We are almost at the point of transplanting a 4.6 into the Big-ass Disko and I was hoping some of you guys could shed some light on a few things. I have done a good bit of research with RPI and D&D but a lot of this stuff is still Greek to me. This will be the first time I have even been inside an engine other than pulling the head of my old Amigo when I was 16 to have a valve job done. Even my rice rockets all we ever did was bolt-ons. If anyone has anything to add please do, keep in mind we are looking for moderate performance increases but do not want to risk [too much] reliability.

The engine we are using to transplant is a 2003 4.6 with less than 4k on the clock and will be left as GEMS.

- D&D has quoted $1,000.00 to provide and install new Diamond Forged pistons which will raise the compression ratio from 9.3:1 to 10:1. Is there a difference between regular forged and diamond forged? I picture diamond forged pistons would be in Puff Daddy’s Bentley… :grinpimp: Seriously, if there is a difference is it something we should be looking at? Mark said that the reliability factor in the diamond forged is much great than stock. Do we even need to be looking into pistons at all?

- The Crower CAM kit w/installation Mark is suggesting is $570.00 and includes a new shaft either 258,430 or 260,446 [depending on the ECU re-chiping,] lifters, timing chain and gear set and valve springs. Any suggestion on specs for the CAM? The vehicle is an automatic and Mark was pretty firm when he stated that we needed he needed to check in ECU re-chipping before we settled on a spec. I know the basic reasons for swapping the CAM but what would the difference in these numbers equate to in the end?

- Composite gasket set is $175.00 and from what I have heard from RPI and others it’s pretty much a given upgrade when going with a higher compression rebuild. Is this correct?

- The next thing is optimizing the heads which we would send in to them to the tune of $1500.00. This includes at least a 3-angle valve job, reducing the valve guides [Mark said they stick into the ports at stock] Can anyone confirm this?, polishing the valves, polishing the ports and just the general piece of mind that these guys build some damn nice engines. Is there anything else we should look into having done to the heads at this point? He also mentioned that porting the intake would not really be required because the gaskets we pretty true, not sure what he means by that. I would assume if you port one side you should port the other side unless the gasket is NOT going to match the port diameters. Any opinions?

- The last thing he mentioned he said we could have done locally which was Micro Polishing the crank which could be had for less than $100.00. He explained that on most Rover V8’s 4.2 and 4.6’s especially the surface on the crank is anything but smooth and it can cause premature damage to the bearings especially under heavy use. For $100.00 I think it this is cheap insurance unless of course it’s not necessary. Can anyone comment?

Granted we have money to spend on this truck and want every advantage to help win but if we are wasting money on any aspects of this please, someone speak up. Hell, I’ll FedEx you a case of beer if you save us a bundle! :D

[Sponsor voice: Limited to one person per house hold. Any relative, friend, or family member of a Red Rhino Products employee is unable to enter. No purchase necessary.] :D

Thanks for any info….

Anything this time PT? I'm getting better eh? :flipoff2:

Regards,

I don't know much about diamond forged pistons but you can use 4.0 pistons to get the compression ratio up in the 10:1 range. $1500 sounds like a lot of money to me to spend on heads with only 4K on them. Yes the guides do protrude into the ports some. Aligning the ports with the manifolds help too. Now if you really want it to breath a set of Buick 300 heads will do the trick.

Why are you spending so much money to rebuild an engine with only 4000 miles on it?

If you do go ahead with the rebuild have you checked the availability of hi-octane fuel at the location the event is being held? Would really suck to do all that, get there and find out they don't and then 'ping' the engine to death.

Tend to agree with aloha.
Having done my share of racing in other disciplines....the more you modify an engine the less reliable it becomes. Extra power doesn't do you any good, if it breaks or runs like crap.

I would think your first priority would be to have steady/realiable power plant.

Hey guys, this is the information I was looking for. I was thinking that pistons was a bit much along with some of the other stuff he mentioned. Originally I was just looking for a cam to give some more thump but then D&D started throwing all this at me. As I said, I am no engine guru and the reliability factor is MOST important. IYHO would be pushing it even installing a upgraded CAM?

As for fuel we should be able to get 92-93 without a problem in most areas.

I think reliablity will be your biggest challenge. With that in mind I would lean towards keeping it fairly stock with only minor upgrades like exhaust and intake(snorkle).
I wouldn't totally rule out a new cam but I don't know the real gain you could get in a 4.6 rover application.
So my vote goes toward keeping it stock or go full out and rebuilt it all expecting to spend $5000 or more. Based on the rest of your build up I'd say that $5 grand would be better used elsewhere.

As for fuel we should be able to get 92-93 without a problem in most areas.

Thats cool.

How waterproof are all the engine controls? I would tend to be more worried about those sort of things, then rebuilding the engine. Hell I would sonsider changing the intake and throwing a carb on just to get rid of all the electronics just for the comp.

Seriously though, unless the 4.6 is known to have issues, or you know that the PO of the engine ran it with out oil or water I really wouldnt stress the engine at all. If you are worried, drop the oil pan and plasitgauge all the bearings. But I doubt you will find any wear at all.

If you are going to keep the electronics, have you looked at reprogramming the CPU? It might offer you the best bang for the buck.
Are you using the 4.6 computer or one from the current vehicle?

IF you just have a bunch of $$$ then by all means look at a new CAM. How much of the event do you envision needing low end torgue versus high HP at 6000 rpm? You can get a cam custom ground to best match your requirements. Port match the heads to the intake and exhaust, valve job, and a port and polish. Look at improving air flow to the engine, maybe use dual snorkles and really open up the amount of air she breathes.

Wow, I am glad to see that I am not alone here. When D&D started mentioning all this work I was a bit concerned about the reliability factor going down the tubes. I was really set on the following:

- Installing a CAM offering a bit more low end torque
- Installing a set of Hedman Headers which we already have
- Port matching the exhaust and headers
- Installing [Wow I thought you all would laugh at this but guess not] Dual Snorkels
- Installing a custom free-flow exhaust

As for electronics we should be ok as we have relocated a few things to help. We also use a product the Military has which 100% disperses water from any sort of electric current. To give you an idea...the demo I oringally saw for the product went like this:

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A man holds a extension cord with a screw in light bulb socket above a clear 5 gallon bucket of water.

He plugs the light bulb in [let there be light] and then sprays the connector with this product.

He then drops the light bulb in the h20 and low and behold nothing happens. No short, explosion, breaker blown the bulb just stays lit.

He then reaches into the water :rolleyes: takes the bulb in his hands and unscrews it.

The light bulb goes off and then WHILE UNDER WATER he screws it back in and viola the bulb comes back on.

At this point I say, "What? There must be some gimmick." Then he grabs me with his other hand... :)
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Needless to say I am still here and didn't get electrocuted and I saw a major use for this stuff on Rovers immediately. I sprayed down everything, I mean everything in the engine bay and all the electrical crap inside [under the seats, dash, etc...] of the Disko before we went to Osceola hoping to sink and kill it but even when driving REALLY slow, and I mean REALLY slow through water above the headlamps and stopping letting the truck fill with water nothing happened. This run was a good 45 yards long at that constant depth. So, I hope we will be able to make it through the OBC, of course we will have spare parts so all should be ok.

As for chipping I have spoke with RPI and they are pricing, supposedly some guy in Indiana does it but I have not been able to get in touch with him as of yet. Still searching.... :shaking:

RedRhino,

most of the stuff you mentioned is geared towards improving intake and exhaust airflow - that doesn't help much at low rpm. Also, I don't know if there's a way to optimize the cam for low end torque without sacrificing the high-end power - maybe.
For this amount of money, you could buy a blower - as long as you don't go overboard with air pressure and keep enough fuel (that one's a bitch), you should be pretty well off.

disclaimer - I didn't do any of that, so this is from my old research on the topic.

RedRhino,

most of the stuff you mentioned is geared towards improving intake and exhaust airflow - that doesn't help much at low rpm. Also, I don't know if there's a way to optimize the cam for low end torque without sacrificing the high-end power - maybe.
For this amount of money, you could buy a blower - as long as you don't go overboard with air pressure and keep enough fuel (that one's a bitch), you should be pretty well off.


Blower would be pretty cool.

You should be able to get a custom cam that will bump low end with out effecting mid range. As long as you aren't going to need to be doing any 120mph+ runs shouldn't matter. I know for the SBC you can get a cam that does a good job of bumping up the low end torgue, has a pretty flat tourgue curve, with out changing stock high end. But this engine had heads, intake, and carb to match. Anyway should be able to get a cam to fit your needs, then get the chip programmer to work the CPU to fit the cam.

You do have to be carefull with the exhaust. With a gas engine you can open it up too much and loose low end torgue. Headers, good. From there back I would probably stick with like a 2.25 or 2.5 pipe.
If you are looking for high RPM HP then yes open it up, hell go straight pipe. But for some reason that I don't fully understand, in this case too much is not a good thing. The engine needs some exhaust restriction to produce low torque.

What you could do is to go large pipe and then make up some restrictors that go between the header and the pipe. Basically cut some metal to the same shape as the flanges. Drill a hole in the center. If you have 3" pipe, make up some restrictor plates with 2.75, 2.5, 2.25 holes in em. Find some steep hill and do some low speed climbs with each plate (as well as none). You will see a difference, find which one you like.
This might not be a bad way for you to go, sinee in effect you have created a tunable exhaust. If you hit a stage where its flat out speed, remove the restrictor.
Just a thought :D

You can't however have too much intake.

Pete

We are almost at the point of transplanting a 4.6 into the Big-ass Disko

Silly question. Where are you planning on driving this "Big-ass Disko"?

Are you building it up from bracket racing? a run on the autobon?

What works best on an engine depends a lot on the vehicle's intended use and the RPM range it is expected to be operating in.

Unless you are doing off road performance events most American trail driving is done under 3000 RPM. Most hot rodding stuff add HP at the top end at the cost of taking some off the low end.

So what works depends upon where you drive, how you are geared and how you drive. I think it would be hard to provide advice without knowing all this.

Of course the first dumb question is why modify a real low milage 4.6 without spending time finding out what the stock engine can and can not do? It could be your best long term solution.

But if you have an itch and lots of money to burn look closely at projected power curves in your intended operating RPM range. Just remember what works at "normal" off road RPMs is just the oposit of what works when the christmas tree lights works down to green.

Lazy Bugger

Nothing says low end power like length of crank throw and swept volume.

Does anyone know what these guys use?
http://www.bowler-offroad.com/PERFORMANCE.htm

They've got 400Nm at 2000rpm from a 4.6. I've come across the power/torque curves for their engines before (torque very flat), but I can't find it now.

I agree with the keep it simple the theory. I just finished building a 4.6 and I actually "de-tuned" it some by lowering the compression ratio a little so I could burn crappy gas if I needed to. Even in it's "de-tuned" state it's cranking out almost a 100hp more than the 3.5 in my 110 that it's replacing.

LB –

The primary use for the Disko will be challenge events. If we do well at the OBC we plan on going forward to the Frogs Island race, ETC... That and we will be taking it on the trails to play here in the states quite often. As for modifying the 4.6 like I said I was kind of against it which I was I posed these questions. D&D brought up a lot of things that with my "inexperience" with building engines I felt I needed some answers to. Some of their suggestions seem to be a bit “overkill” for what we want. Not they gave me incorrect information but possibly they didn’t understand fully what we need this engine to do. My initial thought again was just to bump it up a little bit with the CAM, exhaust, ETC... I think these combined with the correct gearing and a good driver could equate to a reliable performing shot at winning. That all being said from what I have seen, heard and read I think a good bit of low-end torque and decent mid-hi range is what would be best suited for this kind of event. Any comments? I know some of you out there have competed in these kinds of events before.

As for modifying the stock engine it's already semi-broken down so if we want to put in a CAM and work some other angles on it now would be a perfect time. Yes, no?

LRover –

That is not a bad idea thinking about fuel. Even though the OZies say 92-93 is available I wonder what the legitimacy is to that....? Any one care to comment? Strange Rover, are you out there?

Pete -

I like your idea for the exhaust, we may try that out. I guess I put my foot in my mouth when I said "free flow." I am looking at using the Hedmen Headers, a Borla muffler and custom piping with hi-flow cats. There would be some restriction but enough decent flow to let it breathe without taking away too much torque.

You can also buy a remote activate exhaust cut out at jegs or summit. It would allow you the best of both worlds. Course I think you would need two to make it truly effective.

You can also buy a remote activate exhaust cut out at jegs or summit. It would allow you the best of both worlds. Course I think you would need two to make it truly effective.

Doah, didnt even think of those.

I have gone through this buildup in my head several times as well. I have consistently come back to a turbo or supercharger as the best means to add power without sacrificing internal reliability.

In your application, I think a supercharger (roots or centrifugal) along with an appropriate camshaft and ECU tuning would be best. This allows you to keep your internal components all intact, which is great since they all only have 4k on them. I would guess that with a low to moderate PSI blower (6-9psi), proper cam, exhaust mods, and ECU tuning you could see 350hp and over 400tq. Keep in mind a stock 2002 4.6 made 222hp at 4750rpm and 300fpt at 2600rpm.

as far as the fuel quality issue goes, just keep a few bottles of octane booster in the truck in case you cant find premium fuel. cheap insurance.