Leaf blower supercharging

**Fastjeff57** · 05-09-2012

Saw an article on this in Popular Mechanics in which they supercharged a SB Chevy with two gas powered leaf blowers. Motor made great power and, thinking of outboards, it gave me an idea: How about one leaf blower (possibly battery powered) supercharging an OB?

Here’s how it could be done:

Method One: The blower pressurizes an air box with the carb(s) inside. This arrangement requires a way to boost the fuel pressure in the carb(s) or they will lean out as the boost comes up. Also, the throttle linkage has to go through the air box (to the outside) without binding or creating an air leak. Advantages of this method are easy starting and ‘normal’ throttle up.

Method Two: The only carb (a big one!) is mounted on the leaf blower. Advantages of this arrangement are automatically correct fuel/ air ratio (within limits), and no need for fuel pressure boosting. Disadvantages would be rotten throttle response without the leaf blower running, and the need for a pump spray system to get the motor started.

Interesting?

Jeff

**Bill Van Steenwyk** · 05-09-2012

Method #1 was used on the 1980 Model Mustangs with 2.3L four cylinder engines as a less expensive way to provide some additional performance with the four cylinder engines and still maintain decent fuel economy, but used a Turbocharger instead of a centrifugal or rootes type blower with a "blow off" valve to control boost so as to not overstress the engine with too much boost.

I had one of these models and it was a very good car, delivering just short of 5.0L V-8 performance with 25-26/MPG fuel economy. This of course was 30+ year ago technology, and to the best of my memory, not too many computer controls on this engine. I don't remember now how fuel pressure was controlled, or whether a mechanical means was provided so as to allow extra fuel when the boost got high, but there would have had to have been something as the OP indicates.

No air box was used, as the whole internal part of the carb was pressurized by a simple flex hose that ran from the output side of the turbo to the carb inlet, so no sealing of linkage was required. Possibly do a search on this engine and you might be able to find a factory manual that gave more detail as to how and if fuel pressure was controlled if it was. The turbo did not put out too much pressure as I remember as it (pressure) was controlled by a mechanical waste gate as mentioned earlier. I purchased an aftermarket "boost control" which allowed manual adjustment of the waste gate and consequently boost from the turbo to be increased for more power than stock. As part of the kit a water/alcohol injection system was furnished that allowed a mix to be introduced into the carb when the boost was turned up over a certain amount to prevent detonation. This system was no more than a windshield washer set up filled with water/alcohol mix.

The only problem I ever had was I got "too happy" with the boost control kit several times while trying to outrun another car and blew the head gasket. I seem to remember the stock system would only allow about 4lbs of boost, but with the "kit" you could go up to about 8-9 lbs. 6-7 was the limit on the head gaskets the way it was set up, but could probably have been overcome with O-rings around the cylinders. Instead of going to that trouble I bought an 84 SVO Mustang which was also a Turbo-charges engine of the same size but fuel injected and more electronically controlled and the head was designed to handle the increased boost without blowing the gasket. I think the 80 model was rated about 160HP or so which was about 20-25 over the stock engine with very mild boost and not much else in the way of modification except for a lower compression ration to handle the higher boost of the turbo.

I would think for about the same money a Nitrous Oxide setup would provide just as much or more bank for the buck and if purchased from a reputable manufacturer would eliminate a lot of trial/error and costly repairs because of too much boost or a too lean/detonation problem.

**Bill Van Steenwyk** · 05-09-2012

I got really curious about just how the carb on my Mustang in the earlier post worked regards mixture, so I did a search and found that the carb was a special Holley unit that had a rudimentary computer/O2 sensor that would richen the mixture when required. I think the Holley number was 6400 but carbs with that capability built in are probably very rare, especially after this length of time without having a lot of other circuitry built in that would not be required. You might be better off to go with FI and adapt something from an engine that already had the capability to adjust the mixture with a MAP unit or something similar if you want to stay with the forced air induction.

Makes a Nitrous unit look more attractive all the time, especially since the application is already proven and would eliminate a lot of testing, parts replacement and all the other things that go along with trying to gain some power with an unproven system, unless you just like playing around with that type thing. I think I remember Land & Sea had nitrous systems available at one time if they are still in business, or if you build one yourself you have to remember to put more fuel in the engine along with the nitrous to eliminate burned pistons and other components. Again the search function should give you some info on nitrous and outboards.

**Steve Litzell** · 05-09-2012

Originally Posted by Fastjeff57

Saw an article on this in Popular Mechanics in which they supercharged a SB Chevy with two gas powered leaf blowers. Motor made great power and, thinking of outboards, it gave me an idea: How about one leaf blower (possibly battery powered) supercharging an OB?

Here’s how it could be done:

Method One: The blower pressurizes an air box with the carb(s) inside. This arrangement requires a way to boost the fuel pressure in the carb(s) or they will lean out as the boost comes up. Also, the throttle linkage has to go through the air box (to the outside) without binding or creating an air leak. Advantages of this method are easy starting and ‘normal’ throttle up.

Method Two: The only carb (a big one!) is mounted on the leaf blower. Advantages of this arrangement are automatically correct fuel/ air ratio (within limits), and no need for fuel pressure boosting. Disadvantages would be rotten throttle response without the leaf blower running, and the need for a pump spray system to get the motor started.

Interesting?

Jeff

Seems that HOT ROD magazine did that a few months back on a small chev, I think it was in their "Vete Hack" Piece. Check it out at HotRod.com

**Bill Van Steenwyk** · 05-09-2012

Steve:

Thanks for putting the info up about the HotRod web site and the article on the "Leaf Blower" Corvette. I don't know if you read the article all the way to the end or not, but they also, in the "low buck" spirit of innovation, tried just spraying Nitrous over the air intake (did not add extra fuel, etc.) and found that was the most effective, both from a HP output and money spent way to increase the HP on that particular vehicle.

**Fastjeff57** · 05-10-2012

The problem with "Genade Juice" is two fold: Not only is it expensive, it runs out fast and then you have--nothing. A turbo or supercharger, by contrast, runs until the motor runs out of gas. Once it's paid for, that's it. where buying nitrous gets very expensive after a while.

Not only do you hve to inject extra fuel with a nitrous system, requiring solenoids and fuel piping (plus an electric pump) there's the problem of heating the bottle, to get enough pressure to be effective,

Not as simple or cheap as you'd think. Ask any drag racer who's using it..

Jeff

**fyremanbill** · 05-10-2012

The primary problem with forced induction on 2 stroke engines like ours is that there are few good ways to prevent the added charge volume from going out the exhaust port. Turbos work pretty well because they produce a lot of exhaust back pressure "holding" the mixture in the cylinder. I suspect that some very specific port timing/sizing and expansion chamber design might allow a supercharger to work, but most attempts have been disappointing.

**Mark75H** · 05-10-2012

Originally Posted by fyremanbill

The primary problem with forced induction on 2 stroke engines like ours is that there are few good ways to prevent the added charge volume from going out the exhaust port. Turbos work pretty well because they produce a lot of exhaust back pressure "holding" the mixture in the cylinder. I suspect that some very specific port timing/sizing and expansion chamber design might allow a supercharger to work, but most attempts have been disappointing.

Bingo

**Bill Van Steenwyk** · 05-10-2012

[QUOTE=Fastjeff57;120067]The problem with "Genade Juice" is two fold: Not only is it expensive, it runs out fast and then you have--nothing. A turbo or supercharger, by contrast, runs until the motor runs out of gas. Once it's paid for, that's it. where buying nitrous gets very expensive after a while.

Not only do you hve to inject extra fuel with a nitrous system, requiring solenoids and fuel piping (plus an electric pump) there's the problem of heating the bottle, to get enough pressure to be effective,

Not as simple or cheap as you'd think. Ask any drag racer who's using it..

Jeff:

When you posted regards the possibility of use of leaf blowers to be used as forced induction for outboards, I made the assumption that you were aware of the problems that have been faced for years just "forcing" additional air into a two stroke with the normal type porting most are designed with as brought out by "Fryemanbill" in his excellent post regards the use of same on common outboard engines being built today that are naturally aspirated. That is why I mentioned the use of Nitrous as a possibility to achieve the same type (or better) performance boost without trying having to redesign the engine to take advantage of forced induction. Land and Sea did quite a lot of work on turbocharged Merc V-6's in the mid 80's but I don't think any successful kits or engines made it to market, or if they did, they were not very successful. They brought several bass boats to Florida to run for Kilo records in that time frame equipped both with turbochargers and expansions chambers for each cylinder, but were not very successful with it, at least in the competitions I saw.

As far as the use of Nitrous, I recognize the costs involved as I used Nitrous injection on a 500CC Konig in the mid 70's with a special manifold made by Harry Pasturczak that fit between the carbs and the rotary valve housing with all the attendant solenoid valves and plumbing, and provided a means of introducing not only the nitrous but additional fuel to take full advantage of the gas and eliminate the possibility of burnt or stuck pistons or other damage, so I do have some knowledge of the process and equipment required. I have no doubt that Nitrous can prove to be expensive in its use, not only the product itself, but engine parts also if "overused", and that determination was made from personal experience.

If you haven't had the opportunity to do so, the article Steve Litzell mentioned can be very easily accessed by going to the HotRod web site and then using the search function to find the article about the "Leaf Blower" Corvette. The point they make in the article regards using two leaf blowers versus injecting nitrous by just letting some loose over the carb (without additional fuel or a complicated solenoid valve arrangement) is the nitrous application, rudimentary as it was, still exceeded the horsepower gain available with two leaf blowers, showing almost TWICE the gain. Whether the results would be similar on a conventional two stroke would be interesting to determine.

Since most folks that are interested in HP gains are also interested in the "Most Bang for the Buck" and also short bursts of speed are usually enough to prove who has the most HP in a contest, it looks to me that the Nitrous would still win hands down given the porting arrangement on most outboards in use today if you factor all the design and development costs involved in doing the engineering, design and manufacturing or modification of an existing 2 stroke motor that would be competitive cost and weight wise, to take advantage of forced induction against what is currently available.

When it gets down to HP and speed, the saying is "Speed costs money, how fast do you want to go." Any way is expensive, but rather than design an new engine, or modify existing sleeves with different porting in an existing one, plus exhaust tuning which is another black art in itself, I think the nitrous would provide more HP per cubic dollar spent, and be far simpler for the gains available versus the leaf blower application, whether one or two was used.

If you want further proof of this, when Mercury came out with a supercharged straight 6 and 4 a few years back (Verado models) they went 4 stroke with the design instead of staying with a two stroke and conventional porting. Probably modern emissions requirements and cost had something (a lot) to do with the design, but that is the way they went.

Not trying to be argumentative, but your first post was inviting discussion, I thought.