Building up the 305, stroking to 335 (.030 over, all forged internals). I found all the parts including off the shelf Forged pistons made by TRW for this application, however the only problem I am finding is dropping my compression ratio below 9.5:1 for the ATI procharger (intercooled of course) that is going along with it. If you can see a way for me to drop compression so that I can run at least 9lbs of boost please let me know, or do you think it will handle 9lbs of boost on 91 octane gas? Forgot to mention that part... darn california

305
.030 bored over
Stroker Kit
SR torquer 305's (Pocket ported)
BUILT TPI (AS&M semi-siamesed runners, TPIS big mouth intake, etc...)
MSD 6al Ignition w/ boost control
2032 cam

All help appreciated

James

 

You may wish to go with dished pistons if you can find what you want off-the-shelf. A flat-top 335 (305 with .030 overbore, flattop pistons and typical Fel Pro .039" rebuilder head gaskets) will be around 10:1 using stock 305 heads or S/R Torquer 305 replacements (58cc).

If you can't easily buy a dished piston that fits your application you might want to look into heads with more combustion chamber volume. There are several memebers on the board who have successfully used 64cc Vortec heads on their 305s, although they were originally designed for the larger bore 350. You will need a Vortec-specific intake and self-aligning rocker arms but they should otherwise be basically a bolt-on.

64cc Vortecs on the same combo will be around 9.4:1. A slightly more boost-friendly compression ratio.

 

I talked to a member that used a forged version of the powerhouse kit that gave him 9 points of compression, which is perfect, the TRW forged are supposed to give 9.7 on 58cc heads. I don't want to have to add vortec TPI stuff.

What about a smaller gasket (like .15) or will that raise my compression?

Here are the off the shelf pistons, flatlanderracing.com:

TRW L2486F 329 CID 305 3.75 Stroke 5.56" Rod
58cc heads - 9.74
60.5cc heads - 9.46
64cc heads - 9.11
68cc heads - 8.73

TRW L2486F_ 30 335 CID 305 .030 over 3.75 Stroke 5.56" Rod
58cc heads - 9.87
60.5cc heads - 9.59
64cc heads - 9.23
68cc heads - 8.85

The powerhouse kits lists 5.7 rods, it's the same piston for either one, but using the 5.7 rods gives me a much lower compression for example:

TRW L2486F_30 310 CID 305 .30 over 3.75 Stroke 5.7" Rod
58cc heads - 9.23
60.5cc heads - 8.97
64cc heads - 8.64

Shouldn't a longer rod give me a higher compression? (closer to the heads)

I am now guessing that the above compression numbers would be my correct compression? Using forged 5.7, bore and stroking it shouldn't change the pistons (both powerhouse and TRW back that up) and give me the compression I am looking for.

ATI is saying I can easily run 12lbs of intercooled boost, but I want that to be a safe amount of boost. No real extra daily driver wear. If I can get away with a 50% increase using a P-1SC so that less wear and tear is put on the car that would be great, because it would give it to me when I needed it.

What do you think?

James