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Old 04-09-2010, 04:33 AM   #1
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Originally Posted by xtremerevolution View Post
Let me know if you want details on making your L27 go faster. I've spent the last 6 years trying.
YES PLEASE!! I want to know how to make it go faster without custom work.... I have not the first clue on porting and things like that...
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Old 04-09-2010, 05:11 AM   #2
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YES PLEASE!! I want to know how to make it go faster without custom work.... I have not the first clue on porting and things like that...
You are very limited to what you can do on an L27.

You can by Yella Terra 1.8 Ratio Roller rockers from ZZP for a 94-95 L27 5/16" studs for $350. You having a 92 (which I just noticed), which means you probably have 3/8" studs, so you'd have to have the cylinder heads removed and have them machined at a shop ($160 more). This would net you maybe 10-15hp.

Aside from that, you can get a fenderwell intake, a more open exahust, and that'* about it if you don't want to go custom.

As I mentioned, I've spent the last 6 years trying to make my L27 faster, and I've been unsuccessful for the most part. All of my work has been custom, from shortening the intake runners in the upper intake plenum insert, to porting the LIM, and now recently I've taken on the task of porting my heads, which there is a LOT to gain from. Its actually fairly straightforward if you have a steady hand and a dremel, which is all I'm using at this point.

Sorry to break it to you, but if you're not willing to learn how to port your intake manifold and heads, you won't be getting any more power out of this engine. I dropped $300 into my roller rockers and I've been trying to figure out this whole time why my mods aren't making that big of a difference, and while porting these heads, I can finally see why.
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Old 04-09-2010, 05:25 AM   #3
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Well, after searching around a little, maybe I need to clean up the engine bay, considering my Bonnie has over 300K and most of which are unknown to me. Plugs and wires, new fluids, ect... I need to clean the MAF and the throttle body.

It has power, but I have a feeling that it isn't FULL power. I have two 92 bonnies, a red and blue, which I'll be talking about the blue one mostly, considering the red one is basically a beer can now. Runs horrible and basically a project that I'll get to working on.... Later

As for porting. Basically all porting does is makes everything flow better through the engine? Like re-routing the fluids? And all it basically is is like boring ehatever you're doing? Like the heads?
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Old 04-09-2010, 01:52 PM   #4
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Originally Posted by Coburn2006 View Post
Well, after searching around a little, maybe I need to clean up the engine bay, considering my Bonnie has over 300K and most of which are unknown to me. Plugs and wires, new fluids, ect... I need to clean the MAF and the throttle body.

It has power, but I have a feeling that it isn't FULL power. I have two 92 bonnies, a red and blue, which I'll be talking about the blue one mostly, considering the red one is basically a beer can now. Runs horrible and basically a project that I'll get to working on.... Later

As for porting. Basically all porting does is makes everything flow better through the engine? Like re-routing the fluids? And all it basically is is like boring ehatever you're doing? Like the heads?
See my thread for porting my L27 heads. I'm using nothing more than a dremel with grinding stones and 80grit sanding rolls.

https://www.gmforum.com/performance-brainstorming-tuning-96/l27-heads-rockers-3-8-bolts-289967/page2/

Porting is essentially enlarging the openings on the intake and exhaust ports on your heads and intake manifolds, or grinding away imperfections. There are huge gains to be made from both on this engine, but moreso on the heads. There are serious casting flaws as you can see in those pictures. There are ridges that shouldn't be there, and the exhaust ports are MUCH too small compared to the openings on the exhaust manifolds. All you really have to do is grind away those imperfections and make a smoother surface all around, and you should get some noticeable gains. Just be prepared to put down another $100 in gaskets and seals when you put it all back together. Well worth it though IMO.

I used 80 grit because that'* what I've heard is recommended. If you make a completely smooth surface, you will have lower airflow. The concept is that air flows much more easily over pockets of sitting air inside tiny ridges created by 80grit sanding rolls than it would over mirror smooth surfaces. The only way you'll get a mirror smooth surface is by having a perfect port, and even people who TIG weld their own intakes have a very hard time achieving that.
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Old 04-09-2010, 02:26 PM   #5
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Moved out of the Top Swap thread in For Sale section. Steve
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Old 04-11-2010, 08:36 PM   #6
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Thanks for moving the thread Gunner

So all I would really do is grind down the heads and intake a little to achieve better flow? Or more flow?
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Old 04-13-2010, 02:42 AM   #7
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Check the thread I posted. I got some more detailed before and after pictures of the porting I just did. On the L27, you grind away materials to remove casting imperfections in order to improve airflow, and open up the exhaust ports a bit. The same goes for the intake.

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