Hey guys, I currently own a 1988 Firebird Formula. Its got a 305 with TPI and the 5 spd. I have a choice to make. I want to make it faster, so I either want to build a 383 fully tuned (aroudn 5 grand for the whole engine + new tranny) or I can rebuild the 305 and supercharge it (no idea on cost) What would you guys recommend? Either way, I want the T-45 (or is it T-56) tranny - the 6 speed - and am doing a lot of work on my car. Please help me with the pros and cons of each, price of super, and a guesimation of power and torque when both are compared. Thanks guys!

 

Do a search for for Willie's car. He's running an 11 sec supercharged 305, I believe.

My opinion, I'd go with 383 if you can afford it. If not, you can do a cheap 305 rebuild, swap cams and a few other cheap mods then slap a charger or nitrous on it and go fast '_

 

well heres my problem. See, a rebuild of a 305 at 8.5 compression is roughly 1 grand even for me. Then id throw in new cam, new lifters, new rollers, new heads (edelbroke) and a new intakem, 1600-2000 total. Super charger im not sure on the price. Thats like 3500-4500 TOPS.

The 383 is a different story. Thats 3100 for the shortblock ALONE, plus 900 for heads, 350 for intake, etc etc etc, thats a LOT. PLUS it prolly wont be smog legal (difficult to keep it smog legal) and I'll be using way more gas. But the power is insane.

So I was wondering if anybody had any power figures, like a 383 produced X amount of HP and Y amount of torque, while a 305 super with this super has this and with this super has that. Make sense? I kinda wanna compair. To be serious, I live in california, where the smog laws are fierce and gas is expensive, so a supercharger is sounding nice.

Course I could always go twin turbo...

 

A 383 bottom end with half decent components should be able to be purchased for around $2000-2200. You don't need forged everything, H-beam rods, etc. That's only about $1000 more that rebuilding the 305.

Everything else is a wash since you will be buying new heads, cam, etc. regardless of which one you build.

The blower motor might make a little more power but it's a more complicated setup, more complicated to tune, weighs more and will be under more stress at a roughly equivalent HP level to the 383. It probably won't last quite as long and will require more maintenance and upkeep.

383 is dirt-simple. Obviously, with that much of a change in displacement you will want larger injectors and a custom chip to run it, but you PROBABLY would have done that with the blown 305 anyway- so, again, it's a wash.

 

A 383 bottom end with half decent components should be able to be purchased for around $2000-2200. You don't need forged everything, H-beam rods, etc. That's only about $1000 more that rebuilding the 305.

Everything else is a wash since you will be buying new heads, cam, etc. regardless of which one you build.

The blower motor might make a little more power but it's a more complicated setup, more complicated to tune, weighs more and will be under more stress at a roughly equivalent HP level to the 383. It probably won't last quite as long and will require more maintenance and upkeep.

383 is dirt-simple. Obviously, with that much of a change in displacement you will want larger injectors and a custom chip to run it, but you PROBABLY would have done that with the blown 305 anyway- so, again, it's a wash.

 

why does everyone think you need a stroker motor to go fast? cubic inches do make it easier, but the same motor with 1/4 inch more stroke, is not going to make more than a few more horsepower, and 10/20 lb ft.

i would build a good 350, good set of ross/je pistons, some EAGLE SIR rods, maybe h beams if you can get them cheap enough, and have it balanced by a good machine shop,
you could build that motor for 1700ish.
the later tpi blocks have weak cylinder walls to begine with, there is no way in hell i would use one for a stroker, just FYI.

spend your money on your heads/intake/carb, you will make more power.

adam

 

I've never heard of weak cylinder walls in later TPI blocks.

The only time I'd worry about weak cylinder walls is with a motor bored to the max, or a cylinder that's been sleeved.

The problem is, NOT EVERYONE can find a short block 383 for 2000-3000 bucks. Locally here, if I ever wanted to do a 383 for cheap - I bet I'd be looking for almost a year and only save a couple hundred bucks. I bet half the reason why this guy is considering rebuilding his 305 is....parts are cheaper, easier to find & less to worry about

When my stock motor blew up, I was looking at a 400hp dirt car 350 short block. I helped the guy who built the motor, work on race cars and such so he offered me a deal, $800 for the short block. I sent him on a mission to find me heads & everything else so I could just drop it in my car. Well after 2 months we couldn't find much for under $2,000 complete, so I gave up. He handed me back my $800 bucks and I had to find a motor quick & I found a race prepped 305 for $1,000 bucks.

 

well the cheapest and most well known shop of the area quoted me 2700 + for a 383 shortblock and 1900+ for a 350 shortblock. The 305 is cheaper cus I dont have to buy another block, and parts are easy to find.

383s make a lot more tourque and about 50 more horsepower

So you guys all think the 383 is a better idea?

 

the 383 makes 50 more horsepower than what?



adam

 

~50 + hp 383s make over a 350

Im just trying to get the most power for my money here. Almost everybody is telling me to get a 383, yet some say the 383 supercharged is good. I dont want to REALLY make this thing a race car, just a street racer for fun car. its either a 383 or the supercharged 305. I'm thinking the 383 might be a little better choice.

Anybody know of a good online shop to get one built? Ok thanks

 

So you guys all think the 383 is a better idea?

Not everyone, but I like to be different....

 

care to elaborate?

 

a 383 is not neccessarily going to make more power than a 350. when will people learn that?

its all in the combo, but yes, it should be up a few lb ft at low rpms.


adam

 

i'm with you on that willie
but i sure would'nt mind a 383!

 

i'm with you on that willie
but i sure would'nt mind a 383!

 

Go with the supercharged 305!!! Im doing this right this second. Im going to take it to the raged edge safely ????

I been thinkering with a couple of roots blown motors in the past month (friend has 2 cars with them). They are drag only cars though.(they both run 9s) I have built 2 383s and 1 350 , and a 1 305 before. none mine anyways for friends. And while 383s are horibly torquey (stupidly high grin factor) you will have an orgasmic experience with roots blown small block it doenst matter displacement of motor at this point. I know you are probably looking into centrifugal making my poing moot.

I was deciding between this same point myself about 2 months ago. it was going back to my 383 project or supercharging my little 305. (i sold my stroker kit to my friend to get the blower) So me and my friend decided to try an experiment. We took a 305 small block (ive seen his 350 blown small block but wanted to see something else) L03 just like whats in my car now(exept lt1 cam) and put on an old 6-71 blower (i kid you not), and cheap summit headers. Oh by the way I know how to rebuild (convert) these for the street now by the way if anyone is interested. I had bought some 882 heads for my indecisive "blown" 305 project. we put them on after i did a dirty port on the heads. Jetted(closest analogy) the thing to super rich on a predator carburetor set timing at 30degrees flat and i went for a drive!!!

after this im never EVER going back to anything else I SWEAR THIS. It pegged 10psi on the guage. 10% under or so on the drive. I swear i was laughing like a little girl. THe closest thing to it was a big block if you have ever driven in one. (remember comparing 305 to BIG BLOCK) From a 35-40 down it was able to shred tires at will. The torque is so incredible it really feels like the hand of *** pushes you foward. Anyways im getting exited talking about it again.

So as i speak to you guys I had already bought a little b&M 144 roots blower(should be ok for the 305, the 6-71 was set on stun im setting the 144 on kill = same thing) and im lookin into putting Pro action Iron lightning 200cc heads on my 305. I only have the heads to buy (saving up now)

This lead me to another question the pro action heads are 2.02 1.6 valves. I know about shrowding and im not concerned about it with a my blower. But i was wondering if anyone out there could compare a 305 head gasket to some Iron lightning heads. Im woried about collision with the small bore and large valves of the heads. I would try it but i would have to buy the heads just to check :-(

Sorry for the long post and if anyone has some of those heads i beg for help on that.

 

anybody on the iron lightning heads? Help! Pretty please

 

anybody on the iron lightning heads? Help! Pretty please

 

I bought the pro-topline aluminum lightning heads they are crap.

 

Glad I didn't buy a set when I had the chance lol Decided on AFR heads but have yet to get them.

 

I bought AFR's for my race car and a set of lightnings for my cruiser. they stud locations on them suck, you have to use a special set of ARP studs unless you like pulling the valve springs to torque the heads, and the ports and bowls looked nice but the port openings were sized way off not even similar to any gasket until you make them that way. Each AFR head feels like is weighs 50% more than these lightnings, you know what that means right?

 

How did the car run with the lightnings in place? Will you sell them to me? :-)

Im thinking of actually going with the iron version. I have a little thing against aluminums weakness.

If you still have them outside your car could you match them against a set of 305 gaskets if you have them?

This will go later on a 350 but in the meantime its going in a 305 with .450 lift.

Thanks for your time!

 

The car will be running in a few days and I will let you know...

Quote:

Im thinking of actually going with the iron version. I have a little thing against aluminums weakness.

That may be the dumbess thing I have ever heard, but I won't flame you, I figure you just don't know, or you are like 100 years old. The weight of these alum ones will make your car go that much faster, also if you have a mishap that damages the heads they can be repaired, you have to throw irons away usually. The power added by the dynamic heat exchange of the heads directly as well by allowing more timing and reducing detonation sensitivity is another plus lastly but leastly strength? what makes you think aluminum heads are weak? Every major car manufacturer uses alum heads on 90+% of its carlines, some are even using alum blocks too.

Quote:

If you still have them outside your car could you match them against a set of 305 gaskets if you have them?

I bought 200cc because most head manufacturers use 200cc as the cutoff point for 1205 gaskets to 1206 gaskets (intake) these were taller than a 1205 but narrower than a stock stock stock gasket (not anymore though)

Quote:

This will go later on a 350 but in the meantime its going in a 305 with .450 lift.

they do sell some smaller port heads that may not have this problem but I cant promise you, If my alums were this bad I cant imagine what a iron head must have.

 

WOW Somebody is surely touchy!

It is not by far the dumbest thing. I am perfectly aware of the advantages of both aluminium and iron. I prefer iron for a daily driver. Thats from personal experience. To me the same thing as liking a blonde over a brunnete.

Take it easy! Breathe in and out. Im no where near a rockie so please have some respect as to how you address people. Im well aware of the thermal efficiencies of iron the weightsavings of aluminum and the heat disipation properties of aluminum when used with a supercharger etc etc, and if i want my car lighter ill go on a diet! :-D Did you see the smiley face after my comment.

I know they sell a smaller combustion chambered head around 55ccs or so But they however still come with the 2.02 1.6 valves. I am almost positive that with only .450 of lift I wont get any valve interference. But wanted to make sure before spending that kind of money on them.