superchargeing the 260 efi

[roosta tail]

I have a 260 efi with a a-46 box however, ive got a little supercharger off of a 4 cly. mercedes ....can i rig this up on my 2.5.....what will i have to change on the motor. it is stock and with stock heads...can this be done it would be amazing what the benifits could be... any suggestions would be wonderful thanks.....mark

[pyro]

It's been discussed few dozen times already.
It's hardly worth the effort, and nearly impossible to tune.

I would suggest giving the search feature a try.
There's about 8 years of questions and answers already archived here. :)

[ssmith007]

Popcorn please. LOL. Smitty

[1BadAction]

http://img264.imageshack.us/img264/7290/notthischitagainui4.jpg

[Riverratt]

It can be done but with the increase in air flow it blows the lubrication off the muffler bearings causing them to seize frequently unless you add a kneuter valve and a henway.

[roosta tail]

i'll check with older archives to see, but if it can be done that would be a monster!

[STV_Keith]

Chances are that blower would be WAY too small. Given that you are talking about a 2-stroke engine, you have to consider that it will ingest 2x the air at the same RPM as an equivalent 4-stroke. So your 2.5l engine that turns 8000rpm is now equivalent to a 5.0l 4-stroke turning 8000rpm.

Rick Gilman played with a 6-71 roots blower on an OMC V8 years ago, but said it was way too small for the application. FYI.

Good luck - imagination is the mother of all invention.

["HITMAN"]

It can be done but with the increase in air flow it blows the lubrication off the muffler bearings causing them to seize frequently unless you add a kneuter valve and a henway.

..... let's not foreget to mention that the "RECIPPROCATER" bearing has a high tendancy to fail as well!:p

[Mark75H]

Let me get this straight ... a 6-71 is big enough for a 7 liter 4 stroke (I checked on some blower websites), but not big enough for a 3 and a half liter 2 stroke?

How big of a blower would be needed on a 2.5 2 stroke? Would the 6-71 be enough? Will someone have to put an 8-71 blower on a Merc to settle this?

[Way2slow on H2O]

This was done in '92 and according to the Masters involved, the 6:71 on a 2.5 was 4 times too small for adequate air flow, so a blower would be twice as big as the motor to work. :eek: The horsepower loss to turn that big blower does not equal the output gained to be worth while.

Bottom line, if it could be done, it would already be done :cheers:
Now, if you could redesign the intake (Wayne Taylor was on this [RIP]) using power valves, you can build horsepower. :D Keep the gears turning!!! :thumbsup:

[JR IN JAX]

From what I have understood, half of the forced induction air blows directly through the 2 stroke's cylinder until the ports start to close.

Maybe there could be some kind of a rotary EXHAUST valve. What a mess that would be.

[Mark75H]

the 6:71 on a 2.5 was 4 times too small for adequate air flow, so a blower would be twice as big as the motor to work.


Anyone know how this blower must be twice as big as the motor figure was arrived at?

Or, for that matter, how it was determined the 6-71 was 1/4 the size of the 2.5?

The 6-71 blower was originally produced to use with a 2 stroke Diesel motor that displaced 426 cubic inches per revolution, 7 liters, 2 stroke, not 4 stroke. At 1:1 gearing the 6-71 blower displaces 411 cubic inches (6.7 liters) of air per turn. My math says this is 2.68 times the size of the 2.5, not 1/4 ... and ... 4 times 411 is 1644 cubic inches, almost 27 liters, more than 10 times the amount of air it is possible to run thru normally aspirated.

At 30% underdrive it still pressurizes a 327 (5.3 liter) 4 stroke (wouldn't this be roughly equal displacement to a 2.5 2 stroke?) to almost 8 psi.

[hydroViper235]

I have a 260 efi with a a-46 box however, ive got a little supercharger off of a 4 cly. mercedes ....can i rig this up on my 2.5.....what will i have to change on the motor. it is stock and with stock heads...can this be done it would be amazing what the benifits could be... any suggestions would be wonderful thanks.....markhttp://www.montyracing.com/photo_html/photos/big004.jpg

[STV_Keith]

I would imagine Rick used a 4.0l V8 2-stroke.

[hydroViper235]

Looks freakin sweet!:cheers:


I would imagine Rick used a 4.0l V8 2-stroke.

[Umassot50]

the blower pressure just goes right out the exhaust port on a two stroke. I know some guys that experimented with blowers on 2 stroke drag atvs. they only made power when you severly rescricted the exhaust outlets. like water shut off valve restricted on a two stroke expansion chamber pipe.

turbos on the other hand work great have at it.

[SBK]

Walter Kaaden is rolling over in his grave!

[Mark75H]

Walter Kaaden is rolling over in his grave!

No, he's sharing a couple of Sapporos with Michio Suzuki and they are laughing their axes off

[mdc]

It might be possible to supercharge a crankcase inducted 2 stroke engine by adapting an Optimax Direct Injector to give the cylinder an extra shot of combustion air and enrichment fuel after the exhaust port closes. The supercharger could act as a compressor to pressurize an onboard air tank. By regulating the air and fuel pressures to the injectors and using an aftermarket ECU to control the injector timing and pulse width you could tune for various enrichment fuels.

[allyfreak2]

it's so much easier to use laughing gas.

[roosta tail]

Boy did I open a freakin' can. So I would have to buy a 671, modify the thing. And it still would not work....btw, that v8 rude is wild looking how did it perform anyways.....

[gfinch]

Yep, never would work. I heard about someone that was told not to show up at Jasper with his blower project cuz they changed the rules to disallow it. They must have been sure it wouldn't work too. :rolleyes: ;)