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    Thread: How to build a relatively inexpensive, reliable, 'powerful' 2.0 8v.

    1. 12-21-2011 10:20 AM #76
      Gains as in an increase of available air into the intake, absolutely. I witnessed a considerable difference on the dyno with this set-up. (the pics were actually the morning of my 142whp dyno session.)

      But as for building positive pressure into my intake manifold (boost), no dice. I never saw any sustainable positive air pressure on my vacuum gauge. And if there was, it was so minimal that I didn't see it. Positive boost pressure is less than 1% at hiway speeds. Had I more access to welding materials and more budget, I probably could have fabricated something a tad more useful and completely sealed.

      Through all the research I did, the one I was most interested in was a motorcycle magazine test of 5 bikes which used ram air to boost their top end performance. Test were done on a dyno with the aid of some pretty big fans. Although the fans didnt provide the necessary air flow that simulates 100mph+ speeds on the open road, it was enough to test the ram air capabilities of their air boxes and see the gains as a result. It was around 110mph at which outside air ramming into their air boxes overcame the pumping forces /air speed of the pistons. But even then, gains were maybe 1-2%. Its not until speeds of 300mph does ram air actually matter. Rolls Royce discovered this in the 1920's. When they adjust fueling for their engine, they saw power increases of 15%. So realistically, ram-air on street cars: Myth. Ram air on race cars: 1, maybe 2% power increase depending on speed.

      You will get more power gains by air box volume tuning. Ever wonder why our cars have more torque with the stock airbox than a CAI? Just look at the design; Built in ram horn (velocity stack) and the plastic ribs inside the box structure. All this is to increase air flow into the intake tube and control the resonant frequency of the air. Those ribs cancel out any frequencies at specific rpms to deliver a smooth, not peaky, torque curve. When people start 'shaving' the insides of their airboxes, I just laugh. Or when they remove the entire airbox and slap a cone filter right on the end of their MAF. Again, I laugh.

    2. Banned Hurt's Avatar
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      12-21-2011 04:40 PM #77
      Yeah. I'd imagine you'd have to be going pretty fast and have a welded set up for ram air to create any significant amount of boost. I personally hate the whole "ram air" fad that Pontiac started in the 1990's. Ram-Air hoods on the Grand Prix GTP and Trans am, sure. But not on pick-ups, and cavaliers.. I see a ton of cars around here with "ram air" hoods. It's funny that 99% of the idiots who bought them don't even know that they aren't functional.

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      12-27-2011 10:52 AM #78
      Did a little revising/editing, bumping this so people can see it and not start other threads.

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      12-28-2011 10:55 PM #79
      Going to add a forced induction section tomorrow.

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      12-29-2011 04:55 PM #80
      Update: Added information on FI.

    6. Member 2.slowduo's Avatar
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      12-29-2011 05:29 PM #81
      Only obd1 ABA have forged crank and oil squirters.
      While good for boost not really a forged bottom end

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      12-29-2011 06:49 PM #82
      Quote Originally Posted by 2.slowduo View Post
      Only obd1 ABA have forged crank and oil squirters.
      While good for boost not really a forged bottom end
      They have forged internals.. I didn't say anything about oil squirters, or obd1.

    8. Member 2.slowduo's Avatar
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      12-30-2011 07:47 AM #83
      That simply is not true.
      This has been good info. But
      Obd1 forged crank, forged rods, cast pistons
      Obd2 cast crank no oil squirters
      Not being a jerk. Just the way it is
      Last edited by 2.slowduo; 12-30-2011 at 11:09 AM.

    9. 12-31-2011 06:38 PM #84
      mm well which obd2... some had squirters some didnt... i believe it was the aeg that didnt and the later avh and up did. i know my 02 avh engines.. three of them do have squirters... now as for the internals... crank is cast as are the rods and pistons. but according to intergrated engineering the stock crank is capable of 400hp without issue so spend the money on rods and pistons... also squirters can be added

    10. Member Prof315's Avatar
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      01-01-2012 07:19 AM #85
      The forged OBD1 ABA cranks are also about 3 lbs lighter that the obd2 cast cranks.
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      01-03-2012 09:54 AM #86

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      01-08-2012 02:06 PM #87

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      01-14-2012 08:31 PM #88
      Quote Originally Posted by rommeldawg View Post
      mm well which obd2... some had squirters some didnt... i believe it was the aeg that didnt and the later avh and up did. i know my 02 avh engines.. three of them do have squirters... now as for the internals... crank is cast as are the rods and pistons. but according to intergrated engineering the stock crank is capable of 400hp without issue so spend the money on rods and pistons... also squirters can be added
      This is mainly for ABA MK3 and ABA swaps. Not MK4's.

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      01-19-2012 01:46 PM #89
      bump

    15. Banned Hurt's Avatar
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      01-23-2012 08:09 AM #90
      ttt - this thread keeps "OMG 8V FAST PLZ" threads from popping up.

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      02-02-2012 09:18 PM #91
      Bump for the forum's sake.

    17. Member MYGTI_MA's Avatar
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      02-04-2012 04:30 PM #92
      great thread that any noob who wants to mod the mk3 2.0 should/must read.

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      02-06-2012 05:59 PM #93
      Quote Originally Posted by MYGTI_MA View Post
      great thread that any noob who wants to mod the mk3 2.0 should/must read.
      Thanks bud.

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      02-08-2012 08:31 PM #94
      Quote Originally Posted by Prof315 View Post
      The forged OBD1 ABA cranks are also about 3 lbs lighter that the obd2 cast cranks.
      3lbs? Hm.. I wonder why VW didn't stick with them.. Maybe the cost of making them was higher.

    20. Member Prof315's Avatar
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      02-09-2012 06:45 AM #95
      Quote Originally Posted by Hurt View Post
      3lbs? Hm.. I wonder why VW didn't stick with them.. Maybe the cost of making them was higher.
      It's MUCH more expensive to forge metal as opposed to casting it.
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      02-09-2012 11:35 AM #96
      Quote Originally Posted by Prof315 View Post
      It's MUCH more expensive to forge metal as opposed to casting it.
      The obd1 cars also have a slightly more aggressive cam profile and combined with the forged crank, oil squirters, and a few other subtle differences, they had a 6400 rpm redline instead of obd2 cars that had 6200. OBD1 = lucked out

    22. 02-09-2012 12:14 PM #97
      Quote Originally Posted by Hurt View Post
      The obd1 cars also have a slightly more aggressive cam profile and combined with the forged crank, oil squirters, and a few other subtle differences, they had a 6400 rpm redline instead of obd2 cars that had 6200. OBD1 = lucked out
      I don't know where you came up with that hypotheses, but its wrong. Why do you think the OBDI cam is more aggressive? Because it has 1*/2* more duration? Bah...it has a wider LSA and a much shorter lifter than the OBDII cam. Both are designed to match the intake port design of either head to give the same hp/tq figures. Yes, you would see a variance on a dyno if you flipped cams on either head, but its nothing you would feel on the butt dyno. The switch to cast crank, single springs, non-squirters wasn't just about cost, it was also about fuel efficiency. Less rotating mass = more fuel efficient. Which was the sole purpose of the OBDII intake port redesign. Quieter, torquier low end, and better directed the intake charge where it belongs...on the center of the piston. The sacrifice of the intake shrouds was top end power...hence the cam profile difference.

      Also the rpm rev ceiling is moot...these motors stop making torque @ 4500rpms. I don't know why anyone in their right mind would rev one of these suckers past 5500rpms.

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      02-12-2012 03:03 PM #98
      Quote Originally Posted by 911_fan View Post
      the rpm rev ceiling is moot...these motors stop making torque @ 4500rpms. I don't know why anyone in their right mind would rev one of these suckers past 5500rpms.
      I was only pointing out why the redline on the OBD1 cars (bubble clusters.) was a little higher.

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      02-16-2012 07:35 PM #99
      Bump to first page. This is an excellent thread with great info.

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      02-19-2012 07:48 PM #100
      Quote Originally Posted by Grenade Gavin View Post
      Bump to first page. This is an excellent thread with great info.
      Thanks, bud.

      PS: Looking into making a good head-work section.

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