How much fuel do I really need?

[aleccolin]

I always figure around 12% loss for a manual car, 15% for auto. Trucks with bigass driveshafts and tires will get up around 20%. I don't think there's a consensus on what the drivetrain loss for an S550 should be, but no way it's over 15%.

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[illtal]

Burkey I don't get your post. No one said anything about making 800whp.

Simply scroll up and read.

There's enough contrarians online already.
800 at the crank is something like 680-720 whp depending on the type of Dyno.

Erm... to make 800 at the wheels from 900 at the crank, you’d be looking at 11% drivetrain loss. That ain’t happening.
You’d certainly be nearer 950 at the crank, possibly more.
I’m not saying the pump can’t do it, I’m just saying that you’d want to be damn sure of it.
The addition of a BAP should give you the margin you need. Again, testing FTW.

 

[aleccolin]

Burkey I don't get your post. No one said anything about making 800whp.

Simply scroll up and read.

There's enough contrarians online already.
800 at the crank is something like 680-720 whp depending on the type of Dyno.

Does any one if I actually need a return system to achieve 800 rwhp on 93 octane?
I'll be using water/Methanol injection for anything over 3 PSI for the hot summer months in GA.
I have DW95 Injectors, just sorting out the fueling.

Your first post says 800 rwhp, so that's what everyone was assuming is your goal.

 

[illtal]

My bad, my phone does do the auto correct from common words and terms a lot. So I rescind my previous statement. I definitely meant 800 at the crank.

 

[Burkey]

I always figure around 12% loss for a manual car, 15% for auto. Trucks with bigass driveshafts and tires will get up around 20%. I don't think there's a consensus on what the drivetrain loss for an S550 should be, but no way it's over 15%.

Maybe it’s the difference in the dynos you guys use?
Here in Australia, the stock 15-17 makes a smidge over 300kw (400hp) at the crank (different fuel and headers to US cars)
Typical output at the tyres for a manual is anywhere from 230-250kw (310-335hp).
Even at the highest of those readings, you’re still talking 17%, which is a number I used to see see thrown about on this forum quite regularly... accurate? No idea. But it works pretty much perfectly in my part of the world.

 

[Burkey]

My bad, my phone does do the auto correct from common words and terms a lot. So I rescind my previous statement. I definitely meant 800 at the crank.

Lol....
I had the screenshots all prepped up!

 

[illtal]

Maybe it’s the difference in the dynos you guys use?
Here in Australia, the stock 15-17 makes a smidge over 300kw (400hp) at the crank (different fuel and headers to US cars)
Typical output at the tyres for a manual is anywhere from 230-250kw (310-335hp).
Even at the highest of those readings, you’re still talking 17%, which is a number I used to see see thrown about on this forum quite regularly... accurate? No idea. But it works pretty much perfectly in my part of the world.

Well the % is different for manuals than automatics it's always something between 15-20% drivetrain loss.

But the real magic happens on a dynojet vs mustang Dyno vs Eddy current Dyno etc.

You can make certain dynos READ a higher number simply by adding rpm. Eddy current seems to be the most accurate but more importantly least common type. I typically use this kind for my bikes in the past because my shop had one. Super accurate in any temp because of the way it's set up. Reads low in comparison.

 

[illtal]

Lol....
I had the screenshots all prepped up!

Didn't mean to a douche... I really thought about running a dual pump deadhead for now but it seems dumb. I read that you can roughly estimate 2.64 hp per liter flowed for gas engines. That would make the dw400 capable up nearly 1100 hp at 40psi and a little over 1000 at 60Psi.

 

[Burkey]

Well the % is different for manuals than automatics it's always something between 15-20% drivetrain loss.

But the real magic happens on a dynojet vs mustang Dyno vs Eddy current Dyno etc.

You can make certain dynos READ a higher number simply by adding rpm. Eddy current seems to be the most accurate but more importantly least common type. I typically use this kind for my bikes in the past because my shop had one. Super accurate in any temp because of the way it's set up. Reads low in comparison.

Oh, there’s PLENTY of ways to make a dyno read higher (or lower).
Mainline and Dyno Dynamics are probably the main players over here. Both are Eddy current. Dynojet and Mustang dyno don’t even get a look in.
My car would sit around 700-750whp on a Dynojet. DW400, no BAP, no issues whatsoever on regular gasoline.

 

[illtal]

Oh, there’s PLENTY of ways to make a dyno read higher (or lower).
Mainline and Dyno Dynamics are probably the main players over here. Both are Eddy current. Dynojet and Mustang dyno don’t even get a look in.
My car would sit around 700-750whp on a Dynojet. DW400, no BAP, no issues whatsoever on regular gasoline.

What injectors?

 

[Burkey]

What injectors?

DW95s

 

[aleccolin]

Didn't mean to a douche... I really thought about running a dual pump deadhead for now but it seems dumb. I read that you can roughly estimate 2.64 hp per liter flowed for gas engines. That would make the dw400 capable up nearly 1100 hp at 40psi and a little over 1000 at 60Psi.

That number might be a little lower for boosted applications which are usually tuned around 0.77-0.80 lambda instead of 0.85 or so for NA.

Even on the conservative side if you knock 10% out of your number it's still PLENTY of fuel for your application.

The car will target 55 psi regardless, you can go up from there with a BAP, but that's one more thing to tune.

 

[illtal]

@aleccolin. Thanx. Same thing I thought as well. I won't be tuning with the methanol as I said before, but I know timing can be adjusted in the ECU depending on what is seen for iat and Strim(s). I'm discussing a MAF based system with alky control now will dyno both when I'm done.

 

[aleccolin]

Oh, there’s PLENTY of ways to make a dyno read higher (or lower).
Mainline and Dyno Dynamics are probably the main players over here. Both are Eddy current. Dynojet and Mustang dyno don’t even get a look in.
My car would sit around 700-750whp on a Dynojet. DW400, no BAP, no issues whatsoever on regular gasoline.

Roller dynos (Dynojet) are based on the rotational inertia of a very heavy known mass drum, so it's less prone to manipulation which helped it become the standard in the US. They offer an eddy current module upgrade now to better simulate road conditions for turbocharged and/or heavier cars. Eddy current dynos allow more opportunity for fuckery with the numbers, which is how the C8 Corvette was dyno'd by journalists at numbers higher than even theoretically possible given the density altitude and other factors. That shitstorm died down, but I still haven't seen honest numbers, I think GM got really pissed at that and probably won't allow any press to dyno the C8 anymore.

On a Dynojet the S550 sees about 12% drivetrain loss, which is from my tuner who specializes in Mustangs and BMWs and has tuned thousands. For example a '16 like mine with 435 bhp will dyno around 380-385 whp. My car dyno'd 408 whp with just a Mishi elbow and K&N panel filter, plus a safe 93 tune. That's about 464 bhp at 12% loss, for a 29 bhp gain which is about right for basically no mods and a tune.

@aleccolin. Thanx. Same thing I thought as well. I won't be tuning with the methanol as I said before, but I know timing can be adjusted in the ECU depending on what is seen for iat and Strim(s). I'm discussing a MAF based system with alky control now will dyno both when I'm done.

Some cars respond to water/meth better than others. My B5 S4 on high boost (20-25 psi) is known to pick up around 30+ hp on water/meth with no tuning, it sees the lower EGTs and just keeps adding timing until they come back up or the knock sensors tell it to back off. Somehow Audi managed to make the factory engine controls on a 20 year old car do something most new cars won't.

 

[aleccolin]

You said 12:1 and that's the first time I've thought to check the year, have we been talking about a port/DI setup the whole time?

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