JE Piston article about LS Strokes

[mobileaudio25]

I stumbled across this article on google and I was wondering if anyone has done any measuring or can validate this info on 3.900 crankshafts in ls blocks.

I’ve read/heard before that 4.000 stroke causes the piston rings and the piston skirt to swipe the bottom of the cylinder which causes premature wear/failure. This article is saying that with a 3.900 crank (which is kind of an odd stroke) you don’t get that rub on the bottom of the cylinder.
I asked two Representatives about this info on the phone but they both said they haven’t heard this before. I’m curious if a 3.900 crank is more safe because I’m building an LQ9 turbo motor and replacing the crank so if I can safely stroke it while I have it torn apart I would like to.

http://blog.jepistons.com/different-strokes-choosing-the-right-stroker-crank-for-your-ls

 

[64nailhead]

I've seen the article, the summation in the last paragraph says it all. Also, that article is referencing NA builds, but the same applies to boosted builds as well. Without knowing what your goals are and how much money you have to spend, it makes it rather difficult to make a recommendation for you. The items that are needed to be known : HP goal, application, longevity requirements.

Regarding HP, if you are looking for a streetable build in the 600-800whp, then there is no need to push a stock block to it's limits with excess stroke beyond the stock 6.0. On the other hand, if the goal is 1200whp+, then yup, stroke it (and partial fill the block as well.)

Regarding application, drag only vs street only or a combo. Streetable builds need to be reliable and not 'on the edge' IMO. Again, for streetableness, stick with a 6.0. Seldom being driven on the street? Then put in the 4" stroke.

Regarding longevity, the article accurately depicts issues of longevity with longer strokes that push the block and bearings to the limit.

Short, lightweight pistons with ring lands through the wrist pin bores are not for 100,000 mile builds, but they do make for fast revving, quick throttle response builds with added low end torque. It all comes down to what you want, expect, and have to spend. The issue your up against, IMHO, is that you will most likely be able to make all the power you want with stock components. If you can't, then you really should look at an aftermarket block. And if you end up looking into one of those, then you ought to be looking into a larger bore that allows for a shorter stroke to achieve the same displacement - the best of both worlds. You'll find that I practice what I preach with this if you look at our build thread on the second motor. 4.125" bore with 3.875 stroke for 414 in^3 of SBC/LS build.

Lastly, when JE references 'shelf pistons' beware. I assumed that a shelf piston implied that it was a piston that was in stock on the shelf. As I discovered - not so much. I waited almost 7 weeks for a set of shelf LS7 pistons for our build. It really put a catch in my giddyup last winter/spring. I'm not disappointed with the slugs, but the wait was enough to almost give a me a heart attack - lol. I discovered later that if I would've ordered .010 or .020 over I would've gotten them in a less than 2 weeks - silly me.

Answer a couple of my questions so we can see what you have going.

 

[mobileaudio25]

I've seen the article, the summation in the last paragraph says it all. Also, that article is referencing NA builds, but the same applies to boosted builds as well. Without knowing what your goals are and how much money you have to spend, it makes it rather difficult to make a recommendation for you. The items that are needed to be known : HP goal, application, longevity requirements.

Regarding HP, if you are looking for a streetable build in the 600-800whp, then there is no need to push a stock block to it's limits with excess stroke beyond the stock 6.0. On the other hand, if the goal is 1200whp+, then yup, stroke it (and partial fill the block as well.)

Regarding application, drag only vs street only or a combo. Streetable builds need to be reliable and not 'on the edge' IMO. Again, for streetableness, stick with a 6.0. Seldom being driven on the street? Then put in the 4" stroke.

Regarding longevity, the article accurately depicts issues of longevity with longer strokes that push the block and bearings to the limit.

Short, lightweight pistons with ring lands through the wrist pin bores are not for 100,000 mile builds, but they do make for fast revving, quick throttle response builds with added low end torque. It all comes down to what you want, expect, and have to spend. The issue your up against, IMHO, is that you will most likely be able to make all the power you want with stock components. If you can't, then you really should look at an aftermarket block. And if you end up looking into one of those, then you ought to be looking into a larger bore that allows for a shorter stroke to achieve the same displacement - the best of both worlds. You'll find that I practice what I preach with this if you look at our build thread on the second motor. 4.125" bore with 3.875 stroke for 414 in^3 of SBC/LS build.

Lastly, when JE references 'shelf pistons' beware. I assumed that a shelf piston implied that it was a piston that was in stock on the shelf. As I discovered - not so much. I waited almost 7 weeks for a set of shelf LS7 pistons for our build. It really put a catch in my giddyup last winter/spring. I'm not disappointed with the slugs, but the wait was enough to almost give a me a heart attack - lol. I discovered later that if I would've ordered .010 or .020 over I would've gotten them in a less than 2 weeks - silly me.

Answer a couple of my questions so we can see what you have going.

A lot of good info passed on there thank you ! I wasn’t looking so much for a recommendation, but I am just now getting to all of the parts gathering.

My car is only built right now for about 550-600 whp, I have stock spline 8.5 rear end but I do have an Eaton posi with factory 373 gears.

I want the car to be very streetable because that is partially the reason I’m doing an ls swap. I want to be able to make 500-600 whp on low boost then once I get a 9” in there I will turn up boost to 750-800 whp.

I’ve budgeted about 9-10k for everything in the build. I have 2005 6.0L LQ9, stock computer, repinned harness, truck accessories, intake and TB. 2001 4L80e trans. I want to do a turbo setup and I’m pretty sure I’m going to use hooker or RMperformace gbody turbo hotside kit. I’m going to have the block machined and I’m going to do a completely new rotating assembly. I want to keep factory intake and DBW Throttle body. I’m starting to buy everything to do the swap now, but haven’t purchased any performance parts yet.
I know a bigger stroke will spoil the turbo up a little faster so since I was going to buy a new crank I thought about stroking it while it was apart. I’ll probably also have to have the block bored to be perfect, it had 115k on it.
Was recommended to run a Brian Tooley racing stage 2 or 3 can kit. S480 turbo . Some say 8.5 CR some say 9. Still new to this but I’ve been doing a lot of reading

 

[64nailhead]

You want it to be streetable - define that. Here's why, 3000-10000 miles per year doesn't need a Tooley stage 3 cam; you really need to keep the LSA at a sane level unless you plan to cruise on the highway at 3000+ rpms. Compression in the 8.5-9.5:1 is safe if you plan on a lot of street driving, otherwise the tune becomes much more temperamental unless you're running a knock sensor. Something to keep in mind about cams, those BTR cams are designed for 5.3-6.0 size motor. If you add another 40 cubes on, then a Stage 3 acts like a Stage 2 as the displacement increases, and vise versa as the displacement decreases. A local has a BTR stage 3 in a 4.8. It works great at the strip and it is a giant PITA to cruise with, but it's mostly a strip oriented build.

I still think stroking it to a 408 is unnecessary for your goals. A solid built 6.0 with a VS S480 will get you right where you need to be IMO. Also, don't let someone convince you that the S480 might be too big. We have the S480 on out 414 and I wish I would've gone larger or twin S475's. If I had to do it over again it would've had twin S475's.

Regarding your rear, cam pick,etc, for a mild goal of 500-600 you won't be over 10-12 psi, and you should be in the 700 range by 18ish. The big turbo gives you alot of room to let the turbo do the work. Turning up the boost is easy. Regarding your budget, we have less than that in ours with $6500 in the short block and another $2500 on top with turbo and fuel system. And we are using an aftermarket block. I guess what I'm trying to reiterate is that you don't have to spend piles of money on hard parts for 800whp and lower goals.

What are you using for fuel? I ask as I went with twin 044 Bosch's, but if I would've been a little smarter I would've went with a 4303 Magnafuel - same money with a single and capable of much more than the 2 044's. For your goal you could easily get by with a 4302. The Maganfuel's are great units that are guaranteed forever and they stand behind their product.