I've been toying with the idea of putting together a 400+ cu in N/A stroker for my truck, but I want it to look no different under the hood than it does right now for that sleeper theme. I'd like to try to run 12's with it.

I see SLP has a new forged 402 shortblock that is a couple hundred less than the APE 408 without a core plus I could drive to pick it up. Basically it's a block, crank, rods and pistons. They sell it with "high compression" pistons which yeild a CR of 10.5 but I have no idea what head gaskets or combustion chamber size they figured that with. I certainly don't want it any higher than 10.5.

My question is where to go from here? How much of my 5.3 could be reused?

I assume the oil pump and pan, timing chain and cover, valve covers, pulleys, accessories, and intake would all swap over.

Heads - I imagine my stock heads would choke the bigger displacement engine. Should I step up to 6.0 heads or some other heads?

Cam - I have no idea what cam to run. I don't mind something with a bit of lope, but it has to idle. I also don't want to spin it to 7000 rpm. Maybe 6500 max.

Ignition - Is my stock system up to task? I don't see many people upgrading it.

Fuel - Ditto. Can I simply upgrade injectors? What about the fuel pump?

The truck is my daily driver so I need to maintain driveabilty. With my mild head and cam plan mm I leaving so much on the table that it wouldn't be worth the effort? What kind of power levels do you guys think I can get? Would I be better served with just a 6.0 swap and cam?

Sorry for so many questions, but I'm just beginning formulate a plan and need help.

Thanks.

 

My question is where to go from here? How much of my 5.3 could be reused?

I assume the oil pump and pan, timing chain and cover, valve covers, pulleys, accessories, and intake would all swap over.

Yes, all of that will.

Heads - I imagine my stock heads would choke the bigger displacement engine. Should I step up to 6.0 heads or some other heads?

With 400+ ci, you really should go with a minimum of stage1.5 6.0 heads. I would go with at least a stage 2 to play it safe.

Cam - I have no idea what cam to run. I don't mind something with a bit of lope, but it has to idle. I also don't want to spin it to 7000 rpm. Maybe 6500 max.

Cam - something in the 230's with less than 600 lift. It depends on how much extra HP you want vs driveability. You will need LS1 Edit or similar to spin faster.

Ignition - Is my stock system up to task? I don't see many people upgrading it.

Should be fine.

Fuel - Ditto. Can I simply upgrade injectors? What about the fuel pump?

Bigger injectors would be a must. I wouldn't worry about the fuel pump until you start thinking power adder.

The truck is my daily driver so I need to maintain driveabilty. With my mild head and cam plan mm I leaving so much on the table that it wouldn't be worth the effort? What kind of power levels do you guys think I can get? Would I be better served with just a 6.0 swap and cam?

With 400+ ci, you should expect 400+ rwhp depending on cam, exhaust, tunning, etc... As for a 6.0 swap, it all depends on your buget and future plans. But, if I were you, I would not put a 400+ ci engine in something I would depend on for daily transportation. I would go with a direct 6.0 swap and a mild cam for dependability. You also may want to give some thought to the tranny in this equation, because it will become a factor.

Sorry for so many questions, but I'm just beginning formulate a plan and need help.

Thanks.[/QUOTE]

 

i'm building a 408 with absolute stage 2 1/2 zo6 heads for my 99 rcsb!!!!!!!!!

 

Try this: https://ls1tech.com/forums/showthread.php?t=177441

It will look no different under the hood than your stock motor. It may sound a little different though.

 

well, we are kind of spoiled with our heads. Lt1 guys have been making 400+RWHP on 383s using stock head castings for some time now. I think your heads with some good port work could easily support your goals but when cubes come into play you absolutely need the headflow to back it up.

 

For sure find out what deck height and pistons they calculated the CR with. Using the 6.0L heads would definitely make the CR drop and probably be better for future mods like FI.
There are not a lot of differences in the car and truck blocks, other than materials. The 4.8/5.3 block has a bore of 3.78" vs 3.90". The 5.3L engine uses the exact same crank, 3.62" as the car LS1/LS6. You can bore out your 4.8/5.3 block to 3.905" and order a 4" stroker kit, putting you at 383 cubes. All this with a completely stock appearing motor and stronger overall design due to the iron block. Plus, there are tons of cheap truck blocks out there. I got my donor long block for $300 plus shipping.
I am quite sure it is possible since I have just done it! The motor is not together yet ( waiting on the stroker kit ) but I will post build and results soon.

 

What kind of stroker kit are you going to buy? With all of this done do you think it will be more powerful than a stock lQ4 6.0 345hp?

 

Thanks for the advice. What do you think of these heads - Airflow Research LS1

Intake port Volume - 205cc
Intake Valve - 2.020
Exhaust Valve - 1.600
Combustion Chamber - 66cc

Lift Intake Exhaust
.200 145 121
.300 210 173
.400 257 208
.500 290 223
.600 308 233

They out flow Stage II 6.0 heads slightly and have a smaller combustion chamber to keep compression up since I want to be NA. I just can't find them online to compare cost.

I am curious as to why you wouldn't do a 400 ci+ engine for a daily driver. As long as the cam isn't too radical and the PCM is tuned properly, what would be the problem?

I know the 4L60E wouldn't be long for the world, so I'd probably go with a 4L80E swap, Yank 2600, and a transgo and call it a day.

Thanks for your reply.

 

tdrumm, I am going with the Eagle kit due to budget constraints and using the motor for "daily" driving and some light towing. The Lunati kit may be better quality but a price difference of around $2K made my decision easy.
There are some good points on drivability. I think Fast 4.8 is somewhat correct that 400+ cubes COULD get out of hand for daily driving since getting above 400+ cubes is mucho dinero and usually is designed for track use. Some good head and cam choices on the 6.0L motor would definitely get you the power and daily usage you are looking for.
All in all, lots of options out there. Just make sure to keep being specific on your plans like you have been so far. The advice is great and there is always someone out there who has done what you are looking for! Keep us posted.