3.9 V8 performance upgrade suggestions - Defender Source
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  #1  
Old December 2nd, 2015, 07:24 AM
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3.9 V8 performance upgrade suggestions

I'm looking to improve my engines performance, not trying to turn it into a 400 hp beast.

Any recommendations that you've done and seen good results? Aftermarket air intakes?
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  #2  
Old December 2nd, 2015, 07:31 AM
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Built 4.6 with Allisport ECU, stock air intake ;-) only around 325 hp.

LR invented after market air intake: snorkel! Sounds great, better/cleaner air, but no help performance wise except in the water...
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Old December 2nd, 2015, 07:43 AM
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There's a ton of hi-po tech at aluminumv8.com. Go read all that madness then come back here and we will answer your specific questions. I assume you do not wish to disassemble the engine to add a stroker crank and higher compression ratio pistons. From a strictly bolt-on perspective there isn't much you can do. At minimum you'll want a new camshaft and header exhaust. However, that will mess with the ECU fuel mapping, so you may not get any benefit due to that. If you were to switch over to a user-adjustable engine management system such as,say, megasquirt, then that will allow you to dial in the engine to your specific needs.
Bottom line is it is a small displacement engine. As they say at the race track, there's no replacement for displacement. Consider also alternative power such as a Ford Coyote or a GM LS. Those will snap your neck back when you push the skinny pedal.
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  #4  
Old December 2nd, 2015, 07:59 AM
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Other than the Canadian shop with the photoshopped Coyote install, has this been performed by anyone? A section through the Coyote is 2x larger than GM's small block. Just a guess, and probably 3-5x more expensive at the local pick in pull.
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Old December 2nd, 2015, 08:01 AM
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If you want one we will make it work. here's a helpful image:



Of course accessories and plumbing are concerns but I'm pretty sure there's room for this. May mean custom block hugger exhaust. You also can get the engine management system out of any ford with the 4.6
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  #6  
Old December 2nd, 2015, 08:06 AM
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How many miles on you 3.9L?
A good tune up helps...
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  #7  
Old December 2nd, 2015, 08:09 AM
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Curious, what is your current performance is like? When I drive a 3.9 Manual they seem to have decent power when well tuned. More HP IMO would lead to cornering and stability issues. Maybe even braking issues too, no?
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Old December 2nd, 2015, 08:16 AM
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Its a waste of money to do anything unless you can tune the EFI to match the upgrades. Keep it tuned up and carry on.
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  #9  
Old December 2nd, 2015, 08:33 AM
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Quote:
Originally Posted by rover4x4 View Post
Its a waste of money to do anything unless you can tune the EFI to match the upgrades. Keep it tuned up and carry on.
This.
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1966 109 5 door wagon 300Tdi "spermaceti fueled"
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  #10  
Old December 2nd, 2015, 08:38 AM
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Strange. And I think the 3.9 is more engine than the 90 needs....
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  #11  
Old December 2nd, 2015, 08:40 AM
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Depends. Do you have to have your truck emission tested?

If not, then a good tune up, larger injectors, then go get the ECU programmed.

All of that will get you out under $1k and a weekend (a good dyno tune can take all day).

Basically, they can build power by enriching the mixture a bit.
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  #12  
Old December 2nd, 2015, 09:03 AM
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We have built a few 4.6's, and without the ECU correction, total waste of time and money!! Yep, ask how I know...
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  #13  
Old December 2nd, 2015, 09:10 AM
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I agree with everyone saying keeping your truck tuned. The only time I wish I had more power was on a grade fully loaded with gear. Honestly I would rather have more torque than HP.

Maybe freeing up the exhaust would help you a bit. I am not sure if my exhaust gave me any more power, but it sounds like it does. That's all that matters right? I think all the stickers add a few HPs as well.
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  #14  
Old December 2nd, 2015, 09:46 AM
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Quote:
Originally Posted by JSBriggs View Post
That oil filter location would have me worried.

-Jeff
Remote it.
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1966 109 5 door wagon 300Tdi "spermaceti fueled"
1994 RRC LeWiB "ruining the air behind me"
1968 2A 88

All my troubles are Rover
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  #15  
Old December 2nd, 2015, 11:36 AM
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There are a number of shops in my area that specialize in EFI tuning, I can think of one particular Honda tuner. It is incredible the gains he makes by dyno tuning cars, he has put his results up against mail order tunes and the gains are huge. As far as I know there is no one that tunes Rover EFI in the US. Im not even sure that the 14cux can be "reflashed", the TVR guys in the UK have it all figured out.
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  #16  
Old December 2nd, 2015, 12:14 PM
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replace the worn out cam and timing chain


Quote:
Originally Posted by Mpfish82 View Post
I'm looking to improve my engines performance, not trying to turn it into a 400 hp beast.

Any recommendations that you've done and seen good results? Aftermarket air intakes?
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Present:
1960 SII 109"- "Red Square"
1984 90 Tdi- "Yamelo"
1988 RRC- "Chewbacca"
1987 RRC- "Chewy 2"
2008 RRS SC- "The Supersofa"

Past:
1959 SII 88"- "The Little Green Beastie" last seen in NY
1972 SIII 88"- "GreenHELL" now in NC
1988 90 "Eric the Half a Bee" half a truck, sold for parts
1991 RRC- never got a name- long since recycled
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  #17  
Old December 2nd, 2015, 12:20 PM
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Yes, cam and chain are number one.

There are many books written on performance tuning of these engines... The engines are 50 years old. Everything has been done probably before you were born. If you really care, then go do some reading. Asking generic questions on a forum is a complete waste of time.
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  #18  
Old December 2nd, 2015, 12:56 PM
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Quote:
Originally Posted by rovertrader View Post
Built 4.6 with Allisport ECU, stock air intake ;-) only around 325 hp.
Interesting, & that's not the first time that I've seen it implied that ~300hp is inadequate. My daily driver half the year is a RRC SWB with a stock 4.6 swapped in & my biggest complaints are passing power & ability to maintain speed on hills on the highway. Not that the 4.6's ~40% hp increase seemed to help that much, but upgrades adding another 50% increase to ~300hp won't help that much either? Dam, where's the sweet spot?

Or are these highway power issues all mainly in the trans/auto trans controller? Seriously tempted to throw it down into 2nd at times...


FWIW, switching the RRC to 215 85 16 tires seemed to help, but it sure does look squirrely from the front with those on.
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  #19  
Old December 2nd, 2015, 01:19 PM
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steven
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Quote:
Originally Posted by rover4x4 View Post
There are a number of shops in the area that specialize in EFI tuning, I can think of one particular Honda tuner. It is incredible the gains he makes by dyno tuning. As far as I know there is no one that dyno tunes Rovers in the US. Im not sure that the 14cux can be "reflashed", the TVR guys in the UK have it all figured out. Mail order chips are marginal as best.
So, you're saying that it takes a dyno tuning to reap the benefits of engine upgrades & that there aren't any 14cux-competent dyno tuning shops in the U.S....

Does that mean anyone in the U.S. upgrading their engine should also be swapping in a megasquirt or something?
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  #20  
Old December 2nd, 2015, 01:49 PM
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Quote:
Originally Posted by cowboy View Post
So, you're saying that it takes a dyno tuning to reap the benefits of engine upgrades & that there aren't any 14cux-competent dyno tuning shops in the U.S....

Does that mean anyone in the U.S. upgrading their engine should also be swapping in a megasquirt or something?
Pretty much. Catch-22.

Megasquirt...lulz. I've had a long history of attempting to convert my 109 over to MS. I'm trying again in January. However I think faulty wiring is the issue. The few times I could get it to work...it really woke the truck up.

You could reach out to DIY Autotune to discuss the CUX14 box since it is a revised Bosch L-Jetronic system. Also here is where you can find the PIN info:

https://en.wikipedia.org/wiki/Lucas_14CUX

Theoretically, you could make your own adapter cable and run a simple MS1. Or go with an MS2 or 3 and then down the road you could convert to coil packs, getting rid of the distributor. You could talk to them about making a Plug n' play version for the CUX14. That would be quite awesome and there might actually be a market for those if enough people are interested. That would be awesome, a complete replacement box for the CUX14 that is open source.

Then after all of that...take it to the tuners.
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