Reading Max Boost - Question about bhp formula

[Schmieder]

i have one... and am planning on using it when the funds come around to stick a 3900/F40 in the monte... i'll give the 3100/4t60-e one hell of a time until it's too tired to continue or goes sky high...

What is your experience/opinion about knock off turbos?

Seems it has done you good so far knowing you referred to the 3100/trans dying before the turbo does.

What retailer did you get the turbo from? I'm looking at CXRacing. I read around it is the better of knock offs.

[Schmieder]

Here is a question I didn't ask yet or have an answer.

What is considered a dangerous AFR? Just need a range of known areas to NEVER hit, both lean and rich.

Also, if you guys know...

What is the optimal AFR for..
Idle
WOT
Cruise

When I fire it up for the first time I need a base line of values to watch for before I can get into the tuning process.

I know Oil Temps are 230*F max for Mineral and 270*F Synthetic. Trans temps should be similar in safe maximums?

[robertisaar]

What is your experience/opinion about knock off turbos?

Seems it has done you good so far knowing you referred to the 3100/trans dying before the turbo does.

i'm planning on just running the almost 190K mile 3100/4t60e into the ground. i figure the tranny and/or engine will go before the turbo does...

AFR: i like 12:1 or slightly richer while in boost, 16.2 at cruise and low throttle and 14.7 at idle/moderate throttle... works alright for a N/A motor, though while in PE i shoot for 12.5:1 with n/a...

those oil temp numbers seem right for max, though i would prefer to keep them around 180-200*F, i believe that is where they perform the best. tranny temps are best between 170-180*F, or at least that's what most aftermarket companies agree on.

[pocket-rocket]

Keep in mind the whole thing with most fuels being E10, so thing should be a little richer than 14.7:1. Also with the tq before boost at takeoff, at that point the engine/transmission is also fighting a heavy dead still vehicle. I moving vehicle is easier to speed up than one sitting perfectly still which means less stress on the transmission. Like my uncle put it. "The hardest part on a transmission is taking off." You have an engine trying to force the transmission to turn while you have a body trying to sit still.

[Schmieder]

All great answers, thanks.

Here is another 'good' question.

I am welding in a flex pipe (for obvious reasons) and I would like to know the actual pivot point of the engine. This way, I can place the flex pipe at its best place and angle to absorb motion at it's best.

Is the pivot point where the engine meets the trans? Or is it the axle from the trans?

Being the perfectionist that I am, if you haven't yet noticed, I wish to place the flex pipe after the turbo turbine to reduce WOT motion and heat variables.

I plan to mount the turbo with braces incorporating heavy springs. I figured a standard valve spring will be good enough to absorb most vibration and heat stress.

EDIT: Boy oh boy, I have a large list of advice, notes, answers and other information. Mostly from this site. I probably would have messed up something easily w/o all this advice/help.

Measure my thanks in the boost I achieve

[robertisaar]

the "pivot" point would be different depending on the vehicle. on a gen1.5 3100 W, there are two low mounts, one for the absolute bottom of the engine, one for the trans, then the two dogbones on top. it would pivot based on the two lower mounts, since the two dogbones would prevent most movement up top, it would only rotate as far as those bushings allow it...

[Schmieder]

the "pivot" point would be different depending on the vehicle. on a gen1.5 3100 W, there are two low mounts, one for the absolute bottom of the engine, one for the trans, then the two dogbones on top. it would pivot based on the two lower mounts, since the two dogbones would prevent most movement up top, it would only rotate as far as those bushings allow it...

Ok, so i guess general placement after the turbine will be easily sufficient.

Keep in mind the whole thing with most fuels being E10, so thing should be a little richer than 14.7:1.

What kind of variable are we talking about for E10? +0.1, +0.5, +1.0 AFR?

Such a formula would be good to know since the ratio added to fuel could easily be altered in the future, freaking politicians.

Anything harmful with Seafoam in the fuel, mild amounts to provide upper cylinder lube?

[robertisaar]

a little table i made a while ago for differing amounts of ethanol in fuel...

http://60degreev6.com/forum/attachment.php?attachmentid=2976&d=1256176289

[Schmieder]

a little table i made a while ago for differing amounts of ethanol in fuel...

http://60degreev6.com/forum/attachme...6&d=1256176289

That file is going in the keeper folder. Thanks!

EDIT: Just finished reading Maximum Boost for the 1st time. It will be nice reading material while on the crapper. Thats where some good, quality thought goes on. Read some more after nailing the wife. And boy oh boy she is a beauty. I just might have her pose on the hood when I'm all done.

I'm going to reread this book many times. Can anyone suggest any other books that is worth the time and money? Preferably an up-to-date book.

[timg]

Here's one way to think about horsepower. If motor efficiency doesn't change, 2x the air = 2x the power.

New horsepower = stock horsepower * (1+ boost / 14.7)

Example:
New horsepower = 200 hp * (1 + 14.7/14.7) = 200 hp * (2) = 400 hp

Note, these assumptions are used by many tuners when tuning AEM standalone systems (what's called boost comp- the assumption that 2x the pressure = 2x the airflow = 2x the fuel). The assumptions work well once you have a baseline, but comparing NA system efficiency to turbo system efficiency is a bit difficult. A small turbo with log manifolds and low efficiency will make less horsepower than this predicts (It's a less efficient system than you were NA). A large turbo with awesome tubular manifolds will make more horsepower than this predicts (those tend to be very efficient systems). For a good primer on how the efficiency of the system affects the power output, check into some of the testing done in the Honda world. Many of them start with log manifolds because they're cheap, then move to tubulars when the performance sucks. Changing only the turbo manifold, most will gain 50-100 hp at the same boost level (efficiency of the system dramatically increases).

http://www.full-race.com/articles/sr20_turbo_manifold_test_writeup.pdf

http://www.full-race.com/articles/Bseriestest_writeup.pdf

http://www.full-race.com/articles/1.8T_turbo_manifold_test_writeup.pdf

As far as the equation you posted. Rearrange it to solve for the constant based on the horsepower of that engine NA. It's not going to be perfect, but it will give you a good baseline.

Horsepower = Constant x displacement x (PSI + 14.7)
Constant = Horsepower / (191 x 14.7) = Horsepower / 2807.7

If we assume 200 horsepower, then you get the following.
Constant =0.071232681554297

Increase boost to 14.7 psi and that equation gives an output of 400 whp. It matches the example I described initially.

Horsepower = 0.071232* x 191 x (14.7 + 14.7) = 400 hp

Tim