L27 under LN3 Induction
09-01-2005, 08:50 PM
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L27 under LN3 Induction
New member here with my first post/question. The LN3 in my '90 SSE died at 197k miles - developed low oil pressure, never figured that out, wasn't making any noises so kept driving it, day before I intended to get back to it again developed a knock suddenly and quit.
Anyway, water under the bridge.
Found a low mileage '91 Park Avenue engine/transmission on eBay, got it to my house for under $400, discovered the '91 Park Avenue didn't use the same "3800" as my '90 SSE. My research so far has determined that the L27 (assume that'* the proper designation for it, VIN L) has extra ports at the end of each head/intake manifold, for what I assume is the integral PCV. I'm thinking I can block off those ports in the heads and put the induction system from the '90 SSE on that engine. Everything else about the engine appears to be the same, or at least compatible, with the older engine.
Since the L27 doesn't use EGR and has different fuel line connections than the LN3, I figured this would be an easier route than trying to put the L27 in the '90 SSE as-is.
Any thoughts/advice?
Thanks.
Anyway, water under the bridge.
Found a low mileage '91 Park Avenue engine/transmission on eBay, got it to my house for under $400, discovered the '91 Park Avenue didn't use the same "3800" as my '90 SSE. My research so far has determined that the L27 (assume that'* the proper designation for it, VIN L) has extra ports at the end of each head/intake manifold, for what I assume is the integral PCV. I'm thinking I can block off those ports in the heads and put the induction system from the '90 SSE on that engine. Everything else about the engine appears to be the same, or at least compatible, with the older engine.
Since the L27 doesn't use EGR and has different fuel line connections than the LN3, I figured this would be an easier route than trying to put the L27 in the '90 SSE as-is.
Any thoughts/advice?
Thanks.
09-02-2005, 12:07 PM
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I have thought about this a lot lately...
And in the past we have actually used a C engine in place of an L engine... We swapped out the heads from the L engine to the C block... <---- This may be one option for you...
Now onto the L heads, yes thats the PCV system... You may be able to have the PCV ports plugged, and use you C intake setup on the L engine... The exahust manifolds and accessories should bolt right up... I'm thinking that you compressor will bolt to the L compressor bracket if you still have it...
You may want to get a set of intake gaskets and see where the PCV holes are in relation to the gaskets... I have the feeling that the PCV passages can be plugged..
Other than the PCV passages the heads are the same..
One thing you may need to worry about tho, is the Torque axis mount, I forget weather there are 1 or 2 extra holes in the block for the Torque axis mount... we have a member that put a series II SC in his 90 Bonneville and was able to use the Torque axis mount after cheasing or cleaning the threads... He found that everything was there for that mount...
So you may have a few things to look into, But I think you will be able to make it all work..
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And in the past we have actually used a C engine in place of an L engine... We swapped out the heads from the L engine to the C block... <---- This may be one option for you...
Now onto the L heads, yes thats the PCV system... You may be able to have the PCV ports plugged, and use you C intake setup on the L engine... The exahust manifolds and accessories should bolt right up... I'm thinking that you compressor will bolt to the L compressor bracket if you still have it...
You may want to get a set of intake gaskets and see where the PCV holes are in relation to the gaskets... I have the feeling that the PCV passages can be plugged..
Other than the PCV passages the heads are the same..
One thing you may need to worry about tho, is the Torque axis mount, I forget weather there are 1 or 2 extra holes in the block for the Torque axis mount... we have a member that put a series II SC in his 90 Bonneville and was able to use the Torque axis mount after cheasing or cleaning the threads... He found that everything was there for that mount...
So you may have a few things to look into, But I think you will be able to make it all work..
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09-02-2005, 12:53 PM
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I'm not the member..but was there for the doing. If you look under the coolant bottle you will probably see threaded holes in the body. That is the torque axis mount holes. Hmm off to my photobucket acct. Please stand by
Looking just right of the battery tray you can see the 4 bolts that would hold the torque axis mount
Can only find that pic at the moment. However as Jr said..the holes are probably there and it all lines up perfectly... uh...as long as the motor mounts are the same for the subframe. We changed the subframe.
Looking just right of the battery tray you can see the 4 bolts that would hold the torque axis mount
Can only find that pic at the moment. However as Jr said..the holes are probably there and it all lines up perfectly... uh...as long as the motor mounts are the same for the subframe. We changed the subframe.
09-02-2005, 11:23 PM
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I was assuming all of the mounts from the C engine would transfer over the the L engine block/heads, but I'll have to admit I haven't looked it over that carefully yet.
I do have all of the L accessories and brackets, so if needed, they are available. However the torque axis engine side bracket is all that is there, the part to the frame is not. Hopefully the C engine stuff will transfer over.
I was discussing this yesterday with a co-worker who is completely unfamiliar with GM FWD, and he suggested using expansion plugs to block the L PCV head ports. I have the C engine intake gasket set, but haven't opened them up yet. I looked up the head gaskets for the L & C engine on-line, and they had different sized coolant passages. Not sure how much difference that would make. IIRC, the C'* were larger than the L'*.
I've been out at the track racing the '57 all day today, will be back Saturday all day. The next step is to clean off the L engine (probably Sunday afternoon), then get the intake off and take a look. After that, start removing the C engine from the SSE.
Thanks for the help. I'll let you know how it turns out.
I do have all of the L accessories and brackets, so if needed, they are available. However the torque axis engine side bracket is all that is there, the part to the frame is not. Hopefully the C engine stuff will transfer over.
I was discussing this yesterday with a co-worker who is completely unfamiliar with GM FWD, and he suggested using expansion plugs to block the L PCV head ports. I have the C engine intake gasket set, but haven't opened them up yet. I looked up the head gaskets for the L & C engine on-line, and they had different sized coolant passages. Not sure how much difference that would make. IIRC, the C'* were larger than the L'*.
I've been out at the track racing the '57 all day today, will be back Saturday all day. The next step is to clean off the L engine (probably Sunday afternoon), then get the intake off and take a look. After that, start removing the C engine from the SSE.
Thanks for the help. I'll let you know how it turns out.
09-03-2005, 11:30 AM
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Please take pics of the ports if you can, and the diffrences between the heads... I think it will be a great experience for everyone.. 
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09-03-2005, 11:53 AM
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Just out of curiosity here. If putting the L induction system on the C engine, would that yield any performance increases? Since the 92+ intake is not just an open log, but separate runners and whatnot... does that help with laminar flow or more even flow, etc..?
09-03-2005, 12:06 PM
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Larger throttle body and tuned runners for better flow... Most of the reason that the L27 is more peppy than the LN3
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09-03-2005, 10:33 PM
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I've seen numbers of 5 more HP and 10 more ft-lbs torque. I was wondering if that was all the intake or if the cam was a player there as well.
Also saw the L got 22 lb/hr injectors and the C has 19.
Also saw the L got 22 lb/hr injectors and the C has 19.
09-04-2005, 12:10 PM
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Originally Posted by five7kid
I've seen numbers of 5 more HP and 10 more ft-lbs torque. I was wondering if that was all the intake or if the cam was a player there as well.
Also saw the L got 22 lb/hr injectors and the C has 19.
Also saw the L got 22 lb/hr injectors and the C has 19.
I have seen some odd ratings, But the C engine is 165 Hp @ 4400 and 220 Ft Lbs @ 2800...
The L engine is 170 Hp @4800 and 225 ft lbs @3200...
I have seen ratings at 210 Ft lbs at 2000 rpms... I even have a Pontiac Roadcars book that shows 210 ft lbs @ 2000 rpms and 165 HP @ 5200 Rpms.. Some I'm lost as to why the info is so fuzzy... And 5200 on a C engine is redline..
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09-04-2005, 03:31 PM
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Our '91 has always been peppier than the '90, or the '89 we had before that, while still getting better mileage. I've always wondered about that.
Perhaps this will pep up the '90.
Perhaps this will pep up the '90.