Small Blowers

[TurboSuzi]

I am looking for some info regarding the four cylinder blowers out there at the moment. I was wanting to find out what models, ie. import Toyota's etc., that had super chargers and what model of super charger they had. Also, engine capacity and standard boost levels of these models would be good.

[Ben Wilson]

There are 2 types of Toyota supercharger, the SC12 and SC14. The SC12 was used on the 4AGZE and produced 8 or 9 lbs into a 1600 (later model ones had a smaller pulley for the extra boost). The SC14 was used on a 2lt 6 cylinder and I assume it produced similar amounts of boost.

[Chris Rogers]

subaru had a few - made by aisin and fitted to the 660cc 4cyl. boost was 7-8psi.

[Tuna]

Those Toyota items are 'Denso' brand , same mob that make most jap aircon compressors. Oh yeah, dont set it up blow thru, everybody is using them as suck thru (carb)so it must be the better way.
Castlemaine Rod Shop and others are selling kits, along with individual bits like a recon blower with old type Vbelt pulleys in various sizes fitted if needed.
cheers.

[TurboSuzi]

These superchargers have a teflon coating on the fins inside. I don't think that setting them up as a suck thru is a great idea because I think that the coatings on the fins may not like the fuel/air mixture running thru them. What does everybody else think??

[GTSBoy]

How is petrol going to hurt teflon?

[Tuna]

I dont think CRS and many other performance shops would selling suck thru kits if there was a problem with fuel in the blower.
CRS use a 350 Holley in their Holden 6 kit, other 4 cyl kits use a 32/36 or 40adm Weber , all suck thru.
cheers

[Ben Wilson]

A nice petrol mist may well help the blower to seal as well.

[RolinAuto]

They can be used as suck through but reduces the life of the compressor. They are oil lubricated, oil and fuel doesnt lubricate real well. I have seen them last 3 years on a carb suck through setup.

[Tuna]

Originally posted by Ben Wilson
A nice petrol mist may well help the blower to seal as well.
Yes I have heard that is the case , the fuel in the blower increases boost by 1-2 psi over air alone.

[Ben Wilson]

Originally posted by RolinAuto
They can be used as suck through but reduces the life of the compressor. They are oil lubricated, oil and fuel doesnt lubricate real well. I have seen them last 3 years on a carb suck through setup.

I've had a couple of them apart and there shouldn't be any oil in the compressor casing itself. The oil lives in its own little sump and is only for the gears.

tuna - I've been thinking about pre-SC water injection for mine for just that reason....

[mopar lover]

I don't believe you can say blow thru is or isn't the best way to use the blower just because someone makes a kit like that.

Against, is the fact you now have a restriction at the blower inlet. Also generally longer intake paths which can lead to fuel puddling.

For, is less chance of a harmeful backfire into the blower. Also easier fuel system setup. Also a BOV is not mandatory.

[gmh265]

Originally posted by Tuna
Those Toyota items are 'Denso' brand , same mob that make most jap aircon compressors. Oh yeah, dont set it up blow thru, everybody is using them as suck thru (carb)so it must be the better way.
Castlemaine Rod Shop and others are selling kits, along with individual bits like a recon blower with old type Vbelt pulleys in various sizes fitted if needed.
cheers.

the toyota blowers are made by the OGURA Supercharger company http://www.oguraclutch.co.jp/english/e_products/sc/sc-1.htm it also has the specifications for the 1200 and 1400 cc blowers used by toy.

dont set it up blow thru because everybody else is using draw thru? let me guess you bought a vl commodore, put an exhaust, chip, filter and chaser wheels on it because that’s what everyone else did? how about some reasoning as to why not to use blow thru?

castlemaine rod shop will not be selling recon blowers as they cannot be reco'ed for more than one reason.

where are you getting your info from tuna?

They have no problems sucking petrol I have one that is still fine after at least 2 years of petrol going thru it.

[TurboSuzi]

This is what I meant to say about the coating on the fins:- Both of these superchargers are roots-type positive displacement superchargers. The rotors are fluorine resin coated. Taken from a website about Toyota blowers.

[Tuna]

Originally posted by gmh265


castlemaine rod shop will not be selling recon blowers as they cannot be reco'ed for more than one reason.

where are you getting your info from tuna?

So two weeks ago when Rod Hadfield told me face to face that he would sell me a recon blower- in fact all his kits use recon blowers-he was talkin shit?
Or was I imagining it just like I imagined the operation of the Malpassi reg, you really are somethin else gmh265.

[gmh265]

Ask rod what exactly he does to reco the blowers.. it may depend on what you define as a reco.. new oil in the gear case and a quick clean?

Please explain how the malipasi raises fuel pressure with boost yet does not lower it when it sees vacuum? (keeping in mind vacuum is just negative pressure) unfortunately you telling me you have set up a blow thru carb before does not convince me you have any idea what you are talking about.

[mopar lover]

Tuna these blowers are not rebuildable for one good reason. The bearings are a funky size and are NOT available at ANY bearing supply shop. Alot of the OEM jap seals and bearing are like that especially on motor bikes.

Also the OEM oil from Toyota is like $100 per 1/2 litre.

The money required to properly refurbish these $350 blowers wouuld make them cost closer to about $1000 ea at the end including labor.

[Cameron_Datto]

The Toyota Blowers have 3 Vent holes from the bearing /seals ,they reduce Boost pressure around seals which stop the loss of grease from the bearings if these are left to vent to the atmoshpere ,as the as supposed to do . your going to end up air fuel mix being vented ..a Serious fire hazard ! If a SUCk Thru set up is used .
If the 3 holes are blocked up then the fuel /air mixture will over time wash the grease from the bearings causing bearings to fail and damaging the Rotors .. This is the reason why they fail long term ...

[jmac]

There are three reasons that these kits are drawthrough.

1. It's easier to setup - std carbs and fuel pumps (of sufficient size/flow) can be run as is.It means instead it can be direct drive - eliminatiing the electromagnetic clutch

2. Despite it being very straightforward there are actually a hell of a lot of people that don't fully understand how carbs work ibn a blowthrough, and this 'phobia' means they can't set up a blowthrough carb so it becomes the main factor in their choosing drawthrough (and that's not limited to home DIY guys. Believe it or not there are a number of turbo workshops that have _never_ done a blowthru carb, _don't_ know how to set the carbs up and then (ironically) are happy to tell everyone that 'carbs are crap - efi is the only way' . Not all are like this, but some definitely are (doesn't hurt that there is a hell of a lot more profit to be hade from an efi project). A number of years back I enquried at a local (and well known) turbo specialist about what foam to use in teh carb floats so they don't collapse under boost from a blowthru. They b-s'ed me that their 'carby guy' was on leave. I went back a week later, sitll on leave, a month or so later I finally get to see him. I aske him - and he gave me a homer simpson dumbfounded look. He then very sheepishly admitted that he'd never done a blowthrough carb setup - they had only done a few carbed setups -and they were drawthrough. He ended up phoning a bunch of turbo places - and not one he contacted had done one either! yet they all make out that carbed turbo setups are no good. It would mean something if they had done a few blowthrough setups and all turned out to be satisfactory. But it's not the case. Now if a bunch of 'specialists' have no experience or ability to setup a blowthrough carb, then it's probably self evident that most DIY guys would have grave reservations in trying a blowthrough setup. But it doesn't need to be that way - it's actually within the range of practically any person to do at home. Fine tuning would take some work on a dyno, or with a wideband EGO sensor and display - but this is no more the case here than with a blowthrough turbo, s/c or even a normally aspirated engine.

3. you can blowthrough a carb, but it brings up part throttle complications. All you need is a carb bonnet that feeds air into the fuel bowl (99times out of 100 the fuel bowl vent is inside this cover and it works fine, sometimes it need to be replaced by or supplemental means - a fitting driled and tapped direct into the fuel bowl(s) . The air pressure drops maginally as it travels through the venturi (on stock carbs too) and this small pressure drop means there is a difference in relative prssure - the carb throat (after th venturi) vs the fuel bowl (which has full atmospheric)- and it pushes fuel through the jets. The blowthru carb bonnet routes air from before the mouth of the carb to the fuel bowls, the venturi creates a small pressure derop (but still well above atmospheric) - so with full boost pressure in the fuel bowl, fuel still flows.

When you back off the throttle there will be heaps of pressure in the carb bonnet directed to the fuel bowls. There will be pressure in teh carb throat, as the ventui is above the throttle plates. But below the throttle plate is the slot that provides fuel for idle operation (there is stuff all vac signal above the throttle plates at low throttle openings, but having the idle circuit discharge orifice below the throttles allows massive vacuum (compared to atmospheric in teh fuel bowls) and therefore it can deliver fuel well. With your foot off the accelerator on a blowthrough, there is now somewhere around 2 or more times the pressure in the fuel bowl compared to below the throttle plates. That means that when you back off, heaps more fuel is pushed through the idle circuit. On a turbo engine, the turbo spools down quick enough that it's rarely a concern. ON a belt driven blowthru compressor, then even at idle and part throttle, the blower is still trying to force more air in there - the pressure above the throttle plates of such a setup - lets say for a setup that provided 10psi boost at full throttle, well at the same rpm with a closed throttle, the belt driven compressor will probably be creating 25psi above the throttle plates. It'll go massively rich at low throttle openings - and is considderably more difficult to sort

To account for this you need some sort ofr bypass setup, so that at par throttle you don't have this constant pressure between the s/c and the throttle plates. The additional option is that this bypass could be used in conjunction with the on off switch. Yuo can't just switch off the blower alone. the blower lobes will still spin a little bit but will be a major restriction - causing a loss in power big time - possibly to the point of being a pain to drive - kinda like it was always on it's last legs and you were trying to nurse it back home. If you do run the switch you do need a bypass as well.

Actually making a bypass - for a carbed setup - isn't all that difficult. If anyone wants it, there is (or was the moderator has been trimming tge files) a basic drawing I made showing how relatively simple it can be to make (and what basic 'layout' it needs) a bypass. It was at the home page for the 'blowthruturbo' mailing list :

http://groups.yahoo.com/group/blowthruturbo

You will have to register and join the list to view it, but you can suscribe but set the list to _not _ deliver - you will read them from the groups homepage (same as looking back into the archives). that way you can access the diagrams (and other pics) and not have to look at the list mail - whichever suits you

The system I drew could alternatively be made with simple enough throttle position switches (either on/off, or progressive resistance. The system I drew is very simple to make, and the mechanical link to one of the valves means that with a little experimentation, you could get the rate of close, and the starting point of what throttle level will start to close it - well it wouldn't take a rocket scientist to narrow in on it - so that teh transition from low throttle to full throttle is extremely progressive.

I've heard probably 50/50 stories of people running them drawthrough - havlf with no dramas,, and half having experienced s/c failure. That being the case, the bypas setuphas two advantages. Generally it's said to be the cause that the reasons these blowers can fail is heat. On a drawthrough at part throttle (most people would think full throttle would be the drama) the blower is trying to move all the air it can with an open pipe (not even a throttle), so there is a lot of heat created as it constantly struggles. At the same time, there is bugger all air and fuel flowing through them - which is what is really needed to cool it. The blowers are a roots type - though roots blowers generaly have 3 lobes on each rotor - teh toyo ones only have two (which magnifies the issue) They are nowhere near as efficient as screw type or centrifugal blowers (efficiency here is referring to how much they heat up teh incoming charge as they compress it. To try and alleviate it, the rotors are in some case designed so that there is very little clearance between them - the smaller the better for sealing. The problem is, with any significant and/or sustained heat, the rotor temps can rise to the point where they expand. Obviously the clearances are setup by the manufacturer as a result of testing to enable the smallest clearance without unacceptable possibility of damage. Start using them at higher rpms. boost levels, or in such a way as the rotors are likely to heat up more than their factory application and it's definitely a possibility.

ok so all that said, if you run the s/c blowthrough, then you could ensure that whilst the carb may not see higher boost (throuh the bypass), there is still large amounts of air flowing through the blower to keep it cool (with a bypass open, no pressure is being created, - air is merely being drawn through teh blower.

It also means you can run the on off switch. For normal driving (or while someone else is driving the thing ) you coud have the blower off altogether. YOu'd basically be getting a normally aspirated engine - you could mount the switch anywhere - obvious or hidden - you might even like to make it lwork via a second key (ignition key for example so that you could always have the blower switched via the second key - if you lent anyone the car or something you could easily just supply them with the ignition key, and they'd never get to experience boost (or thrash it). Now if you turn the blower on, it'll still only produce boost according to the throttle opening (via the throttle linked valve in the bypass. Therefore you could run it with full power available and no fuelling problems. You could leave it on all day. Personally I'd prefer to have it off most of the time, then switch is as required, or if the road was hilly, I'd have the switch on there and leave it on till on flat roads.

the two advantages from this are extra fuel economy through not needing to spin the supercharger (with the bypass open, it won't be air pressure fighting against you and robbing power, but the internal friction/resistance of the s/c. It won't be gigantic, but any gains are worthy. Secondly - regardless of whether they will fail prematurely or not - whatever their likelihood of failure for each specific setup, it stands to reason that the less time they are spinning the less wear they will encounter. If it's not needed, no snese in costing s/c life by having it spin whenever the engine is running

John McKenzie

[Tuna]

Originally posted by gmh265


Please explain how the malipasi raises fuel pressure with boost yet does not lower it when it sees vacuum? (keeping in mind vacuum is just negative pressure) unfortunately you telling me you have set up a blow thru carb before does not convince me you have any idea what you are talking about.

Im not f3cked explaining anything except that my malpassi reg will hold its set base pressure of 5psi wether it has vac or not, I dont give a toss if you are convinced or not.
Lowering the pressure under vac is pointless on a carby, lower it below 5psi under vac? what the hell for?
You cannot be on about the same reg.

[jmac]

Generally the mal-passi won't show less pressure at idle and part throttle since as a rule it's boost port is connected to the carb bonnet not the inlet manifold. There it sees atmospheric pressure (and supplies the preset fule pressure as produced by the spring tension and the adjustment nut preload) for all normal driving, full boost (actually a fraction more than the inlet manifold sees due to the small pressure drop through the venturi.

I do recall a blowthruturbo list member detailing experimenting with the reg connected to the inlet manifold (not a malpassi reg though - I think it was a mallory 4309. the reason he did it was as an experiment. AT idle with high vac, setting the fuel pressure to say 5psi, would mean that at zero vac (but no boost) it might have been supplying 8 or so psi - which is ok - since there is considerable fuel being used at any condition which sees zero manifold vacuum, so it's using the fuel. Then back at idle, where fuel requirement drops, the fuel pressure is down to 5psi again, and therefore won't overrun the needle and seat and flood the carb. Then under boost, at 15psi, instead of having 20psi (if you route the boost reference line to the carb bonnet) fuel pressure, you'd have more like 22-23 psi. At least that is the theory.He tried it to see if this would end up being extra insurance under full boost.

To play 'devils advocate' - the boost line would be runnign from the inlet manifold. Due to the venturi causing a pressure drop (probably 1psi - though if teh carb is too small it can be as much as 3-4psi - which is bad big time and indicates that you are missing out on defeinite power - to achieve the same boost through a restrictive carb requires more 'work' from the blower or turbo - costing crank or exhaust pumping related losses - furthermore it will also heat the charge a lot more to achieve the same manifold boost level - but i am, as usual, getting off track) - what this means is that in practice the carb bonnet routed boost reference line will see probably 1psi more boost - and therefore although the idle pressure set inlet manifold routed boost ref line should theoretically get say 22psi at 15psi boost, at 15psi (inlet manifold) boost the carb bonnet routed ref line will see 16psi or so boost. With a static setting of 5psi for the carb bonnet routed regulator, at 15psi inlet manifold boost, the fuel pressure will be more like 21psi - so in practice the full boost fuel pressure is almost identical to inlet manifold routed (with a higher static setting being possible as idle vacuum will drag it down to a safe area .



TUNA - I MIGHT HAVE AN EXPLANATION:

On more than a few cars I've been involved in, the fuel pressure couldn't be adjusted below 10-12psi - no matter how much teh screw was backed off. First time it happened I was thinking it had the EFI spring in it by mistake - and came close to replacing it. At the time I was using the factory supply line as the return line - I figured it woudl be big enough (I did alter where it entereed the fuel tank, but used the entire stock supply line, runnign a new feed line - with bigger diameter piping.

This was my big mistake. By chance more than anything else (on paper it should have been more that adequate) I thought that maybe the return line was not big enough. To test it,. all I did was disconnect the regulator return hose and put a short length of 3/8 hose draining into a bucket. Turned on the fuel pump and _woo-hoo_ - fuel pressure went right down to 1-2psi. I ended up turning it up but did so quickly as the bucket was filling. Next day I ran a new return line, the same size as the supply line. Never rared it's ugly head again. That was a number of years ago, and since that time I am aware of a few other people having the same problem - and it was the first thing I suggested (since it's 10 seconds and $0 to check it) to them to try.

Maybe your return line is borderline - not nearly as restrictive as the other ocurances I know of - but just enough to cause the fuel pressure to go no lower than 5psi. It's at least possible, and it isn't exactly uncommon.

Last trivial tangent. On the early holden garret drawthrough turbo seups, when chasing bigger boost, but running twin SUs or strombergs - although the carbs can supply enough air and fuel for reasonable horsepower, they don't have the worlds best flowing needle and seats. I know of at least one turbo specialist who tried and used this option for higher boost without leanout concerns. They ran a holley deadhead regulator - no reutrn line. wehre the adjusting nut on the reg nomally goes, it was replaced with a fitting so that it was part bolt, part hose fitting. They then ran boost pressure to that. Drawthroughs technically don't need extra fuel pressure underboost - as there isn't increased air pressure in the fuel bowls . What the setup did was absically up the fuel pressure under boost. The needle and seats were an issue, so they actually tried (and succeeded) in forcing heaps through - even to the point of coming close to flooding the carb. The needle and seats don't flow well enough, so whilst the extra pressure would over run the needle and seat at idle, under full boost, the rate of fuel usage is greater than the needle and seats ability to replenish it - so the much higher fuel pressure ends up still just falling short of flooding the carb. Get off teh throttle, and the reg will block fuel coming past it until the pressure drops to normal fuel pressure. Since there isn't a return line, the fuel between the reg and the carb has only one place to go - into the carb. It can overrun the needle and seat just after a hard full throttle sprint . The thing to do is mount the reg as close to the carb(s) as possible. The less volume of fuel between reg and carb, the less has to drain off into th fuel bowl to get to a normal pressure - so the less fuel can or will over run the needle and seat. Basically - closely mounted reg/carb and the drawthrough should be a-ok with no flooding on lifting the accelerator pedal

John McKenzie

[gmh265]

tuna - I am on about the same reg, its a shame that your not prepared to sort it out and from now on you will be telling people over the internet the wrong information (like in the thread where this 'discussion' started) Thats the major problem wil internet forums, so many people telling other people incorrect info.

jmac - I also mentioned that if fuel pressure was not going down anymore he may have found the limit of the return line

in this thread http://board.performanceforums.com/forums/showthread.php?s=&threadid=67149154

[jmac]

sorry bout that - didn't know the other thread even existed. After reading it, All the points I was going to bring up have been covered. As such there is no other option but to state the blatantly obvious

Tuna - no other way of putting this - you are wrong about the reg- period. the pressure drop at vacuum may not be massive, but it will _definitely_ happen.

You say "I don't know why I bother" - honestly neither do I. If you beat the crap out of everyone who says the sky is blue, it's not going to turn green

As a weird tangent, on a friend turbo hemi, we experimented with a boost referenced mechanical pump - and were pleasantly surprised that teh stock pump could handle the boost benig few to the back of it's diaphragm and also coped well with the increased volume demand at full boost.

The test engine expired and for reasons I forget - I think it was just adequate time to fit a barbed fitting to attach a hose to the carb bonnet - the quickest place (that would work as a bandaid) was off teh holley using the vac advance port on the holley. It's ported vacuum so idle fuel pressue was retained. Under boost it ran perfectly. At part throttle cruise, it would reduce the pressure so much that it would lean out and then start to stumble. All that was needed to counteract it was that every 30 seconds or so, it would be given a quick squirt of full throttle. That dropped the vac to the modded mechanical pump and allowed it to get the fuel to the carb. All it took was full throttle for about 2 seconds and it was fine.

Even a mechanical pump will display problems if the boost reference line is plumbed to the inlet manifold or even the carb vac advance port...


John McKenzie

[cadet]

the mazda capella 2L deisel use a 'pressure wave' supercharger. it looked to me like it used a pulley and exhaust gas for drive. i never got a close enough look to find out for sure.

[gravelrash]

you all seem to forget the 2.0 v6 mitsubishi supercharger. my mate and i fitted one to his t bucket.

[TurboSuzi]

Yes gravel, I have heard of these but there doesn't seem to be much interest around. Anybody got any info on them. I think that they are a Mikuni??

[gravelrash]

there physically about the same size as a toyota blower but their rear fed and exits out the top.

[TurboSuzi]

Nice. Might have to go chasing one of these cause it looks like the Toyota will be a bastard to plumb air into from the airbox.

[Clark-E]

can someone simplify what is needed for a Draw thru setup..

Carby (45mm weber), reg (what type? rising rate?), Fuel pump (carter Gold?) Mounts, Pulley, belt.

wanting to put a SC14 Charger onto a 2t-G. that is being built with Lower compression, Ported head, peened rods.

and would like some advice..

[SocialSecurity]

Dont beleive you would need a regulator, as with draw thru the fuel pressure would never be fighting against boost??

but maybe they help?

sounds like your on the money for the rest tho

[TurboSuzi]

Clark, you only need a pump that can keep the supply up to the carb. The reg you speak of is for a blow thru setup where you need to equalize pressure at the carb to compensate for the boost pressure.

[SocialSecurity]

thought so

:D

[Clark-E]

Thanks for that Turbo suzi.

so if I used a Carter Gold (as I have had trouble free use of them)
and use a normal low pressure reg.. there won't be a problem?

One other thing.

advice on Carby to use.
it's being installed into a Corolla KE30.

would a 45mm Webber or Dellorto be suitable?
or would a more conventional SU setup be worthy?

[TurboSuzi]

Not too sure on that one, but I would presume that any side draft would be ok to an extent. I think that the only real dramas with these setups is keeping fuel supply to the carb to compensate for the extra air being drawn in under boost. I think. Maybe.