After breaking something in my engine the other night it seems that my rebuild will be brought forward 5 months. I'm rebuilding a 305 with the intention of having a D1sc blower running about 10-15psi of boost. Now, obviously I need forged pistons but what about the crank and rods? From what I've read and been told from the guy in the local speed shop the stock cast items will be fine.

What do you think?

Thanks for the opinions and time. Be well.

Robert

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1987 IROC-Z Auto (LB9)
Black/grey interior with the stance of a streetfighter
I like to think of her as Arnold Schwartzeneger in a dinner suit

Mods
Custom exhaust. 4 Inch pipe from the headders all the way back to a single muffler at the rear. No Cat. K&Ns, AFPR and Air foil.

Future mods:
Cam change
New torque converter
New heads (maybe corvette L98)
Strut brace
Sub frame connectors
Ram Air

Current G-Tech times
0-60mph 6.26 seconds
1/4 14.74@100.2mph

 

RMK,

If you are planning to go anywhere NEAR 15 pounds of boost, you need to not only look at a forged rotating assembly (both rods and crank) but four-bolt caps and probably splayed ones, at that. The 305 is a fairly stout assembly, but when your compression pressure gets that high, you need to be thinking of building a diesel-type bottom end.

Obviously, you're changing compression to something under 9:1 and planning on very good heads - right?

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Later,
Vader
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"Click - Click - BOOM!"
Adobe Acrobat Reader

 

I think you'd be OK as long as the compression of the engine was not too high. (9.0 MAX!!!) I see too many people supercharging and changing pulleys and over spinning the Hell out of centrifugal blowers on L98's, LT1's and even 5.0 Mustangs all the time. Look at it this way, I know several guys that are getting 12 - 14# on top of totally stock LT1's and they have 10.3 : 1 comp. and don't even have forged pistons. One of my best friends has an 89 LX Mustang pushing 16-17# with a freshened up 302, TRW foeged pistons, stock cast crank, stock rods w/ ARP waveloc bolts, and 2 bolt mains. He is running 10.1XX's @ 137+ in the 1/4 and competes at several NMRA events each year. That engine has been built for about 2 1/2 years now(you can see the car on Friend's Rides Page on my Web Site)The bottom line is that #1) all Chevy small blocks have forged rods already, just buy some ARP bolts, and they will take a helluva lot of punishment, #2) How many broke crankshafts have you ever seen before that wasn't the result of something else breaking first to break it?? I have seen one crank that had the front snout right behind the balancer break off. It was bone stock 2 bbl 307 in a 71 nova, that wasn't even being driven hard -- just one of those freaky things, but not typical of 99% of most small block cast cranks. Here's an intesting fact, when Davey Allison first started racing in ARCA in the mid 80's, they were building his engines with balanced cast cranks for an advantage in power due to the crank being so much lighter, We're talking 300 mile races at 8000 RPM plus... look it up if you doubt me. 4 bolt mains would be nice, but I still don't think it would be necessary. Again I would buy ARP bolts or even better studs...with a provision for a windage tray. A Miloden windage tray is $19.99 in Jeg's and has been proven over and over on dyno tests I've read in Circle Track magazine to produce 12-15HP gains plus taking away the risk of pumping all the oil to the top of engine and starving bottom end. I'll buy 15HP for $20 all day long!!! The biggest concern you should have is the clearances in the bottom end. If you buy an all new rotating assembly with all forged parts and have the clearances off, your engine will result in having a lovely skylight in the side of it at that level of power no matter how good the parts are. Unless you're very skilled at engine building, I would recommend having it professionally built and I would have the rotating assembly balanced. Balancing usually costs $120-$150 and is really cheap insurance in a high-po engine.

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82 Z28 383, Ported 215cc Dart Iron Eagle Heads 72 cc Comb. Chambers, Comp custom grind Hyd roller cam, Speed Pro .250" domes, Wheeler Motorsports 4340 I beam rods, Eagle 5140 steel crank, Weiand Team G intake, Holley 830 DP, hedman headers
Trans: Turbo 350 w/ 4000 stall -- Rearend 7.5 w/ Richmond 4.10's, Auburn Minispool
Best ET:11.60 @ 114.56, w/ a 7.34 1/8 @ 93.50, and a 1.622 60'


89 RS, L03 305, Hypertech Chip,cat delete, Dynomax exhaust,K&N open element Filter,160 stat, MSD coil --Trans:700R4 Corvette Servo -- Rearend: 7.5 GM 3.42 w/ posi-lock

Bassett Racing

 

all the engines i've ever built were all NA but if i were building one for a power adder it's have aftermarket rods, forged crank and pistons, 4 bolt caps and studs.

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ICON Motorsports
1st & 3rd
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