ok, my friend swears up and down that "big bore, small stroke" is the way to go to make power... to quote him:

"A destroked motor makes more power than a stroked motor... don't get me wrong strokers have A LOT of tq.....but the all bore is where it is at."

i have some trouble understanding why that's really true. considering you can build a stroked 350 (383) to turn as much RPM as a bored 350 and breathe just as much (if not more) air, then why necessarily will the 'bored' engine make more power? i asked him this, and he said:

"yes, i believe that is because of RPM. Horsepower comes with RPM, so that would explain the large bore and short stroke. i would rather enlarge the bore than the stroke to get HP and RPM."

:confused: you guys care to jump in?

-Chris

bore/stroke combinations are application and combination specific. What works in a 2500-3000 lb car will not work in a 3600-4000 lbs car. The more a vehicle weighs, the more it NEEDS torque to accellerate.

Another point is that a shorter stroke combination will typically have a higher rpm power/tq band. You trade off low end torque for higher rpm performance. While that sounds OK for some, other trade off is increased maintence and higher risk of parts failure.

Lower rpm longer stroke combinations will have less maintence issues and also increased parts durability.

There are many choices out there, you simply have to consider all the pros & cons of each to know which will work best for your intended usage, application, skills, maintence schedule and your budget.

10secBU, i told him the same sort of thing you just said... he seems to agree, but now he claims he can put $2,200 in a 350 and make 650 hp. graemlins/clonk.gif

let's assume he starts with a ZZ4 with 355 horsepower... can $2,200 really get it to 650? i think it would be a stretch...

I'd like to see that trick.

Sure,...if he bolts on a 300 shot nitrous kit on it :D

BTW,...I am a fan of large bore, short stroke. see my sig....

A given pair of heads will flow more with a larger bore. And that would give u more power. Also with a shorter stroke your not throwing around so much crank mass, drop in some long rods for a good Rod/stroke ratio, and as small of pistons as u can. Keep the rotating weight to a minimum, and get more power. Lets the engine rev freeier and faster. Also RPM = horsepower. (300ft-lbs @5500 = 314hp, 300tq@8000 = 457hp, 300tq@12,000 = 685hp). As already said, big bore engines are better for high rpm horsepower. Realisticly having such power at high rpm's wont be great for the street. So whether a big bore engine makes more horsepower over a big stroke engine, it doesn't really matter. Like several had said, it all depends what you need for your application.

I said this MANY times!!!

The only difference between a torque motor and a horsepower motor is that the torque curve moves over to the right on the rpm axis

A stock, L-48, 350 motor will have max. torque right off idle!!

An L-88 will have it up about 5000rpm!!!

Play with D2K by using a family of cams and hold the motor spec's constant and you will see what I mean.

One point is though that once you get past about 270 advertised duration, you have to start increasing static compression so that you keep up with the drop in dynamic compression that a low compression motor with late intake valve closing has so that you can get it to run right!!!!

I personally think that a max. power STREET motor runs best when Torque is right around 4 to 4500rpm and hp is right about 5500 rpm!!! You still have a good lowend, but it will still make some hp upstairs!! As always, jmho...

pdq67

PS., and gearing and tire size enter in here too!!!

Originally posted by four o two:


let's assume he starts with a ZZ4 with 355 horsepower... can $2,200 really get it to 650? i think it would be a stretch... If he's talking about an honest 650 from a 355 on motor only (NO power adders) please tell him to put the crack pipe down and step away.

The heads alone will cost 2200 not counting new pistons to reach 14:1 compression and that large solid roller and he'd still be using a sub-par short that won't keep up with the rpm required for a 355 to make that #.

They got a 355 up to 503 hp ish for danger mouse in Super Chevy.

guys, i'm afraid the BS gets deeper... well sortof... two small block owners posted back at my thread. one said:

"I make around 650 with a 355. and it will turn 10,000 rpm if i needed too. when i build my next new motor i'm go with a race series Dart block, with 18* heads and hope i make power at 7,000, and yes i will drive it on the street all day long "

and another says:

"350 is the stock block - not the final ci
650 is at the wheels too. 15:1 comp actually, 59cc bowtie heads, super victor intake, 650 lift cam. Im actually selling those heads and intake - came off a 9sec 69 fbody with 410 gears and a 3500 stall. oh yeah - i drove it 25 miles each way to work too."

seriously... :confused:

then some volvo boy chimes in:

"another, about u guys and saying a high reving high power band engine cant be driven daily cuz no torque, isn't that what tuning the transmission is for? u can make torque using gears, u cant make horsepower.

the transmission is designed to keep the car in the power band, correct?

for example, my Volvo. it does make good torque, but the turbo fully kicks in at 4000. if i redline 1st (6000) then shift (its got the toptronic auto), ill be back at 4000. thus keeping it in the hp range. therefore, my torque isn't playing much of a role. this same logic could be applied to any low torque engine. yea, torque is a great thing though.

another example, BMW M3."

:confused:

I don't know all the fine points about building motors, but I do know a little bit about money.

Last I've heard, 650 horsepower out of a small block sounds about 100 ponies shy of NASCAR power.

$2200 sounds about $77800 short of NASCAR engine cost in parts alone.

Something's amiss here with your pal's calculations, I believe.

OK..I will say it...YOU wont make 650HP with a 23º head and no power adder. The larger bore/shorter stroke engines can make more HP over the smaller bore engine. This is mostly because you can use larger valves, allowing more flow. Now bolt on some trick SB2 heads and intake...then 650 can be had

personally i like big bore and big stroke. ;)
no replacement for displacement.

Originally posted by four o two:

"I make around 650 with a 355. and it will turn 10,000 rpm if i needed too. when i build my next new motor i'm go with a race series Dart block, with 18* heads and hope i make power at 7,000, and yes i will drive it on the street all day long "
10,000 RPM and he's only getting 650HP? ;)

Had a friend back in the 70's running a G or H modified production 61 Corvette. For you guys not old enough to remember, that was something along the lines of 10LBS of car weight for each Cubic inch of engine. So, everyone used destroked small blocks in the 260 to 280 CI range with light cars. This engine would rev to almost 9000RPM. He went through valvetrain parts like they were popcorn. Same with driveline. It was totally impossible to drive on the street other than to show off in front of his house.

These guys who are telling their stories reminds me of the dozens of people I have met who all had 67 L88 Vettes :eek:

I personally have had lots of experiences with small blocks, and I will never believe that a 650HP smallblock (non-stroker) is a real streetable thing. Just my .02 worth

500 HP at the flywheel cost me about $4,500. That's with an Eagle cast crank, SIR rods, SRP pistons, home ported Trick Flow Heads, solid FT cam, etc. Cost of block and machining included, oil pan to carb.

I think these guys talking about 650 HP at 10,000 RPM from a $2200 355 sound like a bunch of kids just b.s.'ing.