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Looking to build 5.3 LM7 to 800-1000hp. Need advice!!
Whats up guys. I have a 69 nova and just purchased a 5.3 iron block for it and plan to do a budget turbo build for drag racing. I am a complete newb when it comes to these engines. I dont mind spending a little bit of money but dont want to spend ton of money with this engine. I plan to build another spare in the near future.
Want it to push around 800-1000hp & plan to go EFI
Advice I was given already was to do the gen 4 rods, arp rod bolts, arp head studs, ring gap, and felpro mls head gaskets. So my questions to you guys are:
- Was this good advice? If not, what do you suggest?
- Which heads should I run? Will the stock ones suffice?
- Who has a good reputation in tuning these? I am located near Baltimore MD
- Anything else I should know or you would recommend?
- What size injectors? 80 lbs?
I apologize in advance if there is already a thread with this information. I am a newb when it comes to forums as well
im doing the same sorta build for my fox body mustang, so far my build goes like this..
stock block 5.3 lm7 out of a truck with 135,000 km (70,000 ish miles) ljms stage 2 turbo cam kit, come with cam valve springs and pushrods, ls9 head gaskets, ls6 intake ( truck intake works really well its just ugly and tall) Stock Truck Heads, 80lb semens deka injectors, on3 lsx 76mm turbo kit, and i think im leaning towards the holley efi kit for fuel injection.
Stock 05-07 short block, don't do rod bolts.
Stock LS9 head gaskets.
Any of the stock heads you can get your hands on.
80 lb siemens deka injectors.
I already have the early model short block. So should I just purchase the later model (gen 4) connecting rods? Or should I get the late model pistons as well?
Will my early model heads work? If not, what should I be looking for on the web?
You'll have to have the pistons as well. The early ones were pressed pin, the new ones are full floating. You should be able to score a full set of pistons/rods for $150 or so.
You'll have to have the pistons as well. The early ones were pressed pin, the new ones are full floating. You should be able to score a full set of pistons/rods for $150 or so.
I know people have pushed those engines to those kind of power levels, but I would still do a basic forged rod/piston set just for piece of mind.
Spending a few more bux here would still be cheaper than having to tear into the engine again at a later point. There are a few different companies that make some budget pistons for the 5.3 and then maybe even use a set of LSA rods for a cheap but strong shortblock.
I know people have pushed those engines to those kind of power levels, but I would still do a basic forged rod/piston set just for piece of mind.
Spending a few more bux here would still be cheaper than having to tear into the engine again at a later point. There are a few different companies that make some budget pistons for the 5.3 and then maybe even use a set of LSA rods for a cheap but strong shortblock.
Any suggestions or links to those budget forged pistons? I'm not against it....just wanted to build a cheap motor at first and possibly purchase another one to do a really nice forged engine build.
I would just go the cheap route first. Your first turbo build, you might blow it up. Better to blow a $400 engine than a $2500 engine.
I've had mine over 30 PSI half a dozen times on pump gas. Its still holding strong. Low timing and water/meth make these last a LOT longer than anyone expects them to.
Definitely not worth going forged the first time around. You are going to be $1000-$1500 in rods/pistons plus all the machine work. Toss something stock in and have fun.
Stick with Gen IV rods, don't worry about the ARP bolts.
Where do you get gen4 rod/piston assemblies for $150? Haven't seen them that low in a long time. Looked forever for a set for my buddies car... Finally settled on a set just a few weeks ago for $300 shipped!
Definitely not worth going forged the first time around. You are going to be $1000-$1500 in rods/pistons plus all the machine work. Toss something stock in and have fun.
Stick with Gen IV rods, don't worry about the ARP bolts.
Any crazy machining that needs to be done when swapping to gen 4 rods & pistons to early model blocks?
Definitely not worth going forged the first time around.
But it's worth it to have to pull apart the engine again in a short time and *then* spend the $1000-1500 for forged stuff?
I'm sure that stock stuff will last for a little bit, as JoeNova mentioned you can push 30psi at least 6 times through it. But don't expect it to last 50k miles and thousands of pulls. If you car is just a strip car that sees a few pulls a week then it will be ok. If you want this thing to last years and years of daily beating on it on the street then you might want to invest in some stronger stuff.
But it's worth it to have to pull apart the engine again in a short time and *then* spend the $1000-1500 for forged stuff?
I'm sure that stock stuff will last for a little bit, as JoeNova mentioned you can push 30psi at least 6 times through it. But don't expect it to last 50k miles and thousands of pulls. If you car is just a strip car that sees a few pulls a week then it will be ok. If you want this thing to last years and years of daily beating on it on the street then you might want to invest in some stronger stuff.
It will mostly be a strip car. It will see the street sometimes but maybe only 10-20 times per year at most.
Where do you get gen4 rod/piston assemblies for $150? Haven't seen them that low in a long time. Looked forever for a set for my buddies car... Finally settled on a set just a few weeks ago for $300 shipped!
Facebook LSX parts groups, and sloppy mechanics pages on there. I see them all of the time.
Just know that you are building a grenade, How long it lasts before it explodes is going to depend on your tune and hope that you don't crash in your own oil when it does go.
Yes there have been a few people making 800-1000hp with stock part but it seems like those that last are in the 600-700hp range. The guys that make 800+ with stock parts did so by slowing working there way up on boost as they tune. I bought a fully forged 408 from a person who had it built by a reputable shop only to see it blow up on the dyno before it made the 1000hp mark. It broke a main cap in two and ate the crank. It's going back together with pinned billet mains, Not because it was needed but because I have to replace the mains anyway .
You'll break a forged motor just as quickly as an OEM motor if you run into tuning issues and/or detonation. In some cases a "built" engine is more likely to fail. Adding to the OEM bore/stroke will only decrease the already weak block strength. Then you have to factor in all the machine work and assembly. The likelihood of mistakes being made are pretty high in my experience. With an untouched high mileage used engine, at least you know it was put together correctly.
If you're new to the game IMO it makes sense to run a JY motor the first few times around. Get the tune nailed down, then put some money in a "real" engine.
Last edited by Forcefed86; 06-22-2016 at 06:47 AM.
Just know that you are building a grenade, How long it lasts before it explodes is going to depend on your tune and hope that you don't crash in your own oil when it does go.
Yes there have been a few people making 800-1000hp with stock part but it seems like those that last are in the 600-700hp range. The guys that make 800+ with stock parts did so by slowing working there way up on boost as they tune. I bought a fully forged 408 from a person who had it built by a reputable shop only to see it blow up on the dyno before it made the 1000hp mark. It broke a main cap in two and ate the crank. It's going back together with pinned billet mains, Not because it was needed but because I have to replace the mains anyway .
I'm a year in on my 800+ HP stock 5.3. Daily driven, and beat on daily. 60 dyno pulls, hundreds of street pulls, thousands of miles. Had a wastegate fail and hit 35+ lbs and pegged my wideband lean, and it's still running like a top.
You have a 408. When you increase stroke, you actually weaken the block. Mains, liners, webbing, etc. This is the same reason that the 4.8 is in theory the strongest stock bottom end, and the block itself would last far far longer on a 4.8 than a 408.
I'm a year in on my 800+ HP stock 5.3. Daily driven, and beat on daily. 60 dyno pulls, hundreds of street pulls, thousands of miles. Had a wastegate fail and hit 35+ lbs and pegged my wideband lean, and it's still running like a top.
You have a 408. When you increase stroke, you actually weaken the block. Mains, liners, webbing, etc. This is the same reason that the 4.8 is in theory the strongest stock bottom end, and the block itself would last far far longer on a 4.8 than a 408.
The longer stroke crank fits in the block with no additional machining, So how exactly does it weaken the block?
06-20-2016, 09:33 PM
Looking to build 5.3 LM7 to 800-1000hp. Need advice!! 
