Hey guys,

https://www.ford-trucks.com/forums/5...40p-heads.html

I found the conversation this link points to to be very informative, but it did leave some unresolved questions.

I've been trying to get up a parts list of stuff I need to gather up to make my '95 351W roller motor put out about 300-350hp with good torque. I'm on the junkyard budget and would like to stick to Ford parts.

It looks like GT40P heads are the way to go, they flow about 200cfm stock, whereas the E7TE's that came on the engine need quite a bit of porting to attain that. So I'll probably go with those.

The intake manifolds are where things get a little cloudy. The 351 truck manifold set I have has inline oval ports that measure 2" x 1 1/4", measured at the upper/lower interface. The link above seemed to say that these truck type manifolds will peter out at or below 300hp, which is just a tad low for what I want to accomplish. And that they are very low rpm pieces. (My Haynes Ford Engine Overhaul book, for '93 and older, rates the 5.8 at 210hp@3800 rpm, 315 ft.lb@2800 rpm) I understand that the '94 and up roller motors do a little better in the hp department but not much. (Don't have any figures for that).

I went out and measured up the runner lengths of E7 head, lower, and upper, as per page 2 of the above link, and came up with about 23" of runner length. 75000/23 = 3260 rpm. If I add the 500 rpm correction the guy mentioned, assuming I understood that correctly, then that would be 3760. Almost spot on with the book.

This is obviously way too low for a 300-350 peak hp. I'll probably need to turn ~5000. Just looking at the two truck manifold pieces, the lower does not appear to be overly restrictive, but the upper seems to be a mess, as far as air flow is concerned. Not to mention being butt-ugly. Yet the truck type uppers don't appear to be as bad as the car types, in some respects. There are two TB venturi, tho at a 45* angle to the plenum. Once the air streams hit the plenum, they only have to make a 90* turn into the runners, as opposed to the 180* turn the car types have. The air entering the plenums is already headed in the right direction, sort of, to reach the farthest runners in the truck types, while the airstream in the car types has to be split and directed 90* in two different directions in order to flow across the runner inlets and reach the farthest ones. Both types have to make a further 90* turn down into the lower intake, and the truck type lower bank does have to turn perhaps an extra 10* on top of that. Then turn maybe another 75* or so in the lower intake to get to the heads. Every time I look at any Ford EFI intake I'm amazed at how restrictive they look. I guess they work ok, tho, I see evidence of that driving around every day.

Has anyone ever done any flow tests on the truck types? This was also mentioned in the above link but I never saw any figures. Has anyone ever cut the plenums open to see what's in there?

But enough of this ranting. I do actually have a few particular questions.

Is there a Ford car type 351w efi intake manifold set? Other than the expensive and rare GT40 & Cobra pieces with the staggered runners?

Will a normal 5.0 car type or H.O. inline upper mate to the 351 truck lower? Looking at pictures on ebay and such, the 5.0 runners appear more rounded than pure oval of the truck type.

Would a truck 5.0 upper mate to the 5.8 lower? Would there be any benefit in that? Maybe shorter runners? Are they both the same uppers, just badged differently? Or are the 5.0's smaller diameter runners? Smaller TB's?

Given negatives to the above questions, I guess I'll have to spend the bucks for a 351 GT40 staggered lower (or a knockoff) and scrounge up a 5.0 Explorer upper, or maybe a 5.0 Cobra upper. I'm guessing those would work together? Pretty expensive, tho, even an iron knockoff.

I'll appreciate any info and ideas.

Rob

 

Pretty, but not MAF friendly.

 

Your numbers and observations are all good, the factory truck intakes are indeed targeted at low rpm power. To get to your goal you will need an aftermarket short runner car style intake, the runner cross sections are larger which will flow more air overall, and the shorter runners are tuned for optimum flow at higher engine rpms. Unfortunately the only factory 5.8 manifold with any potential was the Cobra version used on the G1 Lightning. These are rare and expensive when found, and will still need porting to achieve 350hp naturally aspirated. It's much more cost effective to just buy aftermarket, there are some very reasonably priced intakes available out there now.

Concerning your other questions...
There is an adapter to put a 5.0HO upper on a 5.8 lower, but that intake is restritive on a 5.0 with some mild mods, so I don't see it helping a 351.
The 5.0 truck intake actually has much larger runners than the 5.8, same length but bigger cross section.. me thinks Ford goofed with the castings and got them reversed. A 5.0 upper won't seal with the 5.8 lower, and it's pointless anyway, runners will be no shorter and airflow will be a mess. One guy here dyno'd a 5.0HO motor with both the 5.0 truck intake and the HO intake and the truck intake made more HP.. would seem to indicate it flows better.

 

what about a generic intake such as

http://www.professional-products.com...roductford.php

 

The lightning 351 gt40 style and is supposedly pretty decent but is hard to find. You can try the national lightning owners club sight (nloc) for parts. Also you can go with a trick flow set up (also pricey).

 

Conanski said:
The 5.0 truck intake actually has much larger runners than the 5.8, same length but bigger cross section.. me thinks Ford goofed with the castings and got them reversed. A 5.0 upper won't seal with the 5.8 lower, and it's pointless anyway, runners will be no shorter and airflow will be a mess. One guy here dyno'd a 5.0HO motor with both the 5.0 truck intake and the HO intake and the truck intake made more HP.. would seem to indicate it flows better.



Yeah, I discovered that today, myself. Went over to my Dads and removed the upper 5.0 efi intake on an old '88 F150 junker. Upper says 'Electronic Fuel Injection' instead of 'EFI'.

The runners are totally different. The 5.0's are rectangular (more or less) and measure 2 1/8" x 1 1/8". The areas of the openings are quite a bit greater than the 5.8. That does seem to be ***-backwards, as you say. I also measured the runner lengths of the 5.0, both upper and lower banks, and they are about 1" longer than the 5.8 lengths.

I suppose with enough welding and grinding you could achieve some sort of match and flow, maybe remove a section of the runners to shorten them, but I don't reckon I'll be doing all that.

I guess I'll be going with plan 'D', then.

Thanks, fellas.

I'll look at dragogt's link, and also at the Lightning club.

Rob

 

have fun and good luck

 

I suppose it would be cost prohibitive, but a custom manifold could be fabbed that would have all the dimensions you want. Then again, I don't know what any of the cast hi-performance manifolds cost.

Dave

edit: just looked at the link in dragogt's post. those look promising. they seem to have used runners shaped like those in the truck 5.0.

 

I've never tried to fab an intake but if you look at trickflow's breadbox intakes, they look rather simple design.

 

hears a another link w/a price this time
http://mustangsunlimited.com/itemdy00.asp?T1=PP54020+01

 

I saw the Typhoon intakes on Ebay and I'm awful tempted to try one out.. unless somebody tells me it's junk. $300 is a great deal though. Of course there's a throttle body and EGR spacer to buy as well....

 

The breadbox is intended for a high rpm or blown motor though...

 

Why not take the 351 upper, have it extrude honed, then port the lower to match. Then use Edelbrock's larger twin bore throttle body on it ? If you really want flow, take an Edelbrock 2x4 intake, mount two EFI throttle bodys on it. Anyone seen that yet? I'm thinking on using their new 289/302 2x4 airgap and mouting twin Holley 500 2 bbl on it, but rotated so the throttle bores are in an inline setup. This will go onto a 331.

 

I'd be inclined to wonder how this worked out... I'd gather you'd be extending some sensor wire and flipping the upper plenum 180* as well.

Would be an interesting experiment with dyno numbers! You can't even get a decent set of gt-40's for that price. And I doubt they flow as well as these intakes...

Get 'er done Paul!!

Mike

 

I've never tried to fab an intake but if you look at trickflow's breadbox intakes, they look rather simple design.



That has occurred to me, also. Especially after seeing the tubular type gt40's for sale on ebay. That's a bit over the top for this truck, tho. This '92 FlareSide is for general usage, I just want enough power to make it fun to drive. I probably won't race it much, but I will tach it up every now and then, just to hear it run.

I think I'll lower my expectations a bit and not sweat a horsepower goal. Just use the gt40p heads and some longtube dual exhaust. Maybe some 1.7 roller rockers. Pony up for the staggered runner gt40 iron knockoff, find an Explorer upper. Maybe do 24# injectors and an adjustable fuel pressure regulator, with a slightly larger throttle body. Do sequential MAF from a Mustang, maybe keep the stock ignition so the computer can run it. Get rid of as much smog junk as possible. Do a little port and gasket matching, and live with the result. That should be good for 300hp or so, I'd think, with good torque for this 4000# truck. I'm told the stock roller cam in this motor is rather good, especially with 1.7 rockers, tho I hear the 5.0 H.O. roller cam also works well. Maybe bore it some to bring up the compression ratio.

If anyone sees any glaring problems with what I've described, I'd certainly appreciate being corrected.

Once I get this 351 in the truck and sorted out, I'll have the '92 roller (I hope) 5.0 from it to put into my Ranger. That's really the motor I plan to have some fun with. I am seriously considering making my own tubular intake setup for that, right from the heads, using a valley pan and skipping the whole upper/lower thing. That's all next years project, tho.

Rob