A better cylinder head

Performance mods and Advanced Stroker discussion.
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SilverXJ
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Re: A better cylinder head

Post by SilverXJ »

Most of these other cylinder heads that are being mentioned are OHC and cross flow. Just something to keep in mind. If going with cross flow I would put the intake on the passenger side and the exhaust on the driver's side. There is too much stuff on the passenger side in the way and most of it doesn't like heat.
johnj92131 wrote: The only big six that comes to mind is the Jaguar 4.2 - not sure what the bore spacing is, but not a bad place to start. Double over head cams, hemi heads.
The XK6 head is very wide. The AJ16/AJ6 head used from 89-97 is a bit more narrow, IIRC. However, unlike the XK6 head, the AJ16/AJ6 has the intake on the driver's side and exhaust on the passenger side.
What about the Jag V12 engine? It started out at 5.3 liters with a 3.5" bore. By 1991 it had been expanded to 7.4 liters in the XJR12
Might be an idea. Its a SOHC though, but the exhaust is on the driver's and intake on the passenger.. or you could always take the other side head to reverse it. The XJR12 was a racing only and the largest production V12 was 6.0L.
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Re: A better cylinder head

Post by Alex22 »

I'll chime in here again, I still do want to make a LS head for a I6 Jeep. The problems is that I have WAY too many projects started at the moment and I'm going in so many directions at once.

I have not seen any modern I6 engine with the same bore spacing as a Jeep, the modern 6 cylinder engines are smaller displacement with smaller pistons and a closer bore spacing. My brother is telling me that I need to stay late one night and lay out all of the proposed heads next to each other and take a picture. There are BMW, Toyota, GM, Ford and I think there might be a Nissan around, but I have taken a tape measure to all of them and none are close to lining up with the Jeep block. It looks like the LS heads are the best starting point.

I'm not liking the idea of milling the side off of the Jeep head, it sounds like way too much work to do for the potential gain. If you do want to use the stock head I would say to have a half set of 3/8 head studs made out of ARP Custom Age 625 and press a sleeve into the existing head bolt hole and make the port wider. If you still want to go wider than that will allow you then the block could also be machined for Time-serts or Big-serts to allow you to shift the 3/8 head stud further away from the port wall which will allow for a larger cross sectional area at the head bolt choke.

Welding two heads together will not be a problem if it is done correctly; I have welded a lot of aluminum heads and my boss has welded more than I can count. The finished head would need to be re heat treated since all of the welding would anneal the casting and obviously all of the machine work would need to be done after the head was re heat treated.

It would need a custom billet cam made, probably a similar cost to Pete's but with the intake/exhaust order swapped around. A dry sump or external pump wet sump would remove almost all of the stress from the distributor gear which would allow the use of a bronze distributor gear without having to replace it every few thousand miles.

~Alex
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Re: A better cylinder head

Post by Cheromaniac »

A crossflow cylinder head and an OHC cylinder head swap onto the 4.0 block aren't viable, otherwise Hesco would have tried them rather than making an aluminium variant of the stock head.

Crossflow: The distributor's on the passenger side so there's no room for an intake or exhaust manifold. The pushrods also go into the passenger side of the head and block so there's no room to cast intake or exhaust ports into the head on that side.

OHC: The distributor is driven by the camshaft in the block so if you go OHC, there's nothing to drive the dizzy. The block would also need to be redesigned to accommodate the altered valvetrain configuration.

If you want an engine with a crossflow OHC (or DOHC) head, you'll have to swap in the whole engine. It's pointless monkeying around trying to make it work on the 4.0 short block.
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Re: A better cylinder head

Post by 1992Rotbox »

ok two things are becoming clear to me, from this thread.
1) Swapping heads from another engine family onto the AMC block isn't likely to happen. This motor has no cousin but the 2.4L
2) However...the design of AMC block will allow for a totally redesigned cylinder head, regardless of the distributor or pushrod bores. The problem is cost, but the engineering is possible. I

Image

This 6.2 diesel is crossflow, four valve per cylinder, using angled rocker bridges to "twin" the valves. The rockers are unequal reach, driven by an odd cam. The familiar straight row of pushrods is on one plane, driving a shaft mounted rockers.

On the cross flow AMC head, the intake manfold could be located on the passenger side, with runners bent around the distibutor. The spark plugs could relocated to the exhaust side. But this would be major bucks to design, and mill. Not happening. No wonder hesco crumpled this idea up. Where's the market for the head, manifold, and exhaust system redesigns?
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Re: A better cylinder head

Post by SilverXJ »

Given Hesco's price on the head alone imagine the price on a complete redesign. Crossflow, OHC, etc. I am sure it can be done but as you say, money.
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Re: A better cylinder head

Post by johnj92131 »

OK, if you can not find a better head, then the path to more torque and power is more displacement and/or forced induction.

A turbocharger system may be the best solution to more the Jeep/AMC 6 engine. After a stroker crank, that is.

Alex, if you ever do anything with the LS head, I hope to hear about it.

Right now I am spending most of my spare $$ on the VW TDI.
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Re: A better cylinder head

Post by Alex22 »

johnj92131 wrote: Alex, if you ever do anything with the LS head, I hope to hear about it.

Right now I am spending most of my spare $$ on the VW TDI.
I'll keep this thread updated when I get back to it.
TDI's are actually one of the things that are on the list above the Jeep engine. I have 3 TDI engines and a pile of heads. My brother has an 2003 for a daily that will be mine eventually.

I don't see the distributor being a problem for the LS head, it would be between two intake ports and down low. Intake manifold and Header will need to be custom fabricated. It will probably be cheaper just to swap in an actual LS V8 engine then to have a custom head, intake, exhaust, external oil pump, maybe some ignition work and a few other things.

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Re: A better cylinder head

Post by I6FAN »

How about the AMC V-8's; what bore centers do they have? There are some pretty good heads available for those, and if they could be fabbed like they've done for the Chevy sixes? They probably don't have the correct bore spacing ect. If you had to keep the non-cross flow design, some sort of semi hemi with heavily canted valves and intake and exhaust tracks that smoothly transitioned is about as good a non-cross flow, 2V design is going to get. But again $$$ :mrgreen: $$$.
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Re: A better cylinder head

Post by Neyo »

Another way to check for the bore size, oil return holes, water jackets and head bolt line up is to get some head gasket. Me I think of putting either a Toyota 2JZ turbo(or NA 2JZ) or the Jaguar 4.0L engine.

I took some so call mock up pictures and I will post them later..
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Re: A better cylinder head

Post by wildjeepchick »

I am having a problem with fueling my 4.9 stroker. I just installed the aftermarket 4.0 head with the Chev valves installed. I seem to be running my fuel rail dry at 4000RPM. I have the injectors that were supplied with the engine, I believe they are 28lbs. The engine runs like a beast up to 4000 and then runs out of fuel. Do you guys know of a bigger fuel pump i can use.
The head did show me more power, and works well with the 4.9, just need more juice
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Re: A better cylinder head

Post by yuppiexj »

1. Welcome
2. Start a new thread.
3. Install a fuel pressure gauge to verify you are losing fuel pressure at WOT above 4000RPM.
4. Check\replace your fuel filter and fuel pickup strainer in the tank.
5. Install a fuel pressure gauge to verify you are still losing fuel pressure at WOT above 4000RPM.
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Re: A better cylinder head

Post by wildjeepchick »

I'm sorry for interrupting this thread with my question. I was reading through these comments and started thinking about my issue, and just jumped in. Thank you though. :doh:
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Re: A better cylinder head

Post by Plechtan »

Well, i started this thread, and have been away for awhile. But i have come to some conclusions i have come to;

1. The most bang for the buck would be to just put a turbo on and your done. it solves most of the head flow issues.
2. Hesco will supply 2 ford V8 heads welded together if you want a cross flow head and have enough money.
3. The distributor on the passenger side is not a problem if you are using a aftermarket ECU or a 2001+ computer.
4. No matter which V8 head you adapt, the exhaust will be on the drivers side and intake on the passenger side.
5. The Hesco aluminum head could be modified by milling the manifold surface back towards the valves about 1" You would have to leave about 3/4" of the deck. The head bolts would no longer go between the ports, they would just bolt to the head, similar to the exhaust side of a V8 head. An aluminum plate would have to be made with a cutouts for the intake and exhaust ports, and a provision for manifold mounting bolts or studs. The plate would then be welded to the head to fill the void that use to be the water jacket between the ports. New intake and exhaust manifolds would need to be constructed. The new head would allow more flow because 1" of the intake and exhaust runners would have been removed.

Crazy hugh?
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Re: A better cylinder head

Post by the_wrench116 »

i vote turbo :slobber: . funny how no one will say what kind of power there pistons are good for. trial and error :boom: is kind of a spendy way to do it. :roll:
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Re: A better cylinder head

Post by Plechtan »

Turbo Tom got about 450 HP out of his motor using the Hesco Turbo pistons. although you could probably get 700 hp without too much work, i don't think it would stand up to Daily driver use. Even at 450hp you will need to upgrade the trans, transfer case, and axles. The Wagoneers and used turbo 400 and 727 transmissions, both of these could handle high hp if built correctly.

The turbo also lets you develop the HP below 5200 rpm and avoids the crank harmonic issues. I higher flowing head would develop more hp, but at higher RPMS.

I think everybody would like to have 300 hp or more, but a built stroker will probably be more in the 250-260hp range. to move beyond that something radical has to be done. If you compare the 4.0 to the newer 3.6L v6 Pentstar engine ( the new Chrysler corporate V6) it produces 290hp @6400 rpm and 260 ft/lbs@ 4800. The basic design of the AMC motor goes back to the mid 1960s, so it is hard for it to produce similar hp numbers to newer engines. However a turbocharged stroker will produce more hp and at a lower rpm ( way more torque than a NA motor). Who winds their motor up to 6400 rpm? Give me 350hp @ 3500 rpm and I an a happy camper.
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