greddy twin build...
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Joined: Jul 2016
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From: Omaha
^there was a 'Everyones Car Scene' meet that night and a bunch of subi's were rocking their BOV's as they blew by me - amusing to say the least ... I was literally just driving on the same road not showing anyone up, not gun'ing it, nothing ... but I'm sure they felt like the ****...
The z is over at my dads place as I have his car ... tearing down his engine as he's got a abnormal 'clink' coming from the front of the block (my guess its a crank shaft bearing or piston bearing - I'll keep everyone posted)
got bored tonight ... Jerryd shared some pics on chopping out the OEM trumpets out of the OEM plenum - obviously kills low end but opens things up on the top end. So I decided to give it a go. I'm also fixing to hack the 6 post out of the upper plenum.
I have a few extra plenums collecting dust, so if it sucks I can revert back to my unmolested OEM. Used a 4" grinder wheel to hack most of the trumpet out, a 24grit wheel to grind it down. I'll use the dremel to round-off the edges and then I'll use a much softer wheel to smooth it.
heres where it's at
The z is over at my dads place as I have his car ... tearing down his engine as he's got a abnormal 'clink' coming from the front of the block (my guess its a crank shaft bearing or piston bearing - I'll keep everyone posted)
got bored tonight ... Jerryd shared some pics on chopping out the OEM trumpets out of the OEM plenum - obviously kills low end but opens things up on the top end. So I decided to give it a go. I'm also fixing to hack the 6 post out of the upper plenum.
I have a few extra plenums collecting dust, so if it sucks I can revert back to my unmolested OEM. Used a 4" grinder wheel to hack most of the trumpet out, a 24grit wheel to grind it down. I'll use the dremel to round-off the edges and then I'll use a much softer wheel to smooth it.
heres where it's at
Looks good man! Let me know how the car acts with that lower plenum chopped up. After Jerryd's post I just ended up doing some light porting on the lower plenum and intake runners on mine. I basically just gasket matched the ports and smoothed the castings as best i could with a die grinder and flapper wheel.
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Joined: Apr 2010
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From: North Denver
^can I assume your heads are 'port & polished' as well? I may end up doing this same thing...
Nice polish on those btw ...
You may want to find a rev-up lower plenum - where they increased the volume of each banks 'airbox'. I'm on the brink of getting tuned and I'll probably swap out the lower plenums (replace my current 2003 OEM for this 2006 modified) to take advantage of the higher flows.
Nice polish on those btw ...
You may want to find a rev-up lower plenum - where they increased the volume of each banks 'airbox'. I'm on the brink of getting tuned and I'll probably swap out the lower plenums (replace my current 2003 OEM for this 2006 modified) to take advantage of the higher flows.
Last edited by bealljk; Apr 21, 2017 at 11:03 PM.
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Joined: Apr 2010
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From: North Denver
this will be a demonstration on how well the OEM intake is truly designed and how low to mid end torque is optimized.
Last edited by bealljk; Apr 29, 2017 at 07:06 PM.
Well the way everything is looking i'll still be running my procharger, so this may be worth it for me.
This has been tried and does make a few more hp above 7500 rpm, loses power everywhere else even with FI. A FL shop owner by the name of Jeremy tried this and posted that old pic. Lesson learned was it was not worth it...
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From: North Denver
Are you saying (in your opinion) the OEM intake manifold is about as efficient as it's gonna get?
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Joined: Jul 2016
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From: Omaha
I would say the only way to find out is to compare them both on the dyno. As easy as they are to change it might be worth the extra money (depending on where you go and who's tuning) to unstrap put the other manifold on and restrap down and test. The Greddy turbos spool pretty quick so loosing mid range power is really not something you will want. I hope it works out for you though! Good luck man!
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Joined: Apr 2010
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From: North Denver
I'm pretty sure I broke my fnck'n pinky tonight...
but...got the car out last night and today...cars & coffee w/homeboy Jeff...it was great! g'damn it was fun...
but...got the car out last night and today...cars & coffee w/homeboy Jeff...it was great! g'damn it was fun...
Last edited by bealljk; May 7, 2017 at 08:28 AM.
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From: North Denver
Spent a few days grinding out the manifold and the lower plenum. Took ~2mm out of each runner at the point where the two bolt together. Really nothing taken off the outlet / downsteam side. Got everything bolted back in and started up as expected. I can't really feel a difference but I really wasnt expecting to.
From very basic cross-sectional area measurements done in cad, OEM was around 18.3cm^2 and after the grinding came to 21.0cm^2 which is +/-12% increase.
From very basic cross-sectional area measurements done in cad, OEM was around 18.3cm^2 and after the grinding came to 21.0cm^2 which is +/-12% increase.
Last edited by bealljk; May 25, 2017 at 04:05 PM.
Thread Starter
Joined: Apr 2010
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From: North Denver
The low end loss didnt feel as bad as I thought it would - could be a deceptive butt-dyno? I really havent pushed the car past ~4500rpm bc my canned tune - so I don't know that it offers top end either (according to the same dysfunctional butt dyno)...
I welded them during the rough sanding/grinding of the plenum - but yes! Thems all closed up!!!!!
