Supercharger for cheap, read if you can help!

[1.2gees]

I'm looking at a supercharger for a total of <$500, with 5-6psi of boost for around a 50+hp hike. I just started my new job as a mechanic again, and can use the shop for this on afterhours/weekends. Anyway, I'm thinking a roots type from a Thunderbird, it would be mounted above the alternator, probably with no intercooler (but possibly a water injector, just picked up some windshield washer pumps, don't know if they can provide enough pressure though). However, I'd consider mounting it where the AC compressor is, if I need the space (but I'd rather keep the AC if possible).



As you can see, this is a roots type supercharger. Anyway here's how I'm planning to handle the possible problems:

Readjust the DME baselines to 3% retarded timing, and 6% richer air/fuel mixture. If further modifications to the fuel/air mixture is needed, I'd consider a 5th injector, or replace the injectors with something larger, or possibly a boost dependent fuel pressure regulator (or if I'm coming close to budget limit, a generic high pressure fuel pump near the tank).

If timing retard of 3% isn't enough, I'll consider the cheapest MSD unit I can find that'll retard the timing based on boost and/or boost. I'd like to avoid this step, and I think I can, considering that the DME can retard the timing further then stock, since the baselines are already knocked back 3 degrees.

I already have a straight pipe in place of the cat, I'll probably go to a straight through muffler as well.

The intake on this unit would be very near where the brake booster is on my 84 944, if mounted in place of the air box. From there, I'd have one bend down, and stick the AFM, and right after that the air filter (probably a K&N cone).

The boost(-ed) side of the supercharger would end up under the unit, and I'd have to route it to the throttle body, the problem is the supercharger outlet is a square openning...



(the intake side is also a weird shape, but since the intake side won't be boosted, fitting something shouldn't be a problem there):


Anyway, there are three main problems I see with this thing, these are mounting/brackets/plumbing, and vacuum for the brake booster/other engine related vacuum possible problems(I think I can fine tune the rest of drivability problems that are sure to arise without too much trouble).
And I plan to deal with them as follows:

Get a supercharger off an intercooled model, as those come with perfectly round fittings on both intake and boost sides, which would be much easier to work with. Make brackets bending metal, and can bolt them to engine lift points by the stock AFM location, as well as balance shaft housing bolts. Alternator, AC, and supercharger would be driven by the same belt, tension adjusted via the AC compressor, as it is now. Vacuum would probably be provided by a vacuum pump, and a small reservoir somewhere, (how's this done on 944 turbos btw?) unless the supercharger has a vacuum port on it, as I'd imagine some would.

If I can incorporate piping, I'd definetely consider an intercooler, but I'll probably stick to a water injector on the boost side for now. To keep the cost low, I'll probably use PVC, or steel where I can afford it for the plumbing.

Does anybody see if this is impossible for a certain reason, or a good idea, etc.?

I welcome all ideas, ups downs to this, and all comments.

PS: I'll also consider a 3.8 GM eaton supercharger intended for use on GMs (are these units really different?), but those seem to be impossible to find intercooled, and I need the square to round fittings for the supercharger. BTW, does anybody know if it's physically impossible to fit that SC under the hood at my planned location? I wouldn't mind cutting the hood for clearence (and covering with a 924 Carrera GT hood scoop). But if the supercharger is simply too long to clear the brake booster, I'll have to look at another model, which is where the GM eaton comes into play (don't even know if that one would fit). I'm seriously thinking about just buying a used set up, and starting this, instead of taking too long to think it out...

Thanks,
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[1.2gees]

Let me clarify before getting any responses to avoid confusion:

"The boost(-ed) side of the supercharger would end up under the unit"-Ofcourse it can be to the side, or over, depending on the angle of placement of the supercharger, but most likely under it.

And an addition/correction about timing + air/fuel mixture:
I've talked to a dude who can reprogram the DME, which can most likely take care of this issue for about $50. I can increase fuel pressure, but would rather not spend a penny more than I have to, hence thinking about PVC piping for much of the plumbing.
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[944pilot]

If you can figure it out, I want one too.
Brian

[TheStig]

Ahmet I went to an offroad truck shop 3 days ago and checked out some superchargers for the hell of it. THe closest I can find to a simple bolt up is the Vortec Centrifugal. I was looking at a schematic of the motor my uncle drew a few months back and i realized that if there is no AC on the car, there would be a great spot do drive the supercharger. I'm still looking into it though....its not gonna be easy...



------------------
Porsche. Es gibt keinen Ersatz.

[Scott R]

If you can't go with an intercooler I have the ERL O2 injection and it's working great! But why the DME adjustments? I have not had any issues with timing and I am running 12psi of supercharged boost.

[Blackfoot]

do you know how to use a welder? if not, i think you're going to learn. if you go ahead with this project, document your work as much as possible. if it works, is reliable & cost-effective, i think there will be a ton of others who will want to attempt it. who knows, there could be a kit you end up $elling.

[marksportcts]

Ahmet, as you already know, I have turbocharged my n/a and being that you are going forced induction, I will tell you what I think of your plans.

If you can do the fabrications to mount this unit onto the engine, BRAVO!! As I think it will need a good amount of dedication. I actually bought one of this supercharger unit from a wrecked T-Bird back in '98 with the intent of getting it on my car, but I ended up selling it as I didn't have the time nor enough know-how back then to properly do it.

I think that the boost pressure you are planning should be fine for the DME 3 degree retard and 6% fuel enrichment. But I ran around 7psi last year and my engine knocked badly that it cracked all but one of the pistons (7 cracks altogether). So if it is knocking, you may need more fuel. I have the ERL MF2 additional injector controller, but there is online info to make a cheaper kit. For the FPR, you can get the 3-bar unit from Paragon Products or the adjustable FPR. I currently run a Walbro 255LPH pump, but it has raised my fuel pressure to 57-60psi, so I may need the adjustable to drop the pressure.

Straight pipe and muffler will help in top-end as the roots type is more of a low-end blower kit.

I have the J&S Safeguard knock sensor that automatically retards the timing when it starts knocking. MSD may be the cheaper way.
I have the knock monitor, and I have seen it retard as much as 14 degrees, but that being in the 15-16psi range.

If you can't intercool it, you should do water injection, such as ScottR's ERL H2O. My AIC unit is the same, just change the jumper and get the water components. Spearco also sells water injection kits, as does Jackson Racing. These parts may be available used on www.thepartstrader.com

I don't think an N/A performance chip off the shelf is a good idea as it advances the timing.

I would recommend you get a air/fuel mixture gauge, and possibly a pyrometer/egt.

[drew1]

1.2,

Sounds like an interesting project.

Vacuum: You ought to check a Ford with tis type of supercharger at idle. If it has vacuum you'll be OK. A 924t pulls vacuum from the intake for the brake booster through a checkvalve on the booster. I think that a 944na has this checkvalve. I think the heater/AC stuff is on the booster side of the check valve but the two carbon canister valves may be on the intake side. You may have to do some creative plumbing or find you need a vacuum resoirvoir to run AC & emissions cannister stuff.

Bosch used to & probably still makes a rising rate fuel pressure regulator that increases with manifold pressure. One concern I would have is stock pump pressure. From memory, with the return line & vacuum lines on the regulator clamped, the pressure isn't that much higher. A 924t or old 911t pump is capable of good pressure.

I would probably go with a boost retard box. The early 924t uses vacuum boost/retard on the distributor & late DIC models use boost & intake temp to determine timing.

Water Injection: Good, but ruuning out could be more dangerous than running out of gas. If you set up for it your intake temp soars & spark knock without it.

Sounds like you need to learn some TIG welding and fabrication skills. These are good skills to have.

Started college yet?

drew1

[1.2gees]

944pilot, I thought about that. I probably won't be interested in making a 'kit', but that may change. I would probably consider installing a system like what mine is going to end up being for <$1k instead of making a kit for someone else to install. If nothing else, I would share exactly what I did with others so they can duplicate it. I'll probably be providing a good bit of the info on message boards

EuroSpec944, Vortecs may be easier to mount but I'd rather go Roots type, they seem to last longer, and the physical mounting of the supercharger would actually be easier in the vertically challanged 944 engine comp. I'm gonna try and do this without removing AC, but we'll see about that. I honestly don't think it's going to be as hard as people think, but hey I havne't even started yet...

Scott R, If you're running 12psi of boost with no intercooler, either your o2 injection is doing a hell of a job or you're comprimising a lot of power, cause your knock sensor is backing the timing off big time. Eitherway, this is probably something I won't be doing because of cost. Water injection only at high boost would probably be my way of dealing with this. I'd do the DME adjustments, because it would take me about 20mins to do, and offer a piece of mind. BTW, did you do something to the headgasket? Mine is not very old, I'd hate to blow it! (Ofcourse I'd consider higher boost once this system is installed and running).

Blackfoot, I'm not familiar with welding, but I'm good with bending/cutting. I will most definetely document everything if I do go ahead with this. I still need to figure out what I'm doing with my transaxle before I get my license back, and I've decided to buy $5k of CDs before I spend any money on anything. I'm looking into purchasing a 57 beetle, and a 79 924. I don't know how all that's going to work out, and when. I've already saved over $700, so it's going good, figure in about 3 months I should have the CDs, and ready to do whatever with money I earn. Ofcourse purchasing the supercharger and starting to work on it wouldn't actually take too much money, but I can't have the car down around oct 19 (when I get the license), as I have planned on a lot of DEs, auto-xes, and trips around then. Add to all this the fact that I'm buying a roll cage/bar, harnesses, possibly seats, and other safety equipment... Anyway, so it's at least another week of research, then could start very soon, but no later than a couple of months, we'll see. I'm not sure if I'm interested in making a kit myself, I may do that, but if not I'll make the work easy to duplicate by somebody who's able.

marksportcts, mounting the unit won't be the trouble, that should be the easy part. Just get some metal (1/4th inch metal?), bend it to shape on the bench, drill it as necessary, and voila. Plumbing is likely to be harder, at least for me... As for your engine knocking really bad, I hate to say it, but I think your knock sensor was bad. I'm going to install a pressure dependent 'relief' valve on the intake, perhaps made to be driver adjustible at some point, it's main intent will be letting me start out with 1-2lbs of boost when I'm first starting. A boost gauge is also probably going to be installed. I really want to shy away from buying aftermarket parts whenever I can, and don't want to do too much plumbing. I think a reprogrammed EPROM chip (I've found somebody who can burn one at any parameter I desire, no way am I going to purchase a performance chip off the shelf, I'm setting forth a budget of less than $500 ) along with increased fuel pressure would be good enough. I'm hoping it won't even come to that. I don't think I'm going to look at anything near 15psi with a stock head gasket and injectors! That's not what you're running with stock compression is it???!!! I will take a look at the link. I also have an air/fuel monitoring gauge already (but can't install it, as it interferes with how the oxy sensor signal to DME, but I will be using it for fine tuning).

drew1, I will check a thunderbird application if I can. There's some funky plumbing associated with this thing, intended at giving instantaneous throttle response, and near vacuum when coating. I wouldn't mind some custom plumbing, along with an electric vacuum pump, and reservoir. Something like the BOSCH rising rate fuel pressure regulator is exactly what I'm talking about. I don't think a 924t runs any higher pressure then the 944 (actually I think it's the same fuel pump, may be wrong). Either way, I'd rather make something cheap work. As long as the parts are high quality, I don't care what they come off of (hence considering the eaton supercharger made for a FORD on my beloved Porsche). About water injection, I'd probably only have it come on at high boost pressures, if I have to rely on it for avoiding detonation (I'm guessing/hoping won't be necessary) I'll prolly use a water level warning, using sensors from a BMW I'd like to learn some TIG welding skills too, and I like custom fabrication. I really don't think it will be necessary like you guys think though. We shall see... I'm starting college next semester, right now I'm still going to a high school part time for 5 more credits before I start college.

Thanks for all the replies, I welcome anything further from this point, I'll be doing more research before I jump on anything. The starting date of this is not determined yet, depending mostly on my mood I could start (should I decide to go with this) in as short as a week, or as long as up to 3 months (but probably no longer than).
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[marksportcts]

Ahmet, none of the 8valve n/a have knock sensors from the factory. I had to install an aftermarket unit. I am running full 951 internals and a 951 head that has been o-ringed, as well as widefire head gasket.
Good luck!!

[kaffine krazed]

What side of the throttle body is the supercharger going to be on? If it is mounted on the air filter side you should still be able to get the vacum from the intake manifold if it is mounted between the throtlle body and the intake manifold you should be able to get vacum between the throttle body and supercharger.

I'm not to familair with superchargers but I belive you need to have a valve that release boost when you take your foot of the gas if the supercharger is located before the throttle body.

It might be easier to inject water before the supercharger since there is no boost the water will still absorb the heat but wont have to be presurized.

Good luck.

[MAS]

"Ahmet, none of the 8valve n/a have knock sensors from the factory."

I thought that the later cars (87 and later) had knock sensors.

-MAS

[944pilot]

More than a kit, I was really looking for the knowledge you will gain doing this. I can weld, bend, etc, and have access to a very well equipped machine shop. I just don't know a lot about supercharging and look forward to your updates. I will build a set-up for myself (and others, if desired) but dont have a lot of time to do the trial and error stuff to figure it out.
Brian

[1.2gees]

marksportcts, you're probably right about the knock sensor... I'm sorry I overlooked that when replying to your post. I probably won't run high boost, at least initially. When the next timing belt is due (or maybe I'll overlook that too for an excuse to open the engine up), I'll probably change head gaskets, then I may go a little higher.

kaffine krazed, throttle goes on the intake side of the supercharger. You're saying I'll be able to get vacuum between the throttle body and supercharger right? This is probably true, but would that be enough, that I'm not sure about. But I'm going to let that be a 'fine tuning' issue! You're right about the location of the throttle body, and yes I am planning on having a 'relief' valve. I don't want to shoot water into my supercharger, though it'll have to be brung up to higher pressure (I really think a washer pump can handle it though) it wouldn't be used to cool down the supercharger, and the piping, but just the air as it goes in the intake manifold, which is what I want. Besides, if injected on the intake side of the supercharger, the sc itself would have to compress the water (keep in mind that intake charge is probably not that hot on the intake side of the sc).

MAS, you're right. See my reply to mark.

944pilot, I wouldn't call myself an expert on supercharging either, but I'm doing as much research as I can. I will keep you updated.
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[marksportcts]

Ahmet, here is one of the simple ways of adding and additional injector:

http://www.frontiernet.net/~volvoic/microf.html

There are more out there, I believe. I remember that when I had the unit, the input pulley shaft was too long and my dad, a machinist was going to make a new one that was shorter. But I didn't have the time to do all the work and sold it.

If you don't have the blower unit yet, check on ebay as there are about a dozen of them listed right now.

[1.2gees]

marksportcts, I'll checkout the link, although I think that if others have gone to 9psi (or so I hear) with no intercooler, and factory chip, I can go to 6 psi or so with water injection, and increased fuel line pressure. However, I admit that an additional injector, or 4 larger injectors would most likely be much more efficient. Infact, the vaporization of the 5th injector's fuel into the intake manifold would probably provide a cooling effect on the mixture.

Also, I'm looking to get something like:

not a long one. The longer ones usually had certain features that I plan to make external, like the relief valve, custom built for certain applications. The units made by EATON, for FORD usually do not have 'custom' housings. Either way, the input pulley shaft is available in different lengths, but I don't think this was the case before this year.

As for ebay, I've been looking there, you know what's funny? Since I've made this post, there's been about 8 new users, with 0 feedback, using other pics I've stumbled upon on the net, selling the type of supercharger I'm looking at, for very cheap. Whatever the case, I'm not going to buy it from a 0 feedback user, selling no other parts... Thanks for the plug though, I'm looking through whatever I can right now to have more input.

Anyway I honestly think this is going to end up being quite easy for me, just not as easy as installing a bolt on unit. I'm interested in what you have to say, and any input you'd like to provide. Thanks for the responses thus far
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[mideastmafia]

http://cgi.ebay.com/ebaymotors/aw-cgi/ebayISAPI.dll?ViewItem&item=594533450&r=0&t=0

http://cgi.ebay.com/ebaymotors/aw-cgi/ebayISAPI.dll?ViewItem&item=594546879&r=0&t=0

[1.2gees]

Neither of those are the type I'm looking for (they have the 'custom' housing made for GM), but something interesting I've noticed: Selling a 'perfect' supercharger from a car with a blown bottom end, hmmm... The other ad you post shows the darkest interior I've seen on a supercharger, supposedly out of a brand new car. I can't help but be cautious with stuff like this going around. I'd rather pay more, than have to pay again for a supercharger.
Ahmet

------------------
It's all the driver...
My page over1g@hotmail.com
Porsche owners Gallery.../My 944

[Scott R]

You should not have a problem with vacume. Just "T" the idle air valve line into the booster. I loose a little pressure every now and then, but if you look at the pressure on the picture you can see that it sits around 15. at idle. (sorry my digital camera is from the stone age.)

[TurboTim]

If you want a sure fire way to control fuel and timing,I would switch over to the 951 DME/KLR combo,2.5 bar fuel pressure regulator(non-adjustable,rising rate),injectors and the assoiciated engine wiring harness.All the sensors can be adapted to the N/A.You might have to tap a hole into your block for the knock sensor.The best thing is that these computers already come premapped with the correct fuel and timing parameters for upto 10 psi of boost. Ofcourse this is on an 8 to 1 compression engine with an intercooler but I think it would be safe.If not you could always use the DME switch to retard the tiing and add fuel.

I realize that you were going to attempt this with your stock computer but.....here are a couple things to think about.You will only retard the timing over the whole range(this is still the same for the 951 DME/KLR) but the big difference is that the 951 DME/KLR will also pull out timing according to boost.Your computer wont.This is very important especially with a high compression, non intercooled application.I think this will also solve alot of the issues that you are going to have to deal with. You mine as well do it right the first time;^)


Tim
86 951
http://www.speedforceracing.com