Dodo

Hello, Im going to start building my old 305, and I want more power.

First of all, Why I don't buy a 350?
Im from Costa Rica, and in here is a little difficult find this engines. But my idea is later buy a 350 block and change it for my 305 block.

For now, I just want add more power to my engine and the way to do that is this:

Procomp Aluminium Heads with 210CC runner size, 64cc combustion chambers. 2.02 1.60 valve size (Don't know if the compression will low a lot)

Flap Top Pistons

Single Turbo 76mm at 10 - 12 psi

What cam, carb and intake should I use?

Any suggestions is welcome.

Drac0nic

Way too big of heads honestly, if I were going to do something "racey" for a 305 I would be doing a set of 180CC something. Right now my thought for my engine is getting a set of aluminum L98s or a set of LT-1 heads and converting them to conventional gen1 coolant flow.

What fuel do you have available? That could make a big difference in what you want to do over all.

What RPMs are you looking to turn this? If it's a race engine what kind of power are you looking for?

Dodo

Thanks for reply.

If put a set of 180CC with flap pistons how much compression it will have ?

Also I have a set of 305 H.0 Heads but I think that it don't low the right compression for boosting.

The fuels available are 91 and 95 octanes.

The RPMs that I m looking is 6000rpm and the Horsepower is 400 to 500.

T/Aperformance

The runner sizes of the heads isn't really as big of an issue as the valve size. I'm not sure if 2.02 valves will clear and end up being shrouded.
Also before people can advise you of what to do we need to know more about the engine, Are you starting with just a bare block or is it a complete running engine ? What car is it going in? what year engine is it?
The best information or advice I can give you is to read everything you can find about engines and turbos, See what others have successfully done.

Dodo

So what size of valves you recommend me?
Is a complete engine and its a l69, I took it out of a 84 trans am.
I've searched info but the most results were about 350.
Thanks!

T/Aperformance

I believe the biggest you can fit on the 305 is 1.94 like in the L98 heads or the vettes 113. With the small bore of the 305 being something like 3.75 in anything bigger would be shrouded. and may have a clearance issue. If I was going to build a 305 I would look at the corvette L98 aluminum heads, maybe do a gasket match port job on them.
On this forum there are a few people who have done and are doing 305 turbo builds, I suggest reading every word they right, Some are doing it on stock bottom end 305s with just head and cam work.
To figure out what cam intake and such we would need to know how you plan do drive the car, is it mainly a daily driver and race it now and then, or is it going to be an all out race car. and if so what kind of racing? Whats your target RPM goal for the engine. Whats transmission and rear gears are you planning to run?

Dodo

Thanks for reply.
Now I m searching some threads in the forum about that, and investigate all the necessary info.

Mainly a daily driver
The RPM goal is 6000.
My transmission is a 700r4 and my rear gears is 3.42

Really thanks for help me!

83 Crossfire TA

iTrader: (2)

LOL, that sounds familiar, I have both sitting around that I ported (well in the case of the vette heads they're not finished yet, I welded up the decks and machined the LT1 heads myself...) for my similar project. In my case I'll decide which I use when I finally decide if I'm keeping the AC- I don't see how I'm going to keep the AC and run external coolant lines with the LT1's, but I'm sure they'll make more power.

you can make 2.02/1.60 valves work by notching the tops of the cylinder bores and being careful about cam specs, but they'll still be shrouded and not flow as much as smaller valves will. Unfortunately, try find some nice heads with decent springs in them with smaller valves, and taking stuff to the speed shop and having them put it together like you want tends to cost _much_ more than finding an aftermarket package.

Drac0nic

Hahaha will be curious to see how they work out. I was thinking about doing something a bit more ghetto than actually welding them up etc. With a stock LB9 short block and a thin HG I think you'd hit 10:1 without a ton of trouble. I was thinking of doing an HSR or similar instead off the LT-1 intake honestly, although it's probably both a good and bad part of doing the heads. The other question I have is why not do a stroker L99 (the old one) by shoving the 305 rotating assembly into an L99 block. That's something I've thought about for a while, it's the gen II GM never made.

The reason I honestly am not too excited about it is that head flow is only relevant to a certain point. Being 17% down size wise compared to a 350, you can take a 180CC head on a 305 and it should be quite large. After a certain point most people aren't sane enough to run the RPMs required to take advantage of huge heads. What use is 260 CFM to a person who red lines a 305 at 6,000? http://www.bgsoflex.com/flowcalc1.html Not sure how sound the theoreticals are on it but it gives some food for thought. Based on punching in a few stock #s for some aluminum LT-1 heads getting to 6500 on them shouldn't be bad even with a basically stock head.

T/Aperformance

Yes I know you can make them work, But did not want to get into what it takes to machine the cylinders to make those valves work, And it is something I would want a quality machine shop do,
Another cylinder head option would be the vortec heads, Still have small enough valves, and decent flow. better than the L98.

86Z

iTrader: (4)

if you are going to do all that work, just start with a 350.

i wish i did.

Orr89RocZ

iTrader: (20)

They did make vortec 305 heads too. Slightly different than the 350 vortecs we all know but similar in most areas and a good head

T/Aperformance

The PO is from Costa Rica and its hard to find or get a 350 in that area. As the PO stated already.

T/Aperformance

Thanks you Orr I did not know that, Even at my old age I still don't know everything about cars but I'm trying to learn it all.

Orr89RocZ

iTrader: (20)

Yup the L30 5.0 truck/van motors late 90's i believe. They are casting number 059. A mini vortec L31 head with some other minor changes

Dodo

Really Thanks to anyone that replied!!

About the heads, the vortec heads are better than the l98 heads. So in conclusion, which Vortec heads are better? The 305 or 350 heads? (Remember that I have to lower the compression)

And with these set of heads, which Intake, cam and carb do you recommend me?

Thanks!!

Orr89RocZ

iTrader: (20)

Vortec heads from a 350 will fit a 305 and will lower compression