408 EFI intake sanity check

[landshark99]

My 408 with AFR 205 heads and 70 mm TB dyno’d 400 hp and 450 tq with the lightning explorer intake.

I think the lightning lower and explorer upper were probably choking the 408 as well.

 

[markw]

Cool Mark... what's the new engine's detsuld?

Not sure what that is The new engine is a Ford Performance aluminum shortblock with AFR 220 heads. TrickFlow intake, 90 mm TB. 60# injectors. Ford harness and computer. Don't recall the cam specs off the top of my head but it's an off the shelf CompCams part recommended by their rep. It's a good running engine but I don't know what kind of power it makes.
The guy who ran the tests on the 408 is very conservative with his numbers. That engine is out of the Bronco and will be overhauled for my yet to be started Adventure Bronco. I may see if I can get the intakes honed and go ahead and re use them. Sure as hell not going to put a FiTech on it!

 

[68ford]

Mark, my new engine is similar to yours. It's a 438 so I have .100 more stroke than you do, but I have the same block and bore size. 10.4 to 1 compression. Same heads as you. Basically a 250 duration 640 lift on a 110 lobe sep cam. Victor manifold with a big Holly sitting on top of it. Peak horsepower is that 560 at 5700 RPM. These large stroker engines need a lot of air. Plus having a lot of flow does not seem to hurt these engines in lower RPM. Mine makes 500 foot-pounds below 3000 RPM

 

[68ford]

Depending on your gear ratio and tire size, but with a 35 inch tire 400 horsepower and 450 foot pounds of torque should actually be achievable at the tires with your setup. Friend of mine with a 427 with AFR 205 heads and a smaller cam than my engine was able to put 398 horsepower 405 foot pounds to the ground through a C6 and 37 inch tires using fitech EFI of all things.

 

[markw]

Those are amazing numbers! I still think we have some room with the tune. I really want to do a live tune on the dyno, just not sure when we can get that done. Be nice to get it before the end of April for the M1K.
Transmission is 4R70W, GR 4:56 and 35" tires. I've been advised that 5:13 might be better but Randy likes what we have right now. Kind of hijacked this thread! I hope this is information of interest to the OP! Mark

 

[68ford]

All I can say is that depending on what stall speed you're using, you may not be able to use OverDrive with 4.56. RPMs will be too low in overdrive and you'll just be slipping the converter and generating a shitload of heat for no reason. Like everything, it all depends on each part of the overall package. Baja is so different and you really can't apply opinions from non racers. And then you reduce information down further because most Baja racers opinions don't apply necessarily well to an early Bronco with four wheel drive.

 

[nvrstuk]

Lot's of good info here for the OP.

What 68Ford said.... These strokers need a LOT of air. To start my 460 sbf we used my 418 tune (the one with the very conservative custom "torque" cam) and took the % the 418 and multiplied it to match up for the 460 (since it was larger) and used it (essentially) to start on my 460... over the course of several tunes he kept saying... "this thing is using a TON more fuel"... needless to say the power difference is night and day between the two and I have gained power down low.

No, it doesn't idle smooth, but it can idle for 15 minutes, hit the skinny pedal and w/o hesitation... it RIPS right off of idle.

Cam @.050 in): 242°/248° @.050" w/1.65 roller rocker, @.050, .594/.618 lift,

 

[68ford]

Mark, not sure why I did not think of this sooner, but my old engine from my TT doorslammer was a 427 with the same heads you have. Same cam, victor manifold and carb I am still running. It made 560 HP at 6200 and 540 TQ at 4500.

 

[EFI Guy]

I've tuned a handfull of 408s running Lightning intakes. They make great power...until they don't. Every one of them showed HP and TQ dropping like a rock at right around 4400 rpm, regardless of head and cam choice. So the intake is obviously the choke point.
I wouldn't hesitate to still use a Lightning intake on a crawler or cruiser with an auto that doesn't ever exceed that RPM range, assuming I already had the intake laying around. If you needed to buy one then I'd just go aftermarket at the point since used GT40s are still so expensive and aftermarket intakes can flow more.

My 408 with AFR 205 heads and 70 mm TB dyno’d 400 hp and 450 tq with the lightning explorer intake. When I built the 427 we had to move up to 90mm and the TrickFlow box intake. With the old setup the 427 made the same power as the 408 so it was obviously limited. I guess no down side to going big if you have the room.

Those are amazing numbers! I still think we have some room with the tune. I really want to do a live tune on the dyno, just not sure when we can get that done. Be nice to get it before the end of April for the M1K.
Transmission is 4R70W, GR 4:56 and 35" tires. I've been advised that 5:13 might be better but Randy likes what we have right now. Kind of hijacked this thread! I hope this is information of interest to the OP! Mark

I seem to remember that first 408 @499tq with your GT40 intake. I remember being disappointed on the last pull because we just barely missed the 500 mark.

There is still more left in the new motor. The timing was left pretty conservative because we had no knock detection and the guys were telling me that there would be no way they'd ever be able to hear ping in that rig. You still have some wiring homework to do before we put her on the dyno to see what she can really do. =)

Mark, not sure why I did not think of this sooner, but my old engine from my TT doorslammer was a 427 with the same heads you have. Same cam, victor manifold and carb I am still running. It made 560 HP at 6200 and 540 TQ at 4500.

That seems pretty reasonable, his datalogs were showing a little less HP but a lot more torque. Carb manifolds typically make more HP but less TQ than long runner EFI intakes.

 

[markw]

Garry you have better memory than I do! We’re in process of upgrading the suspension and replacing the front axle. Hope to be able to get the rig back to Randy in a month or so then we can concentrate on the tune. We do have to stay a little conservative because the fuel situation in Baja can be uncertain. Most stations have premium but not all and I’m not a big fan of additives to boost octane.


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