Greetings all! As I continue to maintain and improve my 1992 F150 Supercab SB, I have finally worked down to the drivetrain. I know my stock 302 needs some love and my E4OD is on the way out. I have posted another thread about the E4OD but this thread I am going to focus on my plan to build a 351W Stroker. After some research, I have come to the conclusion that the 302 block is just too limited on power upgrades since the factory block can only handle about 500 hp before catastrophic failure. And yes, 500 hp is a lot probably more than what I need but the cost to build it puts me in the range of building a 351W with substantially more power. So, I've decided to pull the 302 and save it for another build entirely and go with a 351W Stroker. Looking to stroke it out to 427. The general consensus is the 427 gives you great low end power, but you sacrifice top end performance. You can make up the top end performance with a turbo or other forced air induction system. I am curious if anyone has done something similar to what I am trying to do and advice for the build in general. Thanks in advance!

 

408w, and he is emission compliant, but still better than 500 ftlbs and also built his E4OD to take the abuse, see link-->Seattle FSB 408 Stroker Build | Bronco Forum - Full Size Ford Bronco Forum

 

Seattle FSB built a very strong reasonable stroker. Something to learn from for sure. The extra $$$ to go 427 is very questionable for a street build IMHO.

 

His only mistake was the intake.. the Eddy truck was designed to boost torque on a stock 5.8 but it's way too small for a deep breathing stroker and hurts power across the board. The correct EFI intake for a build like this is Victor, Holley, or Trickflow R with a large single TB, there is no need for long intake runners with 400+ cubic inches in play. 10yrs ago there were a couple members here that build strokers with the Eddy truck intake initially and they too got rather underwhelming results until they swapped on a different intake. One of them contacted Edelbrock for comment on the intake and they confirmed all of this.

 

He still has to pass emissions, is why he had it built, that way, he wasn't going for all out #'s, wanted reliable, torque and he got that and then some, do you think the other intakes would pass smog? for $800 back then, I still wouldnt chose it, I would have just kept old one, every thing I seen about the 35 ft lb tq,on Eddy truck intake, was the top end package.

 

The intake won't have any effect on emissions good or bad.

 

I agree & disagree on the Eddy truck intake. In stock form and paying full new price. There is better options for sure. If you found a deal on a used one. Heck ya they can work very good. The runners are easily accessible if you wanted to shorten them for more RPM's. In stock form the Eddy flows pretty good except for #5 runner. From the video's I have seen from BigDog the Eddy truck manifold outflows most all other Edelbrock EFI intakes. Ported they can flow more than the trickflow's.

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​​​​​​https://www.youtube.com/channel/UCYS...L4b7xcQX4A_PSw

He has more video's on his FB page as well. I can't say if his stuff is any good or not as I have never dealt with him but he seems to be up front about his stuff.

 

Bigdawg, leads you to believe the truck flows a lot, the upper does, all by itself, not with the lower on it, like the others he's flow testing, if you flowed just the uppers on the others(lol) anywho, they would have big #'s also, but he failed to mention, and he is never sure of himself, when he talks about flow, you will be disappointed, with theirs. I did my stock, just hit at it, and I had never done one before. and it suprised me with the gain I made.-->5.8 upper/lower flow number results b4/aft dyno - Ford Truck Enthusiasts Forums

 

If a stock bottom end 351w is pushing max torque 400@4500 RPM because of aftermarket cam, re-worked heads, intake, etc.
What sort of gains would stroking it to 408w keeping same cam, heads, intake etc.?

 

How do you determine that the 351w Edlebrock 3881 truck intake runners are too long for a 408w?
Is this just due to the fact that it is >400ci from others experiences, dyno results, etc?
Or is this calculated?

 

It would make more Torque & HP. Peak torque would be at a lower Rpm if using the same cam. The longer stroke has more cylinder vacuum for filling to get you the extra power.
Richard Holdener on Youtube did a big head test. First using a 302 cuin then a 331cuin. At 8:15 in the video he talks about just adding stroke using the stock E7 heads and why it made more power.

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At 6:00 he shows the 392 with the stock heads. Also note that with each increase in Cuin he used a bigger camshafts with more duration. What all this is showing is how more Cuin will draw on the same heads.


I have tossed around the idea of building a stroker and came across a couple of graphs on Camshaft's VS Cuin. In the chart you can see if using the same cam duration it moves the power band downward.






You should also take a look at these....

​​​​​​https://www.ford-trucks.com/forums/1657157-effects-on-camshaft-when-switching-to-a-longer-stroke-crankshaft.html

​​​​​​https://www.motortrend.com/how-to/crankshaft-stroke-lobe-separation-angle/

 

Flow benches use a constant flow of air but an ICE doesn't work that way.. it flows in pulses so the acoustic tuning of the intake (and exhaust tracts) plays a part in power delivery. Intake runner length(and exhaust headpipe length) have a natural resonant frequency based on thier cross section and length just like any pipe and maximum air velocity happens at that frequency. At the even harmonic frequencies above and below the primary there are additional flow peaks, and in between those peaks airflow is actually restricted somewhat. Carb intakes are generally so short thier acoustic tuning is too high for a street engine so they have little effect positive or negative, but long runner EFI intakes attempt to use this factor to boost power in a specific operating range. So when selecting an intake two key factors must be considered at the same time... both runner length and runner cross section must compliment the targeted rpm range and the overall airflow capacity of the motor, get either one of those wrong and it doesn't work. The word directly from Edelbrock tech support is that the 3881 was designed to boost low rpm power on a stock 200hp 5.8 motor, it's simply not suitable for a stroker that moves more than double that much air.

 

There is not a lot of info out there for runner length but I did come across this a while ago....

 

Back to the measuring devices and calculator, thank you, perfect!

 

Some more info for you.

​​​​​​Tmoss Porting