Supercharging An Rb20det?

[Hakai]

Hey all,

Yesterday I was unlucky enough to fall victim to some retarded driving that landed me up the ass of a van. Not the van drivers' fault, he got cut off by some dumb b~tch and had to slam on the brakes, just happened to do it while I was checking the oncoming traffic to my right to see if I was clear to follow him, sigh.

So now the car is off the road, not a huge deal of damage but it's forced me to find alternate transport temporarily which has got me thinking. I can use alternate transport and save money and pour it into the 32, hmmm.

I want to do something different with my skyline, I have read and very much understand the advantages of using tried and true methods, such as swapping my RB20DET for an RB25DET, or using proven bolt on upgrades for my RB20, however; That's not what I'm after. I want to do something different, something that will stand out, not be expected, but still make reasonable power for money. I would love to build a serious all-motor RB30/26 but I just can't afford to

Anyway on to my idea/questions.

I used to frequent calaisturbo.com when I owned a VL, back then people were starting to supercharge the RB30s with some decent results, but everything was custom as there were no bolt on kits.

What I'm looking to find out is any information on supercharging an RB20 that anyone has to offer. Questions like;

What kind of supercharger would I be using and what is the clutch in them I've read a bit about? Does this mean with a switch I can engage or disengage the supercharger? The RB30 boys are commonly using 4A-GZE superchargers or 1A-GGEs I think.

Boost is boost is it not? If the standard RB20DET internals in good condition can run 18psi from a hi-flowed turbo, would that mean they could handle the same or close to from a supercharger?

How would a supercharger perform on a 2ltr I6 engine? If I had to guess, I'd say that having a supercharger on the 2ltr engine would eliminate the low end sluggishness and give it some serious kick down low? Does the RB20DET crank have enough grunt to drive a supercharger of that size? (4A-GZE, which is a 1.6ltr 4cyl for those who don't know them)

What about top end power? I am not up on superchargers at all if you can't tell, but I have heard things attesting to how superchargers stop making boost at higher RPM or some such. That doesn't make sense to me. A supercharger is just another for of air compressor, like a turbo, except driven by belt from the crank. The crank doesn't stop driving the supercharger at any RPM, so the only reason I could see for the supercharger to stop making boost would be compressor efficiency? If you were running a supercharger with proper compressor efficiency, what reason would there be for it to not keep giving you gains all the way to say, a 6.5k redline?

Anyway, I won't ask anymore questions, I'll just leave this open to discussion. I am very interested in doing something different and this is one of the more different things I can think of. Any knowledge/experience/information would be helpful, even if it's just general supercharger related stuff that would help me make decisions etc and not necessarily related specifically to the RB20.

Thanks

Ben.

[mad082]

one problem with supercharging a manual car is that if you miss a gear and give it a good hard rev in neutral you are boosting the motor up with no load on it. this is one reason why holden never made manual supercharged v6's.

[Hakai]

one problem with supercharging a manual car is that if you miss a gear and give it a good hard rev in neutral you are boosting the motor up with no load on it. this is one reason why holden never made manual supercharged v6's.

I've read that before, in fact I believe you said it somewhere in a different thread

I do understand the fact that it would be boosting an engine with no load, what I don't understand is how that is worse for the engine, than boosting it when under load?

Is it because the fuel map is 3D and by boosting it with no load the ECU won't be fuelling the engine properly which would lead to leaning out and doing good damage to stuff?

That's about the only thing I can think of, but I don't know much about supercharging.

Ben.

[paulr33]

too much heat in the intake system, the compressor on the supercharger will really heat things up for you

[Hakai]

too much heat in the intake system, the compressor on the supercharger will really heat things up for you

Would a well built cold air induction box around the POD do anything to alleviate this? Or are you talking about something different?

[Hakai]

one problem with supercharging a manual car is that if you miss a gear and give it a good hard rev in neutral you are boosting the motor up with no load on it. this is one reason why holden never made manual supercharged v6's.

I was just out getting subway and I had a thought on this problem. As I mentioned in my first post, I've heard about an electronic clutch built into some superchargers, a friend of mine has a S/C on his VR Ute, he can turn it on or off with a switch, I'm guessing that this is an electronic clutch that is doing this.

What if I were to use a supercharger that had an electronic clutch, and rigged it up to my gearbox sensor so that whenever the 'box was put into neutral it disengaged the clutch in the supercharger? This would fix the problem of boosting the engine on a missed gear. I also expect it would work the clutch in the supercharger hard, but it'd be better to be replacing that clutch than replacing an engine wouldn't it?

Whatcha think?

Edited July 9, 2006 by Hakai

[paulr33]

no it will not, you should have a good cold air intake system anyway but this wont be the cause of the extra heat in the intake charge, the nature on how a supercharger compressor works is different to a turbocharger compressor. this is assuming you are talking about a screw / wipple blower (common commodore + toyota ones).

the certifigual ones are differently (look like a turbocharger)

[bbe]

super chargers are way cooler than trubos as they dont run of heat (exhaust )

a super charged rb20 would be bloody awesome ive thought about it many times

do it

[paulr33]

im sorry i dont agree. it is nothing to do with what the driver source is, its to do with how the screw compressor works. it adds more heat into the intake charge.

just because the turbocharger exhaust wheel runs via the exhaust, this doesn't mean the intake charge is hot. the intake charge gets heated up by compressing it. to achieve compressor you heat the air up, or reduce volume, or a combination (im pretty sure).

[Hakai]

im sorry i dont agree. it is nothing to do with what the driver source is, its to do with how the screw compressor works. it adds more heat into the intake charge.

just because the turbocharger exhaust wheel runs via the exhaust, this doesn't mean the intake charge is hot. the intake charge gets heated up by compressing it. to achieve compressor you heat the air up, or reduce volume, or a combination (im pretty sure).

I completely understand what you're saying.

I've done a small amount of research on superchargers and what I've been able to find points to the fact that the best compressor for me to use for the RB20DET would be a positive displacement (screw type), but a lynsholm-type not a roots-type.

The roots-type screw works on compressing air by, from what I can understand, using pressure forced back against the supercharger from the manifold, it's called external compression. The lynsholm-type screw works with internal compression, the air is actually compressed by the screws, I don't exactly understand how, all I know is it sounds like the type of charger I want.

I looked at dynamic (centrifugal) chargers, but all the info I turned up (albeit only a small amount) says that they are quite sluggish down low, which defeats one of the purposes of this exercise for me.

It really all depends, I want something that will boost early on, but I don't want it to be tapering off at 5,000rpm, I want it to be holding boost at least evenly, maybe not increasing, until 6,000-6,500rpm. I'm not sure if a lynsholm-screw type will continue to boost so that's something I need more info on, but I know that a centrifugal unit will not boost early on and will still be putting excessive load on the crank, therefor as far as I can tell, equating to a loss in low end power rather than a gain.

Supercharging may not be for me at all, I might end up building a turbo engine, or I might end up giving up on a built engine at all, who knows. Just after info right now

Keep it coming

Ben.

[qikstagea]

Mate i'd say go for it. Personally id run a centifugal supercharger - being that you can run an intercooler setup as you would to a turbocharged engine. A cold air intake and shielded pod filter are all good, but thats makes a difference of about 15-20 degrees to inlet air temp. By the time the air goes through a supercharger or turbocharger, it's a fair bit warmer than that, i believe.

Basically, the colder the air, the more combustible. Also, the colder the air, the higher psi you can run. With centrifugal superchargers, there is less throttle response due to a longer inlet tract with the intercooler, but that is the only downside. Low down torque is much the same between them, if you run a fmic setup.

Ive owned both a supercharged vehicle and a turbo charged one. Completely different cars, but each had its merits. I must say the supercharger was a much simpler method, easier to work on, tune, and troubleshoot when theres dramas. It ran an APS kit with a Vortech centrifugal supercharger, with a 300x600x70 fmic. inCREDible torque.

Therese no lag on a supercharged engine. When you put your foot down, you better be ready to go, cos the car will be.

Edited July 9, 2006 by qikstagea

[Kinks]

compressing air will always heat it up. Therefore for anything over low-boost you NEED an intercooler or your charge temps and hence power will suffer drastically.

whether you go for turbo or supercharging depends on the character of the engine, availability of parts and your budget. It also depends on what you want out of forced induction, supercharging has the benefit of instant boost availability.

I would go for an intercooled centrifugal supercharger on an RB20. A positive displacement blower would help low down torque as the RB20 is somewhat lacking, but it will limit your top end and this is where the RB engines are efficient.

Given the availability and (relative) low cost of turbo parts I would stick with them, but that's because I'm lazy. A blown RB would sound awesome

Edited July 9, 2006 by Kinks

[paulr33]

i disagree with "instant boost" the compress still has to find into its effiency zone which isnt 0rpm. as the main belt rpm increases so to does the internal gear assembly driving the compressor faster and faster. you dont make 8psi at idle if thats what you are thinking, more like 1800rpm ?

[qikstagea]

Definately not instant boost, no. (i dont see who wrote that or where its written). But itll pull you out of corners better, and get a much better result from low-rev launches than a turbo chrger. In daily driving, youll find yourself just putting your foot down, in situations where you may have needed to change gear in a t/c'd car.

Like kinks said, a supercharger would definately fill the torque-hole down low.

Have a look at the APS (air power sytems) kit for the twin cam RB. See what you think. I had a similar setup (albeit a different trim charger) on an EFI falcon, an 85 XF. (you may know these cars - RB engine owners like to steal their throttle bodies).

[Hakai]

Definately not instant boost, no. (i dont see who wrote that or where its written). But itll pull you out of corners better, and get a much better result from low-rev launches than a turbo chrger. In daily driving, youll find yourself just putting your foot down, in situations where you may have needed to change gear in a t/c'd car.

Like kinks said, a supercharger would definately fill the torque-hole down low.

Have a look at the APS (air power sytems) kit for the twin cam RB. See what you think. I had a similar setup (albeit a different trim charger) on an EFI falcon, an 85 XF. (you may know these cars - RB engine owners like to steal their throttle bodies).

That's what I needed, a kit for the RB twin cam series. I did a goodle on APS superchargers and found what I think is their site, but I couldn't find a link for the RB series kit. If you could link something that'd help a great deal.

As for using a dynamic/centrifugal blower, as I said I've read that they bog down in the lower RPM. Obviously I don't have extensive knowlegde of this, so can you give me an idea of what I'm looking at?

Vortech was my first thought for the blower as they're a very big, very reputable name, what model of Vortech blower am I looking at using? I 100% want to use an intercooler so I guess a lynsholm-type is out of the question, by what you're saying I can't intercool that setup?

So questions are;

1) What model of Vortech blower am I looking at, I want boost to be efficient until at LEAST 5,500rpm, preferably 6,000-6,500rpm on my RB20DET (DET meaning the lower compression engine, not meaning I intend to retain the Turbo).

2) What RPM would a centrifugal unit begin to boost at? When it's not boosting, how bad is the engine going to bog down from the drain of the belt driven blower?

3) Is say 14psi from a centrifugal supercharger the same on the internals of an engine as 14psi from a turbocharger, just at a different range of rpm?

Keep the answers coming guys, I'm loving the sound of this idea so far.

And to whoever said it, yes, I think a blown RB20 would sound f**king unreal

Ben.

[mad082]

if money wasn't an option i'd both turbo and supercharge it. it has been done before with pretty good results. you have the supercharger work down low and the turbos kick in up high.

the disadvantage of supercharging is that you can't just simply wind more boost into it. you have to change pulleys. but you can run bov's on them (depending on the type of supercharger).

wheelspin is also something you have to consider. you are going to get more of it with a supercharger as there is a lot less lag than a turbo as the intake (up the throttle body) is already compressed so when you put your foot down it is ready to go, where as on a turbo engine, if you are at 5000rpm with the throttle shut the turbo is spinning slower than if the throttle was open, so whe you gas it the turbo has to come up to speed and charge up the intake before you get the power. i had a 2000 magna with 170hp at the front wheels and i was thinking about supercharging it for a bit more power, but i thought against it as it was hard enough to get the power down in first gear as it was, especially up hills.

but go for it if you want to be different, and keep us posted.

[mad082]

14psi from a s/c would be awesome. if it kicked in at say 2000rpm it would pull hard!

[paulr33]

http://www.skylinesaustralia.com/forums/in...;hl=supercharge

http://www.skylinesaustralia.com/forums/in...;hl=supercharge

http://www.skylinesaustralia.com/forums/in...;hl=supercharge

http://www.skylinesaustralia.com/forums/in...;hl=supercharge

http://www.skylinesaustralia.com/forums/in...;hl=supercharge

[qikstagea]

14psi is 14psi. no matter what.

couldnt tell you when a 14psi blower would seriously start to puff at. but i ran 9psi on mine, and it was from about 1600, idle being a very lumpy and low 800. Full puff at about 2400 and up. Low revs wouldnt bog down a great deal, no more than usual, cos its still pumping air in, which means that even though it may not be a positive boost reading, its not going to be sucking air in, running vacuum.

And yeah s/charged engine sound awesome, get some gilmer styler belt drives for the whine. And cos theres no exhaust turbine, VERY meaty, throaty note. Awesome.

contact aps. they should be able to create a kit. they are fairly universal, not needing manifolds etc.

Allow $3000.

i know a guy who had a twin turbo setup feeding into a 6/71 supercharger on a 5L V8. Sold the engine, its in a ute now, but went well. Look up Redcliffe Dyno and Performance. Its the owners car, Steve. The only reason he could afford to tune it, dyno time and etc, is cos he owned the dyno.

[mad082]

14psi is 14psi. no matter what.

yeah know that, but if 14psi is kicking in 1000rpm earlier it is going to feel a hell of a lot stronger.