pat, are you thinking that with rather large injectors and a lower rpm, the pistons might last longer? do you think stock engines should benifit from this also? do you think there will be alot of smoke with the 100% over injectors?
Melting pistons.
- Thread starter McRat
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pat, are you thinking that with rather large injectors and a lower rpm, the pistons might last longer? do you think stock engines should benifit from this also? do you think there will be alot of smoke with the 100% over injectors?
This is some interesting discussion. Both times I pulled my engine down, I saw no signs of erosion. Then again, I never ran over 700 HP. The second build might have been a little over 700, but I was never able to prove it at the track as I tore it down before the tracks opened back up. I don't see how rail pressure can be causing this problem. I kind of wonder if it is an RPM related issue. I have never run a lot of RPM in my truck. At least not on a regular basis.
If you can read the little orange sticker on that truck.. It says Fleece Performance 
That truck weighs 7800lbs on street tires and is a 'lil bit faster... Nitrous tuning on a Dodge isn't too difficult..
To keep it on topic though, that truck has very large injectors and we try to keep the programming sane as far as PW goes.
Brayden
That truck weighs 7800lbs on street tires and is a 'lil bit faster... Nitrous tuning on a Dodge isn't too difficult.. To keep it on topic though, that truck has very large injectors and we try to keep the programming sane as far as PW goes.
Brayden
We ran very high RPM's on the LBZ's around here and keep the pulse width down and only use timing as a necessity of RPM to keep EOI at the right time. Having said that the shop LBZ puller (JNeal's) is over 40 degrees timing @ 4800 rpms
I think it's proved why we haven't (knock on wood) cracked LBZ pistons at 700-800hp levels.
Josh I use your calculator that I've modified.. So I guess i owe you a beer and a thanks!
Brayden
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Which truck Brayden? I watch the video again and didn't see an orange sticker. Is it the Dodge in that video?
Download Josh's Calculator!!!!!!!!!!!!!!! NOW!!!!!!!!!!!!!!!!
EDIT: Didn't mean to yell that at you.. but it will help you realize how long past TDC that you're spraying/wasting fuel to create heat.
3250 on 40 overs... Shorten the pulse width to 2600 or so and it would've made the same power and you would still be driving it.
I've been preaching this for almost 2 years now... Just as a rough guide.. Cut your PW table in the lower right by as much as your injectors are over in flow.. It's not a perfect method, but it's close enough to get you started.
Good luck on the rebuild.
Get your sticks honed to 60%'s will it's out.. You'll not regret it.
Brayden
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I'm glad people find my calculator helpful. Makes the time I put into it worth it.
I have the fastest 2005 Summit White GMC 4x4 purchased in Nevada, with a single charger, no front plate, VIN ending with a 6, with OnStar, and fuzzy dice on the mirror, but you don't hear me bragging about it.
You are ****ing priceless!!
Tony Burkhard
Allseason Diesel Per.
I don't know much about this but I happen to know a couple of people who know a little. There are downsides to big injectors as well, like cylinder wash down and the fact they become like a giant cutting torch in the cylinder. Doesn't it make sense to keep the air density in the cylinder as high as possible to tear apart the injection stream as much as possible before it hits the piston itself? This is where boost plays a big factor. Cool intake temps help to cram as much oxygen in the cylinder as possible and lower egt's. As has been said, EGT's and injector spray pattern/quality are probably the biggest reasons for piston failure. Obviously RPM comes in here with the amount of time to help keep things cool. It would be nice to know exactly what is going on inside the cylinder as far as temps relative to exhaust temps.
Cylinder wash down only happens under certain conditions. Mechanical issues aside.
1. If the injector is spraying outside of the bowl.
or
2. If the injector isn't atomizing properly.
High fuel pressures will keep the fuel atomizing efficiently with larger (extrude honed) nozzles.. There is a limit to this of course.
Air density will play a large role on effective timing or rate of burn, and also fuel reaching the cylinder wall if sprayed outside the bowl. I do see where the twins argument would come into play there...but I also see the flip side as well, by keeping the fuel shot in the bowl and pw short.
The factory engineered system sprays fuel into the bowl, at the correct time, for efficient combustion. Boost pressures are adequate to support this without smoke.
The best way to make more power efficiently in keeping with a "factory engineered" approach would be to install a higher flow rate injector/nozzle and increase the boost pressure to burn the increased fuel mass.
If Ross & Paul didn't add B0720, that's the way everybody would have to make power, and I'd bet a set of nozzles that you'd have less piston melting/cracking/bent rod issues.
It's an easy way to make power by adding pulse width, but you're also creating a lot of excess heat and stress on pistons because the timing advance it requires.
I guess a good example of big power with short duration is a P7100 inline pump. That pump can deliver large volumes of fuel in very short durations (30 crank angle degrees or less) the pressure is controlled by the injector which pop's off at a preset pressure which is effectively the control of SOI. The plunger diameter controls deliverd quantity (rack and spill port aside) and the cam ramp and lift determines the pressure and duration. Fast rate cams and high lift = short duration. These guys run large injectors out of necessity because of the lack of tunability. We can learn a lot by looking at where we've been
My $0.02
Brayden
1. If the injector is spraying outside of the bowl.
or
2. If the injector isn't atomizing properly.
High fuel pressures will keep the fuel atomizing efficiently with larger (extrude honed) nozzles.. There is a limit to this of course.
Air density will play a large role on effective timing or rate of burn, and also fuel reaching the cylinder wall if sprayed outside the bowl. I do see where the twins argument would come into play there...but I also see the flip side as well, by keeping the fuel shot in the bowl and pw short.
The factory engineered system sprays fuel into the bowl, at the correct time, for efficient combustion. Boost pressures are adequate to support this without smoke.
The best way to make more power efficiently in keeping with a "factory engineered" approach would be to install a higher flow rate injector/nozzle and increase the boost pressure to burn the increased fuel mass.
If Ross & Paul didn't add B0720, that's the way everybody would have to make power, and I'd bet a set of nozzles that you'd have less piston melting/cracking/bent rod issues.
It's an easy way to make power by adding pulse width, but you're also creating a lot of excess heat and stress on pistons because the timing advance it requires.
I guess a good example of big power with short duration is a P7100 inline pump. That pump can deliver large volumes of fuel in very short durations (30 crank angle degrees or less) the pressure is controlled by the injector which pop's off at a preset pressure which is effectively the control of SOI. The plunger diameter controls deliverd quantity (rack and spill port aside) and the cam ramp and lift determines the pressure and duration. Fast rate cams and high lift = short duration. These guys run large injectors out of necessity because of the lack of tunability. We can learn a lot by looking at where we've been
My $0.02
Brayden
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Its all in the tuning if idle fuel quantity is correct and you have enough fuel pressure to atomize the fuel you should be able to avoid washdown. Also running reasonable PW like brayden said ensures all of the fuel is burnt.
Brayden makes very good points. Look at your stock pulse width, when fuel pressure is over 20000 pulse width is always less than 1500ms. We run 3200+ shots of fuel and expect to not have any issues? Personally in my truck, mostly stock, I feel very fast with only a 2700ms shot
Overall I think higher pressures 24000-28000 and bigger injectors matched to the engines hp will yeild better power by making the engines more efficient.
It's a calculator I made that takes pulse width and fuel pressure to calculate what timing you need to have a given percentage (user selectable) of injection before TDC. I'm not sure if I have the newest version posted anywhere. I'll post it, and you can check it out if you're curious.
We would also have a lot less people into tuning these trucks,I dont dissagree with you but if I had to swap injectors to gain more power I probably wouldnt of gotton into diesel tuning JMHO
Right.. It would've been a pain.. But the "instant gratification" that we are so fortunate to have would have been seen more as an injector tuning table than a horsepower table.
Just my opinion, and I'm guilty of running some 3000uS tunes but that's what you're dealt when you want to make power but stay on stock sticks.
Brayden
Just my opinion, and I'm guilty of running some 3000uS tunes but that's what you're dealt when you want to make power but stay on stock sticks.
Brayden
Can't argue with any of what you guys say, good thread, very much enjoying it. Love Jeff, he's my main man. We're trying new things and so far so good. It's all about turbos and getting air into the motor as cool and as dense as possible for us. We are not running much pulse width and getting good numbers so far.
We're trying new things and so far so good. It's all about turbos and getting air into the motor as cool and as dense as possible for us. We are not running much pulse width and getting good numbers so far.