N/A heads.

[Turbo6Smackdown]

Ok. First question. Will L32 L36, and L26 heads bolt onto an L67? And I heard that the L32 and L36 heads flow more. Is this true?
And, how different mechanically, are all the heads above, from the L67 heads. I want to know because, I'm going to get a class on how to disassemble, inspect, and reassemble an NA, series 2 head, and I just want to ensure they're close to my L67 head. Otherwise, if they're too different, I'm going to forgo the class. Unless of course, this head will A. bolt onto an L67, and B. flow more, in which case I'm going to procure a set of my own.

And last question. Which of these non L67 heads, gives you more compression, when you bolt them on? And how does it do that?

 

[DoubleD]

ok, so first off, yes all the heads will bolt up to an L67, but no they will not work with a supercharged motor. the experience will still be good though because all the Series 2 heads are essentially the same.

The naturally aspirated heads, L36 (older) and L26 (newer) have NO injector holes in the heads themselves and cannot be used on a supercharged car. the only way these flow the tiniest bit more is the fact that there is no casting region in the flow path where the injector would normally protrude into the air stream. valve covers are also slightly different in these because of the lack of injector bungs.

L67 heads and L32 heads are for supercharged motors with the injector ports in the heads. The L32 heads came with a very slightly larger intake valve stock. other than that they are mechanically the same. this also applies to the L36 and L26 heads. all are essentially the same parts and same castings.

The heads have no effect on compression ratio, no matter the engine. The compression differences come from a small difference in rods and mainly in the depth of the dish of the piston.

Taking the class on disassembly may not be necessary... the rockers are bolted on with like 4 bolts, and you'll be using some form of spring compressor to compress the springs, remove the keepers and remove them. inspecting could be helpful in finding the places prone to cracking between the valves. Also, see if you can find the places to improve the heads if you were to port them the short side radius and valve throat can be cleaned up for some quick gains, as well as unshrouding the valves in the combustion chambers.

Anyway I hope that I answered your questions. post more up if you wanna know more.

 

[Turbo6Smackdown]

Totally, thank you! Some other questions. When did L36, become L26, and when did L67 become L32. Do you have the years on these? Am I assuming L36 was series 1, and L26 series 2? Which head is which series?

So besides the spark plug holes, if I get a block of instruction, on how to rebuild an L36 head, I'd be proficient on an L67 head in your opinion? It sounds like I will.
And, I've had quite a few people tell me that the NA heads, bolted onto an L67 SC short block, will increase the compression. Honestly, I'd go about it another way, but I was just here trying to confirm or deny some of the current rumours.

 

[DoubleD]

around 2004 they went to the series 3 engine with the advent of the L26 and L32 heads. the series 2 heads are the L36 and L67 heads.

the spark plug holes are all the same I'm guessing you meant the fuel injector holes.

those people are wrong, sorry to say. they would also have a nice little shocker when they had no place to put the fuel injectors. that's a pretty important part. The only way to bump compression with regards to the heads is to run a thinner head gasket, or run an L36/L26 bottom end with L67/L32 heads on it.

Yes, after taking a course on rebuilding the L36 heads you would be just as good as an L67 head. It is quite simple mind you. but learning other things similar to what a machine shop would look for would be good things to use from the course.

 

[Turbo6Smackdown]

Fuel injector, sorry lol. (was sitting in front of the computer, doing online courses homework for 6 straight hours. Kinda burnt)
And yea, I would imagine the thinner headgasket the better for compression.
So, are the connecting rods in the supercharged shortblocks stronger in anyway, than the NA rods? The SC pistons are dished, correct?

 

[murphinator]

the pistons on sc cars are lower compression (8.5) , coated , and have thicker ringlands , the pistons on NA are higher compression ( 9.5) not coated and have thinner ringlands and are more prone to chipping under detonation ... but it you dont detonate them they can take plenty since zzp ran a NA shortblock in their 8.6 @159 car

as stated above 2004 was the phase in for series 3 allthough for sc engines only gtp's got the L32's with gen 5 blower while regal gs ,ssei ,ultra, monte ss ,impala ss continued with the series 2 L67

wiki is actually a pretty good source for 3800 specs & history , google 3800 wiki and you will see a lot of the specs and the timelines for when the changes took place.

 

[Turbo6Smackdown]

Cool, thanx murph. I was hoping you'd add some. I have checked it out on wikipedia, but they don't know all the technical aspects. The little stuff like no fuel injector holes, or thinner ring lands. cool.
So keep the stock rods and pistons, port, mill, & valve job the L67 heads, and call it a day?
What will a touch higher compression do, on a SC application? Is it ok? I heard it is, I'm just running it by you, to see if I can pick up any more tips.

 

[murphinator]

higher compression works good provided you dont try to go higher compression and more boost without running much better fuel.

top swaps run the 9.5 to 1 na compression with the L67 boosting it , typically you see a larger pulley by a couple sizes than if you ran stock compression. running 9.5 to 1 with sc pistons gives you the beefier ring lands and the coating but I have read several times not to deck the head or block much on l67's so you would primarily raise it with thinner head gaskets combined with slight machining unless you are buying pistons

 

[bigdwg03]

did that zzp car run the series III pm rods? how much more power do you think the stock short block with a good set of forged pistons will take? I heard those guys are making 850+

 

[Turbo6Smackdown]

So which is better, higher compression or more boost? I'm guessing more boost. I should probably leave the compression alone.

 

[murphinator]

did that zzp car run the series III pm rods? how much more power do you think the stock short block with a good set of forged pistons will take? I heard those guys are making 850+

most of the quickest cars run stock short blocks other than cam & chain - they are built to very tight tolerances by gm , this is why the 3800 series 2 & 3 were on wards top ten engines of all time

many of the builds with aftermarket parts come apart quickly. Yes zzp made 850 ish on a stock NA L26 (series 3) block ,crank ,pistons ,rods ,is my understanding

 

[murphinator]

So which is better, higher compression or more boost? I'm guessing more boost. I should probably leave the compression alone.

with an M90 and no IC compression would be better since more boost with an m90 means more heat and in turn less agressive timing to avoid detonation.

probably boost over comp on a turbo conversion or an IC car but I only have experience with a non IC'ed M90 since my budget is small

 

[Turbo6Smackdown]

I see...