Big Inch Smallblock

[pittsburghracer]

I hadn't either until today. Brett Miller has been working on some preliminary W5 work with intentions of having a new casting done. Last week he was looking for Virgin W5 head castings. By Wednesday already had some and 2 day's later had a finished port going [email protected] which is already more than I've seen and better than Indy CNC -1/-2. I'm sure with a better casting without the deep spring pockets plus other fixed areas this will be a wicked head to make some steam. Hope it works out.

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I’m sure you read the Facebook post and were I asked him if it stalled or backed up at .600. He said the head was done and he was questioning going with that big of valve. Look at the .300-.400 lift numbers and check out how bad the valve angle he used hurt the low numbers.

 

[B3422w5]

They will go that high. I was at 340 on mine, but it took a **** ton of work.

I think (THINK) I could get close to 400 out of them, but by the time you did all the work you might as well try and find some W7’s because that’s what you’d have.

Numbers, as well all know, are relative.
Mine went 300 on a reputable bench, and the car at 3220 has been 140 mph on leaf springs.
I don’t know of many that run much if any better no matter the dyno numbers

 

[justinp61]

I’m sure you read the Facebook post and were I asked him if it stalled or backed up at .600. He said the head was done and he was questioning going with that big of valve. Look at the .300-.400 lift numbers and check out how bad the valve angle he used hurt the low numbers.

Have you ported W-5’s?

 

[pittsburghracer]

Have you ported W-5’s?

I bought one W5 years ago that was a display but sold it. I didn’t really want to travel that road but was curious. At that time I didn’t have my seat machine

 

[rumblefish360]

I hadn't either until today. Brett Miller has been working on some preliminary W5 work with intentions of having a new casting done. Last week he was looking for Virgin W5 head castings. By Wednesday already had some and 2 day's later had a finished port going [email protected] which is already more than I've seen and better than Indy CNC -1/-2. I'm sure with a better casting without the deep spring pockets plus other fixed areas this will be a wicked head to make some steam. Hope it works out.

2.17 intake valve!!!!!

 

[RustyRatRod]

Just a question since this has come back up. What has happened to the old adage that you don't spin a long stroke engine very high? Has that been thrown out the window with modern technology, or are you boys with big inch small blocks just doin it anyway? I always understood the longer the stroke got, the more high RPM was possibly limited. Is that a thing of the past now?

 

[273]

Just a question since this has come back up. What has happened to the old adage that you don't spin a long stroke engine very high? Has that been thrown out the window with modern technology, or are you boys with big inch small blocks just doin it anyway? I always understood the longer the stroke got, the more high RPM was possibly limited. Is that a thing of the past now?

Max effort the quality of parts is pushing very high piston speed speeds previously thought impossible, as for more average guy type parts my guess is that time has probably shown that they can spin higher than previously thought, kind of like cast cranks back in the day they thought to have very low power capability now today people build fairly built engines on them.

 

[rumblefish360]

Just a question since this has come back up. What has happened to the old adage that you don't spin a long stroke engine very high? Has that been thrown out the window with modern technology, or are you boys with big inch small blocks just doin it anyway? I always understood the longer the stroke got, the more high RPM was possibly limited. Is that a thing of the past now?

I threw this thinking out (mostly) years ago when I was a young buck when I found out the bore and stroke combo of the NHRA top classes and heard of the rpm they were spinning.

I put “mostly” in parentheses because it comes down to (What I thought then a ways back) the equipment being run above the short block. Now I know the crank, rods, pistons and rings along with the machine work in addition come into play.

Years later in life…. What I realized was the rpm was dictated by the cam size & valve spring to control the valves properly and only better enabled with the proper parts to allow big breathing.

So to that end, I pondered how a big stroke big block was spinning 10,000 rpm and traveling as fast as they did. For me, it became apparent that I had a zero idea of how things work.

I honestly never truly grasped “Ultimate Piston Speed.”
As if they would suddenly break apart and crumble away or something.

Being that I have not watch any NHRA in years, what’s the bore and stroke of the top classes? Are they limited to any certain combo that keeps them at or under 500 inches as I. the way they run the bore and stroke?

Think about how they run the bore and stroke. How does that compare to a 340,360,408,416. Etc…

 

[273]

I remember the old rule of thumb for most was 3,500 fpm for stock type cast crank and rods which is 5850 rpm with 3.58", 6350 rpm with 3.31" and 4500 fpm with good aftermarket parts. Which seems a little outdated/conservative.




Nascar does 5100 rpm and Pro Stock is hitting 6300 fpm.

Fpm x 6 / stroke = rpm.

 

[273]

I threw this thinking out (mostly) years ago when I was a young buck when I found out the bore and stroke combo of the NHRA top classes and heard of the rpm they were spinning.

I put “mostly” in parentheses because it comes down to (What I thought then a ways back) the equipment being run above the short block. Now I know the crank, rods, pistons and rings along with the machine work in addition come into play.

Years later in life…. What I realized was the rpm was dictated by the cam size & valve spring to control the valves properly and only better enabled with the proper parts to allow big breathing.

So to that end, I pondered how a big stroke big block was spinning 10,000 rpm and traveling as fast as they did. For me, it became apparent that I had a zero idea of how things work.

I honestly never truly grasped “Ultimate Piston Speed.”
As if they would suddenly break apart and crumble away or something.

It's crazy that each pistons changes direction 2 times a revolution, 83 times a second at 10,000 rpm.

Rpm
Being that I have not watch any NHRA in years, what’s the bore and stroke of the top classes? Are they limited to any certain combo that keeps them at or under 500 inches as I. the way they run the bore and stroke?

Think it's something like, 4.70" bore and 3.60" stroke.

Think about how they run the bore and stroke. How does that compare to a 340,360,408,416. Etc…

 

[AndyF]

What is your experience in using a 4.250 crank in a smallblock. I'm sure clearancing at bottom of cylinder would be required but is there anything else?

We did this 427 inch small block for Tim's red Valiant a few years back. It worked great. Car went 160 mph at Portland International. Hughes did the heads. Block was a Mopar reproduction 340.

 

[AndyF]

Dyno tested a 428 inch SB Chevy the other day that made 780 hp. Tim's 427 was a street engine so it wasn't that radical. It ended up making right at 500/500 for power and torque. It ran great on the street. He drove that car to work and then took it road racing or drag racing.

 

[Mean416]

Plenty of big stroke engines screaming to the moon.

 

[rumblefish360]

As long as the valve train has been paid attention to and the valve springs are what they need to be, it’ll rpm.

 

[justinp61]

When I hear guys stating that long stroke combos can't rev. I always ask, "what do you considering high rpms"? The answer has been all over the place.