shiftpro
Full Access Member
- Joined
- Aug 31, 2012
- Posts
- 4,855
- Reaction score
- 6,092
- Location
- BC Canada
- First Name
- shiftpro
- Truck Year
- 73-87
- Truck Model
- 1500, 2500, 3500
- Engine Size
- 350, 383, 454, 496!
It looks like this is pretty much settled, but I will say that the compression ratio for the LE9 you have should be 9.5:1. Something like that. I’m sure you’d see a poop compression ratio in the 8s or even 7s with some of the many throwaway heads that came on the 305, but that wouldn’t be the case on the LE9, L69, or LB9 running 416 or 601 heads.
I think the value of the 305 really comes into play if it’s what you already have, either a healthy engine or a good rebuild candidate. Anything you can get out of a 305, the 350 can do the same and perform better, but I don’t think the 305 is anything to scoff at if you bored and stroked it out to 334, ported and polished the heads to 1.94/1.6 (2.02 is probably a stretch), upgraded the cam, new valve springs, aluminum intake (more for ease of assembly than performance), headers, carb recalibration, and went with a traditional HEI with a hotter coil and an emphasis on being able to recalibrate the spark curve in order to get around the 305’s inherent timing sensitivities. I think you could have a truck that had around 375 RWHP, give or take.
400 RWHP is probably the absolute max that’s attainable on a normally driveable, pump gas 305, and that 400 is much easier and a good bit cheaper to attain with a 350/383 stroker. That’s what I’d do.
Big blocks are great, I love them, and in the proper roles, I’d build them, but you talked about being budget friendliness in your initial post. Initially considering the 305 makes me think you want maybe not a daily but a regular driver. The 305 is as economical as they come for old school V8s. Full-size passenger cars with the 305 can get MPG numbers in the low 20s if that tells you anything. The 396, 454, or whatever isn’t that. Maybe the gap between a built 350/383 and a run of the mill, unchoked 454 isn’t huge, but expect half the economy you’re getting with the 305, assuming you average around 17-19 mpg right now, hope for a hair better, and prepare for slightly worse. My other question is would you not be tempted to add onto the 454’s base performance capabilities? I know I would be. I don’t know what kind of decrease in economy that would entail, and it may not be much, but if you’re young, just starting out, have a family, these are factors worth considering. I guess it depends on what you plan to do with the truck and how often you plan to use it.
Your hp figures are probably close, but you're not mentioning torque, which is what we NEED! A 400 hp 305 is going to produce that power at high rpm,
forget about low rpm torque.
Also you are talking about RWHP... in which gear? Do we lose or gain tq/hp at the rear wheel? There must be a calculation used to determine engine
hp when a vehicle dyno is used, compared to an engine dyno. It leaves me confused..