Stroker questions

[bsklein]

What, in general, are the advantages and disadvantages of increasing the stroke of an engine? For instance, you can stroke a 351W to 427 to greater. How would this compare to a big block 427, assuming adequate heads, similar cam, etc., as far as torque and hp curves are concerned? What is the difference between a small bore, big stroke engine and a big bore, short stroke engine?

Thanks all,

[sllib]

Barry,
You are opening up a big can of worms here, but since you asked, I'll put in my $.02 worth. Generally, the stroker will be lighter and probably cheaper. It will have more HP and much more torque than a 351W, but it won't have the sound or the panache of a 427SO. I've been asking these same questions myself for months and months now and have decided on the 427W for my own build. A good source of info on strokers, and Windsor engine performance, is Isaac Martin's book "Ford Windsor Small Block Performance" from HP Books and available at Amazon.com. There are a lot of stroked 351W's in Cobras out there and, hopefully, most of them will chime in. The big-block guys will get in too, but don't listen to them!!
Bill Stradtner

[Toivo]

Strokers are great idea's.
You need to worry about the compression height issues though...a stroker's piston is necessarily shorter in order to fit and this leads to ring land issues. Also, because the piston is shorter it tends to rock in the bore more.
Other than that, I can't think of anything bad about stroker motors. Even the 'won't rev' claim is relatively moot nowadays. The only thing you need to keep in mind is that if you go to a 427 stroker, that thing will need a lot more air than a 302 or 347 so you need to allow for that with the head and cam selections.
It is also way cheaper to build than a 427SO nowadays and you have a far wider selection of parts and places familiar with them.

[bmalone]

Barry:

The stroker builds are quite popular today. THe 418 also is a very common "package" and generally produces more horsepower than the 427 stroker. It is still not cheap to get to 500+ HP. Most 418 builds I looked at were around 20K.

That said, is also true I have test driven Sideoiler, 514s, 520s, 418s on the same day in different cars (I'm buying used). I was most impressed with the big blocks because of the amount of torque. They will really put you back in the seat. THe BB is likely to win a drag race, so it is important to ask yourself what is the intended use of the car.

If you want track time, the SB pulls longer (revs higher, less shifting) and weighs less. If you want a lot of street use and care about drag racing, the BB, with its superior torque will be a blast to drive (nothing like kicking it in 3rd gear when on the fwy.)

My $.02

Bill

[Bob In Ct]

Hey Barry:
The March issue of Hot Rod has a nice article on the subject. Rather than quote it I'll just let you read it for yourself. Before you stroke keep in mind that some of the most popular engines around today are already stroked. I could be wrong but isn't a 460 really a stroked 429? What about the 302 and 427?

Bob

[bmalone]

The 302 is a longer stroked 289. The 427 is a bigger bore, shares the same stroke as 390s and 406s. The 428 is kind of like a stroked 406.

The 460 is definitely a stroked 429.

Bill

[Andy Dunn]

Here are some bore and stroke figures on various ways to make a 427

block.......bore.....stroke
BB...............4.130 x 3.980
BB SOHC.....4.232 x 3.784
BB SHELBY..4.250 x 3.760
SB W...........4.030 x 4.170

as you attempt to increase the stroke of a SB engine, you make the piston travel a longer and longer distance. Toivo made a great point above where he said that you are using a shorter piston that can rock in the bore and lead to ring land issues. The other problem that you can rub into is the side loading the cylinder wall to a greater degree.

I do not think you can rev a SB stroker to the same extent of a BB stroker since piston speed is a function of stroke. Take a SB 427 at 6000 rpm and the pistons is travelling 4,170 feet/min, where a shelby aluminum BB 427 is travelling 3,760 feet/min. Therefore, you can rev an engine with less stroke higher due to piston speed.
http://www.prestage.com/carmath/calc_pistonspeed.asp

Stroker engines are very good at creating torque due to the leverage of the long stroke. These engines often resemble this on the dyno



The majority of performance car owners like the feel of this style engine for street use. It pulls like a freight train from 1000rpm. Racer's generally do not like this curve for the very same reason "it pulls like a freight train from 1000 rpm." On the track, most driving is in higher rpm ranges and torque in the 1000 - 3000 range can become almost useless. For tractor pulling, this is an outstanding curve as well


hope this info is useful


Andy