Edit - Decided on going stroker vs dry sleeved block. Title updated to reflect decision.

What's the more reliable bottom end set up for a daily driver 02 Z28? Not interested in a stock bottom end, either sleeves or stroker. I've done two strokers but even back in 2000 thought NineBall's ALL Bore sleeved set up was a lot cooler.

Budget allows doing dry sleeves or 4 inch stroke but not both. I think my ported heads are sufficient for up to ~388 to 400 CID with careful cam selection but they aren't sufficient for a 427 or 454. The engine will see about 8,000 miles a year, one trip to the drag strip. The car will see a lot of cold weather storage from November to March with temperatures as low as -20 F degrees. Not sure if cold is harder on a sleeved block than a normal LS block.

Other key parts are a Tony Mamo ported 102 Fast LSXR and a set of ported 243's set up for best mid lift flow. The heads have a 250cc intake runner and 2.04 intake valves. Peak flow was 303 cfm on a SF 1020, not that peak flow really matters. Chambers are 63.5 pc's.

Bottom end for the sleeved block would be stock LS1 crank, Gen IV rods & Wiseco or Mahle pistons

Bottom end for stroker would be 4 inch Callies Compstar crank, Callies Compstar rods & Wiseco pistons.

Cam & lifters TBD

4.125 bore Dry Sleeved LS2 or 4 inch stroke LS2?

Look forward to input thank you.

 

I would stick with the 4 inch stroke ls2 for reliability reasons.

 

Stay with the factory sleeves until they have to be replaced, and start with the 402ci stroker. The 2.04 intake valve is perfect for the 4.00" bore. And 250cc intake ports will love the extra stroke/cubes of the 402 vs the 388.

Set the pistons up for the highest compression you can afford/find fuel for, and get a custom spec'd cam set up for the entire combination as a whole.

 

No replacement for Displacement. You can do heads later. Reliability comes with parts chosen and the builder - assembly.

 

I say get the block with the bigger bore. hands down. build your 388 (which is an amazeballs engine). Later on, you want stroke, add stroke. Way easier than adding bore to your stroked LS2 block.

 

Dry sleeved 388 is the way to go. Especially if you're using your LS2 block. That's probably the best platform for a Darton Dry sleeve--has the bay-to-bay breathing, improved webbing, etc.

It'll make more power than the 402 with the right cam and with enough RPM. And when you want more power later, you can toss a 4" or 4.100" stroke in there and different heads and really make power.

And it's more reliable.

The 4" stroke in a stock sleeve (even with proper pistons) is not supported as well as a 3.622" stroke pistons in a stock sleeve.

But the Darton sleeve is 5.85" long... compared to 5.4" of the stock sleeve. The longer Darton sleeves are good for 4.100" stroke and are supported about as well as stock stroke pistons are in the stock sleeve, even at 4.100". So you'd be good for the future there.

Plus the Darton sleeve is stronger... so you get less cylinder distortion for better ring sealing and less blow-by. Which all aid in keeping the sleeve looking good for lots of miles.

 

Either way can be reliable, it's usually your choice of engine builder/machinist that will make or break the combo.

Personally, I think you would like the 402ci combo better since it's mostly a street car. The smaller bore is better for combustion efficiency, so you can make better torque and fuel efficiency with it versus a larger bore engine. If it were strictly a race engine and you have bigger heads, I'd probably lean more towards the 388, but that doesn't seem to fit your intended usage.

Also, Callies supposedly offers the Compstar cranks with 8 counterweights now, but you have to ask for it. It takes a little bit extra machining on the #3 bearing saddle, but nothing major. It's well worth it if you ever really plan to put some power/RPM to it.

 

I say go 4.000 crank no matter what. It'll have great power but oil control as well. I think guys forget Chevy did build a factory 4.000 crankshaft motor.... the LS7. So i think the length of the cylinder matters but its overly talked about or people he over thinking the scenario.

 

I appreciate the input everyone. Lot of excellence points have been made.

For sleeves RED would be the ideal candidate but I'd still need to find an engine builder for the big bore 388. BES can do the sleeves, engine build. within driving distance, and have an excellent reputation locally with road racers. I would probably go with BES to keep it all with one vendor. Plus I can drop off the parts and pick up the engine from BES myself saving shipping. BES would be my top choice at this point for the 388 or 402.

Other candidates would be TSP & TMS also do sleeved blocks and have good reputations but I don't know (face to face) anyone with one of their sleeved blocks. They are too far away to drive to drop off and pick up.

Open to other thoughts on potential builders too.

Regarding combustion efficiency, with 93 octane gas what's the max street friendly compression for a 4.125 bore LS?

Can one still go 11.8 to 12 to 1 with the 4.125 bore?

Or does that need to drop to more like 11.5 to 11.8 to 1 as the safe sweet spot?

 

compression and cam timing to bleed off cylinder pressure go hand and hand. also wait & do a 4 in stroke, hi rpm street engine ..no go. BES is a 1 stop shop ....spoken with Tony on a few occasions.

 

93 octane you can push to about 12.3. That's where I run mine

 

Give Kyle from Thompson Motorsports a ring. He's got both options available and will guide you in the right direction. Great prices too!

 

I Love Big Bore Engines like you know who loves Cylinder Heads.
That said I agree with Scott/Chevelle that the 4.00" stroke is the way to go,
both for your intended application and head/intake combo.
The smaller piston area also has less detonation/octane sensitivity, I can't say
for certain but would guess between .25-.50 more compression.

Since I do not know the CSA of your heads I can only go by the volume 250 cc
and the flow #s (300) given. That sounds like a lazy port when the old school
AFR 205 would flow 300 also. Your MMS Fast 102 deserves better IMO.
MMS 235s,TFS235s,AFR230s,PRC235s, even Tony's "budget" 223 Sportsmen which flow
310+CFM and would be kick a.. on a 402", and would handle a larger cam
without reversion, something like ~235/243 .620"/.600", LSA or Valve Events
between you and your cam guru based on goals and requirements.

I if lived close enough to have Tony Bishoff @ BES build my Engine that's what I would do also.
The 388" Big Bore needs a 7000-7500 RPM Peak and a 7500-8000 RPM shift point to show its
capabilities like BigHammer's Engine.
Anyway those are just my opinions.
I appreciate the Flow Data and the other info/experience you bring to this forum.
Good Luck

 

My vote is for big bore. I'm kicking around a similar build in my head right now and have an LS2 block, as well. I have looked at every variation of head on the market and it basically all boils down to bore size being the limitation. Jake said it best, IMO. You can run the 243's for now and if you want more, you have no limitations later other than runner size/CSA. Makes more sense the more you think about it.

 

The fuel economy thing is real. But let's face it... you're not going to have the most economical car with either motor.

And a 250cc runner cathedral port will support RPM a bit with the right intake.

A 4" stroke is always something you can add. Tho, a 388... or even a 400 (4.185" bore and 3.622" stroke) will make plenty of power.

Just look at 383s vs 346s. Or 408s vs 370s. Or 416s vs 376s. The power difference isn't really that much. You usually gain the cid in torque across the board up until about 5500. And then the bore becomes more of a restriction. And you'll have enough torque for a street car with any of those motors.

 

These are excellent well reasoned statements

The Big Bore 388's/ALL Bore as we used to call them back in 2001, have always fascinated me.

Jake's 4.185 bore & 3.62 stroke would make one hell of a 400, I really like that idea. My 72 vette has a SBC Dart SHP 400 that's a 4.125 bore x 3.75 stroke that's really fun, revs great & runs well.

Here's what my mid lift 243 GMPP's flow on 4 inch bore. I'm guessing they'd pick up 5 to 10 cfm on 4.125 + bore. Bench was a tight reading SF1020. I don't know the CSA but that 2.04 intake is probably the biggest restriction with my heads. An LS3 sized valve would be closer to the ideal 52% of bore.

With Mamo LSXR and the fat 250 cc runner maybe they would work pretty well on a BES 4.185 x 3.62 ALL Bore, depending on how much the pistons are out of the hole and head gasket choice 11.8 to 12.2 compression should be do able.




I agree there are better heads possible at set of Mamo worked AFR's or Land Speed BR7's would definitely rock but that would have to be much later on.

Other details of build will be RPM Transmission Level 6 4L60e and probably a Yank 3600SS or higher. Still have to get that and have installed.

Weak point 10-bolt with 3.73's for now. Speed Engineering 1 7/8 headers with dual electric cut outs, Kook's Y pipe, SLP Dual/Dual. Have this stuff in garage and plan to use it.

 

I think this is the dilemma, Readers Digest version-
You wanna REALLY rev it? Big bore, stock stroke.
Stupendous torque? Stroke it! Plus whichever bore works out.
My .02....

 

I can tell u the avg CSA by as posted the normal port center-line. What”s he’s talk?

 

Just tell me how much U want? You got the budget! Darth designs your cam Done!

The intake Situation F< us on low profile hoods & Hp.. i luv TI...dime trap.
LiVe From...Sav. GA

 

99 they change threads....on that 1!
No matter what i got your CSA..even if you try to mill the intake flange for a Lower CC runner...
Funny cid x rpm x mcsa + Comp ...don't Hinder the Big BOOM ...air & fuel...we luv.

2. Simple