Riddle me something.

[GRotman]

Care to explain how a stock cp3 can support 1000hp on fuel only?

 

[McRat]

Why do Cummins CR motors respond so well to injectors, and I don't see many posts(or much press) about upgraded injectors for the Dmax?

I think if you had full tuning control of the Cummins, you might be able to do the same thing I do with stock sticks. You'd need more air than I run because of the displacement difference, but if the factory pulse was similiar duration and pressure as the Dmax (both use Bosch test lab data), then the limits should be the same.

We are 758rwhp and flat with stock injectors and they are not at their max yet. I'm trying more experiments soon to ramp that up further.

 

[JOHNBOY]

The first post refers to injectors; the second refers to the fuel pump. The stock fuel pump can support over 1000hp on fuel only. I’m not talking about using nitrous. You don’t need two fuel pumps. If you are not going to read the thread and just post to be a dick, go somewhere else.

Being a Dick is what got me where I am. :hehe: If don't like me. That does not bother me. I am not the just spouting on the web in attemp to look cool. I have a good deal of time into these trucks and engines. I have spent a good deal of time on the dyno with my own truck. Tuning it myself. I have made good power and backed it up at the tracks. How about you? How fats has your truck gone? What does your truck dyno?

The only way to get 1000hp out the fuel provided by at stock pump is to push the peak torque way up in the RPM band. At 5000RPM it could be done if the stock pump was able to stay stabile in its output. But it does not. The stock pump runs into issue with float after 4000rpm. High lift pump pressure helps but it is a bandaid. Increasing the rate of the plunger springs in the CP3 has alot of promise. But than it is not stock.

If you are only making 600+hp at the wheels and running out of fuel pump then you either have a BSFC of a jet engine or you haven't fixed the other limitations of the fuel system.

I honestly have no idea what my BSFC is. I never bothered to figure it out. I have a lot to my fuel system since I was last on the dyno. I hoping for big numbers. Time will tell.

Now it is your turn Mr Wizard. Instead of spouting hollow comments. Back them up. :rules: I have.

 

[dieselfan12]

Care to explain how a stock cp3 can support 1000hp on fuel only?

If your engine has a BSFC of 0.45 lb/hph at 4000rpm, and you want to make 1000hp, then you need be able to inject, and burn, approx 1020mm^3 per revolution. The means you need 255mm^3 per injector on an 8-cylinder 4-stroke engine (Dmax) and 340mm^3 on a 6-cylinder 4-stroke engine. The stock CP3 will support this flow rate at 1800bar. The stock injectors won’t. As you add fuel outside the usable duration window, then you will get diminishing hp gains, your BSFC will get worse, your engine will smoke and you may run out of fuel pump.

From this, you can see why there is more potential to make power with an 8-cylinder engine over a 6-cylinder engine. A Cummins injector that can flow 340mm^3/per rev is a very big injector and I would imagine the low and mid range run-ability would suffer.

 

[GRotman]

If your engine has a BSFC of 0.45 lb/hph at 4000rpm, and you want to make 1000hp, then you need be able to inject, and burn, approx 1020mm^3 per revolution. The means you need 255mm^3 per injector on an 8-cylinder 4-stroke engine (Dmax) and 340mm^3 on a 6-cylinder 4-stroke engine. The stock CP3 will support this flow rate at 1800bar. The stock injectors won’t. As you add fuel outside the usable duration window, then you will get diminishing hp gains, your BSFC will get worse, your engine will smoke and you may run out of fuel pump.

From this, you can see why there is more potential to make power with an 8-cylinder engine over a 6-cylinder engine. A Cummins injector that can flow 340mm^3/per rev is a very big injector and I would imagine the low and mid range run-ability would suffer.

This makes sense mathmatically, so why in real world does the pump not keep up?

 

[dieselfan12]

This makes sense mathmatically, so why in real world does the pump not keep up?

It is most likely due to the other limiting pieces in the system or the engine efficiency. The less efficient the engine, the more fuel it takes to make the same power. Most people run very large injection durations; this does not help with engine efficiency. The pump does have higher rpm issues as Johnboy stated, but if you can keep the plungers full or change the pump speed the stock pump is fine.

 

[Big Angry]

It is most likely due to the other limiting pieces in the system or the engine efficiency. The less efficient the engine, the more fuel it takes to make the same power. Most people run very large injection durations; this does not help with engine efficiency. The pump does have higher rpm issues as Johnboy stated, but if you can keep the plungers full or change the pump speed the stock pump is fine.

dieselfan12, do you know of anyone who's making more than 800hp on a Dmax without Dual CP3's and nitrous? If not, I'm assuming this would be due to engine inefficiency? If so, who? Just wondering.

 

[dieselfan12]

dieselfan12, do you know of anyone who's making more than 800hp on a Dmax without Dual CP3's and nitrous? If not, I'm assuming this would be due to engine inefficiency? If so, who? Just wondering.

We’ve made over 800hp with one stock CP3 and without nitrous. Not sure if anyone else has. It seems most people making over 600hp on fuel only are running two. With most engine control systems it’s hard to get enough fuel in without injecting too late or too early, so you may end up needing that much fuel. Don’t know. I heard people say they picked up power with the second pump, but this may be a band-aid for another issue.

 

[Big Angry]

We’ve made over 800hp with one stock CP3 and without nitrous. Not sure if anyone else has. It seems most people making over 600hp on fuel only are running two. With most engine control systems it’s hard to get enough fuel in without injecting too late or too early, so you may end up needing that much fuel. Don’t know. I heard people say they picked up power with the second pump, but this may be a band-aid for another issue.

Are you able to maintain rail pressure at that HP level? And do you have an aux lift pump at the tank pushing fuel up? Do you think you could get 200 more hp out of that pump? And what turbo setup are you running in this configuration?
Sorry for all the questions. Oh, and are you tuning with EFI live?
Thanks!

 

[bones]

pretty sure they are Banks and are using software not available to any others yet

 

[JOHNBOY]

If your engine has a BSFC of 0.45 lb/hph at 4000rpm, and you want to make 1000hp, then you need be able to inject, and burn, approx 1020mm^3 per revolution. The means you need 255mm^3 per injector on an 8-cylinder 4-stroke engine (Dmax) and 340mm^3 on a 6-cylinder 4-stroke engine. The stock CP3 will support this flow rate at 1800bar. The stock injectors won’t. As you add fuel outside the usable duration window, then you will get diminishing hp gains, your BSFC will get worse, your engine will smoke and you may run out of fuel pump.

From this, you can see why there is more potential to make power with an 8-cylinder engine over a 6-cylinder engine. A Cummins injector that can flow 340mm^3/per rev is a very big injector and I would imagine the low and mid range run-ability would suffer.

Ok I am struggling with the .45lb/hph. I figured that would be higher. The info I can find is probably not near what you have access to. Back in my gas days I used BSFC for injector sizing. For my old Turbo Buick I used .7 for injector sizing. I can not find anything BSFC wise for Diesels other than this taken from Garrett's website. Link http://www.turbobygarrett.com/turbobygarrett/tech_center/diesel_tech.html

The examples given, however, are for gasoline engines, so we are going to work some additional examples here using those same equations but with a diesel engine. Matches will be calculated with an Air Fuel Ratio (AFR) of 22-to-1 for low or no smoke performance. Likewise a typical Brake Specific Fuel Consumption (BSFC) is in the range of 0.38.

I would guess that the BSFC would be somewhere in the .60 to .70 like gas. But I could be very wrong.

Any Thoughts?



Another issue in the Dmax fuel system is the injector body itself. I have heard that its poor design really hurts when larger flows are used. I have no data to prove it either way. I can say that the feed to the tip is small. Probably to small to provide enough volume to hold the pressures needed. Basically in my way of thinking the body is restriction. The pressure at the rail may be 1800bar but actual injection pressure could taper of lower like 1400bar. When the injector opens there is full pressure at the tip but the tip flows more than the body can supply so actual injection pressure slides down.

 

[dieselfan12]

Are you able to maintain rail pressure at that HP level? And do you have an aux lift pump at the tank pushing fuel up? Do you think you could get 200 more hp out of that pump? And what turbo setup are you running in this configuration?
Sorry for all the questions. Oh, and are you tuning with EFI live?
Thanks!

Yes, we can maintain rail pressure at that hp level without any issues. This was on an engine dyno, so the fuel supply system is not representative of a vehicle. There could be issues there that may cause you problems. The turbos we were using for that test were done at 800hp, so we never got a chance to take it to 1000hp on fuel only. A lot depends on what rpm you are trying to make the 1000hp at. We are using a Bosch controller and calibration tools.

 

[JOHNBOY]

We’ve made over 800hp with one stock CP3 and without nitrous. Not sure if anyone else has. It seems most people making over 600hp on fuel only are running two. With most engine control systems it’s hard to get enough fuel in without injecting too late or too early, so you may end up needing that much fuel. Don’t know. I heard people say they picked up power with the second pump, but this may be a band-aid for another issue.

One thing I would like to state is when I said mid 600s I was refering to RWHP not FWHP. I gather from your posts that your talking FWHP. Not many refer to FWHP as the Dmax's intermingled electronics make this hard to test.

My 02 LB7 was factory rated at 300 FWHP. Actual chassis dyno was 255 RWHP. 15% loss

My 07 LBZ was factory rated at 360 FWHP. Actual chassis dyno was 305. 15% loss

Applying that loss to the RWHP bring us closer to what you have seen. 650/.85 = 764RWHP.

 

[C.A.P]

Well , Finely a thred that we may get some information from Banks on. Lets keep this going and civil. We all may learn something !

This I can tell you , when we get a after market injector body that is worth a dime with matching tips we may be able to maximize our power. Having 2 cp3 is not a crutch at all. It may be overkill but each one works 50% less than it normally would. Right now its all we got !

 

[dieselfan12]

Ok I am struggling with the .45lb/hph.

I would guess that the BSFC would be somewhere in the .60 to .70 like gas. But I could be very wrong.

Any Thoughts?

I hope your engines BSFC is not that high, but with the amount of smoke I've seen on some engines, maybe. That's a ton of fuel that could have been burned. We've had engines as low as 0.28 on #2 fuel only by correcting the airflow and fuel strategy. Even our fuel only race engines at peak power are not even close to a BSFC of 0.6. We spend 1000s of hours designing and testing our systems, using data acquisition, combustion analyzers, etc. The more efficiently and effectively you get the air in and out of the engine, combined with correct fuel control, the better your engine efficiency will be.

Another issue in the Dmax fuel system is the injector body itself. I have heard that its poor design really hurts when larger flows are used. I have no data to prove it either way. I can say that the feed to the tip is small. Probably to small to provide enough volume to hold the pressures needed. Basically in my way of thinking the body is restriction. The pressure at the rail may be 1800bar but actual injection pressure could taper of lower like 1400bar. When the injector opens there is full pressure at the tip but the tip flows more than the body can supply so actual injection pressure slides down.

We haven't had an issue with the injector body. There is always a choke point in the system, I'm sure at some point the injector body could be.

 

[BIGRPOWR]

We’ve made over 800hp with one stock CP3 and without nitrous. Not sure if anyone else has. It seems most people making over 600hp on fuel only are running two. With most engine control systems it’s hard to get enough fuel in without injecting too late or too early, so you may end up needing that much fuel. Don’t know. I heard people say they picked up power with the second pump, but this may be a band-aid for another issue.

didnt you make over 800 on an engine dyno?? big difference there.

 

[McRat]

didnt you make over 800 on an engine dyno?? big difference there.

Dude, 800 on an engine dyno with a single CP3 is still a record by at least 100HP. Thinking the highest single CP3 trucks are 580rwhp best, or about 700 at the crank.

You gotta admire that.

 

[BIGRPOWR]

oh i can definitely admire that, i was just clarifying. as 99.9% of all reported #'s on here are from chassis dyno's. one guys says mid-600's rwhp and the other says 800 crank, they really arent too far off if you use 20% as your loss. now in banks case, that truck is WAY below 20% in the loss department, that i really admire!!

 

[UNBROKEN]

pretty sure they are Banks and are using software not available to any others yet

Not to mention the full support of Bosch on their injectors.
In case everyone hasn't figured it out yet...dieselfan is talking about the Banks race trucks....either the TypeR or TypeD. He's not talking about his personal truck. Unless dieselfan's name is Gale.

Not bashing here...just clarifying what's being discussed. I got the impression some in this thread thought he was talking about his personal truck.

 

[Big Angry]

Rich,
I kind of suspected that, but I wanted to make sure some one else wasn't throwing big numbers with a single CP3. It was later confirmed by subsequent posts. Not a super realistic representation for most of us, although it's still cool nonetheless.