Hey all,

Have the 408 roaring, but I'm running the stock 5.8 EFI manifolds, and it's unsurprisingly killing my top end.

I was eyeing the trick flow box intake, scored the upper,but lower is discontinued and I cant source.

What's the consensus for an alternative efi setup? 408 with x303, maxes out around 6k in a street truck, so not leaning towards a hi ram that emphasizes top end. Also heard about fitment issues with the Edelbrock, but want to see what you all think.

Thanks,
-glaser67

 

I've never seen one but it appears Holley has a new box style intake with an option for front or side throttlebody. Of course finding it in stock anywhere could be the challenge.

Holley 351W Ford Hi-Ram EFI Manifold 300-241 | eBay

 

If you can find the Edelbrock PN 7184 (351w Lower with bigger port openings that use the 1262 gasket) and match it to the Edelbrock RPM II Upper intake you would have a pretty good intake setup. Other than that keep going to swap meets and searching Facebook for the rest of your Trickflow set up.

 

I have the Box R on my '94 and the Edelbrock EFI Truck intake on my '89. The box does not fit under the windshield wiper cowl. I had to do a substantial amount of cutting and bashing to make room for the box. The Edelbrock truck intake does fit, so long as your body is in good shape. If you cab supports are sagged out or the body mounts are gone, it will hit the firewall. This might be a consideration for your situation.

That said, the Box R performs excellently. Easily breathes out passed 7000 RPM.

The Holley intake looks good on paper but I don't personally know anyone that is running it. I considered it myself but there were claims by Holley that a normal distributor doesn't fit under the intake and you'd have to use their low pro deal or swap over to a Direct Ignition System, and I wasn't willing to pay all that money at the time.

 

Just out of curiosity. How many Rpm's does the Edelbrock truck intake turn up to?? Here's a Video that Engine Power made with the Holley's High Ram on a 408...

 

It's an idle to 5500 intake on a 351W, not nearly enough for a 408W unless you want to be done by 4k rpm and lose a lot of power getting there.

 

On my 351" motor, it noses over pretty hard around 5500. Part of that is the intake, part of that is the cam. The whole truck is set up for lower RPM torque for towing so not a big deal in my case.

 

Great info, thanks.

What I decided on was the Trickflow Box R for reasons that it appears likely to flow more air than any other multi port option, and the side intake makes things simpler harness wiring and space wise. The metalwork to the wiper cowl concerns me, but I have the upper lower right here and I think there's enough aluminum there to mill them and the 1" space down to gain some room, but we'll see during test fit. I like that the box r might work with stock fuel rail which would save some money and time.

Also considered throttle body options for the Box R and Eddy. BBK seemed like the best candidate for the Eddy setup, which for this chart I found over on the bronco forum shows, an 90mm "Mustang upgrade" will flow a little more than the BBK dual 60's,


Also found a single blade Accufab 90mm that their site lists at 1369 cfm if trick flow route.

Where I've goofed up was pulling the trigger before knowing what cfm the motor would need, other than tons more of the stock efi induction except for a 73mm C&L maf housing. So I bought the upper lower with the most anticipated flow capabilities.

What question I have for the group is how are engine cfm requirements determined exactly? I still need to piece together a bore size for the single blade throttle body and MAF sensor, and I anticipate that their flows are as significant as the rest of the engine, and complete the induction upgrade that I think is severely restricting this setup.

thanks,
-glaser67

 

I am not sure on how you figure the size of the throttle body needed but if you are using what is in your signature with 39lb injectors I would say you need a pretty good sized throttle body. You might want to look on this web site and play with there calculators. It might give you a idea.... Wallace Racing - Automotive Calculators
Speaking of your signature you list Promaxx 215cc heads. A quick look at Promaxx web site they dont list a 215cc head. They offer a 210cc Project X, a 210cc Shocker, & a 180 & 175cc. Which heads do you have??

 

Heads are project x 210 cc, 30# injectors. I'll run the calcs from that site then call my builder and report back.

 

I have the 90mm Accufab unit on my Box R. No reason to go smaller than that on a 408" motor.

 

That's great info! Would you match the size on the MAF or go even bigger? Also, what MAF did you go with? I've been eyeing PRO M but can't get them on the phone.

 

I'm not using MAF. PimpX ECU from Stinger Performance Engineering.

 

I assumed the pimpx used a MAF sensor, my mistake. The EFI is from a fox body with a quarter horse chip.

Anyway, my engine builder suggested a 750 cfm carb, but I'll run that by accufab for reference. There 70mm is listed at 787 cfm, which seems small but I'll get there take.

 

Ended up going with the Accufab 90mm TB. It came with stock IAC connection, TPS connection, and offers a throttle cable bracket plate. They and Pro-M (went with for the MAF sensor) both suggested 90mm, and my engine builder isnt real experienced with singe blade TB's, so we'll see how throttle response is. The Box R does hit the firewall where the upper and lower come together. Before the mockup I considered the possibility of having some of the upper/lower surfaces milled down, but here I dont think it will solve it.

Never cut into the fire wall before, and am not what to do with the hole once it's gone. Do I need to fabricate a filler panel out of break metal or use some sort of matting? No idea really, but am curios to know what GNR22 did on his build to the firewall?

Anyway, setup looks awesome and ready to move some air!





Thanks all,
-Glaser67