how to supercharge a ca18det?

Discuss topics related to the CA18DE and CA18DET series engines.
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themadscientist
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float_6969 wrote:A bunch of smart stuff
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Way to say what I said, but without being condescending and mean about it.

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That being said, I really think increasing the compression ratio is going to give you noticeable results that don't require exotic solutions. The compression ration on these engines is from a time past when step one of turbocharging an engine was dropping the compression ratio really low. It's just not necessary with proper ignition timing and efficient intercooling. People are putting boost to FA20s in the FRS and BRZ and it has like 12:1. These numbers are in the neighborhood of what you are looking for.

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That engine has dual injection, though, and the anti detonation qualities of the additional direct injection cannot be ignored and it is 200cc bigger, true, but there is no reason CA18DE pistons wouldn't work fin in a boosted environment provided the crowns were dressed a bit to knock down any heat riser sharp edges.


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float_6969
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That VW engine has continuous adjusting variable intake valve timing, and that makes a HUGE difference on the power band. It's also not running a cheap junkyard SC.

The limit for pump gas on this engine is is 9.5:1 compression due to the combustion chamber design. I ran 10.2:1 compression and had to pull HUGE amounts of timing, even at low boost, to prevent detonation. The FRS's piston/combustion chamber design is LIGHT YEARS ahead of what we have to work with. Direct injection also makes a HUGE difference to the knock limit of a combustion chamber.

I suppose you could optimize the cam timing for low end power and then run more boost in the top end to compensate for the lack of overlap.

I say go for it. I hope you prove me wrong to be honest. Then I can try and copy what you're doing, LOL!!!

Vetal
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Yes it has been proven you can get +50% of torque using S/C. It also is a known fact you can't do this simply by upping CR couple of points. And yes 12.5:1 on 2012' engine on E85 doesn't mean it can be done on 1989' engine on pump gas, indeed technology has advanced quite a lot (that's why I was seriously considering swapping for some newer engine but thought I would try adding S/C first).

So back to topic. Unfortunately only Merc's M45 without clutches are available around me. Will keep searching...

jcd06
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I'm not sure the clutched chargers are suitable.
Correct me if I'm wrong but as far as I know the clutch was forseen to disengage the charger at idle and cruise, so definitely at low rpm.
What you want to do is disengage when the turbo arrives at its nominal pressure ratio.
That might as well be 3000-4000rpm.
Switching too early will cause a dip in the torque curve.

The clutch looks rather fragile…
http://www.benzworld.org/forums/attachm ... aur170.pdf

Vetal
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Well it seems so, it's engaged only when needed, and we should also engage it at WOT and until turbo spins at good speed. Yes almost surely there will be dip in curve that would be hard to refine...
I really don't want to spin it all the time (both fuel wise and extra mass to accelerate past 4000rpm)

Vetal
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Joined: Tue Jan 06, 2004 11:41 am

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Due to lack of clutched superchargers over here I started searching if it's possible to add a clutch and this got me here :biggrin:
http://www.homemadeturbo.com/forced-ind ... -sc-52999/
Looks like it's doable?

jcd06
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Car: Nissan S13

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Cray from the turbo forum wrote:Just take the one out of your A/C compressor and weld it up to the input shaft of the S/C.
I don't want to spoil the fun again but it's a bit more complicated than that.
According to Eaton specs you'll need 25hp and 14000rpm for the M45 to deliver 10psi (0.69bar) at 300cfm.
25hp will be much more than the average car A/C power rating.
So if you use an A/C clutch don't expect it will last very long.
I wouldn't even be surprised if it slips.

Also consider balancing stuff before you want to spin it at 14000rpm :yesnod

Vetal
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Joined: Tue Jan 06, 2004 11:41 am

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Yes the torque rating the clutch can hold is what I will research next. As for longevity, I would use some cheap A/C compressors that could be had for 20$, so if I need to change it couple of times it's no big deal.
BTW, CA at 2000rpm has only ~50cfm.
I guess, I need to just start looking for a/c compressor that is easy to remove clutch from.

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float_6969
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Why not find one from another country and have it shipped to you. It would be WAY less work than trying to fabricate something. Eg;
http://www.ebay.com/sch/i.html?_from=R4 ... =&_sacat=0

And then ask the seller if they'll ship to you. I've found a lot of the time that even though they say they won't in the listing, if you actually message them and ask, they will. Especially if it has been relisted a few times and they want to get rid of it.

Vetal
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Because M45 are as low as $170 here, so if it fails it's cheap to replace, while M62 with shipping would run closer to $400. And with M62 I'd still need custom pulley - either on crank side, or on S/C shaft.
Also if the whole idea fails (most probably due to controlling bypass valve), I will loose less $$

Vetal
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Joined: Tue Jan 06, 2004 11:41 am

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Guys could you suggest some electric throttle bodies that could be operated by a push of the button? I guess for the start I just want to engage SC clutch and simultaneously close the bypass valve by a separate button.

Vetal
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Joined: Tue Jan 06, 2004 11:41 am

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The more I think about it the more I come to conclusion that for smooth transition bypass valve must be opened gradually so it means either developing some separate controller, or going to Megasquirt or Vems altogether...
Good news is, I think it is easy to get Nissan A/C clutch modified to accept pulleys of any size to drive the supercharger

jcd06
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Joined: Sat Aug 21, 2010 7:05 am
Car: Nissan S13

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Sorry for the delay :blush:
The bypass valve on the Mercedes Kompressor is Bosch p/n 0280 750 045 and has an internal diameter of about 57mm.
Here is a scheme of the connections:
http://s584.photobucket.com/user/Four_s ... p.jpg.html


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