This is kind of long, but I would appreciare it if you read all of the rambling in the beginning, especially if you really know alot about turbos. Ok guys, here goes. As I said before, im am a classic and musclecar buff if you remember, it was a while ago. Anyway, I have a few questions about turbos. First, let me explain what I am planning to do. I have a 1984 Craftsman II lawn tractor. I just pulled the 12 hp Tecumseh and replaced it with a 16 hp Briggs and Stratton Vanguard V- Twin. Its good on torque and my father, a machinest, is going to machine a mod for the pulley on the engine that I designed to get the gear ratio high for high speeds and, beleive it or not, I am going to have a bent pipe welded to the muffler where the exhuast flows out and then it will go into an aluminum pipe that is about 2 inches in diameter and the aluminum will be about an 1/8 of an inch thick to give it a deep growl. Anyway, I want some real power and want to either turbo or supercharge it. I dont want a ton of boost, but my dad and I will probably design and he will machine an intake for a dual or even tri carb setup. I might try to port the heads with one of the home port type kits or find someone who isnt a professional that I know but that I can trust to not screw up and to do a good job, my dad doesnt have any home porting experience. Anyway, as I said, I want to super or turbocharge it. Centfigal (spelling?) superchargers seem expensive so I figured I can probably find a turbo off of an old Sabb or something, and sure enough, they are going for like 10 bucks on ebay and im going to call the junk yard tomarrow. I have some questions about turbos though. This one may sound stupid but I know the impeller spins on a stream of oil or something like that I think, is there supposed to be some kind of pump running to it? Also, I dont want a ton of boost, but can my V twin put out enough exhuast pressure to really spin up the turbo. Also, what about a blow off valve. And should the turbo be compressing the air and gas or just the air and then flowing the air into the carb? Thanks for any help guys, it seems like some of you really know alot so maybe I can make this work. And do any of you know much about Briggs and Stratton engines? Im going to the local bookstore to pick up a book I saw there on them before for specs because I need to check the CR and the head specs, maybe I can get some heads off of a motorcycle cheap that will really flow instead of trying to mod the ones I have. Thanks guys.

 

ok i'm a certified small motor mechanic....and doing a multi carb job on it wont do anything and as for the brigs motor.. it needs to be fuel injected and when a tractor runs its like 5k RPM so no SAAB turbo with do anything you need to get yourself a snowmobile motor (fuel injected) custom make a manifold and bolt on a little turbo that will make like 5psi..but i did some looking and i found a garret GT28R turbo that will work on a snowmobile motor.. but now you have to keep in mind cooling breathing internal engine strength....

 

Why would I have to fuel inject it? I know the advantages of fuel injection but im not 100 % sure what youre gatting at. It seems like youre the type of person I need though, so I appreciate your help. Did that Garret turbo come on a car? Does a snowmobile engine run verticle? How about the FI system on a snowmobile engine, is it mechanical or.....?

 

I would get a bike turbo... nice n small

 

i agree with sebba on this one, i would stick with getting the smallest turbo possible because i think you really will have a problem spooling that thing with the small amount of exhaust flow

 

a snomobile motor cannot run verticle (plus they are way too large) so in order to make that work you would want to make the lawn mower belt driven or even chain driven with an easy conversionon the main drive clutch on the snowmobile motor and add a sprocket to the back axle (solid axle so becareful while turning hard) i'm not trieng to criticize you at all i'm just trieng to give you the best possible way to get the most power.....

 

LOL or just use the T25 turbo ...

 

What is the T25 turbo? I didnt want to pour alot of money into this thing to then blow it up with a Turbo. Ill have a car in 6 months anyway, so I would rather pour money into that. I was thinking that I could probably actually modify the turbo to create a supercharger and then just spin it off of the crank. Im expecting something to break quickly if I do it though lol. Im not too worried about too much power though, I just figured that if I could slap a turbo on it and gain 10 hp and some cool points, then it would be worth it. I only want like 4 or 5 psi of boost anyway, im not looking for 12 lbs here because the engine wont handle that at all. Does anyone know of any real small turbos? I looked at the hp and torque curve of my engine and the RPM range, 26 ft lbs at 2600 rpm, 16 hp at 3600 rpm. The graph stopped at 3600 rpm so I assume it doesnt rev any higher than that. BTW, Tidus, do you know of anything that will easily get power out of my engine? Are there anythings like restrictor plates? And, if I open the governor all the way, is that where it should be 3600 rpm? Also, I have a fuel filter and a fuel pump, can my engine handle the revs with the governor opened up?

 

brigs are very very strong motors but one thing i will tell you it not to mess with the gov. you will go faster, yes.. you will screw your motor up quicker also, yes governors are there to regulate rpms under load and no-load conditions...so if you do turbo the motor and have a mis-set gov. you could easily blow it up...umm if you want to for fun and ease of setting it up.. you could run a small shot of N20 it will give you a nice jump in power and if you dont over do it.. the engine will handle it... and as far as 'bolt on performance' there is no such thing for a brings motor.. most racers have fual injected motors and smaller pullys on the front and larger pullys on the back to give it a lil more power... you can get it bored and get new piston and rings in there (along with a new connecting rod) and then u could do a lot with that motor but thats with spending some money at a machine shop.... thats all i can tell ya....and as far as a small turbo look for motorcycle turbos too.. they are small enough to work.. and hell even a PT cruiser turbo is small enough to work....

 

Ok thanks, I didnt think it was a good idea to mess witht he governor. Do you know much about the heads? Do they really restrict power or is it a factor of other things. I would imagine the heads have small valves and ports. Anyway, yeah, I guess for now I will just change the pulley on the engine for a higher gear ratio so I can get it to move fast, it literally goes as fast as I walk in 6th gear now because it had a real low ratio for the one banger that used to occupy the engine bay. Then ill get my custom exhuast and try to find a small turbo if I can. Back to one of my original questions, if I managed to find a turbo for it would I run the turbo into the carb or would the carb run into the turbo and then the outlet of the turbo run directly to the engine? I kind of like the turbo idea because I really just have to mount it anywhere and then have some hoses and then just get some one inch pipebent for each exhuast and run it to the turbo, then I can pick up my custom thick exhuast pipes from there. With a superhcarger I dont think I wouldnt have enough room to run a pulley for it off of the crank because the Briggs engine takes up almost all of the engine bay except a spot about big enough for a turbo in the front.