1 litre supercharger

[mrw82]

im thinking about fitting a supercharger to the 1 litre in my LWB zook. I need more power to get up hills.
thought about a conversion but a 1.3 isn't worth the effort and I cant afford a 1.6 so that rules that out.
has anyone done it before, im running the standard 1 litre carby and unless anyones done a cheap easy EFI than I want to stick with the standard carby.

theres a lot of info about it for the 1.3s and apart from a lot of talk about wanting to do it theres no actual write up of it done. and nothing at all about doing it to a 1 litre. (so if your gonna flame me and say search than dont bother commenting because I have)

Making brackets and fitting pulleys and pipework isn't a problem and as for space I can rip out my endless air compressor if needed.
what will be the best S/C to use, it will only need to be a small one.

SHOULD I do anything to give the engine a longer life and what? Im only looking at 5psi max for the stock engine which shouldn't give me any issues but if I rebuild it later on what can I do to run higher boost.

any help would be great especially from those that have already done it.

cheers, Mark.

[Spike_Sierra]

should have posted this 3 days ago, there was a full amr500 s/c set up for 1l on ebay for 400 bucks. including brackets and everything. But i would be using something like that, and then an adjustable boost pressure valve to limit boost.

I have a sc14(bit big for 1l) here for sale $250, but if your using a boost pressure valve it shouldnt matter.

MART on here uses an sc14 on his 1.3. search for his members thread.

[suzimad]

the thing with boost is you need to add more fuel ... more air , more fuel , you also need to make sure you have enough fuel pressure . for 5 pound of boost you need at least 9psi of fuel pressure .

Due to the shitty nature of carburettors the needle and seat that regulates the amount of fuel that enters the bowl will not handle 9 psi of fuel pressure. you can use a rising rate regulator (for every pound of boost it will increase 1 psi of fuel pressure) but they themselves arent cheap

Also as a carby adds fuel due to vacuum , it will not see boost and add more fuel , the way to overcome this is to use the carby before the supercharger , the ideal carb is an SU carburettor.

If you want brutal honesty , supercharging your car will end up costing more in the long run .. no such thing as cheap forced induction , you do it right the first time or you dont do it at all (ive been down the carby turbo path and it wasnt fun) if you detonate due to a lean out you will break pistons.

[Santos]

also you really need to change your ignition curb to suit (not to mention the stock distributor is vaxuum operated)

If you are really serious about supercharging it my be best to change to a EFi set up and convert the distributer to be electronic ignition . I'm not saying you can't do it with a carb but its a lot harder to 'get it right'

one little thing that i seen in an old supercharging manual was to mount the carb in side a box so that when boost came on the pressure on the outside and the inside of the carb where identical (i'd have to dig through my books to find out the nitty gritty)

[want33s]

the thing with boost is you need to add more fuel ... more air , more fuel , you also need to make sure you have enough fuel pressure . for 5 pound of boost you need at least 9psi of fuel pressure .

Due to the shitty nature of carburettors the needle and seat that regulates the amount of fuel that enters the bowl will not handle 9 psi of fuel pressure. you can use a rising rate regulator (for every pound of boost it will increase 1 psi of fuel pressure) but they themselves arent cheap

Also as a carby adds fuel due to vacuum , it will not see boost and add more fuel , the way to overcome this is to use the carby before the supercharger , the ideal carb is an SU carburettor.

If you want brutal honesty , supercharging your car will end up costing more in the long run .. no such thing as cheap forced induction , you do it right the first time or you dont do it at all (ive been down the carby turbo path and it wasnt fun) if you detonate due to a lean out you will break pistons.

OR.... Blow-through. Put the carby in a sealed box so boost is equal inside and outside carb.
Disconnect the vac-advance and get dissy reCURVED to suit.
Rising rate fuel regulator and electric pump as suggested.
Yeah it adds up to a few dollars but if you are off the idea of a bigger engine how else are you going to get more grunt?

[MightyMouse]

Just make certain that you use solid floats or they also crush quite nicely....

[mrw82]

the 1 litres dont have vacuum advance distributer. mechanical advance in the australian market.

how does the equalised pressure from a box make a difference, I cant get my head around that one.
the carby on the 1 litres are a side draft which makes it similar to an SU carby. dont know much more about SU's apart from that.

also they run a manual choke so to relocate the carby all that is needed is mounting brackets, longer acc cable, choke cable and fuel line. so it COULD be done. but would that work ok having the air fuel mix having to travel through the blower and pipework instead of just straight into the manifold.

keep the good info coming guys.
thanks, Mark

[want33s]

the 1 litres dont have vacuum advance distributer. mechanical advance in the australian market.

how does the equalised pressure from a box make a difference, I cant get my head around that one.
the carby on the 1 litres are a side draft which makes it similar to an SU carby. dont know much more about SU's apart from that.

also they run a manual choke so to relocate the carby all that is needed is mounting brackets, longer acc cable, choke cable and fuel line. so it COULD be done. but would that work ok having the air fuel mix having to travel through the blower and pipework instead of just straight into the manifold.

keep the good info coming guys.
thanks, Mark

Mechanical advance on One litres ... Cool.
Putiing the carb in a sealed box makes the boost pressure the same inside carb as it is outside.
Having no difference inside to outside means a lot less modifications are needed to carb to get it to respond.
Fuel will be carried through internal passages as it normally is instead of forced backwards due to boost trying to escape carb.

A blow-through setup offers the advantage of being a lot less destructive in the event of a backfire(no pipework or aftercooler full of fuel) and easier to tune (pipework and aftercooler will rob the charge of ATOMISED fuel)
Your one litre carb and an S.U are both sidedraughts but thats as far as the similarities go!

the thing with boost is you need to add more fuel ... more air , more fuel , you also need to make sure you have enough fuel pressure . for 5 pound of boost you need at least 9psi of fuel pressure .

A zook (and most 4cyl's) will run fine on 4-5psi fuel pressure.
.5psi boost only needs an extra .5psi fuel pressure.
one pound boost= one pound extra fuel pressure.

[MightyMouse]

And BTW - $250 for a SC14 in good condition is excellent value for money.

An SC14 will do the job well, its going to be able to be run more slowly than an SC12 for the same air output which means its overall efficiency will be higher.

Avoid the need for a blowoff valve by getting the drive ratio right in the first place - a SC14 displaces 1.4 ltrs of Air per rev, you know your engine capacity / rev - you can then calculate the desired drive ratio. It wont be spot on but close.

[Santos]

Even with the pulley ratio spot on the sc14 still has the disavantage of having to spin extra weight. An AMR500 is probably the ideal one since its like half the size and was fitted to factory nissan 1L

i also think a blow off valve might be a good idea from a 'to be sure' point of view, they can't be that hard to install

Another idea if you don't go carb is a single throttlebody from a big Vtwin motorcycle. The injectors are suppose to feed the engine at 14000rpm so even if you got it from a 1000cc bike and used one throttle (500cc) it probably would cope with the 5000rpm of the 1l ( 500cc x 14000/1000 = 7000rpm)

Just throwing in ideas i'd like to see a boosted f10a

[suzimad]

the thing with boost is you need to add more fuel ... more air , more fuel , you also need to make sure you have enough fuel pressure . for 5 pound of boost you need at least 9psi of fuel pressure .

A zook (and most 4cyl's) will run fine on 4-5psi fuel pressure.
.5psi boost only needs an extra .5psi fuel pressure.
one pound boost= one pound extra fuel pressure.

yes 4 psi static fuel pressure and 5psi for 5 psi of boost = 9psi

[MightyMouse]

Even with the pulley ratio spot on the sc14 still has the disadvantage of having to spin extra weight. An AMR500 is probably the ideal one since its like half the size and was fitted to factory nissan 1L

i also think a blow off valve might be a good idea from a 'to be sure' point of view, they can't be that hard to installA

The gains in efficiency of a larger compressor spinning slowly to produce relatively cool boost is MUCH more significant than a few hundred grams of rotating mass. Higher compressor discharge temperatures = more tuning problems / less power

As for blow off valves your thinking turbo here - superchargers being mechanically coupled don't produce the significant shut throttle pressure surge of a turbo. They also don't overboost if the drive ratio is correct - once again they are positatively driven, if anything the boost can fall off a little as they are worked harder, but this is more relevant with smaller units.

No harm done if you fit one BUT your not going to get the "Noise" the turbo boys kill for - and SC12 and SC14 supercharger bypass valves already perform the bleed off function as a "free" side effect of their usual operation.

[Santos]

when you back off the throttle wouldn't the engine still be spinning for a few moments after and the positive displacement cram in more presure increasting the psi above the 5?

i never knew the had built in by-pass valves, in which case how do ppl vary factory boost? Or is it that your talking about a seperate component that recirculate air from the outlet of the compressor back to the inlet?

Cause the second thing is what i am talking about when i say blow off valve. A lot of people fall into the trap into thinking blow off valves are only the 'atmospherically vented' type. (Which really is just a emotional mod)

The SC14 may also be a litle more than a few grams heavier, it is displacing almost 3 times the air per revolution

this is whats got me stuck (more than the weight issue) is even with 'gearing' the rotors have to push more air each sweep which is going the rotor have to push more surface drag and ummm... other things

in fact i not sure how to explain it but lets say with gearing you can make both the amr500 and the sc14 displace the same amount of CC's and sap the same amount of power from the crank.

If power is a direct result of Torque x RPM and the SC14 spins slower then it would need to have more torque to drive it. (and this is assuming it had the same weight as the AMR)

Torque is something the F10a hasn't got to spare even once the supercharger is suppling extra power it is needing extra power to be driven, and it would be less strain on the driveline.

Another idea is get a straw and glass of milk and do one slow steady wip. Then do a quick sip but use half the lung movement. Which one would get the milk faster into your mouth? Wouldn't this increase flow help the charge being gulped by the supercharger compressor

Lastly the heat issue if you use a blow thru set up you can still resort to a monster intercooler up front

[Spike_Sierra]

good discussion here!

i was suggesting the boost regular valve(not BOV) becuase its quite hard to get different sizes of pulleys unless you can make them yourself. The corolla boys seem to have only one other size than standard.

i only suggested an sc14 becuase its just sitting here collecting dust

i hope MART can add to this, as he has done it all(although with SPFI)

[MightyMouse]

Its all about compressor efficiency at the end of the day, both compression and mechanical.

From a compression side, a large blower running slowly will add less heat to the charge air then a small one working hard. For every 6 degrees C charge temperature reduction you gain 1% engine power. Thats why intercoolers are used and make a huge difference.

High charge temperatures also can make tuning a problem, a few degree extra can bring on detonation the requires a significant amount of retard to eliminate. Temperature also kills engines

I've seen many cars that have screwed up the boost to the point there the turbo was working at its limit - charge so hot that the tune had to be retarded and the overall power gains were minimal. Example - an Indy compressored Garret TO4B making more power @ 7PSI than it did at 9PS with a V2-P trim compressor.

Theres also mechanical losses to consider, belt losses are significantly increased as speeds increase as are friction losses from tip sealing. Bearing losses would be about the same as they both have good bearings.

SC12's and 14's both have bypass valves as part of the blower plumbing that allows the engine to run without boost and also work as a BOV for any surges ( small ) - this is standard as they are clutched superchargers.

As for ratios - its a polyvee drive as used on many standard vehicles. The wreckers are full of pulleys off alternators / water pumps / power steer / cranks - yes you have to do some work to adapt them but if your playing then thats one of the easier tasks

Yes bigger blowers are heavier but when you look at rotational inertia the velocity term is squared so speed has a more significant effect than mass.

And lastly ( yep its a bit loooong.... ) the drive is POSITIVE the supercharged CANT "spin on" - blower and engine are linked. If the engine slows down then the blower does as well

I've absolutely nothing against any particular blowers - SC14's maybe mechanically too big to fit - but there are good technical reasons to run a low stressed blower installation if you have the option ( and a $250 blower is cheap )

[cj]

Nice tech. I'm learning from this.

[mrw82]

Nice tech. I'm learning from this.

me too......
was doing some looking and found this site:

http://autospeed.com/A_110294/cms/article.html

has details about quite a few different S/C's and pics too.

was looking under the bonnet of the zook and i reckon I can make it fit!
if I can get a thermostat housing with a different angle and then reroute the top radiator hose. remove the underbonnet jack storage, reposition (or replace) the air box, then I will have enough room to fit it up with short pipework to the manifold and bolt the carb to inlet of S/C with an adaptor plate.
carb mounted before S/C means no pressure issues for it and it will only be short pipework and shouldn't give me too many problems as I dont intend on running an intercooler. (yet, hehe)
I am already running a multi ribbed Vbelt for my endless air and with a strategically positioned idler pulley all I will need to do is work out ratios to set the boost.

thanks for the offer of the SC14 spike, that IS a good price but it will be overkill (although agree with the idea of a bigger unit that doesn't have to work as hard). it will make it harder to fit and I think it will be too long. (plus I dont want a blower thats BIGGER then the motor!).

I am leaning towards the AMR500 at the moment unless I come across a SC12 at a ridicously low price.

[Santos]

mightymouse i really feel on this point with being talking about the same thing. When i am talking about BOV i am talking about the valve that bleeds off excess presure - a bypass valve.

The actual supercharger itself doen't have the valve though does it? It is my understanding its part of the factory plumbing (as is an intercooler) so if you buy a supercharger on ebay or from eg spike this valve is missing.
This is what i am saying you should have in the system, it is very possible that some one goes out, gets a charger plumbs it from the outlet straight to the intake and have some issues .

The other thing is i understand that if the supercharger spins at the same rate as the engine and can't 'spin on' But if you take your foot off the accelerator the engine does not instatly go from 5000rpm to 800rpm, yes it happens pretty quickly but those extra few spins as your engine is dieing down with the throttle closed would be adding pressure in the intake. So your engine is slowing down with the throttle cut but it still spining as it is slowing down.

I too think sc14 at $250 is a good price, but the main thing is i know it comes from a 2lt engine, auto manufacturers always use superchargers displacement smaller than that of the engine, and i can't finish this sentence (how weak)


i'd actually buy it if i had money to spare but if spike REALLY wants to sell it there is always ebay, they go for more than that regularly, i am not campaigning against him i am just trying to help design a solution for a 1lt supercharger