427 Stroker Article in May Car Craft

[jayb]

Just got my copy of this magazine and was surprised to see an article on building a 427 stroker!  Kind of an odd build-up, though.  This engine was really optimized for low RPM operation.  They went .050" over on a 427 sideoiler block, and added a Scat 4.25" stroke crank, rods, and JE pistons to get 488 cubic inches.  But they limited the compression ratio to 9.9:1, and went with a pretty small hydraulic roller cam that was comparatively large on the exhaust.  Cam specs listed in the article are 235/249 @ .050", with .577/.561 lift and 107 LSA, installed straight up.  The engine used near stock Edelbrock heads, rather than some high riser heads that they had on hand; the article implied that they may not have had an intake available for the high riser heads.  It also used a PI intake and a Quick Fuel 850 carb, and a Mallory Unilite distributor.

The article claims a nearly unbelievable torque of 676 ft-lbs at a very low 3900 RPM, and only 561 HP at 5100 RPM.  At 3000 RPM this engine is already making 654 ft-lbs.  The peak torque is nearly 1.4 ft-lbs per cube, which is a great number.

I've never built a 427 that is optimized for this sort of low end torque production, so I don't have any direct comparison data to a different engine, but if those numbers are right, that motor is a real stump puller...

[machoneman]

So......you think those dyno numbers may be suspect?

[jayb]

Well, I'm not sure.  Based on what I know about dynos, I'm always a little suspicious of really good numbers.  But that motor is optimized for a range of power production that I don't normally use.  For example, the 427 stroker dyno mule that I did for my book peaked at around 625 ft-lbs of torque, but that was at 5000 RPM.  It also made 675 horsepower at 6900 RPM.  That engine was optimized for power production in the 5000-7000 RPM range, whereas the engine in the Car Craft article seems to be optimized for power production 1500-2000 RPM lower than that.  So the Car Craft numbers could very well be correct, but I'm interested in feedback from anyone else who has built a similar motor, to see if they saw a similar torque number.

I'd have to say though that I really don't understand why the engine was built the way it was.  You've got a 7000 RPM capable shortblock, and you cripple it with compression and cam that minimizes horsepower production.  Maybe this has something to do with the vehicle (or boat?) that the engine is going into, and what the RPM and fuel requirements of that vehicle are.  For any normal street car, though, 650 foot pounds of torque at 3000 RPM, which is what is claimed for this engine, is practically unusable.  You could give up a whole bunch of that torque and not see much difference on the street, while making another 75 HP after 5000 RPM. 

So, I'm not saying I don't believe the numbers, I would just like to know if there are similar builds out there that exhibit similar performance...

[4twennyAint]

Jay:
I read these articles and then apply the "magazine dyno" correction factor; subtract 10%.  I let my dad borrow your book so I can't look up the results, but has any combo ever made over 500 HP with a PI intake? 

[KMcCullah]

Their TQ is some kind of impressive for fairly mild parts. And those cam specs are damn close to Comps Mutha' Thumpr.

EDIT>>>>http://www.compcams.com/Company/CC/cam-specs/Details.aspx?csid=1485&sb=2
 

   

[shady]

for a street driven car as opposed to a drag car, that there just might be a very fun ride. and last forever.

[jayb]

Jay:
I read these articles and then apply the "magazine dyno" correction factor; subtract 10%.  I let my dad borrow your book so I can't look up the results, but has any combo ever made over 500 HP with a PI intake?

Sure, my 427 Sideoiler dyno mule made around 540 with a PI.  I didn't run that intake on my 427 stroker dyno mule, but it would certainly have made more on that one.  Also, for what it's worth, the magazine's don't always print bogus dyno numbers; the ones on the 390 stroker I did for the Car Craft article in 2008 were printed verbatim with my dyno data, which was completely accurate.

[Drew Pojedinec]

for a street driven car as opposed to a drag car, that there just might be a very fun ride. and last forever.

Not to mention, it'd make a great engine for your dumptruck.

[My427stang]

Oh man....the dump truck comment hurts a little.  My 489 was a ported RPM, 242/248 @ .050, but the heads were worked a bit and it is 10.7.  It sure wasn't a truck motor then with only slightly more cam

That being said, I ended up lashing the cam as tight as I dare, from .027 hot, to .010 cold, and added a ported EFI Victor and it'll still pull off idle in 5th

I do think that build is a bit odd, cam seems late at 107, compression seems low, including DCR.  I wonder if it's even accurate, it's not easy to get a 488 to that low of a static number.  Also, seems like they cranked the cam back to offset the small intake lobe and of course, the PI probably starts wheezing pretty good with 488 inches under it.

If it is a Thumpr cam of some sort, which I assume it is, it likely sounds better than it runs.  Although guys seem to have good luck with those lobes, that tight LSA with all the exhaust duration hasn't impressed me much in the one I used on a 396.  Sounds awesome, but doesn't have the oats a 270S would

[jayb]

Not to mention, it'd make a great engine for your dumptruck.

LOL!  I was thinking the same thing!  (Sorry Ross  )

Talked to Blair P this morning about this, and he is rather skeptical of the 675 ft-lb number...

[Drew Pojedinec]

If I ever meet Ross, I'll be sure to quote him for a custom Gooseneck hitch install. 
Sounds like the next FE related CarCraft article, "Pony car that hauls an actual Pony."

[MeanGene]

I expect nothing less from Chebbie Craft- make the Ford look lame, makes the Chebbie look better 
After they came to Napa and ignored a cherry genuine Webered USRRC/ FIA big fender 289 Cobra, and an original race GT40 (#P1009, very early car) in favor of a fake 69 Z28 that belonged to a friend of mine, started out as his neighbor's wife's 307/Powerglide stripper- and they put it on the cover of the mag LOL...

[cjshaker]

Not to mention, it'd make a great engine for your dumptruck.

LOL!  I was thinking the same thing!  (Sorry Ross  )

Talked to Blair P this morning about this, and he is rather skeptical of the 675 ft-lb number...

Hey, I've got the dumptruck!! I say we try it out!!

[Barry_R]

A 10:1 compression, 488 inch engine with 235 int duration and a 107 LSA is going to be an odd package indeed.  I am also highly suspect of a 1.4 lb per cid torque number with off the shelf Edelbrock heads.  Most moderate street stuff comes in between 1.1 and 1.2 per.  The better EMC engines frequently go between 1.4 and 1.5, the winner might sneak past 1.5.  I'd really like to see the raw data and cell conditions on that one.

[blykins]

That's a Thumpr camshaft.  Probably get a little more torque with a tight LSA, but I too would be *very* suspect of 1.4 lb-ft /cube torque numbers. 

I did a similar engine, it's on Jay's dyno results page.  Little less camshaft, but my peak was 620 lb-ft for 482 cubes.  Made 538 hp as well.  That's with BBM heads (should be heads and shoulders above an out of the box Edelbrock), a modern ring pack, 9.7-9.8:1, and a 224/230 @ .050" hydraulic roller.  I don't think there's anything I could have done to that engine to get another 50 lb-ft out of it......