Help me Armchair build a 'Goldilocks' 4.8L LS engine...

This thread has delivered, thanks everyone! 

It is an iron block 4.8, whatever engine code that is.  Sorry for any confusion. 

I do love the idea of a high-revving, small displacement v8, but also dont want to always have to be north of 5000rpm to make power.  Since the motor is apart, I plan to do LS2 timing chain/gears, and replace the valvetrain regardless, since it's a 'while you're in there' insurance policy for me.  

What I think* is my best path forward, given all of your input, is-

Stock heads with minor/mild porting

LS6 intake (need the clearance)

Ls3/LS7 springs/rockers/pushrods

A cam that'll get me the rest of the way, with a nice flat powerband from something like 3-7k... 7200ish redline. 

Custom intake and exhaust (It's a swap, so sort of necessary anyway)

Professional tuning

That sound reasonable for 350ish whp?   Please nitpick away too, you all are awesome and I really sincerely appreciate your input. Thanks again! 

In reply to golfduke :

On the camshaft shoot for something in the 224 @ .050" range.  This should get you the power you're looking for but keep in mind if you're wanting to use stock LS7 springs you need to keep it under about .550" lift.  Texas Speed has some "low lift" cams that you can look at.

I think you're on the right track. I did a budget built, mildly hot rodded gen III in my truck, here's the quick rundown on that:

LM7 5.3 block, unknown miles - $350

Did a dingle ball hone job, re-ring, new gaskets, oil pump, timing chain, etc. - $??

Junkyard 243 heads milled 0.030", thinner MLS gaskets, should be ~10.5:1 compression - $50 for the heads, $200-ish for the machine work

SUM-8719 cam kit, IIRC 209/217 0.550" lift 112LSA, LS6 valve springs, retainers, etc. - ~$400

Pushrods - $50

Junkyard "NNBS" intake, fuel rail, 30lb/hr injectors - $25

WARR 92mm throttle body (needed for four bolt intake) - $150

Stock F Body manifolds, dual 2.5" x-pipe exhaust 

Stock converter, 3.42 rear

For ~$1500 all in, it's way better than half as good as an LS3 for less than half the price, if you can deal with the weight of the iron block and height of the truck manifold. Essentially a gen IV 5.3 in terms of heads, intake, and compression, it just achieves that via milling the heads instead of flat top pistons. Super mild mannered in normal driving, idle-3500 or so, then it rips from there up to redline. Really that's where the cam, intake, and heads are all going to gain power. Even in a 4500 lb truck, though, it scoots along nicely without giving up anything on the bottom end. Haven't had it on a dyno (yet), but I'd guestimate low 300s at the wheels through the 4l80. The manifolds are probably holding it back quite a bit. 

For play car, I'd definitely go a fair bit more aggressive on the cam, something very close to what Patientzero recommends. Even my truck I probably wouldn't hate something maybe one step more aggressive. 

I have zero actual knowledge but when I googled up a few things in this thread came up with this: https://www.cpgnation.com/fast-vs-dorman-intake-test/

Not apples-apples, but interesting test on a mostly stock 5.3. I don't think any configuration will feel gutless under 5k. At 3k it looks like there's already more HP and tq than the original 325 wagon :-)

I think that test was on a 5.3. A decent rule of thumb is all else being equal a 4.8 will need a few hundred more RPMs for peak. A 4.8 can definitely feel soggy down low with too big a cam (sometimes thats something thats considered mild in a 5.3 or 5.7), it may make more power than the old 325 but the 325 uses a steeper first gear than a 4l60e.

How are you planning on integrating the electronics?  I looked into the e46 is swaps some years ago & it seamed that other than mounts you were on your own.  That may have changed by now, but if you are planning on keeping the factory gauge cluster having a 58x crank wheel may help.  I think they showed up in the gen IV ls engines, there are work arounds but if you have to go into the bottom end you may want to add stroke & compression at the same time.

Caperix said:

How are you planning on integrating the electronics?  I looked into the e46 is swaps some years ago & it seamed that other than mounts you were on your own.  That may have changed by now, but if you are planning on keeping the factory gauge cluster having a 58x crank wheel may help.  I think they showed up in the gen IV ls engines, there are work arounds but if you have to go into the bottom end you may want to add stroke & compression at the same time.

Yeah, things have changed.  Painless even makes a harness for the swap now, along with full DME integration instructions.  I HATE electronics, yet I'm not too fearful of the integration on this.  I've done a GM V8 swap into a 944 already once.  I know it's going to be different-but-similar in terms of complexity. 

So I finally got the engine on the stand and did the once over.  Bores all look great, but I'll replace bearings while it's open.  Heads are confirmed to be 706's.  I talked with a local who said a .030 grind would bump compression to appx 10.5:1, and allow me to use a milder cam for a broader powerband.  Being an ex-machinist myself, I have 'a guy' that'll do that for beer money basically, so I think I'm going to go that direction first.  Followed by TBD cam, Dorman intake, upgraded OEM valvetrain/chain, and requisite exhaust and tuning... and see where that gets me.  Hoping for the same specs-  300+whp, 7500 redline, almost as reliable as stock.

Does all of that make sense though??  I don't wanna bork the project up on the first step, haha. 

golfduke said:

  I don't wanna bork the project up on the first step, haha. 

 You already borked up by taking the LS apart, that lets the magic out. Getting it running with a known runner or even some junkyard special that's still in one piece and then swap in your built motor.

RacetruckRon said:

golfduke said:

  I don't wanna bork the project up on the first step, haha. 

 You already borked up by taking the LS apart, that lets the magic out. Getting it running with a known runner or even some junkyard special that's still in one piece and then swap in your built motor.

Haha.  It was 'purchased' in a state of partial disassembly.  It I mess this one up, I'll move onto your next suggestion, haha. 

What's it being installed in?

If it's small and light, build it to actually make 400 hp and enjoy a wild ride.

If it's big and heavy, build a 325 hp engine and enjoy the smooth power. 

TIL about the Dorman manifolds.

I bet they are as cheesy as the others they make, with no metal posts in the manifold bolt holes, and wood screws into plastic to hold the fuel rail in.

Looks like the Dorman intakes are nowhere to be found anymore, and jegs lists it as 480 dollars. At that price you may want to look elsewhere. In the past at 250 dollars they where pretty slick essentially being a fast lower with an ls6 upper.

For $480 i would get an LS6 manifold...

chaparral said:

What's it being installed in?

If it's small and light, build it to actually make 400 hp and enjoy a wild ride.

If it's big and heavy, build a 325 hp engine and enjoy the smooth power. 

It's an E46 wagon, so... in between? Haha.  This is not going to be a burly track queen, but more fun commuter/autocrosser/sparing HPDE fill-in.  I plan to actually even make this one look somewhat pretty, albeit by honing in on my (lack of) skills.  

honestly, I would try to keep it fairly stock, messing with those heads is kind of a waste of money. 

The truck intakes flow really really well for what they are, so if you can fit it under the stock hood, I wouldn't mess with it. 

For a camshaft, I'd look at Brian Tooleys (BTR) stuff, specifically the truck cams as they're made for the smaller displacement flavors of the LS and work really really well. If compression is what you're after, just put a thinner headgasket on it, that will make up for most of what you'd have in the heads for a fraction of the cost. 

Brians stuff and prices right now are hard to beat

Cheeks said:

honestly, I would try to keep it fairly stock, messing with those heads is kind of a waste of money. 

The truck intakes flow really really well for what they are, so if you can fit it under the stock hood, I wouldn't mess with it. 

For a camshaft, I'd look at Brian Tooleys (BTR) stuff, specifically the truck cams as they're made for the smaller displacement flavors of the LS and work really really well. If compression is what you're after, just put a thinner headgasket on it, that will make up for most of what you'd have in the heads for a fraction of the cost. 

 

Brians stuff and prices right now are hard to beat

Thanks for this.  So I've never even heard of them, just because i'm not a GM or truck guy really.  I decided to give their helpful tech support line a call, and... now he has me rethinking everything sadly... He sort of told me exactly what Keith said-  you can throw the parts cannon at a 4.8, but you'll always be disappointed when iron block 6.0s are just as cheap, are the same size, weigh exactly the same, and take to the same mods by a factor of 2...  I thought he was BS'ing me, and I poked around local marketplace and... he's right on the 'cheap and plentiful' part. 

Gonna have to have a think on the whole thing.  Basically for the cost of half of the E46 swap pan, I can start with a 6l instead of 4.8 and futureproof the entire project forever.  

wwGRMd?

If you really only want AROUND 350whp, you can do it with a 4.8. It will be harder than a 6.0, and youll have to go milder on the cam,  but it can be done, and it will be real hard if you want to run manifolds and not lt headers.

Youll probably need a good intake and heads. Carcraft did 383 crank hp with a 219/223, stock heads, a carbed dual plane and LTs. Probably missing accessories, so that would leave you short, but if you spend the money on a decent intake and port and mill the heads, you should get your 350whp. Good news is those parts would work if you upgrade to the 6.0 later. The 6.0 can run the awesome large bore heads like the L92s, but the small bore stuff still works.

Id get it running with what you have, assuming pulling the engine later isnt the end of the world. That gives you time to sort all the other millions of things that comes with an engine swap, then when I was all said and done, if I wasnt happy with power, I could still enjoy a rad sounding BMW with more power than stock, while I build a 6.0. The 4.8s made like 260-290 hp bone stock with manifolds and a garbage tune from GM, they arent as awesome as the larger motors, but they arent slouches either. A better manifold, tune and some LTs even with the junk cam is still probably worth 30 hp.

golfduke said:

Cheeks said:

honestly, I would try to keep it fairly stock, messing with those heads is kind of a waste of money. 

The truck intakes flow really really well for what they are, so if you can fit it under the stock hood, I wouldn't mess with it. 

For a camshaft, I'd look at Brian Tooleys (BTR) stuff, specifically the truck cams as they're made for the smaller displacement flavors of the LS and work really really well. If compression is what you're after, just put a thinner headgasket on it, that will make up for most of what you'd have in the heads for a fraction of the cost. 

 

Brians stuff and prices right now are hard to beat

Thanks for this.  So I've never even heard of them, just because i'm not a GM or truck guy really.  I decided to give their helpful tech support line a call, and... now he has me rethinking everything sadly... He sort of told me exactly what Keith said-  you can throw the parts cannon at a 4.8, but you'll always be disappointed when iron block 6.0s are just as cheap, are the same size, weigh exactly the same, and take to the same mods by a factor of 2...  I thought he was BS'ing me, and I poked around local marketplace and... he's right on the 'cheap and plentiful' part. 

Gonna have to have a think on the whole thing.  Basically for the cost of half of the E46 swap pan, I can start with a 6l instead of 4.8 and futureproof the entire project forever.  

 

wwGRMd?

 

 

Not a problem, to be honest, he's not wrong but I would still just use what you have. You're not trying to break records so there really isn't any need for a 6.0 right now. As was said previously, everything you put on the 4.8 will transfer over to a 6.0 if you find a screaming deal on one down the road. 

I really think a solid camshaft/thinner headgaskets and a tune are really all thats needed to really wake those motors up, even the smaller ones. 

I do a lot of LS stuff, you might want to look into Richard Holdeners channel on youtube, lots of camshaft tests, intake tests etc with the small cube motors so you can see what everything will do on the same dyno. definitely worth the watch 

Okay, slow afternoon at work.  This seems to be a pretty good cam spec for the 4.8, no?   Just wanna make sure before I pull the trigger on it... 

Obviously with the requisite supporting valvetrain- LS7 springs, retainers, Chain, etc... 

PAC 1218 valve springs ( good to .600" lift), stock retainers and if you absolutely must replace the chain just use a LS2 replacement.  The stock GM stuff is tested way more than the "performance" aftermarket crap.  There is plenty of guys making 3X the power you want to make using that valve train I listed out.

Edit: I've never heard of anyone using LS7 valve springs on anything but the LS7 heads.

Swapping a GM 6.0-Liter V-8 and T56 Magnum Into an E90 BMW 3-series (motortrend.com)

LS, LSX, LSA, and Vortec Engines: Everything You Need to Know About Their Specs, History, Swaps, and More (motortrend.com)

RacetruckRon said:

PAC 1218 valve springs ( good to .600" lift), stock retainers and if you absolutely must replace the chain just use a LS2 replacement.  The stock GM stuff is tested way more than the "performance" aftermarket crap.  There is plenty of guys making 3X the power you want to make using that valve train I listed out.

Edit: I've never heard of anyone using LS7 valve springs on anything but the LS7 heads.

I meant LS6 springs, my apologies! 

golfduke said:

RacetruckRon said:

PAC 1218 valve springs ( good to .600" lift), stock retainers and if you absolutely must replace the chain just use a LS2 replacement.  The stock GM stuff is tested way more than the "performance" aftermarket crap.  There is plenty of guys making 3X the power you want to make using that valve train I listed out.

Edit: I've never heard of anyone using LS7 valve springs on anything but the LS7 heads.

I meant LS6 springs, my apologies! 

those springs will work fine, that camshaft should also. These engines are really hard to mess up, you can generally look at them funny and they'll make more power with a camshaft. I'd say go for 

In reply to golfduke :

Did you ever get this all together? I'm looking at sprinkling in some more power to the 4.8 in my truck without spending too much