theastronaut

Hey, I'm new here (and new to LS engines) but have had experience with hi-po engine builds in the past. I'm building a '66 C10 to be a daily driver with semi-serious pro-touring upgrades. I'm not looking to compete with the truck, just make it more fun to drive hard on an autocross course or open track event. I'm not looking to make max horsepower with this build or else I'd be looking to use a bigger CI engine. The truck should weigh around 36-3800 pounds, and I'd be happy with it running low to mid 13's, which seems doable to me with a built 4.8. It needs to have a broad powerband for autocrossing and road racing, especially autocross since you're usually stuck in a single gear the entire run. It will have a manual trans and around 4.56 gears, and I have a T56 from a LS1 car already.

I want to destroke an aluminum block L33 5.3 using a 4.8 crank/rod length, since the smaller stroke would be stronger (more journal overlap), rev easier, and the smaller displacement would give better mileage. To achieve a wider powerband I'll be using an individual runner intake with four Weber or Dellorto carburetors. I know that the small displacement would usually limit torque, but I think the IR intake would make up for that. I'm EFI illiterate, but have 40,000+ miles of experience with Dellorto's/IR intakes on my current daily driver. I'd be able to tune them myself with a wideband AFR gauge/wideband, as opposed to having to pay someone to tune it if I stuck with EFI. For ignition, MSD makes an ignition controller for LS engines that looks like something I'd be able to use and tune myself. I don't think that I'll need a radical set of heads since the displacement is so small, and L33 engines have heads that are supposed to be extremely similar to LS6 engines.

The intake would likely be an Edelbrock Pro Flo intake with the plenum cut off, the runners reworked, and carb flanges welded on. I can't find an IR LSx intake for carbs anywhere, other than a solid billet one that cost $1,650 bucks- not gunna happen! I'm handy at fabrication, so I don't see any problems making my own as long as I get the runner transition from cylinder head opening to carb flange right. Or I may be better off making my own manifold from scratch, similar to a Hogan's or Wilson sheetmetal manifold.

As stated, I am new to LS engines, so I don't know the specifics of what needs to be done to run 8000 rpm plus, or if it's even possible. I'm sure I'll have to swap to solid roller lifters, but what about the oil system? Will a stock 4.8 crank live at those rpm's? Or am I completely off my rocker to even be thinking these thoughts? I had thought once to leave it a 5.3 and build it the same way but then I'd need better flowing heads ,the crank wouldn't be as strong, and it wouldn't get as much mileage.


Here's a list of my thoughts so far. Let me know what you think!

L33 5.3, 4.8 crank.
Forged rods. Read that Eagle Gen 1 SBC rods will work?
Forged Pistons.
Solid roller cam.
Stock heads. If a 5.3 can make 400 hp with bolt ons, do I even need to port them?
Individual runner intake, Weber/Dellorto carbs.
MSD LS ignition controller.
Valvetrain for 8K plus- ???
Oil system for 8K plus- ???
2005 Vette oil pan- Supposed to be good for autocross/high lateral G rigs.

chrisfrost

iTrader: (8)

How are You doing today ? Car Craft has built up 2 or 3 5.3's 1 of which I have read the whole article . The 1 I'm most familiar with was a junk yard 5.3 L that they first tested with a carb and of course a manifold which I don't know which brand , and an MSD ignition controller and long tubes and they got baseline #'s of 335hp and 350 lb./ft. Then they installed a *****-thumper cam and some valve springs and it jumped to 431hp and like 365lb./ft. These are all flywheel #'s of course , then they installed 2 different sets of heads the latter of which were cnc'd which the netted 459hp and 398lb./ft. I'm not aware of them building any 4.8's but they may have . As far as any road racing goes this is what I can tell You . First if the engine will see extended periods of time at a certain rpm range , You'll absolutely need a timing chain dampener . Do a search in this forum and You should find the info You need for that . Also for any racing with latteral G's being a factor the only way to go is dry sump oiling . Again do a search in this forum and You should find the info You're looking for . Good luck

Bilster

iTrader: (21)

Just an FYI, you can open up that bore to LS1 diameter (3.890) and use a good LS1 forged piston with the 4.3 crank and rods. Opening up the bore will allow better breathing for the ported heads you are going to use.

loudblack97z71

iTrader: (2)

SUBSCRIBED... I have been thinking about building a short stroke screamer to put into a lightweight car with a T56. Except I would run the LS6 intake and keep it EFI.

I would start with a standard LM7 iron block (cheap), 4.8 crank & rods, bore it to 3.89 as mentioned above and use forged LS1 pistons (relatively cheap), Port and mill the stock 4.8/5.3 heads. Use a decent cam, something in the TR224 range with the a supporting lightweight valvetrain might be able to live at 8K rpm? Who knows. But I would love to hear it scream!

Anybody know what displacement this works out to be? Guessing close to 302? Or if there's any challenges or reasons why the aforementioned build wouldn't work?

theastronaut

Thanks for the input! I had found the Car Craft artcle you mentioned when doing some research earlier, and was suprised that just a cam picked up that much power. I'm used to working on aircooled VW's where you only make 200-220 hp with an all out 11/12 sec streetable stroker engine, so adding 100hp with just one change blows my mind! Timing chain dampener is a great ideat that I hadn't thought of; it'll get added to the "to do" list for sure. I was hoping that some sort of baffled/trap door/windage tray oil pan would work without going to a dry sump system- I'd rather not add the weight or complication unless it's not going to live without it.



I hadn't thought of boring the block, that should widen the piston selection a good bit over available 5.3 pistons... The downside is, the bigger the engine gets the less mileage it will get, and I'll need that much better heads to support the airflow it'll need. Either way it would probably get close to the same mileage when cruising, but the 4.8 wouldn't be sucking in as much air/fuel when romping on it- which I'll be doing alot of. I could easily get another 4-5 more mpg out of my current daily driver if I kept my foot out of it... Like I said, I'm not after max horsepower since it's just a driver and something to play with when I've got the opportunity. If it makes 400 hp as a 4.8 with mildly ported heads, that will be plenty to make my goal of it running 13's. I'd rather it get another 2-3 mpg than another 20-30 hp.



I want to use an aluminum block to keep weight off the nose of the truck since I'm trying to get it to handle. I'll already be moving the engine as far back/down as possible to the weight distribution and center of gravity as even and low as possible to help, and another ~100 pounds off the nose would be awesome.

I know I can get away with more duration than normal with IR intakes, but how much more before I start losing driveability? My daily driver VW bug with IR intakes and dual Dellorto's has a 269 adv/239@50 duration cam in it, it pulls stumps off idle but stops pulling around 5200 rpm. My stroker engine should have around 295 adv/263 @50 cam and the guys reccomending it say it'll idle smooth at 800rpm. I know that's probably an apples to oranges comparison since LS engines should have more efficient ports, but thats still a ton of duration for a street engine that has good low end driveability.

8-8500 rpm is probably a little over kill on the street; I'd be happy with a 72-7500 rpm hp peak, and have the ability for it to live at 8k for short burst on an autocross course. There wouldn't be any reason to wind it out that much on a larger road course track.

4WardInv

The 3.27 crank with a 3.898 bore should be 312ci / 5.12 liters. That would probably make for a nice revving set up!

Bilster

iTrader: (21)

I agree. The extra cubes in a 3.898" bore will not hurt gas mileage in my opinion. Might even help considering you'll need additional torque to move the ~3700 pounds of truck. If you want to pick up extra gas mileage, you're going the wrong direction with a carb set up. GMs have some of the most powerful ecm's in the automotive world. Go with an LS6 intake and find someone who is expert in the art of tuning. You'll have horsepower with driveability and gas mileage. Sounds like your goals are torn between originality in a multicarb set up and real world driving conditions. Again, my opinion....the only reason to go carb is too avoid the complications of EFI but your multi-carb set up will be a nightmare to tune without expensive and hard to use sycronizers. Other than show car appearance, you gained nothing.

theastronaut

I may consider boring it to LS1 size, you do have a good point that extra torque helps mpg, and as 4WardInv said, it would still be small at 312 CI. It will have a T56 so I can easily keep it in a rpm range where it's most efficient.

From my experience with IR vs plenum intakes, and what I've read, a stock or LS6 intake would limit the low end torque and driveability of small CI, big cam, high revving engine like this.

The carbs can be tuned for lean cruise and the MSD ignition controller has a MAP sensor input and can add timing at low loads for great mileage. My daily driver VW with IR intakes and dual Dellorto carbs cruises at 16.5-17 AFR, and drops to 12.5-12.7 AFR at WOT. I already have a flow meter to sync the carbs and linkage; its really not as complicated as it looks. You sync the idle flow with the engine running at idle- linkage disconnected, then sync the linkage itself with the linkage on and tension on the gas pedal to pull the carbs open just a bit off the idle stops to simulate driving conditions. On the VW the carbs are sitting about 2.5 feet apart from each other, and only ever need resyncing if I take something apart. I picked up a tad over 12 hwy mpg (24 to 36.25) going to the Dellorto's from a stock carb on an otherwise near-stock engine, so they can get great mileage. And that was with no added vacuum advance; I could have gotten 40 mpg with a combo mechanical/vacuum advance distributor. I've put over 40,000 miles on it with this set up and wouldn't go back to a single carb if you paid me to. The torque gain was unreal, and they extended the top end pull a good bit too. There has not been a single drawback, or negative aspect of going with the dual Dellorto's on the VW engine, and I see no reason there would be on a V8 either. I don't mind occasional maintence/adjustments- I'm building the truck from the ground up and enjoy working on them just as much as driving them.

The individual runner intakes/multi carbs open up a whole new level of what's possible as far as intake air flow is concerned (no reversion as there is in a plenum intake), and that's what I'm after with a small displacement, wide powerband, street engine that still rips on the top end. I know it's doable since guys do it all the time with other engines, I just don't know the specifics to make it work on LS engines.

studderin

iTrader: (28)

Just so I'm on the same page. You want to build a good: autocross, road race, drag truck, not competing, 3800 pound, destroked,high rpm, good mid range power band, bigger cube, built 4.8L, race in one gear, have 4:56s gears, but get good gas mileage, use a individual runner intake, and run carbs. Solid roller cam, 8,000+ rpms, use gen21 SBC rods, stock unported heads, and a 2005 corvette oil pan.

To build a race, but non race setup, and good daily driver out of your 1966 chevy truck.

studderin

iTrader: (28)

Use a quick change rear end like this
http://www.speedwaymotors.com/Winter...-End,5062.html

so you can add a propeller out the rear end. off the shaft. Get a race prop
http://www.dansdiscountprops.com/BuyNow/Powertech.cfm

Then you can do this

http://youtu.be/UO4cw565V98

theastronaut

Thanks for posting something useful. I said that I'm new to LS engines, and I said that I had only read that sbc rods would work, and '05 vette oil pans were good for extended high g loads. I came here so you guys could set me straight, not belittle me.

But to answer your question, Yes. I'm not trying to be smart, but you seemingly are not familiar with individual runner intakes and they're advantages, or that carbs can be tuned for mileage and power. Go take a look at No Limit Engineering's trucks running the Goodguys autocross events, and what kind of results they're getting with 50+ year old trucks. Go look up T56 gear ratios with 29" tall tires- 76 mph at 2000 rpm with 4.56 gears. Look up BMW M3's and their 4.0 V8 engines with IR intakes and 8 throttle bodies that make over 400 horsepower and revs to 8300 rpm while still idling like a BMW. Then come back and say it can't be done.

studderin

iTrader: (28)

A 100% stock used junkyard 5.3/5.7/6.0, with bolt ons, headers, and a mild cam will do everything your looking for.

theastronaut

I fully realize that, but I'm not wanting a drop in/bolt on motor. Nor have it get lost in the sea of "cookie cutter" or "belly button" LSx engine swaps that you'll find at every car show you'll ever go to. It's been done to death, and does nothing for me to see a typical LSx swap, no matter how much power it makes or how fast it is. I don't care about easy, I like working out the details of a build like this and putting the time and effort into making it work. If I wanted easy I'd just go buy a Corvette with American Express-bought bolt ons and do it all better than my truck ever will, but for me there's no fun in that.

BadAndy

I like that you're just doing this for the hell of it and practicality be damned. I wish I had some expertise to lend.

theastronaut

Ok, forget the "wild" intake and carbs. I'll post in the carbureted section about that. What do I need for the bottom end and valvetrain to make it live at 8000 rpm? Won't mildly ported stock L33 heads (LS6 style castings) flow enough since it's only 312 CI? I guess I'll be boring it to use LS1 pistons

I found this company that makes a drop in oil pan baffle that has trap doors to hold the oil in place. Looks like something that could work.

http://www.improvedracing.com/engine...es-c-3_11.html

http://www.youtube.com/watch?v=l6TPV...layer_embedded

DONAIMIAN

iTrader: (18)

Get familliar with the LSX dry sump and solid roller set ups. I would certianly entertain the idea of a larger bore to take advantage of a higher flowing head to support that kind of rpm. Not saying that it couldn't be done with heads on a smaller bore, but you would spend a lot for custom work on heads that may or may not work because nobody really bothers with heads on smaller than the 3.9XX bore. I can't see displacement having anymore than a 1-2 mpg difference. With a motor with that kind of RPM in mind you will need a narrow LSA (104-106) and that in itself will kill MPG.

Bilster

iTrader: (21)

Your carbs are on ebay....

http://www.ebay.com/itm/4-Inglese-We...item19cd1dc279

Exidous

iTrader: (11)

Revving to 8k is going to take really good springs, rockers, solid (probably) lifters, valves, rods, hardware and lightweight pistons. And lots of emphasis on the REALLY good. 7.2-7.5 is more doable. You can get away with not having to buy 1200.00 Jesel rockers.

The bottom end isnt usually the issue minus the rod bolts. It's the vavletrain stability that is a mother.

DONAIMIAN

iTrader: (18)

1200 will only get you the non adjustable sportsman version. He would have to Pro series to gain adjustability.

Exidous

iTrader: (11)

That is very true if he wanted/needed to run a solid setup. I was going to say 1600.00 but that seemed steep. Perhaps not.