BCNUL8R

iTrader: (2)

I was looking for the cheapest way to get a forged motor while reusing my ls1 top end. Basically a budget build to handle a procharger around 15 psi to achieve a goal of 700 rwhp through an auto with E85.

I was thinking a 347 would work fine, but apparently they don't make ls1 blocks anymore. So people are building 347's with 5.3 blocks. I was concerned about boosting a block bored that much so I asked if anyone has done it.

In the process I decided it's not worth the little bit of savings to go with a 347 built from a 5.3 block when I can buy a forged shortblock 364 built with an ls2 block for just a little more.

JoeNova

Boring out a block makes it weaker in basically every circumstance. So why bore it at all? Judging by this post alone, this is definitely your first rodeo.

There are at least 2 stock aluminum 5.3 blocks in the 7s, one of those has a stock rotating assembly.

There were a few of those same L33 blocks being used in X275.
Here is a stock bottom end aluminum 5.3 with a procharger


Boring the block will make it weaker. The LS1 blocks were always bad for boost because some of the sleeves were so thin that they couldn't take more than a .005" hone.

BCNUL8R

iTrader: (2)

it's a heavy street car where low rpm torque matters. Why does anyone waste money on strokers if a 5.3 does everything you need?

look at that dyno sheet in the video you posted. Even with 1200 horse it only made less than 450 ft lbs at 4000 rpm AT THE CRANK!!! Who knows how low it is off idle or 2000 rpms.

JoeNova

You're lookin at it wrong. It made 596 ft-lbs at the crank at 4000 RPM. Welcome to centri blowers. Boost is linear. You'll never get the mid range torque of a turbo or the low end of a screw.

If its that important, get an LS2 or an LS3 block.

JoeNova

He was also spinning over 7000 RPM.

Run a different pulley and a lower rev limiter.. and you end up with much more mid range torque.

BCNUL8R

iTrader: (2)

sounds like your trying to be argumentative I already said I decided to go with an ls2 block now that's what you're telling me to do. For comparison I saw a dyno for a 402 with an F1A making over 800 at the wheels which is way less peak and it still made 625 ft lbs at 3500 rpm at the tires. With boost cubic inches may not effect peak numbers much, but they sure do effect power under the curve.

JoeNova

Not being argumentative. The point is that any well planned setup will hit all of your goals. A poorly planned on is going to cost you money and a failure.

If you want to use a 5.3 block, don't bore it if its aluminum. Works for lots of people, but there's always going to be that risk factor. Iron is a safer bet.

Further comparison? My turbo 5.3 makes the same roughly the same power and MORE

JoeNova

MORE torque than the 402. Its just a decent planned setup.

BCNUL8R

iTrader: (2)

I can agree with all that. That's why I'm here planning 6 months in advance of my build as well as talking to trans builders and shops gathering information.

If I built a 5.3 I wouldn't have it bored to 347 after what I've learned. Also if I was going turbo I'd go with a 5.3, but since I'm going with a smaller D1x procharger I'd like a little more cubic inches to help down low in this heavy car.

tblentrprz

OP, lots of ways to skin a cat. Yeah, I'm not into cats. Sorry if I offend.

Engine is an air pump. RPM is the cubic inch equalizer. 5.3 at 7500 is the same as 402 at 6000 or 8000 vs 6400. If you setup the complete car to produce/apply the power/torque where you desire (based on intended use) the net result is the same. Map out cost for each config (from motor to rear gear) and see what makes sense.

SKINNY69

Why do you continue to go round and round about power at low RPMs? Is this a dyno queen or a race car?

Kfxguy

iTrader: (1)

My vote is for keeping it a 5.3. They can be a man on boost and hold up well.

Kfxguy

iTrader: (1)

What transmission are you going with?

AnotherWs6

iTrader: (17)

Centri on boost is different than a quick spooling turbo in boost. OP wants the thing to feel like a fng animal. Up the cubes!

And whoever said that 5.3's have been pushing full size pickups around, beating mustangs etc ---- nah bro. Yes, they run really hard above 3 grand and can be surprisingly fast. Around town they feel/felt like dog S. Prolly cuz the motor is too small for a 5,500lb vehicle.

BCNUL8R

iTrader: (2)

Neither! If I was building a dyno queen I wouldn't use an auto trans and if it was a race car I wouldn't worry about low rpm torque.

It's a street toy that will be taken to the track on occasion.

BCNUL8R

iTrader: (2)

They don't seem to understand I'm not running a turbo and my goal is only a 700 to 800 rwhp street car that can run low 10's and maybe high 9's. I'm not trying to build a 7 second race car. I don't even think there is a streetable GTO in the 7's. They are just to heavy and too much work to get there.

1bdbrd

iTrader: (12)

I suppose you have proof that it didn't happen? Further I never had a single issue driving around town or anywhere else. No dog found there. Or in my moms 240k mile 5.3 Yukon or my dads 200k mile 5.3 Tahoe. They all run just fine and have zero issues. Now in a lighter car it will be even better.

I never tried to build you a drag car. I gave you a better option than a procharger that will make the same or more power and have more torque. on the street I bet that tvs2300 will drive way better than a procharger. Won't need the steep gears or the high rpms. Plus you can run lsa heads which saves you money. Then run a very mild cam and it will drive even better.

BCNUL8R

iTrader: (2)

I've had a Yukon with a 5.3 as well. It was pretty impressive for a little motor in a heavy vehicle, but it was nothing like my 408 with 11.4 to 1 compression.

They do make a tvs 2300 for the GTO, but they seem to have a lot of issues getting over 700 rwhp. I can research that a little more. I do have about 6 months to research thoroughly before I decide what to do. I could also boost my stock cam only ls1 at 8 psi or so for a while to until I hurt it. If I do that I'd still like to have a shortblock ready to go.

I would build another 408, but if I do that I'm going to want better heads etc. and one thing leads to another. If I build a smaller motor...332, 364, or iron 370 I can save money using my current heads/intake and just run higher boost instead of spending 2000 on heads and 1200 on an intake/throttle body.

I can appreciate productive criticism, but if a 5.3 was that magical no one would ever build anything else.

1bdbrd

iTrader: (12)

Sorry I guess I should have clarified a little bit. If you are going supercharger I'd go ls2 like you are and then do ls3 top end with the heartbeat or the edelbrock tvs2300. I'm Not sure why the ls3 tvs2300 blowers run better but they seem to make more power than the cathedral port versions.

My argument for the 5.3 was before I realized you wanted to go blower instead of turbo so my apologies.

If you are looking for around 7-800whp the lsa blower has made that sort of power in zl1s and ctsv and could be a little better on the budget as well.

DBRODS

iTrader: (1)

Here are some cut aways I did a few years ago. Neither block had core shift issues, 5.3 on the left and 6.0 on the right. So to get to stock LS1 bore size which is 3.898 you would need to bore 0.118 out of a 5.3 to get there. Thats 0.059 off of 0.125 and leaves you with a 0.066 sleeve thickness. Thats 0.010 thinner than a stock 6.0 sleeve.



5.3 top of sleeve 0.196


5.3 sleeve thickness 0.125


5.3 alum around sleeve 0.261


6.0 top of sleeve 0.132


6.0 sleeve thickness 0.076


6.0 alum around sleeve 0.244