super charger

[Enuo]

if the s/c is rated at 500cc/rev, then it needs to run at 1 x engine speed to achieve a VE of 100%, i think
edit, what he said ^

From 80% that should work out at a 25% increase in power... basically what you get from the 1.3, but with added sc weight. You'd have to go for about 120% VE to make it worthwile over just a 1.3 imo (7psi/0.5 bar)

 

[frank]

From 80% that should work out at a 25% increase in power... basically what you get from the 1.3, but with added sc weight. You'd have to go for about 120% VE to make it worthwile over just a 1.3 imo (7psi/0.5 bar)

yes you would need 4k+ rpm and some pretty wild cams in order to achieve 100% VE, so about 75hp eh

 

[h701micra]

You're all forgetting the torque side of things

 

[frank]

so a 1:1 setup like that would be showing a fair amount of boost in the charge pipe at idle and low throttle eh, because apparently "At idle your V.E. might be as low as 15% to 20%" http://www.rbracing-rsr.com/calcinjpulse.html.
bourne out by my recent improved mpg figures with this current CG10+t i,m running atm, ie, i,m having to run more throttle @ cruise on the M6 lately (judging by my vacuum gauge readings)

 

[Enuo]

Unless you have a vacuum operated bypass to dump the pressure

 

[frank]

Unless you have a vacuum operated bypass to dump the pressure

i think a lot of factory s/c cars just disengage it @ idle and low throttle instead ?
here,s my vacuum readings at 60mph (CGA3+t red line, CG10+t blue) so i,m using more throttle/fuel, but at a more efficient VE (even taking into account the different cc)

 

[Enuo]

Cooper s just uses bypass valve ([Ed: the superchers,] they're >90% efficient when recircing apparently so almost no losses).

 

[frank]

Cooper s just uses bypass valve ([Ed: the superchers,] they're >90% efficient when recircing apparently so almost no losses).

90% efficient while they,re not actually creating boost yeh, then 55% efficient @1 bar tho

 

[Enuo]

A screw type yeah, but if you were looking to generate more than 7psi I would personally be looking at centrifugal superchargers (and accept the loss of low rpm boost), but then there is justification for turbo...

 

[Dinky DK]

So my pully ratio is wrong for 6psi using my calculations? I was thinking of 6psi boost with constant sc and an atmosperic blow off valve to avoid sc backing up? @frank what boost you running on the cg10+t? Wondering what a safe limit is to use as shes my daily drive? Do you have a build thread on it?

 

[Dinky DK]

@euno where did you I get the 80% ve from? Is it an estimated figure or from the manufacturer? forgot to take that in to account. Cant seem to find a manufacturers ve chart for the amr500

 

[frank]

So my pully ratio is wrong for 6psi using my calculations? I was thinking of 6psi boost with constant sc and an atmosperic blow off valve to avoid sc backing up? @frank what boost you running on the cg10+t? Wondering what a safe limit is to use as shes my daily drive? Do you have a build thread on it?

Mine,s running 12psi on unleaded still DK, and i hav,nt updated my cisco blog lately.
I,m guessing you will need about 1.5:1 maybe ?

 

[Dinky DK]

Mine,s running 12psi on unleaded still DK, and i hav,nt updated my cisco blog lately.
I,m guessing you will need about 1.5:1 maybe ?

That on stock internals pal?

 

[frank]

That on stock internals pal?

Aye

 

[Dinky DK]

Aye

Done anything to lower the compression? If so what n what ratio you on?

 

[frank]

Done anything to lower the compression? If so what n what ratio you on?

No mate, and they are the shorter coilpack pistons like yours (slipper design, and skinny rings)

 

[Dinky DK]

Thats good to know mate, had any issues crop up at that pressure I would need to know about?

 

[frank]

Thats good to know mate, had any issues crop up at that pressure I would need to know about?

Not that i know of mate, the 1.0,s are a far less stressed engine and will stand higher boost levels i guess

 

[Enuo]

I think @Frank said the 1.3 ran at 80% VE on a different thread a while ago, so I assume the 1.0 won't be far off.

 

[frank]

I think @Frank said the 1.3 ran at 80% VE on a different thread a while ago, so I assume the 1.0 won't be far off.

yes your average 90,s engine will achieve 80% VE at best i guess (apart from a 100hp/litre vtec type engine)
so in other words, a 1:1 ratio s/c fitted to a vtec 1.0 will be different animal to a 1:1 ratio s/c on a 1.0 70,s pushrod engine

 

[Enuo]

Apparently GA engines are running about 66%(!) VE, making them good candidates for boosting *grins*

 

[h701micra]

Apparently GA engines are running about 66%(!) VE, making them good candidates for boosting *grins*

Maybe Nissans poor port work was a cover up

 

[Enuo]

Maybe Nissans poor port work was a cover up

Or they accepted the valves were tiny so made the combustion chamber as efficient as possible to cope.

 

[Enuo]

A-series engines are the same, terrible VE, awesome combustion chamber design.

 

[h701micra]

A-series engines are the same, terrible VE, awesome combustion chamber design.

GA combustion chambers were designed to prevent detonation

 

[Dinky DK]

I have now adjusted my calculations to include 80% VE and a boost of +12psi following frank reassuring me that the engine will cope with it. i believe my calculations are correct as i first worked it out at 6psi and returned the same pulley ratio as Euno. please someone correct me if i have made any errors. Here goes.......

ltrs/Min @ 0psi = (0.998 (engine capacity in liters) x 7300 (Max Engine RPM))/2 =3642.7
Boost Ratio = (12psi (Boost Pressure) + 14.7 (Atmospheric pressure))/14.7 (Atmospheric Pressure) = 1.8163265306
Air required at boost = ((36427 (Atmospheric pressure Air Requirement) x 1.8163265306 (Boost Ratio)) x 0.8 (80%VE)) = 5293.0661224133 ltrs/min @ +12psi 7300rpm 80%VE
5293.0661224133 ltrs/min (Air Requirement at 12psi Boost) / 0.5 (SC Capacity per Revolution) = Air Required at 12psi Boost Produced at 10,586.133244826 rpm at Super Charger
Pully Ratio = (10,586.133244826 (SC RPM) / 7300 (Max Engine RPM) = 1.450155102

So @frank your 1:1.5 pulley ratio was a bloody good guess

So next thing is to work out the fueling. anyone know where to start? was considering using qg15 top feeds and ga/sr throttlebody as per NA setup. would that be suitable do you think?

 

[Enuo]

GA throttlebody probably won't be man enough (GA's consume a similar amount of air to a CG), SR20 one would be where I'd go. CGA topfeed rail with bigger injectors would be a good bet, although I dunno the sizes you can get for that rail but I imagine you'd want 300cc +

 

[frank]

Dont forget that the s/c efficiency drops to about 60% at those pressures tho eh, and 211cc qg injectors should suffice

 

[Enuo]

Dont forget that the s/c efficiency drops to about 60% at those pressures tho eh, and 211cc qg injectors should suffice

That 60% I thought was more an indicator of how much waste heat was put into the intake charge, and was used to gauge how big an intercooler you'd need?

 

[Dinky DK]

Got coil pack so injectors are already topfeed, just need to know whic to fit. Also guna need adj fpr but again not sure of what pressure?

 

[Dinky DK]

Dont forget that the s/c efficiency drops to about 60% at those pressures tho eh, and 211cc qg injectors should suffice

So I need to re calculate at 60% ve at max rpm? So 211 qg injectors and sr20 tb will do the trick?

 

[Enuo]

Thats 60% Thermodynamic efficiency not Volumetric efficiency iirc, different things...

 

[frank]

Thats 60% Thermodynamic efficiency not Volumetric efficiency iirc, different things...

I think you,ll find that the efficiency drops like a stone as the pressure increases andy

 

[Enuo]

I think you,ll find that the efficiency drops like a stone as the pressure increases andy

Which efficiency though? 60% Thermodynamic efficiency means that for every 10hp consumed by the SC 4hp (3kw) of heat is put into intake charge, whereas 60% Volumetric efficency means only 0.3l per revolution not 0.5l (which seems less likely to me)

 

[frank]

So I need to re calculate at 60% ve at max rpm? So 211 qg injectors and sr20 tb will do the trick?

You,ll be achieving about 110hp i guess DK, qg,s would be fine imo

 

[Dinky DK]

Which efficiency though? 60% Thermodynamic efficiency means that for every 10hp consumed by the SC 4hp (3kw) of heat is put into intake charge, whereas 60% Volumetric efficency means only 0.3l per revolution not 0.5l (which seems less likely to me)

So do I need to adjust my pulley ratio calculations to include thermodynamic eficiency at peak rpm aswell as ve? Essentially what I need to know is am I gunna damage/break/destroy anything with a pulley ratio of 1.45?

 

[Enuo]

So do I need to adjust my pulley ratio calculations to include thermodynamic eficiency at peak rpm aswell as ve? Essentially what I need to know is am I gunna damage/break/destroy anything with a pulley ratio of 1.45?

If its its 60%VE you'll just get boost drop off at higher revs, if its 60%TE you'll just need an intercooler so no

 

[Dinky DK]

What would the plausibility be of not using an IC? I know frank wasnt running one on his +t. Could I get away with it or is there a vast difference between +t and +sc thermodynamic efficiency?

 

[Enuo]

What would the plausibility be of not using an IC? I know frank wasnt running one on his +t. Could I get away with it or is there a vast difference between +t and +sc thermodynamic efficiency?

There is yeah, one is yo do with airflow one is to do with heat soak into intake charge. If its TE you'd need to run the SC at a pressure/max RPM that's around the 80% mark I'd imagine.

 

[Enuo]

Efficiency is Isentropic Efficiency, which tells you how much energy is lost through heat/noise/turbulent flow, NOT volumetric efficiency so don't need to calculate it into the VE equations

 

[Enuo]

I figure 12psi is roughly 1 bar, so thats roughly double air intake over NA... so need roughly double injector size needed no?

 

[frank]

I figure 12psi is roughly 1 bar, so thats roughly double air intake over NA... so need roughly double injector size needed no?

members keep posting that stock injectors are ok for 115hp iirc, QG18 engines are 128 hp according to wiki

 

[Enuo]

It'll be close though... SR injectors might be better?

 

[frank]

It'll be close though... SR injectors might be better?

thats what i have on mine 293cc post 2000 SR20, i think a CG10 will be hard pushed to exceed (a true) 120hp tho

 

[Enuo]

Yeah, but I personally don't like the idea of running injectors flat out...

 

[Dinky DK]

Efficiency is Isentropic Efficiency, which tells you how much energy is lost through heat/noise/turbulent flow, NOT volumetric efficiency so don't need to calculate it into the VE equations

thats good to know iv calculated n recalculated tooo many times now lol.

members keep posting that stock injectors are ok for 115hp iirc, QG18 engines are 128 hp according to wiki

So if im gunna be pushing somewhere around the 110bhp mark i could get away with standard injectors? or would i be pushing them past 85% duty?

 

[Dinky DK]

thats what i have on mine 293cc post 2000 SR20, i think a CG10 will be hard pushed to exceed (a true) 120hp tho

are those easy to come by fank? n do you need a modified rail for them to fit or straight into CG10 topfeed rail?

 

[frank]

are those easy to come by fank? n do you need a modified rail for them to fit or straight into CG10 topfeed rail?

aye, straight fit the part numbers are on my cisco blog somewhere

 

[Dinky DK]

nice one pal, il have a look

 

[Dinky DK]

Just had a look, havent found them just yet. Nice blog tho pal. Was wondering what boost you managed to achieve on that on standard ecu? Also did your airbox hold boost pressure ok at that level as it would make running the ducting easier