Corona

Guys who do crazy stuff like this have a few things in common

Free parts
Don't care cause it's more race driven..Fill the block
Build it as a test to see knowing there maybe another engine needed while some drive for many miles.

I ask what gain will be seen from the stock bore of .060 to .070 to the bore size Wanted at? A example of a 4.0030 bore Vs a 4.080 bore size would net around let's say 10 hp.

.080 + 10hp
.09​​​​0 + 13 to 15hp
.100 +20hp

25 to 50+ fwhp over
.125 to 4.185 bore

Quick trick is Ole math

add a little stroke to Make up any differences 4.080 to 4.125 crank with a .070 bore will make hp. Horsepower = Torque x RPM / 5,252.

a Spare gen4 LQ4 block block that would like sonic testing with a larger CCW 4.125 crank... that's a rubbish idea @ this point. But a good idea using 6.00 rods for a better piston pin. The truth is no matter what sonic testing is needed

Set a realistic goal on hp and rpm band no need to Max out Anything.

Corona

https://sdparts.com/i-24498593-genui...rankshaft.html

3.860 stroke
6.250 rod
1.050 piston pin height aka* 4.065 to .075 bore pistons for a 4.125 crank


Equals to having a 0 deck height at 9.230


Ask me how do I know this? what I do for fun. The pistons came from me looking over a 4.125 crank using a 4.065 to .075 over bore.



Idk about the K1 4.125 crank for $800 smakers. Lol.

compression would Stay the same @ (11.5 to 13.2) depending on which manufacturer used for pistons for a .060 to .075 bore and 4.125 crank.

JE has a few also Mahle, Carrillo, Weisco, Diamond

Trust me I've spec'ed a 426 to 424 CID sb all using a 4.125 crank looking for the perfect compression for pump gas. Quick build idea bored.

99 Black Bird T/A

iTrader: (4)

Sounds about right That's pretty insane with .080 on an LS3. Appreciate the info.

I like to crunch numbers for various bore & stroke combinations as well. Way cheaper to build them on paper I collected oo many spare parts over the years: my old LS1 engine, a LS6 block, a LS2 block & an ERL sleeved 5.3 block etc. It would make my day if that LS6 sonic checked it could go 4 inch.

Mavn

iTrader: (3)

I want to do a 4.100 x 4.125 ls3 block with a set of ls7 heads. Maybe one day when I'm not broke 🥵

Utinator

My dad had a 400 SBC in his Gen-2 Camaro when he was racing dirt tracks. I always thought it would be cool to have one in my Camaro, but I like fuel injection and aluminum blocks too much. lol. I like the idea of having a non-stock LS displacement size with an LS motor. For example, I found ways to make a 392 cid (Hemi), 396 cid (BBC), and even a 302 cid (SBF) with after-market parts. If an LS2 can be bored more than .030" over, then I think a 400 cid (SBC) is possible. Of course, there are more options when you re-sleeve, but these sizes are achievable without re-sleeving.


Ok, here's a serious question for the masses: If you have a V-8 engine with a 4.040" bore, and a 3.9" stroke, what cid would you call it?

99 Black Bird T/A

iTrader: (4)

Honestly NA, I'd call it a mistake for not using a 4 inch crank

At ~399 cubic inches, I'd call it either 396, 6.6 litre for Pontiac folks or 400

Corona

don't max out the bore for rebuild or maintenance...
the 15 hp isn't worth it. Put a S/R on your 408 and you could have 8 sec hp. Cam specific. You have more compression than Flyin but 8 cubic inches small = about the same hp Cam specific.

Corona

won't happen as 5.3 is iron and generally is Thicker and can be bored bigger than the typical Ls6 sleeve.
I think I'd need to check before a 100% been a while since I've looked over

RedXray

You left out the 401 AMC guys 4.165 bore X 3.860 stroke

99 Black Bird T/A

iTrader: (4)

Your right ✅

That worked out very close to the AMC 401's actually specs. A++

I wish all LS blocks could be used to build an AMC style Bore: 4.195 in.Stroke: 3.680 in that would ne a hell of a big bore engine.

Legacy of owning a worthless 77 AMC Hornet as first car. I keep trying to forget AMC.

Utinator

Yeah, I knew someone would say that. Lol. I know there's no replacement for displacement, but who else has a 400cid LS motor? I would do it just to be different. Yes, it technically calculates to 399.95 cid. I would still call it a 400 though. The 396 would be a 4.020 bore. I wouldn't call the 4.040 bore a 396.

I see plenty of 408s making over 600hp. I'd be happy with the 400 if it was making right at 600 at the crank. I think this is possible.

99 Black Bird T/A

iTrader: (4)

The 400 making 600hp fly wheel should be do able.. Say ~500 whp to ~535 whp that's pretty sweet in my opinion.

Just teasing with my crank crank comment wink.

Mavn

iTrader: (3)

Engine dyno numbers are all that matter now a days anyway 🥴

Utinator

Well, I can't change my drive train. It's going to rob "x" amount of power from any engine I have. All I can do is maximize the flywheel hp, and hope for the best at the wheel. I'm not really chasing a HP goal anyway. I just like to set reasonable expectations for what it is. In this case, I think 600 fwhp from a 400 cid is reasonable. If I had a "race car", I would do things differently. Since this is a car that I occasionally use to get groceries in, I need to keep it mostly stock looking.

I'm not trying to be the fastest car at the track or on the streets. I know that goal is futile. I just want something that is fun to drive, but still daily drive-able. Besides, anything over 500 Whp is mostly unusable on the streets. Hell, I can barely keep traction on these SA streets as it is.

Utinator

No problem. I understand. The 4" crank is more logical, since it costs the same. I just like the cid options that you get with the 3.9" crank.

I have the 4L80 and full accessories, so I was thinking more like 480-500 at the wheel. That would be plenty for me.

RedXray

Oh man I feel you're pain haha

My first car was a 1969 AMX 390CID 4spd with the rare "Big Bad Blue" color.
In high school (1974) I was hated by the rich kids that owned new Camaros and Corvettes

G Atsma

I can't remember who did AMC's styling those years, but they sure knocked it out of the park! I even liked the Hornets from then.

TKG

Im in the process of rebuilding my 6.0 in my Trailblazer and it needs to go .035 (.040) over. You just gave me hope.

LS1Formulation

iTrader: (13)

Sonic test and check for core shift. Not every block will be able to withstand that much of an overbore.