quick85vet

iTrader: (1)

Im currently putting together parts to work on my fox body/5.3/th350 build in the next month or so. I have access to a cast iron or aluminum 5.3 engine. Was wondering what you all think of the strength differences of the 2? It will have a 125 shot on it as well. Basic build. Head studs, cam,3500 tci stall. Any and all help/opinions are appreciated. Thanks in advance.

2kgtp

I dont know much about the high hp builds but i thin the main reason most people go for the cast blocks is the price and availability factor. I dont think the aluminum blocks show signs of weakness untill you start making big power. People can correct me if im wrong, this is just stuff ive heard over the years

quick85vet

iTrader: (1)

Im hoping to get roughly 5-600 hp out of it. I like the lighter block idea just was wondering about the strength.

lsxRanger94

A 375-475hp aluminum block build with a 125 shot is not unreasonable. There have been 1200 HP builds. The power is there, but longevity is questionable. Most that have BIG power plans step up to building a cast short block from the beginning.

dezlfrek

iTrader: (1)

im making about 640rwhp on 15psi on an l33 block.. so far so good.. runs 9.5x's and driven daily..

lsxRanger94

That's moving into the serious power range. How long have you been running this combo?

HO99Vertz28

iTrader: (3)

Hardly consider that, serious power...

My buddys car that i put together last year makes 650 to the wheels, cam only ls1 nitrous car...had probably 20 bottles through it, tons of track and street racing passes, zero issues.

lsxRanger94

An actual daily driver that runs under Super Gas index, Yeah that's moving. The people that throw some drag radials on their race car and call it a daily driver is another story.

HO99Vertz28

iTrader: (3)

Uhm, what?

My buddy drives his to work daily, races it through the week, and on weekends...we change the oil, fresh plugs, and fill it full of fuel...its been remarkably reliable at hte power level its at.

quick85vet

iTrader: (1)

Looks like i got my ? answered,lol. Im glad it will be a solid foundation. And it gets that much more weight off of the front end. Like i said, im gathering parts at the moment but actual work should start in the next 4-6 weeks!! At that point i will start my build thread as well....

dezlfrek

iTrader: (1)

about 10 months, 5k miles, 50+ 9 second runs down the track.. this same exact combo blew the rods out of an 01 4.8 cast iron block..

HO99Vertz28

iTrader: (3)

Dont forget, TUNING is the main key when pushing these bottom ends...You can scatter anything with shitty tuning, and getting greedy...

quick85vet

iTrader: (1)

I have been reading up on the tuning aspect of it as well. Will do that in small steps so as not to blow the bottom end out of it. I currently have a Holley fuel pump and reg, msd ign set up too. Gonna try to keep quality parts in this thing. Should be fun!...lol

KCS

iTrader: (20)

Without boring either block out, the wall thickness at 3.780-3.80" is plenty thick. Shouldn't have any problems with 6-700whp.

rkreigh

I'm on the fence on this one too.

I have an LS6 TTix turbo car that puts down 800

but I'm scared of hurting the block (and the tranny) so I dial it at 600

I'm looking to put the 800 down reliably with a haltech and boost by speed, and wondering if the iron block would be a better choice

the weight bothers me on the vette, or it would be a no brainer building the iron block

I'll have all the tuning capability in the world with the haltech once I get it figured out

quick85vet

iTrader: (1)

Ok. I bought the cast iron 5.3 engine as well as the aluminum version. Turns out the al one has a badly spun rod bearing and ate up the crank. So im gonna be using the cast motor first and gather parts to build the al one next year. Cast motor is really clean and looks good so far. Gonna replace the head gaskets and stud them as well. Will be starting a build thread before to long, and thanks everyone for your input/ideas on these 2 engines.....

2muchboostNY

iTrader: (8)

@Dezlfrek....any more specs on the build?

As far as the capabilities of the aluminum block, check out S13LSX's build before he passed away. 600rwhp for those motors are not a big deal but as someone mentioned....it has a WHOLE LOT to do with the tune.

https://ls1tech.com/forums/conversio...3-bw-s475.html

cam

iTrader: (9)

Unless your running the ragged edge and tuned to perfection? Your going to break just about every other part in the engine before the block fails. Lifting heads and bending rods are much much more common that block failures.