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  #21  
Old June 27th, 2016, 04:23 PM
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Quote:
Originally Posted by 1of40 View Post
Yeah, you'll probably notice a peppiness with the 412's. Be careful re exhaust. The higher rpms will give you a drone that sucks at highway speeds over long periods of time. Double check tire size again. My 255's are true 33's not 35's.
10-4. I've already had this setup on my 98. Headers, MagnaFlow hi flow cats, Borla cat back, with the 4.12's on 315/75 KM2's. It sounded pretty badass when I got on it. It had some drone at highway speed. Not terrible, but I'll be looking to tone it down a bit this go around.
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  #22  
Old June 28th, 2016, 01:55 PM
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You should buy Tony's built 14CUX 4.6.
I was going to say the same thing...
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  #23  
Old June 28th, 2016, 02:41 PM
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When I did my 4.6 I spoke to Mark Adams (Tornado Systems) and he was very adamant about not using 4.0 pistons. I took his word as it carries a lot of weight when it comes to 4.6 engines.

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That's where I'm headed I think. I do all my own work.


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  #24  
Old June 28th, 2016, 02:58 PM
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Originally Posted by blaughva View Post
When I did my 4.6 I spoke to Mark Adams (Tornado Systems) and he was very adamant about not using 4.0 pistons. I took his word as it carries a lot of weight when it comes to 4.6 engines.
Did he say why? Not that I don't believe him/you...I just like to know the why so I understand better.
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  #25  
Old June 28th, 2016, 03:07 PM
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Quote:
Originally Posted by fishEH View Post
Did he say why? Not that I don't believe him/you...I just like to know the why so I understand better.
Here is what he wrote:


"The only concern I have with your conversion is the use of 4.0 pistons. You do need to be careful using the 4.0 Litre pistons in a 4.6 engine, as it can produce an extremely high compression. Typically this will be 10.9:1 assuming that the heads have not been skimmed at any time. This will require a very high Octane fuel to prevent pinking/detonation, which I believe is not easy to get in the USA.

Even if you use the earlier 3.9 heads the compression will still be around 10.0:1, and you would then have the difficulty of mounting the ancillaries to the heads. Really it is a combination I wouldnt advise."
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  #26  
Old June 28th, 2016, 03:16 PM
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Ray Gerber
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Sharing a lightly edited dialogue with a friend and long term Rover owner just because his words convey context to the 4.0 piston discussion:
Quote:
You can do the 4.0 pistons for just a bit more cost and it does make a difference. If you port and polish the heads to truly get the benefits you want to put a performance cam in it too. All of those should be reliable. I run a 4.6 with 4.0 pistons stock cam and heads. I have almost 50,000 miles on that set up I put it in the winter before Oakridge. Truly no worries but it does push oil due to the compression and it is leaking oil but don’t they all?

I did a stock 4.6 in ___ truck so she would not have the Premium gas worries

If you do the 4.6 with 4.0 pistons you MUST run good premium gas.

Opening the heads and adding the cam will add - if you did the 4.0 pistons heads and cam I can see you getting close to almost 245hp NO proof or Dyno to prove that estimate but a stock 4.6 should net you 220hp. I guess if you don’t mind the premium gas think of it this way. You will add around $1000 to the build and it will feel like going from a 195 hp 4.0 to a 220 hp 4.6 only you will be going from a 220 hp 4.6 to a 245 hp performance 4.6. It should be reliable and dependable with no worries. The GEMs fuel mixture can handle it without a CHIP but if you added the Mark Adams Chip to work on the timing and mixture (costly $1700) you might even gain another 10 – 15 hp. How much is enough? and how far do you want to go?
Keep in mind this was for a GEMs engine and I do wonder if the fuel management system there may be a little more forgiving but that's supposition on my part. The emphasis I added was to illustrate a real world long term (I consider 50k in a Rover long term) application.

Put another way if/when I start building a replacement for Coyote I'll likely find a 4.0 GEMS block (i.e. not the later year 4.6 blocks), put a 4.6 crank/rods in it with 4.0 pistons, port/polish myself and a mild cam. That's daydreaming of course. First I have to have little things like my household goods show up and such....
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  #27  
Old June 28th, 2016, 03:27 PM
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Good input Ray. Although I run 4.6 pistons I do have a stage 2 crower cam as well as Mark's chip (It's around $650... but on sale now thanks to Brexit), a setup which also requires premium gas. There is definitely a noticeable difference from my 3.9 which makes paying more for gas acceptable.


Quote:
Originally Posted by Ray_G View Post
Sharing a lightly edited dialogue with a friend and long term Rover owner just because his words convey context to the 4.0 piston discussion:
Keep in mind this was for a GEMs engine and I do wonder if the fuel management system there may be a little more forgiving but that's supposition on my part. The emphasis I added was to illustrate a real world long term (I consider 50k in a Rover long term) application.

Put another way if/when I start building a replacement for Coyote I'll likely find a 4.0 GEMS block (i.e. not the later year 4.6 blocks), put a 4.6 crank/rods in it with 4.0 pistons, port/polish myself and a mild cam. That's daydreaming of course. First I have to have little things like my household goods show up and such....
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  #28  
Old June 28th, 2016, 03:36 PM
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So are the 4.6 benefits primarily in 0-60 or 70-90?
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  #29  
Old June 28th, 2016, 03:43 PM
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I've noticed a significant increase in pick up. I almost always start in second, even on incline. I can also (not that it is a good idea) cruise at 80.

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So are the 4.6 benefits primarily in 0-60 or 70-90?
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  #30  
Old June 28th, 2016, 04:05 PM
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Originally Posted by 1of40 View Post
So are the 4.6 benefits primarily in 0-60 or 70-90?
In my D2, I found the 4.6 benefit mainly from 24-32mph... or not at all



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  #31  
Old June 28th, 2016, 04:11 PM
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Quote:
Originally Posted by 1of40 View Post
So are the 4.6 benefits primarily in 0-60 or 70-90?
As in MPH? I would hope 0-60. My highway cruising speed is 65-68mph and I get around 16-17mpg. Maybe more if I factored in the larger tire size/slower odometer.
I have no desire to push 70+mph in a D1.
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  #32  
Old June 28th, 2016, 04:14 PM
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Quote:
Originally Posted by Nomar View Post
In my D2, I found the 4.6 benefit mainly from 24-32mph... or not at all .
I wonder if that's the dif in curb weight, that big ass on a Dii does add a bit
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  #33  
Old June 28th, 2016, 04:16 PM
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Originally Posted by Ray_G View Post
I wonder if that's the dif in curb weight, that big ass on a Dii does add a bit
"Does this D2 make my butt look big?"

yeah, the D2 is a bloated pig.
A 4.6 in a RRC or a D1 is a slightly worthwhile endeavor...


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  #34  
Old October 1st, 2016, 01:18 PM
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94 ecu

If you project is complete any chance you want to part with an ECU? 94 NAS

------ Follow up post added October 1st, 2016 12:20 PM ------

Any chance you want to part with a spare 3.9 ECU for a 94 NAS?
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  #35  
Old October 1st, 2016, 02:19 PM
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Originally Posted by Sned View Post
If you project is complete any chance you want to part with an ECU? 94 NAS

------ Follow up post added October 1st, 2016 12:20 PM ------

Any chance you want to part with a spare 3.9 ECU for a 94 NAS?
If he doesn't want to I have one from my 1994 D90 from when it was converted to a diesel.
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  #36  
Old October 3rd, 2016, 03:22 PM
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Sure I'll take it. Look for PM.
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  #37  
Old December 29th, 2016, 04:07 PM
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For what it's worth as far as "closure" on some topics here - I have Tony's 4.6 project motor in my garage now, finally on an engine stand. Shortblock is on the stand, I should say. Build up will commence any day now. However, will not be bale to comment on performanc ein a D1/D2 as it's going in a HCPU that I'm trying to keep as light as I can.
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  #38  
Old December 31st, 2016, 03:03 PM
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I had a 3.9 for years in my D90 and the replaced with the 4.6. Crower high torque cam, Pendy's refuelling chip, slightly overbored using RealSteel pistons. I had 60K on the 3.9 so not used up by any stretch and I did notice a difference between the two motors. I live in CO and the hills are everywhere and I went from sluggish on the hills of I70 by the tunnels to being able to keep up alright. Stock gearing. It is a good upgrade.

Now that I am towing an offroad trailer, however, I am looking for something a little more grunt/low end torque... Still deciding on what. Maybe a TD5, maybe a 2.8 Cummins, maybe an LS.... If it wasn't for the towing, I'd be perfectly satisfied with my 4.6
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