B&M supercharger (Page 3/6)
pmbrunelle OCT 03, 06:49 PM

quote
Originally posted by Spadesluck:
It is tough to tell an engine guy he cant do that, just going to push him to do it even more.



I was expecting to take flak for doing a turbo V6 project from the naysayers here... I mostly kept quiet about it, and then shared my project once it was well underway.

It's easier to show people what you've done, versus thinking out loud.

[This message has been edited by pmbrunelle (edited 10-03-2020).]

Coolkoolpyle OCT 03, 08:39 PM
I will be sure to get lots of documentation as I go.

And yes it's easily possible to build power like that with a turbo.

We were building 1000 hp supra motors 20 years ago
With a two stage turbo and about 36 lbs of boost big power is easily achievable.

You can't operate something like that around town.

No way your using pump gas
and
those turbos won't last long with street driving

There's a reason supercharging is the preferred boost by auto manufacturers.
They last.

Turbos are awesome power builders but not so great at long life.

As a general rule I use turbos for racing
and
superchargers for street


So I'm calling apples to oranges on that

Two completely different animals.

Racing engines are not to be compared to street engines.

I own my own machine shop and have far more freedom to play with ideas.

I already said the 3800 was a great motor

What I'm doing is proving that it isn't the only option for great performance.
That the 60 degree V6 has lots more modifications available to it than most people realize.
and

It's cheap to do compared to other options

I'm thinking perhaps I should do some videos on the subject.

I'm a pretty busy guy but maybe over the winter I'll find the time to show the 60degree guys the tricks to power and long life.
(there are a couple of oiling system mods that are game changers in the bottom end)
Especially the 2.8.

Maybe I should do one of those "how to Hotrod the 60* V6"
books you see on the more popular engines.

In any case I'm excited to get started

More than anything
I really enjoy projects like this.
fierosound OCT 03, 08:51 PM
GM's Chevy Power Manual when engine came out.
http://fieroinfo.com/manual...0V6_Power_Manual.pdf
OntarioKev OCT 04, 04:13 AM
I would argue that supercharging is only the preferred method for domestic V8 auto manufactures. Almost all foreign manufacturers currently use turbos for their street cars, as do the domestics on any engine other than the v8.

Turbos have come so far superchargers are now a niche market limited to a few models.

Dont get me wrong I enjoy superchargers as well, but they are going away unfortunately.

I think the 3800 V6 is the best performance option for anyone that doesnt want to touch engine internals and has limited fabrication skills (this clearly isnt you).

Any engine out there can make power if you are willing to put the time and money into it. In your experience if you wanted a reasonably reliable (modified car level, not factory level of reliability) 300 Whp, with at least the same Wtq out of the 2.8, what is required?
sledcaddie OCT 04, 11:04 AM
[QUOTE]Originally posted by OntarioKev:

Dont get me wrong I enjoy superchargers as well, but they are going away unfortunately.

According to Automobile Magazine, there are currently 19 car models available with superchargers, including: Shelby Mustang, Camaro ZL1, Challenger Hellcat, Charger Hellcat, Jaguar, Jeep Grand Cherokee Trackhawk, Range Rover SVR, Lotus Evora, among others.

Most factory installed turbos are usually not set at a very high pressure, to improve longevity.

Just sayin'....
OntarioKev OCT 04, 04:52 PM
Now go to the trouble of counting models with a turbo, and compare the numbers...
Patrick OCT 04, 07:19 PM
I have a '98 JDM Subaru Impreza WRX STi, which is turbocharged from the factory. Just out of curiosity, I was seeing what was available in regards to a supercharger for the boxer engine. I watched a few videos, and what struck me the most ...was the whine!





I like what a supercharger can do, but I don't think I could tolerate listening to that racket for too long.

[This message has been edited by Patrick (edited 10-04-2020).]

Coolkoolpyle OCT 04, 08:10 PM
The whine is from the gearing in the centrifugal supercharger

By design the spin very fast
and
that requires some serious overdrive gears to achieve actual boost.

They tend to really whip up the air too
Generating friction related heat on top of the compression related heat.

If there is 50 degrees of temperature in one cubic foot of air and you compress it to one half cubic foot you will have a temp of 100 degrees.

There is the same amount of thermal energy
It's just in half the space.
Thereby doubling the ambient temperature in that space.

In reality the math is a bit more complicated than that but you get the basic principal.

Now add friction.

Yes friction

If air can burn up a rock falling to earth then the leading edge of the compressor impeller (moving well past the speed of sound)
is getting pretty damn hot.

Roots superchargers don't nearly have this problem.
Because they are generally mounted on a hot engine so the air will pick up additional manifold heat but not usually enough to need a intercooler like a turbo or centrifugal compressor.

Everyone assumes the turbo heats up the charge because the exhaust heat. Not so much. The air is passing too fast to allow much thermal transfer.

If it did all that cool outside air would drop the exhaust heat significantly.

If you've ever been under the hood of a turbo charged engine you would certainly notice they are damn hot.

Very little of the heat was carried away. And what was only passes back thru as exhaust.

From a physics standpoint roots and especially screw compressors will be most efficient at creating boost with the least amount of heat generation.

Why do so many asian made cars have turbos?

Simple

It's cheep.

In most asian countries
(Especially japan)
There is a legal limit on how many miles you can put on a engine.

If a engine must be replaced in its entirety at 60k miles
The relative short lifespans of the turbo design isn't a real concern.

Find me a turbo with 200k miles on it and I'll almost guarantee it's been rebuilt or replaced

twice.

But as the 3800 guys can tell you

Do a good job of maintaining you engine and the supercharger will likely last the life of the motor.

The original 6-71 blowers came off two stroke diesel engines made in the early forties.
Ran half a million miles

Then in the late sixties and seventies
Some hot rodder pulled it off
Threw some new bearings in it and pushed it another 100k or more.

I've got more miles on my original gmc 6-71 than most of you will ever put on any one car

and it had 40 years on its original production duty on a big diesel.

Unfortunately
They are much more expensive to manufacture and machine than turbos so they will always be only for the higher performance engines.


Otherwise they would be used on everything
We would be getting more out of smaller engines and using less fuel to get where we are going.

Bottom line
auto manufacturers are cheapskates.

As for the earlier question of how to get 300 hp out of a 2.8

I'll get into that one later when I'm done with helping my kids do homework.
OntarioKev OCT 04, 09:41 PM
Please do, I am very interested in learning about it from someone with hands on experience!
Coolkoolpyle OCT 04, 10:51 PM
300 hp.

I start there.

Using basic laws of physics I can easily determine the amount of fuel that would be required to produce the target

Once I know how much fuel I must burn I turn to volumetric efficiency.

How many cubic inches of air must be consumed to burn the needed fuel.

At 2.8L the efficiency is well past 100%

It is at that point you must consider how you are going to achieve this efficiency.

You will have to re calculate fuel at this point because there will be a significant parasitic loss from whatever method you choose to produce the volumetric efficiency you need to reach your target.

Parasitic loss can be easily calculated for things like oil pressure or coolant pump electrical generation ect

Now granted each engine design has slightly different costs to your overall energy loos but not much.

It takes a given amount of energy to pressurize oil per pound.

Laws of physics
No way around it.

You can lower it's cost by using thinner oil
or
modifications to the oiling system to combat restrictions in the design
but
the vast majority of the energy used is simply the physical cost to move the oil at it's set pressure.
Can't change that.

So
Knowing the costs to your overall figure you are now well over 400 hp in fuel required.

You can easily design a configuration that when applied to any engine will allow you to build any power output you desire

Within the laws of physics

Now you have to take that energy generated and divide it by the number of cylinders to determine how much per cylinder you must make. In this case its about 78 hp.

You must have components to withstand the forces applied

No way a stock rod is going to hold up
or
piston

but since you know exactly how much power it must deal with you can easily choose the correct part like a pro.

Now

Before you make any sort of move you now must look at how the energy is transfered

The 2.8 has a 3 inch stroke and 3.5 inch bore

You must effectively transfer that power from reciprocating into rotating.

There have been many debates about ideal bore to stroke ratio
It all comes together as a nice ratio of 75% the bore size in stroke.

So at 2.625 as being ideal stroke for the bore size you either accept the loss of energy in that transfer
or correct it.

When you add stroke to a engine taking it out of this range you make more power for the extra cubic inches but lose some due to the over stroke on the bore

So

You need a bigger bore.

A 3.1 bloch at +060 is where I'd start
That puts you in the ideal stroke as 2.800 range

So my short block would consist of a 3.1 block bored .060
H beam SBC rods machined to fit
a custom piston from JE

So we know you need a certain amount of boost to achieve the goal power output

We have lowered that number a bit because we just added some cubic inches to the engine

but not much.

Meaning I had to sit down and recalculate my numbers

I have to know how much air I must burn in a known amount of cylinder volume to determine what kind of boost I need to determine what kind of compression I'll be running.

Hence what information I give my piston guy

So to sum up what I got so far is a shortblock with 6" rods as they are of the closest ratio to stroke for ideal rod angle

So that's the shortblock
Of course I'm using arp hardware
A main girdle for cap support and a well balanced assembly clearenced correctly.

It's bed time

If your still interested in hearing more I'll continue with valvetrain tomorrow.