Hey guys, I've been searching around and finding some usefull stuff here and there, but I'm still unsure on what course of action i should take.

The Situation
I have an 84 Z28, completely stripped down, ready for bodywork, electrical, suspension, I plan to build this one right.

I have 2 305's out of car, one may be an HO(how could i tell?), both run pretty well.

I have the tools, time, and knoledge (or access to relatives with the knoledge, as well as the ability to fail my way to success) to do all the work myself

As far as suspension and engines go. The car will be driven daily. I want performance it to be focussed on road racing and autocrossing (to me this means cornering, braking, and acceleration, however, i wouldn't mind some bragworthy power numbers). Plans currently include adding SFC's, a cage, better springs shocks tires and brakes, and a bunch of custom bodywork (for those who have been waiting for pictures, My house went into renovations shortly after i started, and my car has been on hold, nothing to show for so far)
Anyways
All in all, i believe i will have roughly 2000 CDN left over for the engine.

Questions.
1. Will a 305 be welll suited to a car of this nature? Would i be happier with a 350 in the end?

2. If some self controll is excersised with a 350, would fuel milage be competitive to that of the 305?

3. My father thinks a good aproach would be to build the 305 to spin up higher rpms, and to find power up there instead of swapping to a 350, saving weight, and making the car more unique. Is this reasonable given the 2000$ cap on my wallet? And more importantly, is it a good idea?

4. I have a T5 right now. Are they really as weak as i've heard? If I don't abuse it, should it hold out if i can't get a replacement at first?

Thanks in advance for anything you can tell me

 

if you're going to use it in any sort of competition firstthing i'd do is get a rule book.

milage and preformance usually don't go together but basically eityher will diliver abouit same milage

it's going be a lot harder to make a 305 run at higher rpm than a 350


for autocrossing i'd be looking at a differant transmission

 

I was thinking t56, the trick would be finding one for cheap

I was under the impression (based on another thread) that the smaller bore, pistons,etc of a 305 made it safer/easier to run the engine up higher. What makes the 350 easier to build in that way? Is it simply parts availability?

 

H.O.A.M.,

Generally speaking (and very generally, at that), a shorter-stroke, larger bore engine is "safer" to run at higher RPMs than a smaller bore/stroke ratio engine combination. The centrifugal forces of a longer throw crankshaft and rotating assembly at higher RPM can easily overcome the ability of the moelcules to hold together. That's mostly why the older 283 and 302 SBCs can wind up to 7,200 RPM and live to doi it again, while a 305 with only a couple more cubic inches would likely ventilate the sump at those RPMs.

If you want a tigher power band at higher RPM, you might want a larger bore/stroke ratio. If you want enough torque to pull the heavy car out of turns and engine brake better going in, you should retain some stroke in excess of 3". The 350 compares favorably on both counts to the 305. Of course, parts availability for the 350 is greater. And fuel economy at cruising speeds should be identical to the 305. It will have a greater thirst in stop/start traffic, and at the track, but that extra fuel at the track should be a direct result of greater power.

As has been mentioned, the case is the cheapest part of any engine build. The parts and labor you pour into it are far more costly, and comprise the greatest percentage of the total cost. Part-for-part, the 350 will be cheaper to build. Labor is identical regardless of the displacement. It's your call.

BTW - Good luck finding a "cheap" T-56 that isn't broken.

 

You will be far happier with a 350! Far happier. It is a better engine in every way.

When I swaped from a 305 to a 350(years ago), EVERYTHING improved, including the gas milage -by 1 mpg. I always track my milage very accurately, so this was a calculated observation. NOT "I kin go 5 days on a tank 'nstead of fer! yuk, yuk."

A 305 will save you ZERO pounds. They share the same block, heads, crank, rods, flywheel, balencer, etc, etc, etc. They only difference is the piston bore size, which is smaller on the 305.

While a T-56 is a VERY nice piece, the T-5 will work fine for you, if not maybe a tad better IF YOU DON'T OUTRIGHT ABUSE IT!! Here's why. The only things you get from a T-56 are durability, an extra and a higher overdrive gear, slightly better shift feel, sychronized reverse, a lighter (stock) flywheel, but at the penalty of more overall weight. For autocrossing, that weight is bad, you;ll never need the durability, and you'll NEVER see any gear above 3rd anyway.

As for durability ingeneral between the two, the T-56 is fairly indestructable for the power you're talking about. But the T-5 will hold up fine for you too, if NOT BEATEN. I have run a T-5 in my car for the last couple years behind the sbc 400 in my sig. with only one problem. I broke a shift fork. I replaced it in less than two hours, and it cost a whopping $12.00 bucks. Now for a little history. For the last couple years, I have been drag racing the car every other Friday night, all summer long, plus daily driving, autocrossing, and road trips -it gets used hard. At the strip, I full-throttle powershift, every gear, everypass, and it never let me down, except for the one shift fork -which broke because I was powershifting with the stock shifter. I think it'll hold just fine for you. Just keep the fluid changed, get a shifter w/adjustable shift stops, and don't do hole shots all the time just for yuks.

I have run BOTH a t-56 and T-5's in my car. I like both -I like the T-56 better, but under the constraints of real life (a budget), the T-5 will deilver for you.

 

thanks guys

 

If you DO use one of your 305s make sure it is the HO version. The rods are better and will let you rev higher safely.

 

Check out rebuild kits from Hanlon Motorsports to increase the torque capacity of your T5. http://www.HANLONMOTORSPORTS.com

 

or g-force

the g-force trannies look to be fairly stout, and pretty easy on the pocket book (relative, tranny work is always a bit of $$$)