I'm going to be putting a Procharger on my 383: I'm looking at 600hp (or whatever I can get out of a P600B) for now, and I'm thinking I'll eventually upgrade the head unit or do a turbo setup for 1000hp. The highest I would be turning it is 6200.

I was originally planning to have my block drilled for splayed 4 bolt mains, which I believe should handle 600hp no problem. However, I read 1000hp would be iffy in the long term. I semi-daily this car, so longevity is a big factor. I haven't had a chance to call a machine shop yet, but I'm thinking the 4 bolt conversion (machine work, caps, and fastening hardware) will cost me around $700. I should probably also have my block sonic checked, which would add a bit more.

I realized for about twice that much I could get a Dart SHP block, which would be a lot more durable and give me more room to grow. Thicker cylinder walls, thicker deck, priority mains oiling, blind head bolt holes (mine just won't stop weeping)... Of course, there will also be some necessary prep work on the SHP block that would add to its cost. (Anyone got a number on what I could expect for that? I found a place that sells prepped blocks for $1950, but I'm not sure if there'd be shipping on top of that.)

If I were certain I would be going for 1000hp, I think the SHP would be a no-brainer. However, I'm not sure if that extra $1300 would be worth it at 600hp. There's a lot more happening than the Procharger (other engine upgrades, fuel system upgrades, standalone ECU, trans rebuild), so every dollar I spend one place forces me to compromise elsewhere. For example, picking the cheaper option here could let me upgrade my old AFR 190s to some new Eliminators.

What do you guys think?

 

The dart SHP is just a cleaned up version of the stock block allegedly rated for around 600hp as well. Honestly unless you're flogging it all the time 1000hp isn't going to be an issue on even a stock block. The nice thing with SHP is you can get a 4.125 block and do 400+ cubes and make more power with less boost and other components. It's up to you but I'd say splayed stock is adequate for your goals. Save the extra money for the components as the SHP isn't a huge upgrade... its a mildly improved factory block at best. The higher up dart blocks are better imo.

 

Thanks for the perspective. I would have thought that the siamesed bores and priority mains oiling would be advantages over the stock block? I assumed the alloy was stronger too, but it doesn't look like it. Their website doesn't seem to specify metallurgical details, but from SuperChevy:That said, that's a hilariously low tensile strength. Nylon has a tensile strength of 2-3x that. Perhaps they meant 30,000 psi.

Agreed on the benefit of the 4.125" bore, I wouldn't do that right now but it would be nice to have the option in the future. What do you consider "flogging it"? I don't track my car, but I put the pedal to the floor at every available opportunity, whether that's an on ramp or a red light.

 

More than a few seconds at wide open... if your driving style comes out to like you've made several 1/4 mile passes per drive its a toss up. Some last. Some don't. Really depends honestly. Having seen good builds come apart during break in and trash ones lasting forever it really is up to odds more than anything. You'd more than likely be fine with either imo. I don't feel one is substantially better than the other... thats more or less what I mean.

 

I am also starting to build a new engine, which will last a 1000HP but I'll take it off just 600-700hp. Now I have a standard L98 block with a Procharger's P600B etc. And I just build a new engine and use the same supercharger.

I was wondering if I would use an old L98 block or some other used 2 bolt block or change to a 4 bolt block so I ended up getting a whole new block that would definitely last more than enough. I don’t take the risk of a used block blow.

I have planned to build this
-Dart SHP race prep block
https://www.cnc-motorsports.com/race...mains-2pc.html
-383 forged crankshaft, connecting rods and pistons
-compression ratio about 9.0: 1
-7q oil pan
-AFR 195 Eliminator 70cc
-Comp Cams supercharger cam
-Bosch 4 injectors
-Stealth ram bace plate
-custom made plenium
-Meth / water injection

About 500hp with the engine alone and the rest with the supercharger.
Budget 10k

 

Been running 640 or so crank hp out of stock 1993 bottom end for years

gonna run nitrous on top of the boost.

not worried about it

 

Not to get too off topic, but are you saying you're planning to take the P600B to 1000hp? I've yet to see someone making more than 700hp on a P600B without overspinning it, and it seems like a lot of people hit a wall well before that. Possibly due to belt slip from its low step up.

Are you buying the SHP from CNC-Motorsports?

That's a 4 bolt, correct?

 

Sorry, I meant that the target for the P600B is about 600-700hp but I build the engine so that it lasts 1000hp. Yes, I know the P600B maximum is 600-700hp. If sometime in the future I want more power again then the block is durable and the supercharger I can upgrade for the better.

Yes, I meant to order from there. They helped just fine when I asked "stupid"

 

Is your block a 2 bolt block?
I know the cost of machine work is different in other areas but in my area 7 years ago the machine shop wanted 500 just to install the caps (and that was me supplying the caps). Then it has to be line bored, not honed.

I would consider the total machine cost vs a new dart block, and for me, it would have to be quite a bit of savings to machine the old block.

 

the Dart block brags about how ‘thick’ it is

IMHO just means extra weight

When alum block lsx based motors are your targets, every ounce counts

 

Makes sense! Would you be having your block shipped or would you be picking it up? If the former, I'm curious what shipping adds.

Ouch, if it ran that much the SHP would be a no brainer. I'll have to call a shop to get a number. Off the top of my head I'd call $800 the threshold for drilling my current block vs buying a new one. We'll see.

I disagree. While there's no agreement on how much power a stock block or a SHP is good for, it seems pretty well agreed that the SHP is at least somewhat stronger than a stock block. I'm getting that a bare SBC block is ~160lbs (estimates vary wildly). Dart lists their block at 175lbs. That 15lbs would represent about an 0.4% addition to my car's weight. Everyone has their opinion, but general consensus seems to be that a splayed 4 bolt is good for about 800 reliable horsepower. The argument goes that distortion in the cylinder walls and the block as a whole starts to become a factor at that point. If I added 15 lbs to my 800hp, 3400lb car, I would need to gain just 4hp to keep my power to weight ratio the same. Wouldn't you agree that 15lbs of strategic reinforcing could add 4hp worth of strength? And that assumes that quality is the same; for all I know I could get my block sonic checked and find it has terrible core shift.

Of course, the SHP's extra weight is totally useless if you don't need the strength. Perhaps that's all you were saying. I plan to run this car for many thousands of miles (a hundred thousand? who knows really) at these power levels, so I think increased strength would benefit the engine's longevity.

 

Shp block is rated at 600 hp in literature. Meaning it will not break with sustained wide open throttle use at 600 hp. Very conservative rating. They'll take 1000 for a street car. Stock 350 block wouldn't even be a consideration if I were doing what you have planned.

 

Also the less cylinder flex alone will often show a 20 hp increase, even on a 550hp 383 by using the shp block.as in build a 383 to 550hp then take the guts out of the stock block and bolt it all into an shp block and see gains immediately. With no other changes.

 

I asked what it costs to deliver to Houston, it costs about $ 200.

 

I wasn't planning on chiming in here (this might get long) but I want you to know 93 ragtop is speaking from experience as to putting $$$$ in a stock block. I built his 385" LTX based engine a few years ago, so he knows what quality work cost. He didn't have a choice as there are no other options for the GEN II LTX.

The cost of machining an engine block is no joke for quality work.... and putting splayed caps on a stock block, should be expensive because it is a ton of work and fitting up those fairly inexpensive imported billet splayed caps for stepped 2 bolt registers, most times require so much extra work, it's not possible to charge enough to be profitable on the job. I am speaking from experience there as I own a machine shop. I can assure you that its not like drilling holes in sheetrock to hang a mirror.....

As for the advantages of a Dart SHP vs a production GM 5.7L block.... they are not even in the same class. The SHP is leaps and bounds better. I have honestly rebuilt engines that were orginally in GM production blocks using a new SHP and picked up 6-10hp with no other changes.... Another thing is that the cast iron itself in the SHP is harder and engine life extends 3x compared with the same engines in a GM production blocks. These are 600+hp limited Dirt Late Model engines that turn 8000+rpm all their life. The cost and performance advantage of a $1800 Dart block far outweighs the initial cost savings of $700 in maching a stock block over the lifespan of even these engines. As for the H
P rating Dart assigned to the SHP.... I'm not really sure why they did that other than market placement and to prevent encroachment on the Little M. The Little M and Iron Eagle aren't rated at all. Now in my experience the SHP will support well into 1000hp for a long time. I have a number of 700+hp NA SHPs spraying 300+ nitrous and turbo charged SHPs making well over 1K at the wheels. On a couple of these builds I'd of preferred to use a Little M because it is a better block but the customer already had the SHP, so we used it and it's holding strong. That experience has led me to have confidence to build new envines with the SHP block when the customers budget is tight but HP goals are lofty...lol.

Now I'm not saying that you have to have the SHP. A P600B can't make enough power for ****. The step ratio sucks, it has a small volute and straight impeller that just can't make any real power. I can honestly make more power NA on e85 than most make with a P600B or P1SC on a built 383. It's just designed to be a bolt on deal for stock engines and that's the kind of power it makes on everything.

If you're serious about 1000hp get yourself a F1A94 and make it.... and if you're really serious about having 1000hp someday and any kind of reliability the Dart SHP would be the minimum block I would use.
Will

 

Good to know! That's surprising that the rigidity alone would get you that kind of power. Do things bind up when the block flexes?

Thanks!

Thanks Will, I always value your input. That's really good, detailed info, which I'm sure will help many more than just myself. Hopefully I can swing the SHP now, and if not I'll be upgrading before I dial things up.

Yeah, I'm definitely not planning to take the P600B to 1000hp. I'm hoping it'll get me to 550-600 on E85, and once I feel the need I'll throw on a F-1 or something. Who knows, I might decide to go turbo at that point. I just need a stepping stone between 350hp and 1000hp, and it helps that the P600B kit is CARB legal.

 

I was unaware there was that much of a difference with the SHP. This is good to know and thank you for taking the time to clear that up sir.

 

Machine work varies in price..... But by the time you put cam bearings, freeze plugs, bore it, deck it, clean it, and then all the work to put the caps on, its easy to spend $2,000.00 in machine work on the block alone.
BTW I cannot overstate how blessed I am to have rklessdriver as a friend and living close by. I would have never built the motor I have without his help.......

 

Ouch. My block is pretty fresh, so I probably wouldn't need much machine work other than the caps, but good perspective. And yeah, you definitely have it good! By the way, where do you guys race? I'm in Lynchburg, and the closest 1/4mi strip I can find is a couple hours away. Looks like you're not much farther than that.


Did a few people post and delete their posts? I got notifications but see neither post here.

Anyway, to address the point they were discussing: engine block strength is highly variable. For one, there are the obvious differences from block to block from core shift. Second, fatigue is a highly statistical science. My fatigue buddies tell me that fatigue testing often has a margin of error of 2-3 orders of magnitude. In other words, apparently identical test samples could last anywhere from 1mil to 100mil cycles (for example) before they break. And there's no way of knowing until it breaks.

Actually, for fun here's a S-N (fatigue magnitude vs number of cycles till failure) chart for gray iron. You can see there's at least an order of magnitude difference between various points at the same stress amplitude. For example, one specimen lasted ~40k cycles at ~75MPa (stress is measured in pressure; force applied divided by sample cross-sectional area), whereas the rightmost point lasted just over a million cycles at a greater stress amplitude of ~80MPa.




Even ignoring the statistical nature of fatigue strength, everything has some lifetime. Maybe the guys running 1000hp on a stock block are on the left side of that curve, where they only get 10k cycles to failure, whereas the stock power level is on the right side and will last a million (or forever if that's the endurance limit).

I don't want to roll the dice, since I plan on driving this car for many years to come.

 

my guy was pretty reasonable. It was like 600 for mag, deck, hone, clearance for the stroker kit, align the mains and new brass plugs and all bearings. Had them build me a pontiac 400 and it think it was like 3k assembled. I had the parts but they replaces what needed to be done, balanced everything up and built it as a street strip type. It was very stout when finished but they said it took a lot of decking to get the block and heads good. My only complaint is they are slow but they've come highly recommended from the few guys I know that still race... took 3 months for that 400 but it's like an anvil. They even did a little port work on the heads to clean them up. From the outside it looks like a hole in the wall type place but the machines inside are insane. Good work is hard to come by and their pricing is very reasonable compared to what I've seen others quoted at.

And they're like the only place that actually still understands Y blocks and flatheads... the main reason I found them being honest. They have a stockpile of access to those hard to get parts.