I wish one of you that have these large head 383's lived near me. I am not trying to argue about streetability, but I would like to ride in one of the cars with the 'larger' heads just to see how it drives stop light to stop light.(I understand that gears, power brakes, etc. play a role). I say this b/c I would like to upgrade my engine, and would like some real world knowledge of the combos and how they act. Anyone near north MS???

I just want to make sure that this post was not percieved in a bad way. I am only meaning that streetability is a very subjective thing. I really would like to see how some of these large head small blocks run.

 

I have no doubt the 383 is capable of much more power than what I've proposed. Clearly, you have illustrated some fine examples of what is possible - very impressive. But, I have no plans on taking the vette to the track - I live in northeast where the roads are winding and bumpy. I just want to make as much power as possible while keeping it streetable.

That said, lets' say I do take it up a notch, and go with a XR282HR cam, some AFR 195's and Dynomax 1-3/4" coated headers.

The cam has more lift and duration (Lift is .510/.520 and duration 230/236 @ .050" and LSA = 110). According to the comp cams dyno sheet it had 9"Hg @ 800 RPM (this was in a 350 with Dart Sportsman II heads).

First, would this be streetable due to the vacuum requirements or would the vacuum be greater in a 383 than what is specified for the 350?

Second, would there be any loss of low-end power? It appears that the power band starts to move up the RPM curve as both the cam and intake runners get larger.

Third, if I go with the headers, what else do I need in terms of brackets etc. to get them to fit in my 71? I've got A/C and all the power options. Is there a good post on this subject that someone can point me to?

Lastly, if I jettison the iron heads, ram's horns and, of course, the stock intake in the process, does the reduction in weight mean I have to cut a coil off the springs to get back to a stock ride height? (I'm
running VB&P 460 coils).

Thanks again for feedback and guidance.

 

Mine has never been to the track. I cruise around in 4th gear with a 3.08 rear end at 1500 RPM all day long, in other words very streetable.

I give up, you say you want the most power possible and still be streetable. I can give you a combination that will do just that ( 500 HP/ 500 TQ ) , good luck with the smaller heads they will work just fine

edited my post, don't want to get too negative

 

You said in the original post you would trade low RPM Torque for high RPM Power. That said the AFR 180 heads would be great. With the 383 you would have very good intake velocity with these that will be killer off the line and in the working RPM you are using. The bigger ports will give you more power up top but that is not what you said you are looking for. If you are looking at a drag race application go big ports. If yoou want to tear them up stoplight to stoplight AFR 180. The cam choice I would bump it up a little to the 282 version. Good lope, Still streetable tons of low end and midrange power and no slouch at 6000 RPM either

 

I too am starting to get a little confused about what you really want. I think if you better clarify what your definition of streetable is then we can guide you a little closer to your target. 427HotRod has a naturally aspirated big block pushing about 800hp and he drives it across the country every year with no problems at all. But I would say his is an extreme case. Although Jim is extremely modest about his ride, very few have pulled off what he's done. So....tell us what you think as streetable cause everyone has a different opinion.

 

After reviewing this thread a bit, I can see where my definitions may be conflicting. Sorry if I've confused the issue - I'll attempt to clarify.

By streetable, I meant that I would like to have a fairly smooth idle, run all the related vacuum accessories, use pump fuel in the 91 octane category (that's the highest most stations carry up here) and generally be able to use this car as a driver in the summer months. This would include a variety of travel conditions from highway to back roads to potentially dreaded stop & go traffic during rush hour.

I may have been a bit overzelous in my statement that I want to make as much power as possible. What I should have said is that given the above constraints, I would like to do the best I can in the power department. In reality, I think anything in the ~425+ hp range with ~450+ lb/ft of torque would be sufficient. Also, if a tradeoff must be made, I would opt for low RPM torque over high RPM horsepower.

I'm not sure if that clarifies things, I'm not an engine guy so my vernacular may be a bit imprecise. In any case, I do appreciate all the feedback, and your replies have helped me to understand what is possible as well as some of the potential tradeoffs.