L27 series 1 modding/ turbo? - GM Forum - Buick, Cadillac, Chev, Olds, GMC & Pontiac chat


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Old 03-15-2008, 11:45 AM   #1
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Default L27 series 1 modding/ turbo?

okay so i'm wondering if anybody makes any performance parts for an l27 at all, how i can squeeze around 300 horses out of it for the least amount of money, and if I install a turbo, what mods i'd have to do to the engine itself.
any help is appreciated. TIA.
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Old 03-15-2008, 11:54 AM   #2
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Start with an L67 bottom end to get the better pistons, rods, and wrist pins. Use your stock heads.

The rest is up to you. Nobody has bothered to try on the L27 yet, although a couple have the LN3 (previous non-Series 1 motor).
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Old 03-15-2008, 12:57 PM   #3
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If you are dead-set on using an L27, give it a THOUROUGH going-over before doing anything to it. As with any motor, helping it breathe and exhale better will go a pretty long way.

For forced induction, if you use L27 pistons, make sure you are run RICH...not pig rich mind you, but a few steps beyond stoich. L27 pistons do not like knock at all, and are much more prone to damage than L67 pistons (L27 pistons do not have the heat-dissapating coating on the crowns like the L67s do, and their compression ring is higher up, making chipping very easy). A richer mixture will help keep things cool, relatively speaking.
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Old 03-15-2008, 01:16 PM   #4
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Alot depends on how much boost you intend to run (and your transmission budget), but the best route by far is an L67 bottom end.

Compression on the L27 pistons is a major factor. Even if you only run 5ps of boost, it will raise your effective compression ratio from 8.5:1 to 11.4:1, and I doubt the L27 pistons are going to like that for very long.
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Old 03-15-2008, 02:06 PM   #5
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thanks for the help!
does anyone have any ideas on how much the bottom end of L67 would run? (pricewise)
and would i have to do anything with the valve train?
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Old 03-15-2008, 02:16 PM   #6
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Finding GOOD, used L67s (Series 1) are hard to come by. Best bet is to find one from a Buick, as those are better taken cared of, demographically speaking.

You can make an L27 into an L67 fairly easily. You can buy the rods and pistons new, and use the L27 block and crank.
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Old 03-15-2008, 02:30 PM   #7
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Thanks a lot everyone!
You know this is the only place i could find anywhere on the internet that actually had useful information about the L27.
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Old 03-15-2008, 02:51 PM   #8
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You want a 93 L27 to start with, or a 94/95 L67. Those were roller pivot rockers. 91-93 L67 and 91-92 L27 were not roller, and the 91/92 heads used different valvetrain bolt sizes.

If you don't have a 93/94 already, you need to go 94/95 to get the good heads and valvetrain.

Check your local wreckers for a motor.
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Old 03-15-2008, 02:55 PM   #9
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You will find this place is a cache of all kinds of info. Most of us on here share info instead of keeping it locked away. And some of us know the answers now because we found them when we mixed water and hot oil

Almost all the modifications done on this forum deal with the L67. There are a few of us though, that have tinkered with the L27. Here is what we know:

1) If properly cared for, they last a long time. They can also reliably make more power than they currently put out. Just how MUCH more power, we are still trying to figure out.

2) Only difference between the 27 and S1 L67 is in the rotating assembly...pistons, rods, and connecting pins. THATS IT.

3) There isn't much difference between the LN3 and the L27. Biggest mechanical difference is in the timing train design IIRC. There are a few other subtle changes, but for the most part, the LN3 and the L27 are near identical, longblock speaking.

FYI, I'm running an L27 core in my SSEi. Been like that for...15 months or so. I don't drive it regularly, so I can't say for any certainty how long it will last under constant use. I know what needed to be done to help ensure a longer life, but it is no guaranty. All I CAN say is that it starts up every time, and handles the boost I gave it. And it was done knowing full well it may not last long at all.
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Old 03-15-2008, 06:15 PM   #10
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Quote:
Originally Posted by willwren
You want a 93 L27 to start with, or a 94/95 L67. Those were roller pivot rockers. 91-93 L67 and 91-92 L27 were not roller, and the 91/92 heads used different valvetrain bolt sizes.

If you don't have a 93/94 already, you need to go 94/95 to get the good heads and valvetrain.

Check your local wreckers for a motor.
Would a turbo work with the 91 heads and valvetrain?
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