Brucato Promax 56lb curve

[Iowafshr]

Has anyone adjusted the 225 Promax fuel table for 56lb regulator and have any feedback?

I've been comparing some fuel tables of what i'm told are a 39lb A48 curve and a 56lb A6 curve. The attached image shows the fuel value as a percent difference between the 2 curves. There are some differences in some of the areas, but it shows a trend of roughly 10-15% reduction in the value across the table.

DeatschWerks has a calculator that could support this change when you enter the injector data. It works out to a 16% increase in fuel, to 539cc, from 39-56lb on 450cc injectors.
https://www.deatschwerks.com/fuel-ca...ure-calculator

So my thought was to adjust the values on a 225 table reducing them by 10% across the board as a starting point.

Am I overlooking anything? Do you think there is an advantage running higher fuel pressure? Is there any data to support better atomization?

The engine has some mods like a slide front, milled front and ported exhaust chest. It will need a custom tune. If anyone has any tables they like to share feel free to PM me.

I'm not opposed to sharing anything I come up with either.

[Iowafshr]

I've done some more research and took this from the instructions page:

"The values in the Fuel Map are based on a logarithmic scale, therefore to change a value by1% simply subtract or add 1. Or to change by 10% subtract or add 10, regardless of theoriginal value. Please note that value changes on the steamwheel or potentiometer equatesto the exact value change on the Fuel Map."

So I've adjusted the table to show just a difference in the values.

[texasvector]

the A-6 is a good starting point for your motor..... you will def have to "customize" it to get full benefits of going to 56lbs. an adjustable regulator can help you dial it in

egts are very helpful... steamwheel makes life easier.. the PCU is a great tool as well

what ive seen you'll be pulling fuel out in some places and adding fuel in others

how much, when and where all depends on load and motor.... EVERY MOTOR AND SETUP IS DIFFERENT

taking 10% off the promax tune would put you on the FAT ="safe" side of an A6

when you start... always use same prop/load and fuel psi(if adjustable)

attached is a tuning spreadsheet i made to help keep track of changes... every adjustment i make write down egts and make note to side what motor is doing(i.e. picking up speed/slowing down/4 stroking)

ALWAYS GO UP BEFORE YOU GO DOWN!

GOOD LUCK!!

[Iowafshr]

Thanks for the input and the PDF.

I just cut down an aluminum prop to a test wheel per the Merc manual specs. I realize it may not be exactly the load I need for given scenarios, but I'm hoping it is close. I do have a steamwheel now that I'm really looking forward to using. The old tune I ran was supposed to be a 225 SVS tune, but it always was real lean in the midrange and after I compared it to a stock 225 tune I can see why.

Here is a link to the spreadsheet: https://drive.google.com/file/d/1K4K...ew?usp=sharing

I removed the tunes as I don't know what all would be considered proprietary info from Brucato. All you need to do is copy and past the tables in the respective areas and it will highlight the differences.

[JCSmile]

The change in fuel going from 39 to 56lb curve is actually about 19.8%. The formula for injection flow that I have found is Flow2=sqrt(PSI2/PSI1)*Flow1. Sqrt(56/39)=1.1982. I'm not sure if this hold true for all injectors or not at this point. This can be seen using the calculator you posted as well using a 450cc/min as an example if you use the percent change formula (% change=(New-old)/old). This yields (539-450)/450=~19.8%.

On your motor I think you could cut fuel by 10-15% on the 39lb curve ran on a 56lb reg and still be rich enough to end up on the "safe" side to start testing even with some porting changes.

[JCSmile]

the A-6 is a good starting point for your motor..... you will def have to "customize" it to get full benefits of going to 56lbs. an adjustable regulator can help you dial it in

egts are very helpful... steamwheel makes life easier.. the PCU is a great tool as well

what ive seen you'll be pulling fuel out in some places and adding fuel in others

how much, when and where all depends on load and motor.... EVERY MOTOR AND SETUP IS DIFFERENT

taking 10% off the promax tune would put you on the FAT ="safe" side of an A6

when you start... always use same prop/load and fuel psi(if adjustable)

attached is a tuning spreadsheet i made to help keep track of changes... every adjustment i make write down egts and make note to side what motor is doing(i.e. picking up speed/slowing down/4 stroking)

ALWAYS GO UP BEFORE YOU GO DOWN!

GOOD LUCK!!

What is your technique are lower RPM's where EGT numbers aren't necessarily as cut and dry? Obviously at 3500rpm your EGT's aren't going to be near the "1150-1200" WOT that everybody states. Do you typically just add fuel and see if it increases RPM or in the case of starting on the rich side back fuel down and see if RPM's jump?

I would assume it mostly comes down to plugs and piston tops.

[texasvector]

at lower rpm... i hold motor at say 3k... while holding steady speed turn fuel up and down monitoring egts and rpms

youll hear and see motor speed up and down.. when happy motor will be the fastest= ideal fuel/air ratio should yield most hp

we were looking at drag motor boat riding curve tonight.... 800s at 3k..900s at 4k... hit 1000* around 5k

[texasvector]

plugs and piston tops have final say in tune.. make them happy.. you good!

fastest drag tune we made plugs looked "boat riding safe"!!!(edit... im not saying fastest drag tune we would slap a big prop on and go boat ride... im strickly talking about plug reading )

alot will disagree with that but time tell the truth

[Iowafshr]

Any recommendations as far as fueling goes to improve hole shot and acceleration? I've messed with the accelerator pump screw, but I can't tell a difference in performance. My initial thought is the promax curve is a little too rich in the lower RPM range.

[texasvector]

i set sensitivity at +7...vol +4

the 56lb will make it snappier

and once u get the tune dialed in itll pick up even better

[HStream1]

Heres what i have found when i was playing with My race Injectors on my Injector machines comparing Flow at different pressures. On the Bosch 0 280 150 036 Injector for the 260, 280 & S3000 because of the pintal size the injectors hit a wall at 65 to 67 psi. After that it didnt matter how much PSI I tried the flow rate didnt change. Basically no matter how much PSI you apply at a certain point a certain size hole will only allow but so much to pass through. Of all the Laser style Pro max injectors Ive done for customers I never tried anything more than 40 psi so i couldnt tell you where that type of injector hits the wall.

[Capt.Insane-o]

Pulling 10% out of the a6 curve for a 225 will put you on the safe side of close. I think i have the curve from one i did a couple years ago saved but it was for a pretty stiff prop.

[Iowafshr]

What are the flow specs for the Bosch 0 280 150 036? From the bit of googling I found a spec of 533cc @ 48psi.

[JCSmile]

Pulling 10% out of the a6 curve for a 225 will put you on the safe side of close. I think i have the curve from one i did a couple years ago saved but it was for a pretty stiff prop.

Cap't, would you be willing to send a copy of the table via email? I've got a promax that I typically run 28-30p on.. I think you're right in the 10% being close based on the stock a6 curve I've seen

[HStream1]

Bosch 0 280 150 036 2.5 Ohms 504 cc @ 48 psi

What are the flow specs for the Bosch 0 280 150 036? From the bit of googling I found a spec of 533cc @ 48psi.