Help with 5.3 Engine build in rock crawler

I need to rebuild my 5.3 I got for my rock crawler, and wanted to get some advice on what all I can and cant do with my budget. I would like about 400hp but more is always better. I would like to use alot of the stock parts to keep down cost and availability.

What is the limit for the stock rods? I would like to add a bit of compression and possibly run it on E85. I figured decking the heads, and maybe some good pistons could get me to that limit.

Also, what camshaft would you guys recommend? I cant run a really high stall converter due to overheating issues and its just a pain to build alot of RPM to make it over stuff. I need to be able to be on and off the throttle alot, and I will have a big cooler with fan.

Would I need to run larger injectors for the E85? What about the fuel system? Can i just use a Walbro pump for 400hp on E85?

I appreciate the help guys, this is what its going in...

https://sphotos-a.xx.fbcdn.net/hphot...03214868_n.jpg

You can use 4.8 flat top pistons for the bump in compression. Stock rods will be fine. Get some ported 5.3 heads milled to around 60cc. The bump in compression will help your low end torque. A cam around 220 duration will be fine with a stockish stall. There's really no need for e85 unless you really want to run it and larger injectors would be needed. You'll need to upgrade your injectors for best results anyways, even with 93 octane. A Walbro 255 will work for your goals.

A stall around 2600 and a cam calling the lines of 216/230 would go great. Upping the compression to around 10.5:1 is a great idea. Mill the heads anduse 4.8L flattops. I wwouldn't expect 400hp out of a 5.3 however big off throttle torque is totally what you want and can get. If you plan on staying NA then a walbro 255 should be fine with 42lbs injectors and your good to go. Even with E85 I would imagine 42s and a 255 would be fine or maybe a 340 to be safe.

Call Texas Speed they got my buddy set up for his ls1 in his crawler.

212/218 low lift cam had great low end in my 5.3. Ran it for a bit with stock stall. I wouldn't go much over 220 duration cam choice with lsa of 112-114.

I appreciate the info guys.

So it would be a stretch to get 400hp out of a 5.3 with just a cam and bump CR? I thought you could get 100hp with just a cam swap?

I assume the stock injectors are 42lb?

repost...

Stock wouldn't be 42lbs...400hp at crank yes not that hard. 100 from a cam swap only would be a stretch. Haven't ever seen it happen. With more aggressive cam you could get more hp but would loose too much low end for your plan. Plus have to run a nice size stall to take advantage of the power band.

Gotcha, thanks!

So what about a TSP 220 .581 112lsa? Or could I go bigger? Id like to stay at or under a 2800 stall.

Would anyone how much I should take off the heads?

It needs to be kept in mind certain conditions. Are you talking about crank power goals or to the wheels? How tall are your tires and gears? If you are going 2800 stall then a 220/224 would be a good choice for something a tiny bit bigger. Anything larger than 224 is going to move the powerband up too high for your desires. Keep the LSA low around 112. A split duration cam will open up your power a bit wider so it comes in sooner and ends higher. I would take about .030 off the heads for a nice bump in power. 400 to the crank is possible. 350 to the wheels can be done.

A crawler is a very different animal as far as trying to figure power for. Honestly I don't have to have off idle power due to all the different ratios I can run. I can run dual t-cases with low gears in them, also run low axle gears and I run a TH350 trans, so I have three gears there. The lower ratios I have available, the more gearing options I have. So say my lowest ratio is 120:1 I can run an engine that makes its power at 3-4k RPM and be totally fine because at 3k RPM ill be moving 5mph.

I just want the most power I can have without running a really high stall.

Its got 42" tires, 4.10:1 axle gears, and will run a stock NP205. If I need more gearing, Ill add a doubler, ect. The thing is, with more power I don't need such low ratios, and can hit obstacles with momentum and wheel speed instead of crawling the best line. I'm more of a mat it and close your eyes kind of person, than a technical driver. I think its more fun my way. LOL

I am talking flywheel HP.

Quote:

---

Originally Posted by kerrige

I would take about .030 off the heads for a nice bump in power. 400 to the crank is possible. 350 to the wheels can be done.

---

Granted its degreed correctly, do I need to worry about piston contact with the flat top pistons and a larger cam that meets my goal, sub .600 lift? Any guesstimate, maybe from similar setup as to what CR would be?

Max lift how aggressive the lift milling and more is going to Effect PTV issues. I wouldn't be surprised if it became an issue at 600ish lift flattops and milled heads. You may need to fly cut piston reliefs or go will a lower lift cam. In order to be in the power at 3000 rpm I would imagine you would need to keep the duration below 224. However, utilizing a good split will sacrifice peak power for a wider power band. A 222/226 .591/.598 LSA111+3 would be a fantastic cam matched to a 2800 stall. Lots of mash able power and the compression will keep the torque strong out of the gate. There is no magic combo however about 11:1 compression with everything else should make for a very fun setup. I could see a setup like this producing over 400@the flywheel.

Will the stock rods handle 11:1?

Quote:

---

Originally Posted by Bodie

Will the stock rods handle 11:1?

---

Should do just fine, however, LS2 style rods would be better and are cheap. Arp rod bolts are a good idea.

I tore the engine down today, looks like I am going to need to have it bored. I couldn't run a 6.0 piston could I?

No, but it can be bored to ls1 specs which would make your 400hp goal more attainable. A high compression ls1 would make 400 pretty easy with the right cam and a little port work.

Is that .030 over? What are yall porting on a mild job? Port matched, or bowl work?

I dropped the block and heads off today at Longs Machine. Can I do a .040 over without any kind of problems?

can go .120 but gotta becareful

heres a little 53 I put together for my lifted jee

http://www.youtube.com/watch?v=eXpA5...eNbygkIVUo4iFw


GMT900 intake with 90mm tb, thumper 1 cam, ls3 manifolds with dual 2.5 exhaust, CAI this combo should make some decent rwhp for what I have into it

specs are 219/233 553/537 109 lsa...using 08 injectors

Where can I get a .120 over piston?

.120 over makes it the same size as an ls1. Just look for ls1 pistons.

Are they a direct replacement after that? Pin height the same? Can I use the stock 5.3 rods and everything?

What is the danger of going to a LS1 piston? Would I have rod concerns with that size piston on a stock 5.3 rod at 11:1 CR?

bump....

A 5.3, ls1(5.7), and 6.0 are all the same stroke with different bore sizes. A 5.3 block can be bored to ls1 specs. There are a lot more piston options for a ls1. Put the ls1 pistons on the 5.3 rods, rebalance and assemble. Its that easy!

Thanks man.

I am going to buy HP Tuners to tune this setup, would anyone have a base tune to get me started they would share?

all depends on what route you choose

Quote:

---

Originally Posted by Bodie

Thanks man.

I am going to buy HP Tuners to tune this setup, would anyone have a base tune to get me started they would share?

---

I think a couple tuners out there will get you a startup base tune for like $150.

Quote:

---

Originally Posted by George C

all depends on what route you choose

---

So far...

LS1 pistons
P&P heads
42lb injectors
224 5xx/5xx 112 cam (just going to go with what the cam manufacture recommends, prob TSP)
1 3/4" long tube headers
decked heads for 11:1 or higher CR
E85

Quote:

---

Originally Posted by kerrige

I think a couple tuners out there will get you a startup base tune for like $150.

---

Meh, Ill just do more research. LOL

that build shouldn't be hard for a file to be created

Are there any good oiling mods I should while I am in there?

Has anyone had any bad experiences with DNJ factory replacement pistons?