How to build a FAST 6-banger Maverick (Lotsa Photos)

Yep, my drag car project will be a 6-cylinder. And I fully intend to put the V-8 cars back on the trailer before I drive it home at night, so it will be a contender...

Here's the progress so far on the "Motivator"...

I'll be starting with the most bulletproof engine ford ever built, the 300 Inline six, produced 1965-1996, displacing 300 cubic inches, and sharing a bellhousing, flex plate, and damper with the 302 ford...internally balanced, however, so the V-8 crank parts won't work without conversion.

Bore is 4.00", stroke 3.98", and it's a two-valve, non-crossflow head...similar to the Nissan L28 head, but cast iron and manifolds on the other side. Even flows similarly, with stock ports moving 160-170CFM intake, and when "race ported" moving 220-225CFM per intake port. Exhausts, stock, moving 120-125CFM and ported flowing as much as 150CFM...

However my L28 is a little over half the displacement of this engine so that's certainly NOT what I want! It's also cast iron and heavy as hell...fully dressed, the 300-6 weighs in at 594lbs dry.

Picked up a shortblock at the parts yard last spring, 100$ out the door, complete with grease, flywheel, and oil pan. The bottom end is in great shape and could be used as-is up to about 500HP, as long as it was kept under 5000RPM. It is already bored 0.040" over, so it won't be really up to par for the final engine, but for the mock up and initial testing it will be fine.

Scrubbed up and painted Ford Blue:


Instead of that cast iron head, I chose to build an aluminum, crossflow head. Something with better flowing ports, and better aftermarket support in the valvetrain department. You've probably seen a few people attempt this before, but as far as I can tell, no one has done it "correctly" yet.



Let's get started, shall we?



Jigged, welded, and on to the next section:


Tacked up, checking alignment before working the weld some more:



Basically rinse and repeat till I've got all six segments on the block.

Bores is properly aligned...I've not seen anyone else who has attempted this, even give the first shit about doing it properly. Bore alignment is very important to consistant valve flow, and making sure every cylinder breaths the same goes a long way to crankshaft life and power production. You can only make as much power as the least powerful cylinder allows!



In the end, I got something similar to, but slightly different, to this one I did earlier. THIS is how I learned to make sure and check the damn bore spacing first! Cylinders 1 had an intake valve touching the bore, and cylinder 6 had the exhaust valve touching the bore. I only cut this one in three sections, and that doesn't quite work...gotta go the extra mile and chop out six individual cylinders.



Anyway, end result is a 300" inline six that will make about 400HP naturally aspirated, but with two T04B-H3 turbochargers helping it breath, I aim for about 850HP.

I think that should be adequate to do the job, you guys think I need more to get it done?

(PS, I do custom heads, intakes, headers, and exhausts every now and then in the shop, so this is all just fun-stuff for me.)

 

I like it. Nice work. I was looking for a pre 97 f150 shortbed with the 300 6 for a turbo project but couldnt find any good ones. Seems like theres alot more room in the engine bay with an inline motor. I have a v6 turbo and everything is crammed in there. i have to pull the inner fenders every time I want to work on something.

 

Some of those mtrs came w/ a steel crank,I would find one if I were you.Back in the late 70s or early 80s a guy built one in a Mav or a Fairmont(can`t remember which),used 3 351 cleveland hds welded together.They were 4v hds & the mtr had a full inch lift camshaft in it,it had a 1100 carb,went high 10s.GOOD LUCK TO YA,I applaud your effort.

 

You're talking about Bruce Sizemore's H/MP Maverick, "Preparation H", I believe. Ran mechanical injection and 6-sections of Cleveland head furnace brazed back together, and later some others used 429 heads done the same way. Could also be talking about some of the slingshot dragster guys, I am not 100% sure Preparation H ran the frankenhead.

Now that I actually have a maverick to put this engine in, I'll put some more time into it. Pushrods have to run outside the block, I am looking into a roller cam...however I don't think I'll need the roller to make the power. Will be quite spendy to get proper roller lifters, the steel billet cam isn't so bad though, I can make that myself.

I have a few jobs ahead of this in the queue for when I get home from California, but then I'll get back on the FrankenFord.

The steel crankshaft for the 300 six is not so common...pretty much have to luck into one as no one will sell what they have. I am not concerned, a billet crank will fix it if I have to. I will go to the nearly indestructible 240" crank, more likely, but for initial testing with no turbos, I'll run the 305" bottom end I already have. Once the head is proven at the 400HP level, I'll swap the bottom end and we'll lay some boost on it.

 

That's pretty cool, I imagine you will have some work matching cooling ports.

 

Aluminum heads are usually heat treated so that they hold up. Your welding will take out the heat treat.

 

I came across this thread the other day and just stumbled onto it again.

http://www.garagejournal.com/forum/showpost.php?p=4644714&postcount=1

 

He doesn't give any details. That's cool, but it sure looks big and heavy.

 

Very different build - looking forward to seeing it as it progresses - it's like reading the first chapter of a mystery novel waiting for chapter 2 - good luck with the build

 

Very cool! I always wanted to switch to a inline 6/ turbo setup.

 

Yes, aluminum heads are heat treated. Yes, heat treated heads can be welded. Yes, welding does destroy the heat treatment in the weld's Heat Affected Zone, aka the HAZ. The rest of the casting would remain unaffected. No, welding does not preclude further heat treatment and NO, welding a head will not make it more likely to warp, crack, leak, or blow headgaskets...IF the welder knows what he's doing.

Standard response to that kind of comment, I get it all the time from racers and restorers alike.

I do aluminum head repair and modification as kind of a side-business, this engine will be more for advertising the fabrication side of things in how it's built, and the paint will advertise my PDR business.

During the welding process, the head must either be kept between 150F and 300F degrees, never exceeding 320F or so, or kept below 150F. Both methods work, different strokes for different alloys and welding methods. Once the weld is done, due to the wire alloy I choose to use, the welds are peened, HARD, while still warm. Literally beat the snot out of them. This causes significant work hardening of the alloy and will actually bring them up to only slightly less hardness than a new, unwelded head, in the case of these GM semipermanent mold castings. With these castings, and this rod alloy, if you DON'T peen the snot out of the welds, they will be pretty soft and won't hold a headgasket properly.

The heat-treatment of the base alloy is a solution heat treatment, the alloy is cast, then while still over 900F, is quenched to below 200F and then it is dead soft...the hardening is then either allowed to happen naturally over a period of six months to two years, or it is artificially aged, by heating to around 800F and holding at that temperature for hours per inch of casting thickeness. This simulated aging actually can't achieve the same ultimate hardness of natural aging, but it gets close and works "well enough" for most castings.

So, quick explanation of why welded heads *can* work properly complete.

As far as the cooling ports, they line up pretty closely, actually. There are some ports that conflict with the old pushrod holes, and some ports that will have to be drilled into the LQ-4 head casting sections that were not there in the original head, but nothing really huge since the whole deck gets welded up solid anyway. The bigger cooling issue is the one inherent in any inline-six that has a front-mounted water pump...cylinder 1 runs cool, and cylinders 5 and 6 run considerably hotter, and are easily pushed into detonation. I am working on a reverse-flow coolant system to help alleviate that issue, pushing cool coolant into the head and down through the engine block. I'll feed coolant from the front and back of the head, hopefully the shorter circulation paths will allow a more even distribution of heat.

 

wow.. lots of backyard engineering and old fashioned type hotrodding going on here. I love it.

I have seen one functional LS head conversion on the 300, was chopped in 3 sections IIRC, and they can surely make good power.

Just keep in mind that getting 400 horses from 300 cubes will still take a bit of extra rpm irregardless of the LS heads decent area under the lift/flow curve. These pushrods are VERY LONG and VERY HEAVY and 850 horsepower will typically take one helluva spring to keep the valves on the seats when and while they're supposed to be there. So, rather than just going towards a thicker walled tube.. maybe figure that larger diameter PR's may also be in order as well.

The lighter LS valvetrain helps of course but any thing else you can do to shave weight from the valve-train will make life much easier for you and your parts. The hollow stem LS stuff is nice bang for the buck for the N/A stuff.. but I probably wouldn't push my luck with them on the turbo motor combo.. unless they were at least ceramic coated on the faces to better control heat/reduce tensile strength loss/and also reduce detonation potential.

Also thought I'd mention that in the future, you may want to consider the idea of moving the intake valve even further away from the bore wall.. even at the expense of the exhaust valve side of the chamber being right at the edge of the bore. This further moves/unshrouds the valve away from the bore wall and also allows the use of larger intake valves in the process. A bit of extra boost will still easily do the job either way though, so there's still that little bonus.

I can see you easily getting by with a moderately sized stock core size grind for the N/A build, but the camshaft will surely need to be a billet unit for the TT setup due to the spring requirement and tendency to flex due to length.

 

The pushrods in the converted engine are actually SHORTER than standard LS pushrods. Turbo engines do not need massive cam profiles and the myth that you somehow need more spring pressure on the intake valves due to boost is just that...a myth. I almost always have a smaller cam profile in my turbo engines than I run in the NA or blown engines, and usually make more power. (Even on the blowers, the turbo engines make more)

As far as moving the bore, I've already got more room between the intake valve center and the bore than the LS3 does, and it is running a 2.19" valve. Without moving the intake valve guide, I can't fit more than a 2.09" valve before hitting the exhaust seat anyway, so no reason to move it over. I'll just use the area to unshroud the valve that's there, reshape the chamber for less swirl and more tumble. It really won't take a lot of work to get this engine pumping out that 850HP with the turbos...hell I bet I can do it on a stock cam, but boost pressures will be up around 22PSI. I'd rather not push that high, 16PSI should do it with a well selected cam.

That 400HP N/A is conservative, look at it not from a total cubes perspective, but a cubes per port perspective. A stock 300" six with the LQ4 head leaves the port slightly small, but portwork brings it up nicely. 7000RPM is not an issue with a quality crank damper on the front and a lightweight flywheel on the back, and dropping to 240 cubic inches improves both the cylinder-to-port matching and the RPM ability if I run into issues with the crank.

Essentially this is 3/4 of a 400 cubic inch turbo LS....which will easily make 1500HP all day long. The big problem here will be the camshaft flexing, I may need to install extra cam bearings to keep flex down and prevent breakage. That's by only worry in the valvetrain, is cam breakage, and I don't really think I'll need to deal with it with the profile I'll be running.

Obviously, the stock rods and pistons are getting the boot...Stock rods would be fine to 400HP, but I don't like the rod bolt cutouts, too square and sharp for me.

 

Thanks for explaining that. Just curious, how do you keep the head in one of those temperature zones while welding?

 

more boost fixes just about everything airflow related. carry on.

now I'm even more curious how you effectively lopped off nearly 3 inches in PR length here? Is the valve-stem height differential just that large between the 2 head designs?