Bosch type 2 or type 3 injectors for an lt1? Help me decide
05-13-2012, 04:44 PM
#21
If this theory was true you could run the stock injectors up to 400rwhp. You can't do that.
Its not about can it work, its about longevity. The reason they probably see quicker times is obvious with an injector swap you need to tune for it. So they probably didn't have a correct tune to begin with thats why they saw faster times coming from going down in injector size.
Its not about can it work, its about longevity. The reason they probably see quicker times is obvious with an injector swap you need to tune for it. So they probably didn't have a correct tune to begin with thats why they saw faster times coming from going down in injector size.
05-13-2012, 05:29 PM
#22
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Depends what you mean by "float" there are cams designed to "loft" the lifter at medium to high rpm to gain extra lift fairly common and a proper valvetrain setup will be in control well after peak power so the power dropoff would have you shift anyway.
Far as word from Racetronix they certainly sell and make good products but their argument leans more towards theory than practice. There has already been a link about some very quick cars specifically using small injectors because they find improved time in it. How about someone disprove that?
Again if the AFR is fine how can you argue that the DC is a problem. From what Racetronix is saying those guys should be seeing erratic AFR readings and if they were they would be looking for the cause.
Maybe there is a middle ground here? Like say running in the 80-90% range at peak the AFR does get a little wonky BUT once you get up to 100% DC, they are more or less static and just spraying what the engine needs without trying to open and close????? Static would be the most consistent way to use an injector.
See what I am doing here? Instead of dwelling on theory I want to come up with an explanation for what happens in the REAL WORLD.
I know there are videos out on the web showing spray patterns and such, anyone seen one where modern injectors were run 80-90% and flow tested showing the metering to be less accurate?
Far as word from Racetronix they certainly sell and make good products but their argument leans more towards theory than practice. There has already been a link about some very quick cars specifically using small injectors because they find improved time in it. How about someone disprove that?
Again if the AFR is fine how can you argue that the DC is a problem. From what Racetronix is saying those guys should be seeing erratic AFR readings and if they were they would be looking for the cause.
Maybe there is a middle ground here? Like say running in the 80-90% range at peak the AFR does get a little wonky BUT once you get up to 100% DC, they are more or less static and just spraying what the engine needs without trying to open and close????? Static would be the most consistent way to use an injector.
See what I am doing here? Instead of dwelling on theory I want to come up with an explanation for what happens in the REAL WORLD.
I know there are videos out on the web showing spray patterns and such, anyone seen one where modern injectors were run 80-90% and flow tested showing the metering to be less accurate?
05-13-2012, 05:34 PM
#23
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If this theory was true you could run the stock injectors up to 400rwhp. You can't do that.
Its not about can it work, its about longevity. The reason they probably see quicker times is obvious with an injector swap you need to tune for it. So they probably didn't have a correct tune to begin with thats why they saw faster times coming from going down in injector size.
Its not about can it work, its about longevity. The reason they probably see quicker times is obvious with an injector swap you need to tune for it. So they probably didn't have a correct tune to begin with thats why they saw faster times coming from going down in injector size.
Ran 109 mph in the 1/4
Tuned by the same shop 3 times that's all it had.
Switched in 24s and ran 115 in the 1/4, after being tuned by the same shop.
Are you saying that if I found a better tuner I could swap 30s back in and run faster?!
05-13-2012, 05:43 PM
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For example. We are currently running 42 lb injectors at 42 to 46 lbs of fuel pressure. I want to switch to 39 lb injectors and up the fuel pressure over 50 lbs using the same basic fuel map. I am almost certain we will pick up ET.
05-13-2012, 05:46 PM
#25
That is 3 people on this forum(one of them also referencing a 4th car he is involved with) documenting smaller injectors made them faster and one saying he had the opposite experience.
Longbob I believe you said you keep them way down in the 70s, how high did you try and run them with the smaller ones?
Like I said I wonder if there is an area in between say 80-90% where it does hurt fueling but then once they go static it helps. Just speculation, trying to make sense of other people's results.
Longbob I believe you said you keep them way down in the 70s, how high did you try and run them with the smaller ones?
Like I said I wonder if there is an area in between say 80-90% where it does hurt fueling but then once they go static it helps. Just speculation, trying to make sense of other people's results.
05-13-2012, 05:57 PM
#26
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Let me give you a little more background. I one of the few people that I know of that has figured out how to convert a LT1 to run on sequential using a FAST ECU and adhering to the NHRA Stock Eliminator rules. We have to use an Optispark or equal replacement. Bernie Cunningham is doing it with a Holley ECU and I am not sure where he located his cam sensor.
I was told by everyone, and I mean everyone that what I wanted to do simply was not possible. Well, a few months of hard dyno and track work I have picked up over 2 tenths with tuning alone. It is safe to say that I have done more dyno and track tuning that has backed my theories which the results of my efforts show.
Just take my word on it that targeting 70 to 75% duty cycle is a sweet spot. It will give you a little room if you go over and stay below 80%.
I was told by everyone, and I mean everyone that what I wanted to do simply was not possible. Well, a few months of hard dyno and track work I have picked up over 2 tenths with tuning alone. It is safe to say that I have done more dyno and track tuning that has backed my theories which the results of my efforts show.
Just take my word on it that targeting 70 to 75% duty cycle is a sweet spot. It will give you a little room if you go over and stay below 80%.
05-13-2012, 06:06 PM
#27
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That is a big delta of performance between the 24's and the 30's. I doubt with your combo the 30's would be better even with the best of tunes because I think your fuel pressure would need to be too low to make the 30's work.
For example. We are currently running 42 lb injectors at 42 to 46 lbs of fuel pressure. I want to switch to 39 lb injectors and up the fuel pressure over 50 lbs using the same basic fuel map. I am almost certain we will pick up ET.
For example. We are currently running 42 lb injectors at 42 to 46 lbs of fuel pressure. I want to switch to 39 lb injectors and up the fuel pressure over 50 lbs using the same basic fuel map. I am almost certain we will pick up ET.
05-13-2012, 06:28 PM
#28
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I'm asking because so many people use 30s now I am feeling like I left power on the table. My tune was done in the 1990's when all this stuff was new. I was thinking of getting the tune perfected this year and maybe picking up a couple 10ths with 30s. I guess the only way to tell for sure is to wide band dyno tune.
My post wasn't as clear as I intended. I am somewhat rushed getting ready for Topeka next weekend. I am running my Firebird in Stock Eliminator and a '68 Hemi Cuda in Super Stock. This will be my first race in the Hemi. Happy happy joy joy!
Without looking at your logs, I feel you are running exactly the right injector for several reasons. First and foremost are your results. That was the purpose of my "delta" comment. Another compelling reason is your combo. I am running 30lb Ford Racing injectors in my combo which is quite a bit quicker and more mph than yours. 10.35 @ 127 mph 3300 lbs in 2,000' density altitude.
Stick with your 24's and fine tune it from there. You are on the right path.
05-13-2012, 06:34 PM
#29
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Jason,
My post wasn't as clear as I intended. I am somewhat rushed getting ready for Topeka next weekend. I am running my Firebird in Stock Eliminator and a '68 Hemi Cuda in Super Stock. This will be my first race in the Hemi. Happy happy joy joy!
Without looking at your logs, I feel you are running exactly the right injector for several reasons. First and foremost are your results. That was the purpose of my "delta" comment. Another compelling reason is your combo. I am running 30lb Ford Racing injectors in my combo which is quite a bit quicker and more mph than yours. 10.35 @ 127 mph 3300 lbs in 2,000' density altitude.
Stick with your 24's and fine tune it from there. You are on the right path.
My post wasn't as clear as I intended. I am somewhat rushed getting ready for Topeka next weekend. I am running my Firebird in Stock Eliminator and a '68 Hemi Cuda in Super Stock. This will be my first race in the Hemi. Happy happy joy joy!
Without looking at your logs, I feel you are running exactly the right injector for several reasons. First and foremost are your results. That was the purpose of my "delta" comment. Another compelling reason is your combo. I am running 30lb Ford Racing injectors in my combo which is quite a bit quicker and more mph than yours. 10.35 @ 127 mph 3300 lbs in 2,000' density altitude.
Stick with your 24's and fine tune it from there. You are on the right path.
05-13-2012, 08:28 PM
#31
Yeah Pat couple of guys with 10 second NA Impalas must be stupid.
I think it important to do as Jeff Green says and not look at outright ET/MPH but look at how something performs given what it is. Compare two cars performing similarly and if one is aftermarket everything and lighter where the other is heavier with ported stock stuff the ported stock stuff car is doing more with less so there must be something right about it.
Longbob, far as I know the LT1 pcm the rest of us run is batch above 2500rpm. Maybe that is part of the equation here?
I have spoken to GIZMO about the whole stock eliminator thing and it is a hard class to run, expensive and chasing .001 is what it is all about, I think you guys do it for the challenge. I also do not think everything translates over to the street/strip cars.
I think it important to do as Jeff Green says and not look at outright ET/MPH but look at how something performs given what it is. Compare two cars performing similarly and if one is aftermarket everything and lighter where the other is heavier with ported stock stuff the ported stock stuff car is doing more with less so there must be something right about it.
Longbob, far as I know the LT1 pcm the rest of us run is batch above 2500rpm. Maybe that is part of the equation here?
I have spoken to GIZMO about the whole stock eliminator thing and it is a hard class to run, expensive and chasing .001 is what it is all about, I think you guys do it for the challenge. I also do not think everything translates over to the street/strip cars.
05-13-2012, 08:47 PM
#32
He you're saying it not me. When an engineering says this building is only rated to hold 150 people and go oh okay and stick 155 people in, it will probably be okay but you just surpassed what it was designed for.
Just because it works, doesn't mean its the right thing to do.
What ever floats your boat. OP you have heard both sides of this story, you make your own choice.
Just because it works, doesn't mean its the right thing to do.
What ever floats your boat. OP you have heard both sides of this story, you make your own choice.
05-13-2012, 09:04 PM
#33
again 100% DC is not about what the injector can handle, it means it is held open. The analogy about a structure holding people does not work.
Again you are ignoring real world data multiple people are reporting in favor of theory without any wish to reconcile the two. I am not saying Longbob is lying or anything I believe his results, just like I believe Pat, GIZMO, Jason and Pat's friend Mike when they see better results with small injectors. Difference is I would like to know why we have conflicting results and I am the only one trying to propose ideas to figure out what is going on. You are just hanging on to theory and one person's experience without any will to UNDERSTAND.
Again you are ignoring real world data multiple people are reporting in favor of theory without any wish to reconcile the two. I am not saying Longbob is lying or anything I believe his results, just like I believe Pat, GIZMO, Jason and Pat's friend Mike when they see better results with small injectors. Difference is I would like to know why we have conflicting results and I am the only one trying to propose ideas to figure out what is going on. You are just hanging on to theory and one person's experience without any will to UNDERSTAND.
05-13-2012, 09:11 PM
#34
Explain why then these people are picking up speed just by swapping injectors?
People who are not engineering, people who develop anything, just run cars are seeing results, why the people who design these are strongly disagreeing with them.
I'm am currently waiting a response from RC and FAST on the emails I sent them the other day.
Here is a formula from probably one of the worlds most foremost experts on Turbocharging. Corky Bell.
He says Lbs per hour = expected bhp x .55 / number of injectors.
So say 400hp.
400 x .55 / 8 = 27.5lbs per hour
500 x .55 / 8 = 34.4lbs
600 x .55 / 8 = 41.25lbs
People who are not engineering, people who develop anything, just run cars are seeing results, why the people who design these are strongly disagreeing with them.
I'm am currently waiting a response from RC and FAST on the emails I sent them the other day.
Here is a formula from probably one of the worlds most foremost experts on Turbocharging. Corky Bell.
He says Lbs per hour = expected bhp x .55 / number of injectors.
So say 400hp.
400 x .55 / 8 = 27.5lbs per hour
500 x .55 / 8 = 34.4lbs
600 x .55 / 8 = 41.25lbs
Last edited by F0x Slaughter; 05-13-2012 at 09:56 PM.
05-13-2012, 09:28 PM
#35
I would like to see EGT sensors on each tube on these cars or a wideband each primary tube.
I am thinking the reason why this works is because of the fuel rails being plumbed in series and not all injectors see the same exact pressure.
Any of these guys running a parallel fuel rail system?
Car companies spend countless hours and millions of dollars developing their engines and combinations.
There has to be a reason why they used the injector size they did.
A LS1 factory rated was 345hp. At 58psi at 100% DC calculator says you only need 19lb injectors, yet GM put in 28.8lbs for 2001-2002.
So why wouldn't they just put in like a 20lb injector if it will safely make more power?
I am thinking the reason why this works is because of the fuel rails being plumbed in series and not all injectors see the same exact pressure.
Any of these guys running a parallel fuel rail system?
Car companies spend countless hours and millions of dollars developing their engines and combinations.
There has to be a reason why they used the injector size they did.
A LS1 factory rated was 345hp. At 58psi at 100% DC calculator says you only need 19lb injectors, yet GM put in 28.8lbs for 2001-2002.
So why wouldn't they just put in like a 20lb injector if it will safely make more power?
Last edited by F0x Slaughter; 05-13-2012 at 09:55 PM.
05-13-2012, 10:00 PM
#36
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caprice,
I have done as much controlled testing as about anyone and have been on both sides of the duty cycle argument with multiple sets of injectors. I have even seen the difference between batch fire and sequential. Batch fire is a far more dramatic fuel dump over sequential than the higher duty cycle vs. lower duty cycle argument can ever be.
Burning the fuel more efficiently and keeping the cylinders as close to equal for AFR simply makes a little more power and a far better power curve which equates to lower ETs. You have me and an injector manufacturer on the same side of the equation. You can tune your ride as you see fit, but if you want to get the best possible ET out of your pass then you might try what I am suggesting.
I have done as much controlled testing as about anyone and have been on both sides of the duty cycle argument with multiple sets of injectors. I have even seen the difference between batch fire and sequential. Batch fire is a far more dramatic fuel dump over sequential than the higher duty cycle vs. lower duty cycle argument can ever be.
Burning the fuel more efficiently and keeping the cylinders as close to equal for AFR simply makes a little more power and a far better power curve which equates to lower ETs. You have me and an injector manufacturer on the same side of the equation. You can tune your ride as you see fit, but if you want to get the best possible ET out of your pass then you might try what I am suggesting.
05-14-2012, 06:21 AM
#38
I AM an engineer. I DO know the theory. I DO look at the data. I DON'T simply swap injectors without tuning it for each.
When I see duty cycles at 110% and still can adjust the AFR as seen by the wideband, I know there are factors at play that we just don't find out about from internet reading. This is a hobby and I don't spend much time at it. If it were my livelihood, I'd be more inclined to dig further and offer a better explanation for why it works the way it does. And BTW, every car I know about is running stock fuel pressure.
If you want to disregard extracting maximum performance, then don't worry about tweaking YOUR setup, follow the manufacturers' and vendors' guidelines for the general public, and you'll be just fine
When I see duty cycles at 110% and still can adjust the AFR as seen by the wideband, I know there are factors at play that we just don't find out about from internet reading. This is a hobby and I don't spend much time at it. If it were my livelihood, I'd be more inclined to dig further and offer a better explanation for why it works the way it does. And BTW, every car I know about is running stock fuel pressure.
If you want to disregard extracting maximum performance, then don't worry about tweaking YOUR setup, follow the manufacturers' and vendors' guidelines for the general public, and you'll be just fine
05-14-2012, 10:00 AM
#39
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Hmm... well maybe I should leave my 30# injectors in and try em out before I buy 4x# injectors...
I am running stock fuel pressure with stock regulator with the racetronix hotwire & walbro 255.
I know my gears are not up to par and it probably will be a turd down low but im putting in this cam in because the motor is already out cause of a broken crank.... unless I could find some 4.10s dirt cheap ill slap em in there...
I am running stock fuel pressure with stock regulator with the racetronix hotwire & walbro 255.
I know my gears are not up to par and it probably will be a turd down low but im putting in this cam in because the motor is already out cause of a broken crank.... unless I could find some 4.10s dirt cheap ill slap em in there...
05-14-2012, 04:53 PM
#40
This is an email I recieved today from RC Injectors.
"Our injectors will work without any issues up to 85% duty cycle.dum Other injector designs will typically go full static somewhere in the 83-87% duty cycle.dum Operating the injectors any higher will not yield additional fuel as the injector is already wide open."
"Our injectors will work without any issues up to 85% duty cycle.dum Other injector designs will typically go full static somewhere in the 83-87% duty cycle.dum Operating the injectors any higher will not yield additional fuel as the injector is already wide open."