Old vs. New Injectors?
12-09-2009, 11:20 PM
#91
um, I'm confused, Mr. Pump. You asked where you said "stumble on acceleration"? Please refer to your post and tell me where I misread you.
I don't have any issues with folks looking into alternatives, nor do I have issues with your reasons for going with a replacement rather than rebuilding, if thats your preference. If you are happy with it, I am happy for you and am pleased that you can verify some of the data points being discussed here. My comment was only meant to point out that people shouldn't jump to to the conclusion that the replacement was "better" than the original injectors. A properly functioning 968 should exhibit the same four characteristics you describe, regardless of injector type.
Regards,
I just installed the injectors that you purchased John. My wrench who is a licensed Bosch dealer measured the injectors and installed them in my car and there was no fitting issues to speak of. Initial seat of the pants impressions were as follows,
1/ Smoother acceleration
2/ No more stumble when powering off from a stopped position.
3/ Appears to have more power in the top end (this is subjective of course).
4/ less RPM flutter at idle.
The reason I installed these injectors is that I was unsure of their condition and these were a cheaper alternative than OEM (I prefer new to reconditioned parts).
As a result I let my wrench test drive my car as I thought he would be more objective in his opinion. Suffice to say he promptly snapped up my other four injectors I had.
So far so good. I will be checking the AFR when the weather improves.
1/ Smoother acceleration
2/ No more stumble when powering off from a stopped position.
3/ Appears to have more power in the top end (this is subjective of course).
4/ less RPM flutter at idle.
The reason I installed these injectors is that I was unsure of their condition and these were a cheaper alternative than OEM (I prefer new to reconditioned parts).
As a result I let my wrench test drive my car as I thought he would be more objective in his opinion. Suffice to say he promptly snapped up my other four injectors I had.
So far so good. I will be checking the AFR when the weather improves.
I don't have any issues with folks looking into alternatives, nor do I have issues with your reasons for going with a replacement rather than rebuilding, if thats your preference. If you are happy with it, I am happy for you and am pleased that you can verify some of the data points being discussed here. My comment was only meant to point out that people shouldn't jump to to the conclusion that the replacement was "better" than the original injectors. A properly functioning 968 should exhibit the same four characteristics you describe, regardless of injector type.
Regards,
12-10-2009, 04:48 AM
#92
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12-10-2009, 12:50 PM
#93
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The mentioned "759" injectors i bought from ebay arrived today, already installed them, ill give a running report tomorow after a spirit drive later on.
the installation was trouble free, just take the old ones out andd put the new ones in. no fiting probs
cheers
the installation was trouble free, just take the old ones out andd put the new ones in. no fiting probs
cheers
12-12-2009, 09:12 AM
#94
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went for a drive this morning to test these injectors.
1 the cold start is fine just like factory no probs
2 cruise drive in the motorway seems smoother
3 acceleration in high gears seems quieter and smoother as well
4 idling in traffic just like factory
5 on the B-roads in 2nd 3rd and 4rd gear seems to have more torque, probably because of better atomization of fuel
In all for $169 for 4 inject is a bargain, its the same money of getting your original inj cleaned and with its newest tech im quite happy with theses.
1 the cold start is fine just like factory no probs
2 cruise drive in the motorway seems smoother
3 acceleration in high gears seems quieter and smoother as well
4 idling in traffic just like factory
5 on the B-roads in 2nd 3rd and 4rd gear seems to have more torque, probably because of better atomization of fuel
In all for $169 for 4 inject is a bargain, its the same money of getting your original inj cleaned and with its newest tech im quite happy with theses.
12-12-2009, 11:14 AM
#96
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went for a drive this morning to test these injectors.
1 the cold start is fine just like factory no probs
2 cruise drive in the motorway seems smoother
3 acceleration in high gears seems quieter and smoother as well
4 idling in traffic just like factory
5 on the B-roads in 2nd 3rd and 4rd gear seems to have more torque, probably because of better atomization of fuel
In all for $169 for 4 inject is a bargain, its the same money of getting your original inj cleaned and with its newest tech im quite happy with theses.
1 the cold start is fine just like factory no probs
2 cruise drive in the motorway seems smoother
3 acceleration in high gears seems quieter and smoother as well
4 idling in traffic just like factory
5 on the B-roads in 2nd 3rd and 4rd gear seems to have more torque, probably because of better atomization of fuel
In all for $169 for 4 inject is a bargain, its the same money of getting your original inj cleaned and with its newest tech im quite happy with theses.
12-12-2009, 09:14 PM
#100
My gas mileage has jumped noticibly since having my injectors rebuilt, if the one tank of gas I have gone through is any indication. About a 4mpg increase, and definitely more power to boot.
I'll be very curious to see how gas mileage is affected by the new injectors. I'd also like it if someone that is installing new ones would do a bit of pioneering work for us. Can you please make a log of gas mileage over the next two years. I'd be interested in seeing how much drop off you get and when it happens so I can compare that to the original rebuilt injectors.
Regards,
I'll be very curious to see how gas mileage is affected by the new injectors. I'd also like it if someone that is installing new ones would do a bit of pioneering work for us. Can you please make a log of gas mileage over the next two years. I'd be interested in seeing how much drop off you get and when it happens so I can compare that to the original rebuilt injectors.
Regards,
12-12-2009, 09:50 PM
#101
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Well, the result you get depends on who does the cleaning, what they actually do, and how they do it. So that is one reason to go with new injectors, if in doubt. You know at the very least they really will be clean.
12-13-2009, 01:31 AM
#102
Y'all ought to try WitchHunter in WA. Pretty much everyone in the KC Wrenching Society uses them and has had great results. It cost me $108 including overnight shipping back to me. They did before and after flow tests and returned the used parts. Its a great way to go if you want to stick with stock parts and should be good for another 1o years or so.
Regards,
Regards,
12-13-2009, 06:32 PM
#104
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Just my thoughts on this topic (for what that's worth.....)
My turbo conversion is currently running 52# old style injectors with aftermarket FPR. It is tuned to be very rich at start-up, but once it's running it runs in the normal range i.e. not rich and not lean according to my gauge. My theory is that it that it runs rich(higher fuel/air ratio) at start up and when it gets cold or below 32F, it has trouble starting. In fact it has fouled more than one set of plugs when it has flooded. What I have done is to change spark plugs from 10's to 5's and I always get confused whether this is going from a "hotter" plug to a "colder" plug or visa versa?
My observations are (and I wish I could back them up with real science but this still makes sense to me):
Clean injectors flow well and work well, but when the same flow rate is coupled to better atomization, as in the "new style" injectors it has got to be better. Hopefully, in my case, it will start easier with the new more atomizing injectors. The improved atomization should also allow for more complete/efficient combustion of the fuel. This should result in some increase in power and possible decrease in fuel consumption.
Again this is just my unsubstantiated opinion and I am open to education and other opinions
My turbo conversion is currently running 52# old style injectors with aftermarket FPR. It is tuned to be very rich at start-up, but once it's running it runs in the normal range i.e. not rich and not lean according to my gauge. My theory is that it that it runs rich(higher fuel/air ratio) at start up and when it gets cold or below 32F, it has trouble starting. In fact it has fouled more than one set of plugs when it has flooded. What I have done is to change spark plugs from 10's to 5's and I always get confused whether this is going from a "hotter" plug to a "colder" plug or visa versa?
My observations are (and I wish I could back them up with real science but this still makes sense to me):
Clean injectors flow well and work well, but when the same flow rate is coupled to better atomization, as in the "new style" injectors it has got to be better. Hopefully, in my case, it will start easier with the new more atomizing injectors. The improved atomization should also allow for more complete/efficient combustion of the fuel. This should result in some increase in power and possible decrease in fuel consumption.
Again this is just my unsubstantiated opinion and I am open to education and other opinions
12-14-2009, 12:36 PM
#105
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My injectors went in today, needing no spacing adjustment. The driving experience is much improved now: a pronounced hesitation is gone, and the driving experience is much more pleasing. This problem did not clear up significantly after a RunRite cleaning at 106,000 miles, about 28K miles ago*.
I'm hoping my cold-start problems will clear up as well: we'll see.
ON EDIT 12-17-09: Cold start was not improved by changing to these injectors.
I can't honestly say that I feel any extra horses, but no before/after measurement has been done. There's no dyno shop up here any longer anyways. The car is more fun to drive.
Fuel pressure was tested to 52/62 psi: within spec. Jon's theory was that the FPR would be a few psi below spec on my 133k car and that this would balance out the slightly higher flow of the 759 injectors.
I am shipping the old injectors to Jon for testing, cleaning and his assessment: he asked to see them.
*For some time now it my car been fitted with a modified airbox, K&N filter, RS Barn header/exhaust and RS Barn chip.
I'm hoping my cold-start problems will clear up as well: we'll see.
ON EDIT 12-17-09: Cold start was not improved by changing to these injectors.
I can't honestly say that I feel any extra horses, but no before/after measurement has been done. There's no dyno shop up here any longer anyways. The car is more fun to drive.
Fuel pressure was tested to 52/62 psi: within spec. Jon's theory was that the FPR would be a few psi below spec on my 133k car and that this would balance out the slightly higher flow of the 759 injectors.
I am shipping the old injectors to Jon for testing, cleaning and his assessment: he asked to see them.
*For some time now it my car been fitted with a modified airbox, K&N filter, RS Barn header/exhaust and RS Barn chip.
Last edited by John Etnier; 12-17-2009 at 06:26 PM.