Stroker question

[willowbilly3]

Strokers, I wonder how far you can go? It seems like if it can be made to fit then do it. I haven't ever done one, probably never will but it seems that just the old bigger is better mentality has taken over on this subject. Back in the 60s-70s we always wanted to stay over square on the bore/stroke and looked toward engines that had a larger bore/shorter stroke for serious performance. Of course there are other considerations like connecting rod angles and lengths, bearing speeds ect.
I still am not sold on under square engines, that is a larger stroke than bore. Maybe they are torque monsters, maybe I am stuck in the past but I am curious on this concept. I would like to hear other substantiated opinions.

[My427stang]

First great discussion topic, I'll break my opinion into chunks.

1 - Some of the magazines and many people have tested bore versus stroke, and in terms of displacement ONLY, there really is no difference in power on how you get displacement.

Where it comes into play for power-only, is if your bore starts limiting airflow through shrouding and/or valve size limits.

With that in mind, stroking a street FE, especially for a truck, never gets to that level of RPM or airflow

2 - Rod angularity can be a problem in some short deck motors. With a shorter rod, comes more angularity that forces against the cylinder wall. A big issue on 351Cs and some SBFs

FE strokers though use a 6.7, or even a 6.8 inch rod that reduces that angularity, and with the tall deck height still has a decent compression height on the piston, so it really isnt an issue, even at 4.25 stroke (rod ratio of 1.57)

It really comes down to HP/torque per cid, and ultimately how much you want to spend (not invest LOL)

Realistically, its pretty easy for a truck FE to get to 350-375 HP, and remain reliable. That is .96 hp per cid. To do soemthing like that, you need to use the entire RPM range to make the power, often above the intended use.

Now, if you still use the entire RPM range, that same motor with a stroker crank at 445 cid (assuming adequate head flow of over 200 cfm, which is almost ANY FE head), will make 430 hp.

Now, that extra 50 hp will be a serious benefit, but also adds quite a bit of cost. If we consider two complete rebuilds that buy the same quality of pistons, bearings, cams, etc, a 390 can make the high 300's in HP without buying a crank and rods. The 445 needs approx 1000 dollars extra for those parts.

1000 for 50 hp sure isnt a bad deal, and if you compare it to someone pulling out a 360, that same motor would have to rev even HIGHER and would probably only make 325-340 hp (fun with math, might not even get there) so in that case the 445 could get you an increase of 100 hp for 1000 bucks.

Its a good deal if you have the dough.

I love my 489 stroker, which is almost square (4.277 bore x 4.25 stroke) but I will probably stroke the F100 to 445. The only thing that will stop me is if I build a BIG Boss motor for the Mustang and put the 489 FE in the F100.

BTW, Barry at Survival is a good guy and sells good parts, but there are other guys that do too. Doug Garifo on the west coast has been selling FE strokers since inception and is who I buy mine from. Certainly a shipping cost savings for guys out there

[willowbilly3]

OK, here is a real life comparison I always go to. The 400 Oldsmobile. The first ones were shorter stroke and bigger bore, I can't remember numbers. Anyway in 1968 when the 455 came out, the stroke was changed on the 400 to the same as a 455. Long story, anyway we are talking about the same engine design, same heads, as comparable of a baseline as you could find. The larger borexshorter stroke 66-67 400 would trounce a 68-69 long stroke 400..bad. I realize there is some unshrouding of the valves involved but I don't think that is the only element that made the short stroke engine rev quicker. You can talk about numbers, horsepower and torque but at the end of the dragstip, the car ahead is what really tells the story. I'm not dissing any of the theory and numbers. Just giving my 2cents on a seat of the pants and real world comparison. Obviously the short stroke engine had a smaller rotating mass and probably even smaller torque numbers. Probably more optimum con rod angles ect.

[427]

When I built my F.E. I started to use the 3.98 428 crank that would have given me 454 cid. but i chose to use the forged 3.78. It would have been more tourqe but I like the quicker revving of the smaller stroke. It would have been a good combination and very reliable.Brian.

[My427stang]

OK, here is a real life comparison I always go to. The 400 Oldsmobile. The first ones were shorter stroke and bigger bore, I can't remember numbers. Anyway in 1968 when the 455 came out, the stroke was changed on the 400 to the same as a 455. Long story, anyway we are talking about the same engine design, same heads, as comparable of a baseline as you could find. The larger borexshorter stroke 66-67 400 would trounce a 68-69 long stroke 400..bad. I realize there is some unshrouding of the valves involved but I don't think that is the only element that made the short stroke engine rev quicker. You can talk about numbers, horsepower and torque but at the end of the dragstip, the car ahead is what really tells the story. I'm not dissing any of the theory and numbers. Just giving my 2cents on a seat of the pants and real world comparison. Obviously the short stroke engine had a smaller rotating mass and probably even smaller torque numbers. Probably more optimum con rod angles ect.

You dont have to believe me, build whatever you want. Seems like you already have an opinion.

Just trying to share some info. Consider it worth what you paid

[willowbilly3]

I'm sorry. I wasn't trying to be argumentative of your statement. You gave some very good information. As I said before, I am not building anything, just trying to find center between some older thoughts and new approaches. I thought it would be an interesting subject, not just one person give the theory and end of discussion. There is no substitution for cubic inches and stroking accomplishes that. It seems like there might be a bit more to it than that

[My427stang]

No problem, I'll look into the Olds motors and see whats there. I have done a mild couple 403's, a single stock rebuild of a 425 and the square root of nuthin for 400 and 455 Olds, so I am no Olds expert.

There is no doubt that the olds 455 is an extreme, but I wonder if there is more to that one going on. Change in deck height may have changed the intake design, compression or head change, I dont know. For that matter, with that one maybe it just got to be so small of a bore that it couldnt feed 455 cid.

A good rule of thumb is 2 x intake flow for max hp, and I have seen a change of 15 cfm on a buddies Edelbrock heads going from a 4.13 to a 4.23 adapter on a flow bench, so the bore really can be worth a bunch of airflow.

I have buddies pulling 500 hp with a 390 based stroker though, and not so wild that they couldnt be in a truck (although probably a little rowdy for that) So they really do OK, and these arent anything fancy, decent set of heads and a cam.

[willowbilly3]

Olds kind of did like Ford and juggled a couple blocks and cranks to come up with different engines. In stock form they all made their power pretty low, not high revvers at all, 5000 max.
The 425 shares the same stroke as the early 400 iirc. The 425 was an impressive engine and could easily shred a set of tires on a big 88. I am not sure on head flow of the big blocks but the 350 Olds heads of that era would out flow Chevys best 350 (I read )
The 403 was a small block and had good proportions but from what I've read the wimdowed block was too weak be considered for any serious performance.
Well, anyway, this isn't an Olds forum (although we do know our fearless leader harbors some)
Do you have any graphs from dyno pulls showing the differences of different stokes on the same basic engine? I would like to see the different torque curves and numbers for different combinations

[427]

427 Stang what kind of block you running in that 489 stroker? Thanks Brian.

[My427stang]

I dont have anything, or know anyone that did, in terms of back to backs that would be comparable.

Brian - Mine is a 63 center oiler block, sleeved in a couple holes where the walls were a little thinner than I liked.

[427]

427 stang my block is a 64 center oiler. Its had a rough life. Back rod broke and went through both sides of the block and busted back cylinder. I got a good deal on it and got it fixed back. Did your block have cross bolted mains?

[My427stang]

Absolutely, all 427's are cross bolted.

Mine suffered a similar fate, not to many of these old blocks lived without some injury

[willowbilly3]

I used to see marine blocks that had been repaired, seems they cracked in the lifter galley when they froze.

[GT-Racer]

Since you brought up rod ratio's... What is to much (to risky) for the street? I was gonna stoke my 351w to 426ci but I've read where 408ci is a more favorable rod ratio. Do I really need to be that concerned in a "fun" street truck that isnt thrashed continually? Just getting opinions and thoughts...
I know I dont need a 408 or 426 but it will be nice if the wallet allows just to have the extra.

[hotrod ford]

talking about risky. is it anymore risky to sroke a 360 as you would a 390? would a 360 be able to put up with it?