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Location:
Blue mtns
Registered:
November 2003
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4AGE and carbies
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Thu, 22 January 2004 07:30
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i've been wondering around some of the 4AGE tuning websites, and saw that in the U.S. it isn't uncommon to pop carbies onto your 4AGE. to me that sounded strange... when i think of carbies, i always think of old school V8's and stuff, but after thinking about it and reading what it had to say, it makes perfect sense to rip out fuel injection and throw on carbies.
has anyone in aus done this with a 4AGE? i'd be interested what kind of set up it is, and how much "real-world" power gains are to be had. also merely interested how hard it was to set up on the 4AGE.
i've got an 86, and i'm looking to pop in an 88kw rwd drive engine myself, so any info on tuning would be appreciated.
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I supported Toymods
Location:
Epping, Sydney
Registered:
May 2002
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Location:
Blue mtns
Registered:
November 2003
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Re: 4AGE and carbies
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Thu, 22 January 2004 09:11
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i saw it on club4ag.com, it had some interesting articles on it...
if you've seen the volume of best motoring where they road test the new evo vs the WRX, they've got a segment about the last of the straight sixes which are going out of development (supra, skyline, blah, blah) and they had some sweet sixes which had carbies on them. those engines went freek'n hard!! you should see the mines skyline... INSANE.
anyway, i thought something like carbies were a thing of the past, but obviously not...
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AGE and carbies
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Thu, 22 January 2004 10:53
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You can buy the bits - redline manifold, set of webers, etc. easily. Others HAVE done it, and maybe someone will admit to it. As for power gains etc. - only whenever you've done work (cams, head, etc.) and are too cheap to fit tunable EFI. EFI and multi throttles will always be much nicer than the carbs can ever be, but, it does cost more admittedly...
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I supported Toymods
Location:
melbourne.victoria.austra...
Registered:
June 2002
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Re: 4AGE and carbies
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Fri, 23 January 2004 05:56
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i have this....custom dizzy (thanks IRally) and a gas research LPG carb...so far so good 
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Location:
Melbourne
Registered:
May 2002
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Re: 4AGE and carbies
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Sat, 24 January 2004 02:24
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I''ve done the Twin Dual Throat carby conversion on my car, and if I were to do it again i'd go injection. Cost of all the bits and pieces add up quite quickly. You also need a distributor if you don't plan on starting with the EFI loom computer.
Tuning isn't that difficult to get your head around, you just need a decent weber or dellorto tuning guide. Just be sitting down if you need to rejet your carbs. Every jet x4 equals some very costly brass.
Drivability is not so bad, depends on the weather, how close synchronisation is, position of the moon. I've had no end of trouble with my linkages which balnce my carbs, but that may be due to the fact that my carbs are 20 yo and probably in need of a rebuild. It's great when i can get sync'd.
Really the only reason you'd go carbs is because you already have them, and they are jetted to suit.
A short run down on cost
Manifold 250
Carbs 400
Jetting 400
Linkage 200
Trumpets 100
Soft mounts 30
Filters 120
Dizzy 400
TOTAL 1900
Costly, indeed, gains, yet to be proven. A decent aftermarket EFI system will probably come close to this, but you won't have to shell out every time you need new jets to tune it. The stock RWD tvis manifold will take you to 190 hp anyway with some BIG cams.
Daniel
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Fri, 27 February 2004 14:33
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could someone please tell me how on earth changing to carbies is meant to gain anything?? sure if there is no computer but otherwise???
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Location:
South Australia
Registered:
July 2002
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Re: 4AGE and carbies
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Sat, 28 February 2004 00:17
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I imagine it's mostly for the increased throttle size area, allows more air into the engine at higher revs. I seriously doubt anyone who has done this conversion has ever got it engineered in australia without five catalytic convertors though...
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Sat, 28 February 2004 00:49
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hold this is assuming that the standard intake manifold and throttle body causes a resriction. I doubt this to be the case with the manifold because when from what I hear people who have a big port have put a small port intake manifold on for a gain in low down power without a loss in the top, which means that the standard big port manafold cant be a restriction. If its the throttle thats easy swap it. Mechanicly its real easy I am almost finished converting mine. Electrically I am unsure about the compatibility. What I think causes a possible increase in high end power is that the airflow meter is removed, and surely theres a better way to solve this than going back to the dark ages with carbies.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AGE and carbies
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Sat, 28 February 2004 04:56
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My suggestion? These days, some places sell 20valve engines as the cheapest 4ag they have, because they find the older ones a bit hard to get... Therefore, why not buy a 20 valve first up, and an aftermarket box to control it. That way you can get rid of the dizzy on the back of the head, along with the inlet airbox/plenum, and run socks+trumpets instead. It probably won't end up costing any more than the carby setup, it'll go harder, run better and may even SOUND fatter - who could argue?
Other thing is, I wonder how many have THOUGHT their 4AG went harder with the carbs, simply because it was making more noise  That said, I will say that a set of carbs in brand new condition, painstaikingly tuned, WILL run fairly well, better than most people think, but hey, they're still carbs! 
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Sat, 28 February 2004 05:07
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mrshin: if you talking about using that 20V in a RWD setup which I assume you are then you are missing a massive amount of work that needs to be done. What you mentioned is the easy part, the cooling system is the problem. Otherewise 20V 4AGs would be a more common sight.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AGE and carbies
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Sat, 28 February 2004 05:13
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Yes I am talking about using it RWD, and I'm aware of the water pipe issues... I suppose sometimes I take these things a little bit lightly, because I've always been able to just go out to the shed, and use the lathe, oxy torch, etc. to make fittings to overcome these sorts of problems, and probably others find it a bit harder That said I have seen a couple of 20 valves mounted RWD (no, not just clubmans...)
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Sat, 28 February 2004 05:19
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oh we would find it harder all right! I am kinda weary about modifying (aka bashing the shit out of) the firewall.
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Location:
South Australia
Registered:
July 2002
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Sat, 28 February 2004 13:58
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I bet that if an aftermarket EMS was run with a map sensor arangement with a proper intake instead of the stock airflow meter then it would have more power than the best carby setup.
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Location:
Montrose, VIC
Registered:
May 2002
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Re: 4AGE and carbies
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Sun, 29 February 2004 01:30
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Next point: multi throttles and just a MAP sensor don't often go so blindingly well together  Also, air flow meters aren't always as bad as most people suggest, plus nearly all the 16v 4ag's that people play with in Australia are MAP ones anyway
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Location:
S.E suberbs, Vic
Registered:
December 2003
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Re: 4AGE and carbies
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Sun, 29 February 2004 02:30
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that is very true. However isnt it also true that a multiple throttle setup does not give any extra power over a good single throttle setup? doesnt it give just throttle response and well .. better sound! In the 4AG this may not be the case as the intake manafold is not a tapered shape and it may well distribute the air unevenly.
Has anyone ever tried modifying the standard manafold? like with the Plenum?
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Location:
South Australia
Registered:
July 2002
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Re: 4AGE and carbies
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Sun, 29 February 2004 03:20
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Short answer to multi v single - Depends on the head work done.
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Location:
Kita-Ku, Sapporo, Japan
Registered:
January 2003
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Re: 4AGE and carbies
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Sun, 29 February 2004 04:24
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| mrshin wrote on Sun, 29 February 2004 12:30 |
Next point: multi throttles and just a MAP sensor don't often go so blindingly well together Also, air flow meters aren't always as bad as most people suggest, plus nearly all the 16v 4ag's that people play with in Australia are MAP ones anyway
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just t blow this opinion out of the water forever 
yesterday i spent some time tuning an Alfa 2L twin cam (in a hot rod) using Megasquirt. it has suzuki GSX individual throttle bodies, and i think 250cc injectors? cams are around 230-240 @50 thou (ie around 270-290 advertised duration, bigger than most 4AG's)
the 8 RPM bins were evenly spaced from 1000rpm to 7000rpm.
the 8 MAP bins...
well. the car idles at 75kpa (absolute pressure, ie 1atm is 100kpa), it cruises at 80-85kpa. and WOT was 95kpa.
the MAP bins were set up as 60, 80, 83, 86, 89, 92, 95, 98.
the O2 sensor correction was set to work up to 50% throttle (which gave about 90kpa manifold pressure), and had a range of +-20% correction with 1% correction per 16 ignition events, and 75%-100% throttle was at 92-95kpa.
even with such a small MAP range on the table, the thing starts cruises and accelerates/decelerates as good or better than OEM cars.
there's no hesitations, flat spots, bucking or popping.
the guy had the cruise table worked out ok, and it took us about 10-15 minutes to get the 50% to 100% throttle part of the table worked out. damn it goes hard now
everyone said the motor would not run on speed-density, and he would have to use alpha-N.
speed density works fantastically, even tho the normal MAP range is only 75-100kpa (or 75%-100% load on a Wolf setup). there is no reason why a 4AG would not also work with almost exactly the same setup.
and yes, AFM's arent really that bad, they don't have that much effect on the air going thru (ask anyone who bitches about them if they have measured the pressure drop across the AFM )
Cya, Stewart
ps, his yellow rod is in the current issue of "Australian Street rodding" pages 22-25.
[Updated on: Sun, 29 February 2004 04:27]
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