properly sized injectors. I jumped on the LS1 Edit beta tester list as soon as it was out in early 2002. Those SVO injectors were not too hard to tune at all. Yes, there was a little abnormal fueling at idle compared to driving. But tuning has come a LONG way since the first version of LS1 Edit was released. I'm sure I could get the SVOs running right pretty quickly now. If I remember correctly, there is a common colored wire for all 8 truck injectors, which is the ground. I hooked the black wire from the pigtails to those wires, but it may not make any difference.

 

In my opinion, these mototron 60s are too big for your setup. Bigger isn't better for fuel injectors. Sure, you need to get some that will cover what you need now and have a little room to grow, but going from 42 to 72 is a huge jump. For anyone else thinking of going this route, I suggest the 42 pound SVO injectors, since they will act like 49 pound injectors at our fuel pressure. Thats about a 20% increase, which should be good for near 700fwhp for forced induction.

 

I'm not being critical, thats just my opinion. I really appreciate those guys who have a problem (like your fueling issue), then take it upon themselves to find a good solution. Spending 15+ hours tuning those injectors shows some strong determination. Good work. Now get back out there and swap in a smaller pulley.

 

Richard

[TurbochargedBerserker]

Just a small correction to what Richard said -- the common colored wire in the injector pigtails is 12v positive. The varicolored wires are grounds from the PCM.

 

Also, 60# @43.5psi = 69# @ 58psi, not 72#, that could be part of the tuning problem. There is also some question as to whether the mototrons are really 60# or 57# as are the seimens deka injectors that the motos are built from. If they are 57# @ 43.5 then they are 66# at 58psi. This is the assumption I used when tuning my truck and it seems to have worked out pretty well.

 

It looks like your WOT AFRs are much better, but could still use a little tweaking to get a flat curve. I'd also recommend backing off to 11.5-11.8 for the range. 10.9 is just too rich, IMO.

 

I read on the megasquirt site about how tough it is to tune with an idle of 1.9ms and the MS allows me to adjust the idle pulse width. I experimented with several different idle PWs from 1.5 to 4.0. 1.9 was by far the best for my truck and the easiest to tune.

[BenKey]

Nice write-up I admit some was a little over my head.

 

I have a set of SVO 42s, got them yesterday. Anyone thinking of going this route, will still have to do everything mentioned in the "going larger than 42lb" thread, because that injector is a standard size injector. Just a FYI.

[BigTex]

Thanks for the correction Erik, its been over 3 years since I did it.

[H2Racer]

Well, the idle thing won't be much of an issue as I'll be dropping in a cam soon that will help make that a little longer, after that comes a 2.75 pulley to get the boost back up as much as possible. The eventual plan is a 402 when stuff breaks.

 

It was pretty amazing to tune in the 60's and get them to run on a STOCK LQ4 cam. But it can be done. It would have been a lot easier to go with something more like a 50 because of the resolution you lose in tuning a large injector.

 

The main thing to take away from this is that if you have a 2004 and are right on the edge of your 42's you can extend them with a voltage booster. If you are going larger in the future... go ahead and convert to a bit larger injector and forego the voltage booster. You won't need it with larger injectors.

 

In the beginning when I used my wideband and posted the results I was told 42's were plenty for a lot more power than I was making. I think I've put it to rest that 42's don't support much on a 2004 "no way, no how".

[H2Racer]

Also, 60# @43.5psi = 69# @ 58psi, not 72#, that could be part of the tuning problem. There is also some question as to whether the mototrons are really 60# or 57# as are the seimens deka injectors that the motos are built from.  If they are 57# @ 43.5 then they are 66# at 58psi.  This is the assumption I used when tuning my truck and it seems to have worked out pretty well.

<{POST_SNAPBACK}>

 

I think there are several way to get them to run right. In the end all that matters is getting them to that point. We had them running pretty decent with a scaled injector constant that was telling them they were 49's or so down low and that worked okay. The method I posted would seem to be the most direct path to success with whatever size you assign. I'll bet that your truck would have been easier to tune either way because of the healthier appetite for fuel.

 

I'm very happy I was able to pull it off and get it done quickly because I think a few others are on the fence with going larger than 42's on a 2004 and my post should help them make the decision.

[SSLink]

Thanks, H2Racer for all the work and the thorough writeup. Looks like I will have to decide on an injector to swap up to and just forego the voltage booster.

 

What had not occurred to me is that these 60 lb. injectors are actually much bigger at our fuel pressure. Something a bit smaller would probably suit me fine and be easier to tune.

 

I'll go with the 60's some day on my 427 stroker. Thanks again to everyone weighing in.

[H2Racer]

Thanks, H2Racer for all the work and the thorough writeup. Looks like I will have to decide on an injector to swap up to and just forego the voltage booster.

 

What had not occurred to me is that these 60 lb. injectors are actually much bigger at our fuel pressure. Something a bit smaller would probably suit me fine and be easier to tune.

 

I'll go with the 60's some day on my 427 stroker. Thanks again to everyone weighing in.

<{POST_SNAPBACK}>

 

I would recommend a injector in the low 50's range. You'll have an easier time. I was looking for a true 60 lb injector and didn't really notice that the motron 60's are rated at 3 bar until I had them coming. I'd have backed off a bit had I keyed on that point earlier. A low 50's injector should be just what you need. Either that or convert to the rising rate (at least for boosted trucks) 03 fuel system. 50's would be easier

 

Also, check my post on LS1tech about this same thing. I've clarified some of the tuning steps in it.

[SSLink]

Does anyone have any experience with the Delphi 50lbers listed on the Racetronix website? They are rated for 58 lb/hr at 58 psi. Would these be compatible (with different connectors)? Looks like the next step down would be the SVO 42's.

[BenKey]

Does anyone have any experience with the Delphi 50lbers listed on the Racetronix website? They are rated for 58 lb/hr at 58 psi. Would these be compatible (with different connectors)? Looks like the next step down would be the SVO 42's. 

<{POST_SNAPBACK}>

They'll work with the different connectors and fuel rail modification.

[SSLink]

Does anyone have any experience with the Delphi 50lbers listed on the Racetronix website? They are rated for 58 lb/hr at 58 psi. Would these be compatible (with different connectors)? Looks like the next step down would be the SVO 42's.  

<{POST_SNAPBACK}>

They'll work with the different connectors and fuel rail modification.

<{POST_SNAPBACK}>

 

Thanks, BenKey. Yep, as you pointed out in your prior thread, I will need to get new connectors and some tubing to fabricate some spacers. Just thinking these may give me a little more grow room than the SVO 42lb'ers but maybe less tuning headaches than the big Mototron 60lbers. Does anyone know of anything in between?

[H2Racer]

Does anyone have any experience with the Delphi 50lbers listed on the Racetronix website? They are rated for 58 lb/hr at 58 psi. Would these be compatible (with different connectors)? Looks like the next step down would be the SVO 42's.  

<{POST_SNAPBACK}>

They'll work with the different connectors and fuel rail modification.

<{POST_SNAPBACK}>

 

Thanks, BenKey. Yep, as you pointed out in your prior thread, I will need to get new connectors and some tubing to fabricate some spacers. Just thinking these may give me a little more grow room than the SVO 42lb'ers but maybe less tuning headaches than the big Mototron 60lbers. Does anyone know of anything in between?

<{POST_SNAPBACK}>

 

A 50lb giving 58 at 58 psi would be preferable to my 60's giving 71 or so for sure. They would probaly idle at around 2.0 ms whick would give better tunability.

[SSLink]

I am hearing from Racetronix and their dealers that the Delphi 50 lb/hr injectors are hard to tune from idle, paricularly on the LS1-based engines and PCM's. Apparently the Siemens 57 lb/hr are considered better because of faster opening closing speed (like the 60's H2Racer went with). I just think 57 lbers (at 43.5 psi) are still too big. Is there nothing workable between the SVO 42's and these? Any more thoughts on this anyone? I guess if Farmtruc and H2Racer can get the 60's tuned in, it's doable.

[H2Racer]

I am hearing from Racetronix and their dealers that the Delphi 50 lb/hr injectors are hard to tune from idle, paricularly on the LS1-based engines and PCM's. Apparently the Siemens 57 lb/hr are considered better because of faster opening closing speed (like the 60's H2Racer went with). I just think 57 lbers (at 43.5 psi) are still too big. Is there nothing workable between the SVO 42's and these? Any more thoughts on this anyone? I guess if Farmtruc and H2Racer can get the 60's tuned in, it's doable.

<{POST_SNAPBACK}>

 

Look out.. everyone will act like you're crazy and or stupid ;) Do what you have to do to make your combo work.