jfairladyz

Well I put some time into those online calculators and came up with a low cost alternative to the 3.1 stroker.

Option 1:
L28 block
L28 Crank (no, not the diesel. Your stock crank)
L24 Rods (or atleast the same length if you go aftermarket)
88mm pistons (the LZ22S has the correct pin height for this setup but are only 87 mm. You'll need aftermarket 88mm versions of these pistons)
This will give you 2.9liters. This doesnt sound like much of an improvement but thats because displacement wasnt the main goal here. Heres the benefit of this set up. The rod angle will now be signifigantly lower than that of the stock setup or when using the standard 3.1 components. This will signifigantly raise the RPM potential of your engine. The rod angle of this setup is lower than some higher revving engines like the RB26

Your other alternative is to source some pistons with an 89mm bore but the same pin height and you'll get 3 liters out of your L28 plus you get the great rod angle. I cant verify compression ratio cause for one there are different headgaskets that can be used and the different calculators I used gave me different compression ratios for identicle set ups. As far as I can tell the biggest expense, other than machining would be the pistons (they'd have to be aftermarket). But if you cant source an LD28 crank used in good condition then the cost of pistons is most likely going to be less than the cost of a new crank. You also get to keep the lighter L28 crank which means less maching needs to be done. And with 88mm bores you get to keep a little meat on those cylinders.

It's a win win situation. Now I'll try to source some 88mm pistons with the correct pin height.

CanyonCarver

the only way to increase stroke is to increase the distance from the crank main journals to the crank rod journals. :-)

Bleach

so this is not a stroker, its just a larger displacement engine by means of an overbore. The rod angle change is good though.

Did you calculate the deck height of these pistons or are we just to buy aftermarket pistons that have zero deck height?

jfairladyz

Yeah technically speaking it's not a "stroker" but it does increase the displacement. Not by much, but like I said thats just an after effect. What I was going for was rod angle and rod to stroke ratio.

With those pistons the deck height is spot on. The pistons sit just under a half millimeter below the deck. And with a 1mm gasket it puts compression and a very turbo friendly 7.5:1. So you get a higher revving boostable engine. If you use the earlier heads (this was calculated with a P series head) then the C/R goes up. The reason I got into this was because finding a used diesel crank is getting pretty difficult. There are other pistons that can be used (I dont remember off hand) that are a bigger bore. But with these you keep the bore to a minimum. Even with the stock 87mm pistons mentioned in the original post you get a bump in compression, but the main thing is the L24 rods. This combo would be much easier on the engine then even the stock setup, hence the ability to rev even higher without putting the internals in danger. You'd need to upgrade the fuel system to keep up with the higher revs but you'd need to do that with a stroker anyways. L24 rods can be had for cheap and using the LZ22S (not E) pistons is cheap as well.

Bleach

If I had the time and money, I would love to build an NA high revving engine like you desribed. I just love how my L18 sounds at 6K rpm with the Weber carb... an L29 would be even better at 8K

SHADY280

Your Deck Height Will Depend On The Block You Use Though. Early Blocks Will Produce A Much Higher Comp Ratio And Even Stick The Piston Out Of The Hole Like My Engine

jfairladyz

As long as you use an L28 block then that combo is spot on. Either of the L28's will work just the same. The heads do make a difference though. The P79 (and P90) is something like 10cc's bigger than the previous heads. So the I should've specified: With that combo and the P series head (any of them) you'll get a boostable compression ratio. If you use the earlier heads then you end up with a higher C/R. You can also get the pistons with what ever design you want too to affect compression ratio and then theres head gaskets. But neither of the L28 blocks will have the piston sticking out above the deck. It actually falls short of the deck just slightly (you can run more lift for the higher RPM's you'll get )

Bleach

I thought there were only two different height of blocks.

short block: L16, L18, L20(a), L24, L26, L28

tall block: L20b

jfairladyz

I wasn't sure about the rest of them but I knew both L28's were the same

SHADY280

I Have An N42/ N47 Block In Mine, Thats The Short One, Or Its Where The Crank Is Placed In It, My Other Car Is The Tall P79/p90, It Makes A Huge Diff. It May Be Where The Crank Is, Because I Bought Overbore Stock Flat Tops For An 82 And The Stick Out Of My Block, The 82 I Have They Dont Stick Out. I Think We Need More Decisive Research.

jfairladyz

That block might have been shaved at some point then or its possible that the pin height on the pistons is incorrect (compared to stock). All the L28's are identical. You dont have a diesel crank in there do you? Or different rods? Deck height is identical on both engines (and the L24 and L26). All the internals between those two L28's are interchangable. The cranks are the same, the rods are the same. The pistons are the only difference. This is according to every source I've ever seen. I've never once heard a reference to there being a difference between those two engines (atleast not the way you explain).

I should also point out that I've never actually tried swapping pistons between the two block either though. So maybe you're right and there is a difference. I just can't believe that in all this time I've never heard that til now.

Dorifto

You're giving me evil ideas, J. Sounds like a feasible plan. I may have to try this on my L28 soon. Good research.

SHADY280

Ive Built 4 L28 Engines And Found This Out The Hard Way. The F54 Block With Flat Tops Is The Best, They Sit Just Below Deck Height Stock. The N47 With Dished Pistons Also Sit Flush But Pin Height Is Diff. Now Do What I Did Before I Found Out. N47 Block, Stock Crank, Stock Rods, Aftermarket Pistons (flat Top) .030 Over. And Then A 1mm Gasket, P79 Head Decked .080 Thou,then Cumbustion Chamber Relieved .025" To Make The Golden .050" Piston To Head Clearance. That Equals 11.7:1 Comp Ratio. Try Running That On The Street. I Had To Run -5 Deg. Timing On 94 Octane Gas. Now I Put In A 2mm Head Gasket On Lowered My Comp. Ratio To 10.7:1. 92 Octane Gas. My Friend In A Local Z Club Did The Same Thing, Not Knowing The Diff. 3 Years Before Me, Then Never Told Me Or Anyone Else. Hope That Didnt Come Across As An A$$ho.

jfairladyz

No you didnt come across as an A$$hole. I just find that interesting. I had no idea. How far above did it stick out? Like I said that combo puts it below the deck on a F54 so depenging on how far they stick above on the N42 block will determine whether it's feasible or not. Of course the compression ratio on the F54 block with the P79 head with that combo makes the engine very friendly with boost. With the eariler head then you're looking at a higher C/R obviously.

I'll tell you what does make you an A$$hole though: Having 94 octane (or even 92) gas We get a miller light like 91 at best

Lost Vegaz

I thought only the west coast got stuck with the 91, while everyone got the 92 or higher prenimun.

jfairladyz

Nope, we've got 91 out here in VA too (atleast in my area). I remember back when 93 was the norm. Ah, the good ol days

Dorifto

J, that makes us sound so old ... We only get pisswater 91 here in Utah, but in redemption to the valley I live in, they offer 115-unleaded, C16, and JP4 at the pump just a few minutes North of me. -Dave-O

NismoPick

Indeed! Everyone in SLC goes South to fill up before they race.

SHADY280

The Pistons Stick Out .020". Dont Forget This Is Canada Where All Cars Make More Power. Like My Sig Says, Colder Air. We Get It From Chevron, And Sometimes Petrocanada, I Can Just Go To My Local 76 Fuel Guy And Get Any Race Fuel I Want Too. Or If You Want, Just Use Zylene As Octane Booster. My Friend Runs 13:1 On The Street That Way.