Supercharging An Rb20det?

[mad082]

and before someone gets on here and goes on about how you will make less power than a turbo, the low end power would eat a turbo powered engine. as everyone always says, its average power that makes a car fast, not just a number at the end.

[qikstagea]

yeah but no real difference. It'd be fine.

The point of pressurising the charge is simply to get more air in the engine, so you can up the fuel and still keep the same air fuel ratio, to make more power. Means you can have the same amount of combustible particles in the cylinders as a cylinder with a larger volume, but without the weight a big bore engine.

And the intercooler cancels out the heat that compression causes, creating a more combustible charge.

Thats it simplified. Doesnt matter how you do it, or at what RPM you do it. Just means itll be on power earlier. Cos with a supercharger, the speed it spins is in direct proportion to the speed of the engine. The lower the engine speed, the less air it needs, the less the supercharger pumps. The higher the engine speed, the more air the engine needs, the more the supercharger pumps. Its all in ratios.

[qikstagea]

and before someone gets on here and goes on about how you will make less power than a turbo, the low end power would eat a turbo powered engine. as everyone always says, its average power that makes a car fast, not just a number at the end.

true to an extent. Torque is the number that counts, really. In my opinion anyway. Its torque that launches your car, and more importantly for most of us, torque that spins your wheels. and being lower revs, your engine will love you, and last longer.

My falcon made 160rwkW. Shit all. But with the amt of torque it made, it could sit at 2200rpm in 3rd gear, smoking 265s til they popped. This is not even halfway to redline! Albeit this is a 4.1L six, not a 2.0. So you arent going to get these results, but still. Lets see a high kW turbo do that...

If you are one for red-light rendevous up to the speed limit, then torque is what you want. if you want to drift, torque is what you want. If you want circuit racing and qtr miles, go for horsepower.

[paulr33]

how much torque do you think an xr6turbo makes at 2200rpm?

probably just as much if not more as your supercharged setup

[AlexCim]

Actually, 14psi is not 14psi.

Ever heard the "its not about boost its about flow" saying?

[mad082]

the xr6t makes the same torque from 2000rpm to 4000rpm. and ford quotes 480nm of torque.

power is found by measuring torque then multiplying it be a few things to give you power.

[CruiseLiner]

from my limited experience with a vn group a ss with a vortex t -trim blower it makes boost linear to the rpm and they sound absolutely crazy when winding up

i think the 4agze one would run out of puff up top for sure and hence the drop off of power at low rpm because they are only made for a 1.6L engine.

thats my useless 2 cents

[Hakai]

from my limited experience with a vn group a ss with a vortex t -trim blower it makes boost linear to the rpm and they sound absolutely crazy when winding up

i think the 4agze one would run out of puff up top for sure and hence the drop off of power at low rpm because they are only made for a 1.6L engine.

thats my useless 2 cents

Noones' 2c is useless mate. Experience is the best thing I can go off now.

I think you're right too, the 4A-GZE blower isn't what I'm looking for.

From what I'm reading here, I'm leaning towards a Vortech centrifugal blower, as I absolutely want an intercooler setup, which I aparantly can't have or can't have as easily or effectively with a screw type blower of either sort. Also aparantly they aren't as "laggy" as I've been led to believe thus far, which leaves them as a great option, they also look alot cooler than screw type blowers rofl

In regards to 14psi being 14psi, I understand that airflow makes power not boost, as boost pressure isn't a constant, but is relative to other factors. Basically what I meant was, if you take a supercharger compressor and a turbocharger compressor that both flow the same CFM, then 14psi from the supercharger would be the same load on the internals of the engine as 14psi from the turbocharger, correct? I know this is alot of what ifs and buts, but I'm looking for a comparison so that I can assess how well the RB20DET motor is going to hold up to boost from a blower compared to a turbo.

From what I can see now, the hardest part of this whole endeavour will be mounting the blower. Other than that, pipework, intercooler, BOV and intake setup will be basically the same as a turbo setup, assuming I'm using a centrifugal unit. So mounting right now is my biggest concern, after obviously getting the cash together to afford the blower and associated good bits

Keep the input coming people, cheers.

Ben.

[CruiseLiner]

i hope your good at fabrication or its gonna end up alot of money on labour as everything is gonna be made as a one off, like the blower bracket and other bits and pieces, and $60 per hour adds up quickly

if moneys an issue i reckon a rb25 conversion would be a cheaper alternative and better but i know u want something different, but a good vortex blower is pricey, and my dads t-trim cost around 5-6k from memory and thats without brackets etc.

the whole kit installed at a shop was 10k and thats with all parts that bolt staight on. (we ended up installing it at home but the kit was still around 7k or so)

the t-trim is the higher rated version for 13psi or something, and the lower s-trim is only rated to 8 or 9psi.

being different costs money and lots of r&d unfortunately. what happens if u spend 6k on the setup and its shocking to drive? its a big gamble in the end.

sorry dude im not trying to put you off im just telling u the possible outcomes

Edited July 9, 2006 by CruiseLiner

[Hakai]

i hope your good at fabrication or its gonna end up alot of money on labour as everything is gonna be made as a one off, like the blower bracket and other bits and pieces, and $60 per hour adds up quickly

if moneys an issue i reckon a rb25 conversion would be a cheaper alternative and better but i know u want something different, but a good vortex blower is pricey, and my dads t-trim cost around 5-6k from memory and thats without brackets etc.

the whole kit installed at a shop was 10k and thats with all parts that bolt staight on. (we ended up installing it at home but the kit was still around 7k or so)

the t-trim is the higher rated version for 13psi or something, and the lower s-trim is only rated to 8 or 9psi.

being different costs money and lots of r&d unfortunately. what happens if u spend 6k on the setup and its shocking to drive? its a big gamble in the end.

sorry dude im not trying to put you off im just telling u the possible outcomes

Mate, any advice is good As I've said already, other peoples' experiences are my best source of information. I was looking at Vortech blowers and noted they were extremely pricey. I would be fine with an 8-9psi blower though, especially since it's going to be kicking in down low.

I have a mate who is a metal fabricator, so if he's willing to give me a hand and has spare time at work (Which he does and I think he'd love to help, esp since he'll get to drive it lol) then I can probably get the metal stuff taken care of quite reasonably.

What about my mounting point? I was thinking if I have to high mount it, then I can get a bonnet modification, like a bulge just over the supercharger, would look kinda awsome I think

Also what about the belt to drive it? Do I need a custom balancer that has provision for a supercharger belt? Is there something I can strap it to on the standard balancer?

Something else I haven't covered yet, ECU. The Stock RB20DET ECU, would it handle it? Could it be remapped to work, would an RB20DET powerFC be programmable for an application like this? Am I looking at a completely custom ECU?

Once again, please keep the info coming people. Any experiences or knowledge is helpful. I've only been looking into this for a day now and already I know 100x what I knew yesterday.

Cheers

P.S: Don't be sorry if you're putting me off the idea. Original ideas are great, but you're correct, I don't wanna spend a bunch of cash and have a shitty engine in my car. If I get discouraged from the idea it will be because I honestly feel from the information I have gathered that it's not the right or viable option for me to pursue

Edited July 9, 2006 by Hakai

[Jago]

just twin turbo it like mine and have fun with the narrow power band lol

[FORZA-MOTORSPORT]

Hi there mate i would use a toyota sc14 1.4L supercharger from a 1ggze that is a 2L 6cyclinder anyway. Now it would be easy to set this "roots" type blower up on your rb20, as it uses a serpentine belt and you could run it off the air con pulley and mount it where the air con compressor is. These superchargers run an electronic clutch which can turn the supercharger on and off i would hook this up to my ac switch. Then you would need to run an intercooler or alcohol water injection and your set! Any more info just pm me i have done 3 of these setups on 2L motors before, the response and torque is awesome, on a 2L fiat motor 1/4 throttle in 3rd gear at 40k's no traction in the dry! Also boost can be regulated by pulley size, i wouldnt run over 18psi as the supercharger would start to generate more heat then power.

[Hakai]

Hi there mate i would use a toyota sc14 1.4L supercharger from a 1ggze that is a 2L 6cyclinder anyway. Now it would be easy to set this "roots" type blower up on your rb20, as it uses a serpentine belt and you could run it off the air con pulley and mount it where the air con compressor is. These superchargers run an electronic clutch which can turn the supercharger on and off i would hook this up to my ac switch. Then you would need to run an intercooler or alcohol water injection and your set! Any more info just pm me i have done 3 of these setups on 2L motors before, the response and torque is awesome, on a 2L fiat motor 1/4 throttle in 3rd gear at 40k's no traction in the dry! Also boost can be regulated by pulley size, i wouldnt run over 18psi as the supercharger would start to generate more heat then power.

Can I mount this type of blower in the same place in the inlet system as a turbo/centrifugal blower? For example; After the air filter/AFM then have it blowing through the intercooler and then into the throttle body? Obviously using a BOV to regulate closed throttle backpressure.

What RPM range would it be efficient for? Would it make boost early and still last through to say, 6,000rpm? Preferably 6,500rpm.

Can I setup the electronic clutch to disengage when the gearbox goes into neutral to prevent off-load boosting into the engine?

How much would one of these blowers cost me? Where would I get one? What would be the cost of having it rebuilt once I've bought it (I don't wanna put things that are going to go broke on me quickly on the car if I can avoid it).

Thanks again

Ben.

*EDIT*

Lastly, you say it's a roots type blower? This means it's not a lynsholm-screw type and it works on external compression rather than internal compression. Isn't external compression extremely inefficient and doesn't in generate alot more heat than internal compression?

Also what is a serpentine belt? What type of belt does a lynsholm screw type blower run, what does a centrifugal blower run? What's the difference between the 3?

Edited July 9, 2006 by Hakai

[FORZA-MOTORSPORT]

Can I mount this type of blower in the same place in the inlet system as a turbo/centrifugal blower? For example; After the air filter/AFM then have it blowing through the intercooler and then into the throttle body? Obviously using a BOV to regulate closed throttle backpressure.

What RPM range would it be efficient for? Would it make boost early and still last through to say, 6,000rpm? Preferably 6,500rpm.

Can I setup the electronic clutch to disengage when the gearbox goes into neutral to prevent off-load boosting into the engine?

How much would one of these blowers cost me? Where would I get one? What would be the cost of having it rebuilt once I've bought it (I don't wanna put things that are going to go broke on me quickly on the car if I can avoid it).

Thanks again

Ben.

*EDIT*

Lastly, you say it's a roots type blower? This means it's not a lynsholm-screw type and it works on external compression rather than internal compression. Isn't external compression extremely inefficient and doesn't in generate alot more heat than internal compression?

Yes the supercharger blows threw the intercooler and into the tb/plenum, ofcourse you can run a bov. These superchargers cost $300 from a jap wreckers be sure to pick a good one. Not sure on rebuild cost, you would have to ask around. It would be so easy to setup make your own custom brackets to mount it where the aircon is, lol infact if you in adelaide i would make the setup for you, i love modifications! These superchargers taper off around 6,500rpm but it doesnt really make a difference as you change up a gear anyway. 8.5:1 is also a good compression or are the rb20de's higher compression??? this will determine how much boost you can run but obviously you will want a good computer pfc and injectors etc if you are going to run over 5psi boost. I dont understand what you are saying about the supercharger on idle to prevent off loading boost? The supercharger wont boost on idle well might get close to this would only cause a problem if you where stationary for a long period, personally id setup an alcohol water injection system set to 1.5 psi pressure switch and you would have no drams with pinging or overheating.

[Hakai]

Yes the supercharger blows threw the intercooler and into the tb/plenum, ofcourse you can run a bov. These superchargers cost $300 from a jap wreckers be sure to pick a good one. Not sure on rebuild cost, you would have to ask around. It would be so easy to setup make your own custom brackets to mount it where the aircon is, lol infact if you in adelaide i would make the setup for you, i love modifications! These superchargers taper off around 6,500rpm but it doesnt really make a difference as you change up a gear anyway. 8.5:1 is also a good compression or are the rb20de's higher compression??? this will determine how much boost you can run but obviously you will want a good computer pfc and injectors etc if you are going to run over 5psi boost. I dont understand what you are saying about the supercharger on idle to prevent off loading boost? The supercharger wont boost on idle well might get close to this would only cause a problem if you where stationary for a long period, personally id setup an alcohol water injection system set to 1.5 psi pressure switch and you would have no drams with pinging or overheating.

My engine is an RB20DET. 8.5:1 compression.

If my current injectors can handle 10psi boost through the current turbo, why would I need to upgrade them? I understand boost is irrelevant and airflow is the real factor here. I know my injectors can handle 15psi or so through the turbo, do you think that the blower you're recommending would flow more CFM of air at 5psi than my stock turbo does at 15?

What about my ECU, it being the turbo ECU would it be able to cope with boost from a supercharger as opposed to boost from a turbo? Is there any difference to what the ECU sees? Or does the ECU just take the AFM reading and apply the fuel accordingly?

What I meant by disengaging the blower in neutral with its internal clutch was to prevent revving the engine when missing a gear change and causing potential damage by forcing boost into an engine that's not under load, aparantly that's a bad thing, I'm not sure why?

Can you asnwer my question about the roots type vs lynsholm type blowers, or are you unsure like me lol? Does the blower your recommending use external compression or does it use internal compression, as explained Here. Sorry to be a pain, it's just that external compression as explained there doesn't sound that enticing to me.

Also, do I -have- to remove my air con compressor? And what is a serpentine belt? Lol?

Thanks again

[Hakai]

how much torque do you think an xr6turbo makes at 2200rpm?

probably just as much if not more as your supercharged setup

It is a different kind of power though is it not? Even if it made the same power/torque at 2200rpm, the delivery is kinda different so the effect might not be the same? I honestly don't know, just throwin it out there

[Cubes]

As a comparison my rb30det running the stock turbo @ 12psi tailing off to 9psi by 4000rpm made:

100rwkw by 2000rpm

130rwkw by 2600rpm

160rwkw by 3200rpm

170rwkw by 3800rpm

176rwkw by 4000rpm and then held flat until 5000rpm where it would nose over.

It would spool to 12psi at 1500-1600rpm if you were in a high gear, lower gears the rev's flick too quick for the turbo to spool at such an rpm.

Yes it felt like a diesel.

So what I'm getting at is drop a little gt2871r on the old 250xflow and it would have spooled just as early yet made a heap more power, pushing close to mid 250rwkw's.

[Hakai]

As a comparison my rb30det running the stock turbo @ 12psi tailing off to 9psi by 4000rpm made:

100rwkw by 2000rpm

130rwkw by 2600rpm

160rwkw by 3200rpm

170rwkw by 3800rpm

176rwkw by 4000rpm and then held flat until 5000rpm where it would nose over.

It would spool to 12psi at 1500-1600rpm if you were in a high gear, lower gears the rev's flick too quick for the turbo to spool at such an rpm.

Yes it felt like a diesel.

So what I'm getting at is drop a little gt2871r on the old 250xflow and it would have spooled just as early yet made a heap more power, pushing close to mid 250rwkw's.

I must be missing something, or I'm just too tired... (Though WTF can't I get to sleep tonight god damnit)

I'm not meaning to be rude but I'm missing the comparison to a supercharger on my lil old RB20 here, sorry dude, please explain a bit better, I'm quite dumb tonight

[Cubes]

It was more so of a comparison to the 4.1ltr supercharger...

I believe you'd be much better off with a 2.5ltr and a stock turbo making close to 200rwkw.

There's no point having a shiet load of torque at 2000rpm with the skylines gearing, some torque yes and then a rush of power from 2500-3000rpm onwards.

Even with a supercharger the rb20 won't make as much torque at lets say 2500rpm as a larger motor (rb25 or rb30) running a suitable turbo to spool similiar.

If you do decide to go supercharger on the rb20 your still going to have bugger all off idle torque until it gets going at around 2000-2500rpm or so.

So... drop a 2.5ltr in it with a std rb25 turbo and experience similiar but with considerably more off idle torque possibly similiar mid range yet a shiet load more top end.

I'm tired also.. hope that made sense.

[Batski]

The point of pressurising the charge is simply to get more air in the engine, so you can up the fuel and still keep the same air fuel ratio, to make more power. Means you can have the same amount of combustible particles in the cylinders as a cylinder with a larger volume, but without the weight a big bore engine.

And the intercooler cancels out the heat that compression causes, creating a more combustible charge.

The intercooler generally only partially removes the heat created through compression as the intercooler like most things is only so efficient. Cooling the charge doesn't create a 'more combustible charge' it increases its density so that more mass of charge fills the cyclinder.

Doesnt matter how you do it, or at what RPM you do it. Just means itll be on power earlier. Cos with a supercharger, the speed it spins is in direct proportion to the speed of the engine. The lower the engine speed, the less air it needs, the less the supercharger pumps. The higher the engine speed, the more air the engine needs, the more the supercharger pumps. Its all in ratios.

The matched engine speed/air supply ratio you imply is only really going to occur with a positive displacement supercharger (even then volumetric efficiencies change throughout the RPM band). Centrifugal superchargers however obviously provide a flow that is not linear against their speed of rotation. Consequently depending on when the supercharger is providing adequate flow to start producing boost good power may or may not be coming on any earlier.