Will Piggy back computer allow for cut cams?

J

jlozinsk

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Hi

I have a ford 3.9 in my Thunderbird. I plan on sleeving and stroking it to 4.8
I want to cut the cams but do not know how far I can go without needing an engine controller.
I also want keep the VVT as this is a street car.
Also can I run 4 or 5 pounds of boost without a controller? I was hoping larger air intake & sensors.

John
 
elephantrider said:
money will buy you happiness.
Click to expand...

To piggyback: The only thing that's stopping you, is you yourself.

The 3.9 has a high compression ratio that makes it difficult to boost. It is also pretty maxed out from the factory in N/A form and custom cams won't give you much power at all without going to some absurdly lopey cam designed to only run at over 4,000RPM.

How do you plan on stroking it to 4.8? Where are you getting your crank? Because no one makes anything for this engine besides oversized crank bearings.

------------

Do not take offense to the incoming replies if they are negative and/or condescending. Hundreds of people have come on here saying they have a plan, they know what they're doing, they know what they're talking about and we don't, and how rude of a group we can be, but the reality is none of them have come back with a success story. There are a handful of people who have gone and made serious modifications, but they walked into the LS with a lot of previous knowledge. As far as I know, there's been one supercharger, 3 turbos, and 3 engine swaps. The SC was a bit conservative. One turbo guy disappeared. One is here, but had 18 months of downtime for an engine rebuild. Not sure about the 3rd. None of the engine swaps functioned correctly.

What do you want? A straight up hotrod? Do an LS1 or 302 swap and don't even bother trying to run any electronics (dash, AC, ABS...).

We want to see it happen. But we're also jaded.
 
Piggyback controllers are generally not a good idea. Might look into Megasquirt as an engine controller. You'll need to figure out a way to run the computer and still have the factory sensors put inputs to the factory computer to keep things like traction control and ABS happy.
 
Wicked Ace said:
From a Jag 5.0?
Click to expand...

well if using internals from a 5.0 with it also having a larger bore, wouldn't that make it a 5.0 instead of a 4.8?

I guess that would be cool if the crank actually fit, I was under the impression that the gen three AJ motors were quite a different beast being redesigned from the block up.
 
 
1LoudLS said:
well if using internals from a 5.0 with it also having a larger bore, wouldn't that make it a 5.0 instead of a 4.8?

I guess that would be cool if the crank actually fit, I was under the impression that the gen three AJ motors were quite a different beast being redesigned from the block up.
Click to expand...

That was a "tongue in cheek" comment I made. You thought it out way too much, or not enough.
If you recall when our cars came out, along with the Jag S type, there was American vs English interpretation of the engine displacement. The Lincoln got a 3.9 liter and the Jag a 4.0 although both were essentially the same engine(horsepower is another sticking point).
Following that line a Jag 5.0 put in a Lincoln becomes a 4.8 liter engine.
 
FYI. The AJ-133 Jaguar engine has a wider bore spacing, therfore the 5.0 crank wont fit into an AJ-V8 series engine.

The max you can increase displacement in an AJ-V8 block is 4802CC. Cylinder spacing = 98mm, max sleeved bore =92mm, 4.2L stoke = 90.3. (This is what has been already done, and I have done on the engine I am slowly building up.) You can only stroke the crank a couple of mm before the rods will hit the lower side castings of the block. (Think Atson Martin crank, if you can find one.) From my perspective not worth the added cost to try to get closer to a 5.0 engine.

Keep in mind that with the 92mm bore you have to go with custom pistons. I am not trusting of the stock 4.2 rods so I am going with custom rods.

There is one person that I know who has reprofiled his cams and added about 15% lift. He is still having problems tuning the ECM, so he still runs the engine timing retarded.

These engine builds are all based on 2003/4 AJ-34 Supercharged non VVT engines. If you are really serious and willing to spend $10+K on your build, AVOS on the Jaguar forum is the Guru due to his 600+ hp streetable build. Waste of money to build up a 4.8 engine if it will be N/A. You need to supercharge it or add turbos to make it worth the money.

You'll have to scrap the 3.9 block, interior cooling channels are too small. Best to start with a newer 4.2 Jaguar block, 2006-2009. Different/stronger block casting and larger interior cooling channels that can handle sleeves bored out to 92mm.
 
Tijoe, was the AJ33s ever installed in the S-type? The Aj33S and AJ34S are very similar, both supercharged 4.2s, but the 34 has VVT. I thought all S-type 4.2s had VVT, but I'm finding the 33-34 change happened during the S-type's facelift
 
I believe that VVT was add in 2005 to the supercharded engine, but could have been 2006. Yes during the facelift when they got rid of Brembo brakes.
I know for sure that 03 and 04 STR engines didn't have VVT.
 
LSFrank said:
To piggyback: The only thing that's stopping you, is you yourself.

The 3.9 has a high compression ratio that makes it difficult to boost. It is also pretty maxed out from the factory in N/A form and custom cams won't give you much power at all without going to some absurdly lopey cam designed to only run at over 4,000RPM.

How do you plan on stroking it to 4.8? Where are you getting your crank? Because no one makes anything for this engine besides oversized crank bearings.

------------

Do not take offense to the incoming replies if they are negative and/or condescending. Hundreds of people have come on here saying they have a plan, they know what they're doing, they know what they're talking about and we don't, and how rude of a group we can be, but the reality is none of them have come back with a success story. There are a handful of people who have gone and made serious modifications, but they walked into the LS with a lot of previous knowledge. As far as I know, there's been one supercharger, 3 turbos, and 3 engine swaps. The SC was a bit conservative. One turbo guy disappeared. One is here, but had 18 months of downtime for an engine rebuild. Not sure about the 3rd. None of the engine swaps functioned correctly.

What do you want? A straight up hotrod? Do an LS1 or 302 swap and don't even bother trying to run any electronics (dash, AC, ABS...).

We want to see it happen. But we're also jaded.
Click to expand...

THank you for the information most of you are correct yet you have not done your homework, Darton will sleeve the 3.9 to a 92mm bore my machinist has looked at the Rover 2006 to 2009 crank and with a small ofset grind it will reach 91mm. Supercharging in a Thunderbird is a NO GO as it is just to much trouble i have an expert and also talked to Jaguar Specialties on the XK conversion. I am an EE designer. What I wanted was a little more power but what it is beggining to look like is just take out the motor and put in cayote 5.0L 420HP motor backed by a 6 speed 6R80 or if possible the new 8 speed with a computer. I am a trust fund baby who does not live in America but has car businesses in the USA. My managers will probably agree just put another motor in the problem is how to make it work well and maybe go with the 5 liter AJ V8 from the Jaguar. My friends and partners are pro's so before I go to them to build I do my homework. Stroking to 4.8 and small cam ramp increases so as to not disturbthe computer with maybe a small eaton with 3 or 4 pounds of boost and an English chip remap (England will probably only net me 50HP so you guys are correct leave it alone continue building my other toys like my mast 640HP XK and my fake orange GTO that my DZ302 motor with 220 Magnacharger will go into. THe problem is I like my tbird but I do not want to not have it to drive for aa long time. it is very low miles. I have massive brakes and performance 45 series tires. So I as if i just take a 3.9 from a junk yard for $350 and sleeve it and increase the ramp on the cams and port & polish the heads when I drop it in will it run OK? They can change motors with about 35 hours labor I was told as on of my shops pulled one. They said it was a pain.
 
SO from what I am hearing most every mod to the 3.9 does not make sense
So my question is if I bore and stroke a block to 4.8 and swap it into my 2004 thunderbird with no other mods will the computer still work correctly? I think that would give it a little more torque. The transmission will probably require lots of machine work but I want a new 8 speed ZF My machine shop has done this kind of insanity for me before.
 
Measure them up any reputable forged piston manufacturer will make a set for around $700
 
Only non supercharged jag motors got vvt no need on a supercharged
My tbird has 48 degree vvt the earlier vvt vvt was like 18 degrees
 
This was good info I did not know about the cooling
I am now thinking 5.0L cayote motor $7,999.00
 
Thank you guys

Hi,

Because of you I learned it is stupid to sleeve the 3.9 as cooling passages are to small.
I will send my Tbird to Bulgaria where I live it is a nice car.
I will build a 1997 to 2002 hard top xk8 with a T56 for the USA and my occasional consulting contracts.
I was hoping for more power and torque but it sound like it is not practical.
 
One other option you might check into, if you can get the car tuned. SCT does make tuners for this car but I don't know how deep into the programming they go. STS Turbo makes a turbocharger that mounts underneath at the rear of the car. Turbo lag is not supposed to be any more of a problem than it is on a front mounted turbo. Since it sounds like you can afford it, you can have the engine gone through and have lower compression pistons put in to better take advantage of a turbocharger. Good luck to you on this.
 
well if you got the mad cash, call the people alex did to have some stronger internals made for you, then TC that biotch right up.
 
The machinist Steve for Darton Sleeve will put 92mm sleeves in your motor but on a 3.9 cooling passages may be an issue so look at the Rover 4.4 motor which is also an AJ V8
the crank on the 4.4 is 88.5mm I think which means you can offset grind it to 91mm
enjoy slowly I will ship it to Bulgaria where I live and increase torque by increasing displacement
but I think a T56 and rebuild a 4.4 short block is practical. Sleeving is $2,200 and brings fuel and other problems.
 
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