4v cobra conversion.. WHAT WILL I NEED?

0h3gt

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May 16, 2009
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I'm looking into buying a rebuilt 4v 4.6 cobra engine from Powertrain Products Inc. ..Supercharger INCLUDED, So what will i need to do the conversion?
radiator?ecu?harnesses? :shrug:
 
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You need to explain why you need to do this. My car hit 643rwhp at 6000 rpms and 9 degrees of timing and we aren't even close to completing the tune. With the forged components and cams is set up to go to 7000. We are guessing it's going to hit 600rwhp on pump gas and 750 or more on 109 octane. It kind of kills the reason why you need 4 valves for most street apps. Far easier to do heads/cam. Talk to Livernois because this combination is 100-200hp higher than we were expecting. Their head work and cams rock.
 
I concur, build your 2V up. This isn't 2000, you have plenty of options that will make just as much power as a four valve and cost far less when all is said and done. Not trying to bash, just point out other possibilities.
 
If I was doing a build I would use the Boss 5.0 block, notched 3.70" pistons (notched for superior camshaft profiles) with 3.75" inch rods. That would give you 323CID and really unshroud 2V cylinder heads, especially if you work the combustion chamber for a 3.70" bore.

Figure 850 on the block plus 100 to get it machined, 550 for pistons, 550 for rods, 200 for piston rings, 300 each for rod and main fasteners and another 300 for head studs, 100 for bearings and 80 for a cobra oil pump, and 100 for a gasket kit. Reuse most everything else. That puts you at just over $3400 and you have a shortblock that can support nearly 2000 hp.

Assuming you do your own assembly, thats it. But you will need a lot more cylinder head, cam, and intake than stock equipment can support. You should definitely look into trick flow heads, custom cams, and an aftermarket intake. Naturally aspirated it should be able to support well over 500hp on an engine dyno. A properly designed 2v can support well over 1200hp on forced induction.

Anyway, that's the short and ugly on my next project (proposed), good luck with yours.
 
You probably need to explain how much horsepower you are shooting for. If you are using a stock 4v block, they you aren't going much above 450rwhp anyway. The 2v can hit that without forged internals. Neither the 2 or 4v are going much above that safely without forged internals. Although the conversion isn't impossible, it's expensive and labor intensive with lots of little parts, computer, wiring harnesses, etc... Keep in mind that if you start going above the 400+ range, you need to start looking at tranny, fuel delivery, and suspension issues that may occur with the extra horsepower. So, in summary, you can get to 400-450rwhp with a simple s/c and fuel system upgrade and that is a few hours versus days of work at minimum.
 
rconaway makes a good point, if you are just looking to do stock terminator power levels, you don't need a short block or a 4 valve. For an idea of what the cost of a good 2V would be, check out the Junkyard Jewel article in Hot Rod from June.

They took a junkyard 4.6 and put on Trick Flow heads, an Edelbrock intake (carburated with a Holley 550), and Trick Flow stage two cams. All told they spent less than $6000 and got 453 engine hp at only 6400 RPM. And there is definitely power left, they used the wrong spark plugs (half height plugs instead of full height meant a compression loss and horrible spark location) and exhaust was stock. With the right plugs, longtube exhaust, and a fuel injected Trick Flow track heat intake, I bet it could make real close to 500 engine hp...if not more. And as a bonus, you will pick up fuel mileage by freeing up a lot of pumping losses.

Once you add in your drive train and accessory losses you are easily over 400rwhp....not bad for a stock displacement NA 2V IMHO.

Oh3GT, let us know what your power/torque or MPH/ET goal is. With the experience a lot of members here have, we can probably help you save a lot of money, time and frustration.
 
You probably need to explain how much horsepower you are shooting for. If you are using a stock 4v block, they you aren't going much above 450rwhp anyway. The 2v can hit that without forged internals. Neither the 2 or 4v are going much above that safely without forged internals. Although the conversion isn't impossible, it's expensive and labor intensive with lots of little parts, computer, wiring harnesses, etc... Keep in mind that if you start going above the 400+ range, you need to start looking at tranny, fuel delivery, and suspension issues that may occur with the extra horsepower. So, in summary, you can get to 400-450rwhp with a simple s/c and fuel system upgrade and that is a few hours versus days of work at minimum.

Sounds to me like he's getting a terminator engine not a NA 4v with a blower bolted on. Stock terminator engine is good for well over 450RWHP.

If he's going for stock terminator power levels then a simple blower on his 2v would be fine. The wiring isn't that much different, changing out the PCM isn't a big deal either but you need a matching key or having to get your key done to match the PATS and that can be a pain. Or he can have the car tuned with the existing PCM and it won't matter. Alot just depends on what the end goals are but you can't go wrong either way.

Also here is an article with some info on the swap.

http://www.modularrevolution.com/forums/4vswap.php
 
Midnight2v, Thanks man that gives me something different to think about, i'm actually looking into it right now haha... although i've always wanted to have a supercharged car...
 
Midnight2v, Thanks man that gives me something different to think about, i'm actually looking into it right now haha... although i've always wanted to have a supercharged car...

if 400-450 is what you want , id supercharge it in a heartbeat , if you go the 4v swap you will probably find yourself lost in the middle at one point or out of pocket money or cant get it to run right for whatever reason.

with a supercharger little bolt-on here and there will start to shine and plus... 400 is never enough and you will want more... a supercharger will give you a bigger ground to play on and a lot of simplicity.
 
yea but that raises the question...do i need forged internals with a supercharger????

if you go intercooled and get a decent tuner , you wont need forged internals for 400-450.
only reason i have forged internals is because of a drench accident water got into the engine... don't ask :lol:
 
Plus on the blower for more torque and ease of installation. Total cost of 5,000 and maybe $300 on misc. stuff.

Plus on the HCIE for increased fuel mileage and bottom end integrity. Cost of roughly $4500 including fuel pump and 42# injectors. Another plus on room for growth f you decide to add a power at a later point. Minus on install complexity or cost for a shop to install. Figure on 2,000 to do it.

Me personally, I would do HCIE first then go FI at a later point. Buts that's just me...Its your build so its your decision. Whatever you do, enjoy yourself and your project. Good luck.
 
alright but ya'll are all talking about roots s/c's..what about a centrifugal s/c like vortech ?? I have a speedshop near me that will install a vortech for $3200 out the door, then i figured i'd have extra money to do heads or w/e.....
 
To answer your question completely, there is no simple answer.

Here's the thing with supercharging, if you go positive displacement as in roots or twin screw, you can negate the install of the intake manifold. It saves you money, and you get great low end torque, but you are locked in to the engine profile of the runners that are part of the blower package. With a centrifugal you retain that flexibility at the cost of most of the low end torque gained by the positive displacement blower. I really don't consider that an issue because once you are in the powerband in first gear (properly geared), you never come out of it and you are more traction limited than torque limited in first gear anyway (even NA). The only place it would really matter is on the street - light to light, and if you are big into street racing this probably isn't the best forum to get most of your information from anyway.

Now as to the shop that supercharges for $3200....what kind of vortec are they offering? Is it used or new? My guess is that they are a vortec direct distributor so they can save on parts. However, if they are offering the smallest blower Vortec makes, non-intercooled, using a FMU to support fuel in this special, I would pass as it really offers no room for growth and will likely max out flowing no more air than can support 425RWHP.

The reason I recommend heads/cams/intake/exhaust first is this: If you do a blower first, and then decide to build a top end, you end up tearing off the blower to perform this. That completely negates the money you already spent installing it in the first place, now you get to pay extra for them to remove it, and to top it off you get to pay for a second installation. If you do it the other way, there is no backtrack installation involved....unless you decide to build your lower end at some point, which is not necessary for H/C/I/E or a base kit like you are asking about. But if you do both, then it becomes a necessity.

The Vortec supercharger option you mentioned will probably get you around 330-350 RWHP on a stock setup, and around the same amount of torque (maybe a little more or less). I say 350 because to go beyond that is beyond what a kit with a FMU can handle. Any more power without intercooling and you exceed the fuel capability of the system, which adds significantly to the cost of the kit in the form of injectors/pump and the installation associated. That power/torque level is going to be right at (or possibly less than) the levels that the H/C/I/E can achieve, with none of the other benefits the H/C/I/E can give you that I previously mentioned.

Even considering the special that your shop offers, unless I am just totally incorrect concerning the equipment they install, I would still build NA prior to going FI. I just don't see them offering the right equipment that would satisfy your needs for $3200.

Hope that answers your question, if not, let us know.