Rotating Assembly

[AmericanZ28]

Is this a good choice for a rotating assembly? Im starting to assemble a parts list for a Fall rebuild, and need some advice. My ultimate goal is 450-500 HP N/A with the ability to add nitrous in the near future (150 shot at most). Thanks guys!

[fastTa]

Is this a good choice for a rotating assembly? Im starting to assemble a parts list for a Fall rebuild, and need some advice. My ultimate goal is 450-500 HP N/A with the ability to add nitrous in the near future (150 shot at most). Thanks guys!

Where's your link?

If you truly plan on spraying the motor, make sure you use all forged internals. Some people spend a ton of money on custom cut n2o pistons, and billet rods only to forget about the crank. The crank should definitely be forged as well.

Most engine builders won't tell you this (most of them don't know) but it is always wise to use a gas ported piston with n20. It will not only provide better ring seal, but it will provide a small dynamic compression buffer in the unwanted event of n20 pre-ignition or detonation. Also use at least a 4130 wrist pin.

Check these guys out. They have very good prices on complete shortblocks. I talked to this guy and he has all of the latest CNC equip. including a diamond hone machine. After talking to the guy (I can't remember his name but he seems to always answer the phone) he seemed very knowledgeable as to LT1/LS1's.

www.strokerkits.com

How big of a shot do you plan on? What type of system do you plan on purchasing?

[AmericanZ28]

Woops! I think I posted that a little too early on saturday morning Heres the link: Rotating Assembly

I was just looking at it, but it doesnt look like the components are forged. Im looking at a 150HP shot of nitrous at the most! Would a 383 set up require the main caps be splayed? If I remember correctly, the LT1 is a 2-bolt main, so im assuming that a 4-bolt conversion is a must. Furthermore, what kind of effects on driveability do forged internals have?

These kits here seem to be really good, but it looks kinda pricey: R. Assembly

[Injuneer]

ESP Street & Strip Rotating Assemblies are the perfect choice for Street Performance/Towing, yet economically priced, it includes the following 5140 Steel "SIR" Rods, Cast Steel Eagle "ESP" Crank, Keith Black Hypereutectic Flat Top Pistons & Pins,

As you detected, that's a cast crank, with low alloy forged connecting rods (even Eagle only rates them at 500HP), and hypereutectic pistons. Definitely not what you want with nitrous. You want a forged crank, 4340 forged rods, and forged aluminum pistons. Keith Black makes a very strong case for using hypereutectic pistons with nitrous, but I'm not sure everyone agrees with that approach.

Are you looking at 450-500HP at the flywheel, or at the rear wheels?

You should go ahead and do a 4-bolt conversion (or find a Corvette 4-bolt LT1 block). Splayed is not necessarily better than "straight".... another area where you will get two schools of thought. I've seen a 4-bolt Corvette block LT1 ("straight") hold up to 1,125HP - you still need forged caps. If you weren't running nitrous, the 4-bolt conversion would not be necessary.

There will not be any "driveability" affects from forged/high end internals... you will never know they are there, other than having a thinner wallet than you started with.

[AmericanZ28]

As you detected, that's a cast crank, with low alloy forged connecting rods (even Eagle only rates them at 500HP), and hypereutectic pistons. Definitely not what you want with nitrous. You want a forged crank, 4340 forged rods, and forged aluminum pistons. Keith Black makes a very strong case for using hypereutectic pistons with nitrous, but I'm not sure everyone agrees with that approach.

Are you looking at 450-500HP at the flywheel, or at the rear wheels?

You should go ahead and do a 4-bolt conversion (or find a Corvette 4-bolt LT1 block). Splayed is not necessarily better than "straight".... another area where you will get two schools of thought. I've seen a 4-bolt Corvette block LT1 ("straight") hold up to 1,125HP - you still need forged caps. If you weren't running nitrous, the 4-bolt conversion would not be necessary.

There will not be any "driveability" affects from forged/high end internals... you will never know they are there, other than having a thinner wallet than you started with.

Im looking for 450-500 HP at the Flywheel. Is something like this possible with an LT4 Conversion Kit W/hot cam, and a 383ci Rotating Assembly? I was looking at the nitrous to add another 150HP on top of the 450-500HP N/A. Im aware of the other upgrades that are necessary to achieve even 400HP with the LT4 conversion kit, but Im assuming that a more agressive cam might be necessary to achieve my goal along with the rotating assembly. Now, compared to you, Fred, and Kevin, Im a newbie! LOL! So bare with me, if my figures are off. To convert my 96 LT1 block to a 4-Bolt main, what is necessary? What does the process consist of, and what does something like that cost? What kind of Nitrous shot would I be able to run (if any) without having to convert to a 4 bolt main set up?

[fastTa]

Definitley do the 4 bolt conersion. Essentially an extra 2 holes are bored and tapped per main web. Their are 5 main bearings and thus 5 main caps total. However most people only convert the middle 3 mains (#2,3,4) to a 4 bolt main cap.

The LT1 block wasn't produced with very much nickel and it also has thin main webs. Main webs are the area of the block into which the main cap bolts or studs are screwed into. Because of these inherant weaknesses of the LT1 block I would most definitely do the splayed outer bolts. These are either done at a 10° or 11° angle in relation to the inner main bolts. Having the splayed outer bolts will not only greatly increase the strength of the main webs, but it will greatly prolong the main bearing life due to the significantly reduced main web and main cap deflection. At high RPM under load with a significant amount of horsepower, the main caps will actuall try to elongate themselves due to the force being placed on the crankshaft.

Here is a pic of some 4 bolt splayed caps. It is not an LT1 block but you get the idea:



Also make sure that you have someone that is experienced in doing an LT1 specific 4 bolt splayed conversion. There isn't much room for error when drilling into the LT1 main webs.

[Injuneer]

One school of thought considers that the engineers who designed the LT1 block knew they were using a straight 4-bolt configuration, and put the metal in the web to support the straight configuration. A close comparison of the LT1 block to the Chevy "Bowtie" block shows that there are strong similarities, explaining the block's ability so support up to 1,200HP in the stock configuration.

This is a splayed conversion, and it is on an LT1 block..... I'm not convinced I'd do it again that way.



The parts will cost you about $250. Figure $150 minimum to do the block to accept them.