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Shades wrote:So where in the engine bay are you gonna mount this two stroke engine?... on the hood, new hood ornament?
What RPM is the two stroke gonna be turning at to provide you with enough air flow?... will it even turn fast enough?
You're adding more weight to the car and using up more fuel... interesting.

Every 100 lbs is a tenth of a second. Big deal, a 2 stroke engine isn't that heavy.

If you're making boost regardless of the extra weight you will be making more power.

This is actually a really good idea, I could totally envision a little lawn mower engine in the back hatch rigged up with custom exhaust plumbed into the cars exhaust or something.

lol what and when you want to go fast you open the hood and pull the cord?

I have access to a motor (one I gave to Cjthor) that weighs about 20 lbs that could run a supercharger. It's for a Stihl chainsaw, and it's smaller than my car battery. It can mount where the battery used to be, and if I can't get an electric strater for it, I'm sure there's a similar engine that has a starter. I could just run the exhaust into the car exhaustpipe. I would love to hear how that would sound at the end!
I don't remember if I addressed this; The engine could run at whatever it's powerband is, and be geared to run the S/C at the neccessary speed.

wytbishop wrote:Speaking purely theoretically...I am no expert.

When the SC is connected to the car's crankshaft, it obviously runs at the same RPM as the car. However just like a Turbo, the SC produces optimum boost only within a specific window. A larger SC is best at higer RPM while a smaller one will improve mid range...etc. Driving it with an external source theoretically allows the SC to be run at optimum RPM all the time. So you could in theory vary the RPM of the SC independantly of the engine to have it in it's optimum rnage more the time. Determining the optimum SC speed at all engine speeds is beyond me but the controls are not too difficult.

It's a very interesting question.

I'm not usually one to start sh.t, but wrong and wrong. I am no guru by any means, but I do know a thing or two about blowers...

A supercharger will spin much faster than engine rpm's. Normal SC speed can vary anywhere from 15k rpms to 50k+rpms, depending on if it's a roots, twin-screw or centrifugal unit. Step-up drive gears people. Google it up.

However, NOT like a turbo, a supercharger (when tuned properly) will make peak boost typically right around 2k-2.5k rpms, because it doesn't rely and wait on exhaust gases to flow through like a turbo needs to spool (twin-screw and roots shine with this). Centrifugal units will lack a little bit of low end compared to the other two but will beat out the others in peak. This is pretty much the big downfall of a Centrifugal unit, but it's still considered to be the best of the bunch. A SC setup will have a much more straight torque curve than pretty well turbo setup as well.

Jesse, sounds like an interesting idea, but 100hp? I dunno, I'm skeptical, then again I usually am with pretty well everything. If you follow through with this, keep posting details. This is something I'd like to see.

thebonestockkid wrote: A supercharger will spin much faster than engine rpm's. Normal SC speed can vary anywhere from 15k rpms to 50k+rpms, depending on if it's a roots, twin-screw or centrifugal unit. Step-up drive gears people. Google it up.

However, NOT like a turbo, a supercharger (when tuned properly) will make peak boost typically right around 2k-2.5k rpms, because it doesn't rely and wait on exhaust gases to flow through like a turbo needs to spool (twin-screw and roots shine with this). Centrifugal units will lack a little bit of low end compared to the other two but will beat out the others in peak. This is pretty much the big downfall of a Centrifugal unit, but it's still considered to be the best of the bunch. A SC setup will have a much more straight torque curve than pretty well turbo setup as well.

Indeed a supercharger will spin much faster than the motor's RPM's, but I'm sure he means that the output is linear to the rpm's of the vehicle. My truck uses a roots and it peaks boost around 3000rpms, but there's a boost bypass mod that I found out about in which there is no information about how to do it since it seems that it's been over 4 years since it was discussed and all Xterra-specific sites with that information are gone, but i've just brought it back into the light, so hopefully we'll figure it out. But basically you can reroute the vacuum for the bypass vacuum solenoid to get it to boost sooner, but more specifically, it gives it another 2-3psi on the top end. Also putting on a smaller pulley not only gives you more boost as well, but it boost sooner. All superchargers have an optimal range of rpm's to spin at to make power, as well there's also a point where it'll spin too fast and won't work efficienly, but it's a large window. Also you have to take into account the load on the motor itself. A smaller pulley allows the supercharger to spin faster, but in terms of leverage, it put more of a load on the motor, but it usually more than compensates for the extra work is need to do.

Actually here's one guy's results:
Stock: 5psi@3000RPM, 8psi@5900RPM
2.3" Pullley: 9psi@3000RPM, 12PSI@5900RPM

I'm planning on going with a 2.3" pulley hopefully next year, but one thing that I wanna do it put on an intercooler before I do. The X doesn't use one, and as far as I can find, no one has ever put on, so I wanna see if I can be the first

Yeah, I set my goals pretty lofty. My company's motto is "We strive for perfection, and excellence is tolerated".
I'm wondering; How much HP does it take to run a Supercharger?
Unfortunately, I can't get on this project soon, because my girlfriend's job went under, and there's nothing out there, so we're living on savings, and not spending any extra $$.

No rush, the car will always be there, hopefully...

Not sure to be honest, but I know looking into the boost bypass mod, one article on a Ford Lightning forum said it uses 1/3 when it's not pressurising the air (with the bypass open so no boost is produced).

You may like this:
http://www.youtube.com/watch?v=OrDe1md6AWg" onclick="window.open(this.href);return false;
http://www.youtube.com/watch?v=UQ7YWT6rX0o" onclick="window.open(this.href);return false;

so what about an electric motor? it should way less if your not trying to over kill it put a smaller wheel on your alternate and it will spin faster and create the extra juice you would need i think or just get a bigger one and the wires to run that i think would be easier then having to run the fuel and exhaust for the two stroke and then get a programmable ecu like their putting into the big turbo diesel trucks then split off something from the rpm wire and have that control how fast your motor is spinning i saw a cheap thing like this on ebay but the dinky motor they put on there wasn't spinning fast enough to force air into the engine just need a fan that will move 2500 cubic inches of air per minute and that would give you about 5psi of boost.

aufgehdraht wrote:so what about an electric motor? it should way less if your not trying to over kill it put a smaller wheel on your alternate and it will spin faster and create the extra juice you would need i think or just get a bigger one and the wires to run that i think would be easier then having to run the fuel and exhaust for the two stroke and then get a programmable ecu like their putting into the big turbo diesel trucks then split off something from the rpm wire and have that control how fast your motor is spinning i saw a cheap thing like this on ebay but the dinky motor they put on there wasn't spinning fast enough to force air into the engine just need a fan that will move 2500 cubic inches of air per minute and that would give you about 5psi of boost.

Do they have punctuation where you're from?

And Mike...thank you for getting my point regarding blower speed. Clearly to avoid being flamed I need to select my words more carefully.

aufgehdraht wrote:so what about an electric motor?

I thought about that, but my goal is to add power without taking any away. This is the reason I think I can get 100 HP. My engine is making a little over 200HP, so since atmospheric pressure is about 14.7 psi, I should be making +50% HP at 7.4 psi. A turbo sees about 80% efficiency, so 7.4 psi would make a little less. Since there would be no parasidic loss with my setup, it should be possible.

Theoretically

you'd only loose horsepower if you had to put a different alternator. unless you have a pretty loud radio or something else that drains a lot of power it should be fine

aufgehdraht wrote:you'd only loose horsepower if you had to put a different alternator. unless you have a pretty loud radio or something else that drains a lot of power it should be fine

Not so.

Adding an electric motor to drive a SC to the existing charging system would substantially increased the load and cause the alternator to be much much harder to spin. Meaning more power would be diverted from the crankshaft to turn it. Energy is never, ever free. That's why he wants to drive the SC using a completely separate source. The reality of your idea is that the belt would not be able to turn the alternator at all and it would slip and squeal like a pig.

better throw a really quiet muffler on that lawn mower buddy or when your engine is idling it will sound like a 50cc two stroke bike..not very attractive.
i would not do it: sure it is original, no one else has it. but original is not always good. you will end up having more problems than you think and because no one else is doing it - you wont have anyone's help, so unless you are an expert and know exactly how things work, you should not try it.
plus, having an engine on top of an engine just doesn't feel right..
..but if you pulled it off AND it acctually worked it could be good..purely for the power output.

I was going to tie the exhaust into the car's exhaust Imagine what that would sound like!
The 2-stroke would be mounted below where the battery was.
I know it won't be easy, and am willing to accept that I may not get it to work well enough.
I have a good idea of how it would work, and am learning everything I can.
It's a hobby

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