I'm getting very close to building the motor for my 69 FB. I want a Streetable but very powerful engine. I want all I can squeeze out of it within my parameters. The car will have a M-20 4 speed and a 3:55 posi. The motor will have iron #48 big valve D heads and a hydrolic roller camshaft, and most likely a stock intake. I plan on running factory style headers and keeping the compression where I can run pump premium gas.
Since I will be replacing the crank, rods, and pistons I can't see why not go to a 4.5" stroke? I understand doing this will require 4 bolt mains and a line bore. I am trying to determine the downside of the 4.5" stroke (excluding the cost issues). Appears more Cubes make more power with the same cam, idle better, make more torque sooner in the rpm range, and should be reliable if the rpms are kept under 6500 rpm. I've had both a 400 and 455 in the past, and with the exception of gas mileage, the 455 was better in every other way. So, seems like a 4.5 stroke with 500 cubes would make huge torque and power sooner than a 455. So, I read about so few 4.5 " street car strokers , there must be a reason most seem to go with a 462. What am I missing! Anyone running an engine stroked to 4.5" on the street. How does it do?
You can do 4.5" stroke but just like everything else it comes down to $$$$ If I was building that engine I would not be using a stock intake and factory heads, would be leaving way to much power on the table.
I agree the iron heads are a limitation. The goal was to run a factory ram air hood and draw fresh air in. Iron heads ported from Butler, i think they should flow 250 cfm. I may be able to run another intake, possibly a performer rpm by thinning the seal an inch between the hood and carb plate. My target et was 11:99 or less. (With no nitrous) I figured it would take about 600 hp to reliably do 11:99 or less ET. Do I sound way off some where in my thought process?
Not sure but I thought I heard that the block needed to be clearance to run a 4.5 stroke. No proble making 600 hp but it might be hard to do with iron heads. Be much better off going alum. It all comes down to money. The more you spend, the faster you go, the more hp you get. Of course the money you spend on the hp might not end up being the only money you will spend. Once you start making that kind of power other "weakest link" pieces with show themselves. Then there are things like the $1K that you might have to spend on the fuel system upgrade to feed all those new ponies. Hey, nothing's free man no matter what they say on the Velocity channel.
I agree the iron heads are a limitation. The goal was to run a factory ram air hood and draw fresh air in. Iron heads ported from Butler, i think they should flow 250 cfm. I may be able to run another intake, possibly a performer rpm by thinning the seal an inch between the hood and carb plate. My target et was 11:99 or less. (With no nitrous) I figured it would take about 600 hp to reliably do 11:99 or less ET. Do I sound way off some where in my thought process?
Save your money you don't need all that to run those numbers. I just ran 11.53 with my pump gas 455 with 220 cm #16 D-ports today in 94 degree weather. This is a street car that gets driven everywhere.
Hey Cole, do you have Jim Hand's book "How to Build Max-Performancs Pontiac V-8s"? If not I suggest you get a copy and read it over. He has a lot of usful info and tips. He also runs a 455 with Iron heads, has thousands of 1/4 miles runs and uses the station wagon as a driver.
What are you starting with 400 or 455? I thought a 4.25" was a tight fit, could be wrong though. Man that's a big crank, IF you can get it to fit you'll be moving a lot of air, more than you can get through a set of 48s, and more that you can get through a performer rpm. I traded out the #48 Ram air III heads off my 428 for aluminium as I had detonation with the 48s. I don't think you can make the chambers big enough to run a crank that size and not suffer detonation with 48s. What would you use for rods and pistons? Then, as Firebob says, what are you going to fuel it with. Listen to Bigchief. Not that I'm trying to discourage you, I'd love to stuff a monster crank into a Pontiac block and have all the necessary parts to have it scream down the track then stop at the A&W on the way home. But I don't have the many thousands of dollars it would take to do it. If you do, go for it.
Oh yeah, I bought an aftermarket crank for my 428. Even though it's 45 years newer than the old crank, made with newer tooling, and modern technology, it looked like it was made by Fred Flintstone, compared to the old one. I had to have the thrust surface machined smooth and the seal surface was out of round, had that machined as well, this on a brand new crank. The rods and piston were beautiful, not so much the crank.
Ain't that the truth bluebird. Some if not all the aftermarket parts are garbage. My cam is 251/259 duration @.050 I have 20cc dished pistons and my compression is exactly 9.4:1 and running 91 octane You can use factory heads these days as there are quite a few aftermarket pistons that have the proper dish to bring the compression down. I'm building a 1967 400 next week that's using 670 heads. Using a dished Icon piston on that build that will put compression at 9:1
Neil it depends on the quality of the fuel available. Do you guys in Canada have the same problem as us with the ethanol added to the gasoline. It's a cap shoot to know what the actual octane rating is from station to station week to week. As far as compression ratio. 9:1 should be fine with slight variations in the gasoline. Back before they started with messing with gasoline I had no problems running 72cc heads and flat top pistons on 93 octane. I was having problems in yesterday's heat with 91 octane. I was told that this stuff boils at 100 degrees now. My fuel pressure was up and down by 3lbs. But that's another thread.
Bluebird, I was considering sending my 400 block to butler, and have him clearance the block for the crank and build the short block out for me using one of his balanced assembles. Along with that we were going to add 4 bolt main caps and line bore it. The next set would be porting the heads and putting it together. I just remember how a hot cam in a 400 seemed pretty mild in a 468. I figured a 500 would allow a smooth idle, good vacuum, and a broad torque range with a cam duration of 250 at .05 spectrum. But I have plenty to learn and that's why I ask a lot of questions. I also have a 70 455 I could stroke and build the 400 stock. I do have alcohol free gas available but I would have to buy local. (Actually in Mineola, tx)
Big Chief, Is there a good quench pad with those pistons, a D shaped dish instead of a round? And do you have the edge of the pistons ( the non-dished portion) at a zero deck height? One exception to the aftermarket junk I found was the Ross Racing pistons, those things are so nice I wish I'd bought nine just so I could have one on display.
Niell, if interested. I have 10.5:1 static compression and 8.1:1 dynamic with a 230/236 camshaft that has the intake valve close 43 Deg. ABDC. I would imagine a 251/259 cam on a 9.1:1 static engine would have a dynamic a lot lower than mine. I put in a rather mild camshaft, for the build, as I wanted more low end torque than high RPM horsepower, if I was racing as Bigchief is, I would put in a bigger camshaft and take it up to 7000 RPM for the horsepower and speed.
Cole, Sounds like fun. If you're getting Butler to build your bottom end you should end up with a good stout package. Have you/they determined what you will have for chamber size and what your piston dish/dome will be?
I'd like to chime in here, if you guys don't mind. I'm no expert, but I've done quite a bit of bracket racing.
The OP says he only wants to run in the high 11's. As some have stated, you don't need a 4.5 stroker, or 600hp to run 11's. Those numbers should put you in the 10 sec zone.
As has already been mentioned, the 4.5 stroker will cost MUCH more, and tear up more parts. 400-450hp and 500ft lbs of torque will get you in the 11 sec zone. My 455, with #215 heads, runs 7.30's in the 1/8 mile, in a '74 hatchback Ventura. I think that figures out somewhere in the high 11's in the quarter.
Even back in the old days, my '67 bird ran 11.80's with a 455, RA4 cam, Rhoads lifters, unported iron heads, a 750 Q-jet, and TH400 with a stock 13" converter.
Both of these engines had 4.21 stroke and heavy TRW pistons. The Bird engine even had cast rods. I always used a rev limiter, set at 5500, and we shifted at 5000 rpm. It's all about the torque. With a RA4 cam, the peak torque of a 455 is probably around 500ft lbs @ 3000 rpm, or just a hair over. No need to turn 'em 6500.
And if the car will be driven on the street, at all, hard street tires wouldn't have a chance with a 4.5" stroker. It could be downright dangerous. Besides the MUCH higher cost involved, I can't see one single reason to build a 4.5, just to run high 11's. But the thread title asks the question-- Streetable ? The answer to that question is: sure it's streetable. There use to be lots of Cadillacs running 500 cubes.
If you get just the correct combination of parts, you can build a very strong machine. Or, you can overbuild it, with the wrong combo of parts, and wind up with a wild, dangerous, parts and money eating monster.
But, that's just my opinion. That's what we do on car forums--offer our opinions.
Now the OP ask if anybody was running a 4.5. Yes, there are quite a few. My engine guy built a 400 block, 4.5 with KRE High Ports and a solid roller cam. It made 755hp on the dyno, @ under 6000 rpm. It was for a Modified dirt tracker. But our local track closed, so he put it into a '69 street GTO, with a 5-speed stick. And he drove it to several car shows. He sold the car recently, but had to swap in a smaller engine for the new owner. A 500 cube Pontiac ain't for everybody.
But, if you got money to burn, then, as they say, "Knock ya self out." If I had unlimited $$$, I'd blow HUGE amounts on Pontiacs and Pontiac parts !
