So the wife told me I can start building an engine....it's going to be slow due to costs of the parts, but I want some opinions.

Block is a stock LT1 and going to have splayed caps on all 5 mains
Eagle 4" stroke crank for a 1pc rear main possibly a Callies Magnum XL custom
H-beam 5.85" rods - brand undetermined again possibly Callies custom either I or H beam, depending
custom 4.030" 18* pistons - brand undetermined
Brodix 18X CNC ported heads
Solid roller - specs to be determined
7/16" 1.6:1 roller rockers - brand undetermined changed to shaft mounts
3/8" pushrods
rocker girdle no longer needed

I'm thinking total seal rings, and coated bearings.

I'm going to have to use a single plane intake as it would probably hurt me to use a modified LTx intake, so that will most likely be a Brodix intake converted for injection with a 4bbl throttle body. I'm planning on going with the 24x conversion and most likely a th350/400 swap since the little 4l60 in there won't last long. The goal is 750+ at the flywheel and then maybe some spray on it for when I get bored. Believe it of not this is going into a primarily street driven car, that will see occasional track time. Now before everyone says you won't like it on the street, I'm the type of guy that doesn't mind adjusting valves every oil change and changing springs every couple of years. And on top of that, I'm going to convert over to a hydra-boost system since I'm sure the vacuum signal will be near nothing. Plus I only drive my car a couple miles a day, unless something weird happens, so my street driving is far different from most peoples.

Go ahead and nit pick and let me know what you guys think. Please don't bash the fact that it's a 408. I'm looking for constructive criticism.

 

Personally I don't see the need for the end caps to be splayed.... I would use the added cost of those elsewhere in your build like upgrading from an eagle crank to callies. Other than that it sounds like you have a good start on thinking out a plan. What kind of suspension do you have in place or going with?

 

Have you considered all the costs involved with this? You realize you will need a set of $2000 headers right, unless you can make them yourself.

I wouldn't be using a cheap eagle crank, and then pouring money into a topend like that.

I also wouldn't recommend stud mount rockers you will need shaft mounts if you plan to run a cam that will appropriately compliment those heads...

I would REALLY set down and pencil out your budget. Then double it, and see if you're going to have enough.

I really don't see why you need to go 18 degree. What are your goals? There are bolt on SBC 23 degree setups that have made over 750HP naturally aspirated. Just have them converted to reverse cool and bolt them on. Use a conventional intake, and normal headers.

Just something for you to think about.

 

How much for some seeds from you money tree?

 

With a goal like that go LS, you are already going LS computer.

 

Yea might as well.

 

Again, I like being different. The Budget is as it comes. I plan on buying parts as I can afford it and as for the money tree....I work hard for my money and my kids come first so this may take some time. Headers will be built myself. I plan on using 2" primaries into 3.5" collectors and then most likely a 4" mufflex...I'm not a fan of true duals....The real decision will be shaft or stud mount...I really have no problem spending the extra money, it was more of a thought that I had, since the 18x's don't need offset lifters or rockers.... If I wanted an LS, I'd do a 427+ cube LS, but I'd rather do an LTx...more sentimental I guess.

So change the stud mounts to shaft mount.

Suspension will be full tubular, and most likely going to an 8.8 or S60 rear. Going 18* is more an experiment for me...I just want to do it...why do what everyone else does?

 

No need to splay the outer 2 mains, and if you're going through the trouble of custom pistons and a SR 18* setup you should really should also be looking at shaft mount rockers and you'll need someone like Lemon's to make you a set of headers (unless you are very confident in your fabricating skills and want to tackle that job yourself).

For the kind of power you are talking about you'll need a huge billet cam, expensive SR lifters, huge custom pushrods, expensive high pressure springs, everything will need to spin over 8K rpm so lightweight everything, and reliable shaftmount rockers. Expect a true $20k on your NA engine when all is said and done. You also wouldn't want to spray it...a cam that makes NA 750 from a smallblock is not going to be very nitrous friendly, the pistons in a 408 won't be thick enough for a big shot, and cylinder pressure will already be through the roof with the compression you'll need to run it. E85 would be great on a high compression SR 408.

Interesting build, and honestly I'd try a max effort NA LT1 like that if I had the money...but I'm already ~12K into my little 23* 383 and am only expecting between 600 and 650hp. You are talking about making 100 more then that, on a valvetrain that i wouldn't want for a 600hp build...

At that point, you would probably be better off looking for some SB2.2 castings and a discarded GM Race team intake - at least that route has been done before, and it made over 700hp NA.

Not trying to dicourage you from anything, just shooting around some points and making sure you know the kind of cash you are talking about to get something like this done.

 

I think you should keep it simple. With what you listed to be done may look great on paper, however with what you are wanting to do will most likely become a huge undertaking. I have seen this before where people who haven't done something like this buy all the parts and end up over their head, get discouraged and scrap the project at a massive loss.
If it were me I'd definitely do a short block. If you want to stay a little different then do a 396 and have your heads/intake ported by someone who knows what they're doing. Do a solid roller if you'd like, but keep it w/in the PCM's limits. If it all comes together right, you start it up and hit the gas you will forget wanting to be different because the setup will yield fantastic power.

 

IMO espically with the rpm that that engine will be capable of with the 18* heads and a large SR there is no way I'd run a 4" stroke in the stock block......

 

RPM will be kept within the limits of the LSx pcm (I believe it tops out around 8K). And so far my research has shown that an 18* head will make anywhere from 50-100 rwhp more than a similar 23* head. Considering I've seen proven 355 combo's make the 750 flywheel at 7500, I think my goals are pretty mild by comparison. The big reason I don't want to go with a shorter stroke is the torque. With the car being street driven, tq will be my friend. The biggest issue is I would like to do this with shelf parts (except the cam) so that's the reason for choosing the Eagle crank....No one else offers a 1pc. 4" stroke crank. The block is going to need a short fill mostly at the bottom of the water jackets since clearance for the crank "could" open one up. The idea behind doing all 5 mains is two fold....one there will be a huge crank swinging around in them, and I prefer to over do things when it comes to longevity. I figure that it won't hurt anything in having the extra strength. As for money, I fully intend on this costing $20K for the engine....for the power I'm asking, it's inevitable.

If nothing else this will be something different from everyone else.

 

So why even ask for constructive criticism if you aren't going to listen to anyone's suggestions?

 

........



OP lets get into this a bit more...........with that kind of weight moving the extra distance even at 7500rpm which is high rpm.......there is a massive amount of force on the block and mains.......much more than a 3.75" crank at that rpm........that was a big reason why i built a 385ci with a 3.75" stroke vs. a 396 w/ a 3.875 or the 4" stroke.............durability would be an issue not to mention block twist and cylinder deflection at high rpm due to the massive stroke in the block.........personally I would advise against running it.........espically in your application.......

there is no way i would build a motor that would make power at 7500rpm plus with a 4" crank in a stock LT1 block for anybody.......i just simply wouldn't design it that way.......

 

Just don't Puck your build up.
And you'll be fine with an Eagle crank. Just make sure the shop checks it well. Especially taking measurements of the flywheel flange and crank snout to ensure they are w/in spec.

 

After 450-500rwtq it's not your friend on the street anymore.

 

yea but its always nice to start your burnouts at a 40mph roll

 

Why does this engine have to be an RPM giant? I plan on upper limit being 8K, but if it comes sooner say 6800-7K would that be a bad thing? Since the cam is un-chosen, the power band has yet to be determined. We all know that displacement will change what a cam does rpm wise, ie. the GM 847 is less radical in a 383 than in a 350....so what's to say I have to spin 8K to make my power goals? That being thrown out there, if I can get the HP goals at lower RPM, then I have over built the entire engine by planning for 8K RPM. So the question now is where do I draw the line? This is part of the reason for over building the bottom end.

 

You can't just make any power at any RPMs by changing the cam...a smallblock wants REVS to make big numbers.

I don't see 750hp being made at 7k, even on a 408, no matter what parts you use.

 

have you any actual experience with an 18* platform on a sbc shortblock??

 

Like everyone else has said. I would use a Callies Crank and there H Beam Rods.

I would at least talk with the guys over at TEA. I love the heads and Intake setup they made for me. They really know there stuff.

I have heard good things from the new Brodrix.