Hedman headers on DII

bryno · Jan 25, 2006

I have seen lots of posts on the Hedman headers, PN 39800, but all seems to be installed on DI (Thanks Joey for the posts by the way).

Has anyone personally installed or have knowledge of these working on the DII. It appears by sight that there is enough room for the tubes, but experience is worth a thousand words.

I am doing the 4.6L upgrade fo my '99 DII 4.0 and thought that since I was there, headers would be a nice addition, but I cannot find anyone, including D&D or RPI who have personal knowlede of these fitting, or not, on a DII.

Any help would be great for all of us.

Bryno

Joey · Jan 25, 2006

Not sure if it has been done or not, but do yourself a favor. If you decided to do this upgrade the coupler gasket while your there.... less than two years and I was under there the other day changing out the gaskest because they started to leak... what a pain. Bought some lifetime alluminum ones. $20

bryno · Jan 27, 2006

Come on DII guys

I can't believe that the DII guys out there have never tried to upgrade their engines to this degree.

Is it really an impassable task?

Is the ECU really that corrosive that it will downgrade any upgrade to the engine?

Or has this really not been attempted by a DII guy yet?

Please post any info that you have. I am going this weekend to 4 wheel dyno my DII prior to the 4.6 & header updgrade and will be posting before and afters within the next couple weeks.

mr_katanga · Jan 27, 2006

Is the ECU really that corrosive that it will downgrade any upgrade to the engine?

I would really find that very hard to believe.

That being said, I agree with you and am surprised that this has not been tried. There is no reason that it shouldn't work with proper modification to the intermediate pipe. If you find anything out, let me know. Especially with larger tires (and without gears) the D2 with the 4.0 is a real pig.

bryno · Jan 27, 2006

I also find it hard to believe that the DII ECU is the ALL horrible monster that it has the reputation for, but people seem to believe it. As I understand from those in the know, the ECU will compensate for quite a lot of modifications, i.e. larger throttle body, larger injectors, etc. by leaning out or enriching the fuel/air accordingly.

I guess the primary reason for the headers is efficiency of exhaust extraction. Although I know that there are not HUGE power gains to be had, any at all is worth something on the Disco. Plus, it has to sound and look great.

That being said, why aren't people doing it. Is there not a ready-made header that will fit?

Bryno

lgoldd1 · Jan 27, 2006

Hey Bryan, Where is that 4 wheel dyno located? I'm in Granbury, TX. I would love to put mine on it as well. I've got Heddman's on my 95 D1 with a supercharged 4.6 running on a Accel digital FI system and 29lb injectors. I used to live in CO and would like to fine tune it for Texas without spending alot of seat time adjusting ignition/fuel curve settings.

I'm not savy on DII engine management computers. My initial thought is that the system would adapt to the increased exhaust temp. The only possible problem that comes to mind is the O2 sensors might need to be upgraded.

Oh yeah, I had to replace my stock steering shaft out for a 97 RR shaft due to a tolerance issue. You could also weld up an extension.

Good luck!

bryno · Jan 27, 2006

Lee, sounds like you have quite a hotrod. Wouldn't have thought about upgrading the O2's. Do you really think that would be necessary? Any other thoughts would be great.

The dyno I was going to is at Alamo Autosport in Arlintgon. However. I called today to get an appointment and since it is an above ground they can only accept vehicles less than 6'2". That puts us all out. I m looking again, will post if any success.

Bryno

frickjp · Jan 28, 2006

bryno said:
I can't believe that the DII guys out there have never tried to upgrade their engines to this degree.

D2 is only a couple years out of warranty. Folks ususally don't hack up a truck until the warranty expires. Also, the availability of tested and proven bits, headers, for instance, won't be popular until there's a market for them. Now that you can pick up a whopped D2 for $5k, they'll start getting more popular.

As for the 4.6, stuff it in there. Runs fine with the 4.0 software. The 4.0 and 4.6 ECU's are the same part, just different tunes. We (dealer) can't put a 4.6 tune into a 4.0 without setting codes, as all 4.6 engines came with SAI and DMTL.

We have several 4.0 to 4.6 D2's out there running perfectly well. One was actually an oops. Ordered a 4.0 for block porosity, opened the crate, and there sat a 4.6. Gave the customer the option, and not being stupid, said he'd prefer it, thank you. His mileage went down half a point, but as he puts it, fun per mile went up considerably.

bryno · Jan 28, 2006

frickjp,

What kind of 'tune' are you talking about. I was under the impression that the 4.0 ECU would just read the need for added fuel/air and adjust accordingly. Maybe this is the case and an added adjustment inceases the performance. Would you please expand on the subject?

Thanks, Bryno

frickjp · Jan 28, 2006

Software loaded onto the ECU to set parameters based on known values. When you swap a 4.6 where a 4.0 was, some known values are a bit off. Like airflow. The Bosch system is quite good, and adapts well. Yes, it will learn the new values, and yes, it will run flawlessly. Some folks are under the impression that the car will explode like Little Boy if you swap an engine without changing the software. I am not one of these. I only speak from my personal experience, however, not from what I've read while parked on the shitter.
Once I see a dyno sheet on before and after readings for a software change, I will be a believer. Until then, I just can't see it making that large a difference, if any.

kellymoe · Jan 28, 2006

I would take the stock manifolds off and have them port matched, smooth out the insides and have them ceramic coated with something like JetHot. My muffler guy told me about a process where a abrasive sludge is forced thorugh the manifold smoothing out the inside. I was going to put hedamans on my truck and the muffler guy talked me out of it and said I could get the same gains by doing the above process and having them Jet Hot coated, and they will last longer than your truck. Here is a shot of my manifolds from my 130. The coating also reduces heat in the engine compartment.

bshinn · Jan 28, 2006

Here's what Kelly is talking about.

http://extrudehone.com/afmpro.html

Works wonders on 911 heads & things like tuned intakes on Euro cars. I looked into it for a 951 I built back in the early 90's but it was just too costly for a poor 20 something @ the time.

Supposed to give outstanding improvements on turbo housings & the like. Bunch if guys I used to know when working in a motorcycle shop did their Jet Ski impellers & swore by it!

If I get a wild hare I'd extrude hone/jet hot the stock manifolds B4 going the header route.

syoung · Jan 29, 2006

I've had a couple engine extrude honed- Had the carb bodies, intake and heads on a little MG 4 banger done when I built it to Stage II factory specs. Fastest 4 banger MGB I've ever seen short of the supercharged ones.

Jeff- is there a four wheel dyno in Buffalo? I need to find one and there aren't many in the US.

rdoane · Jan 29, 2006

syoung said:
I've had a couple engine extrude honed- Had the carb bodies, intake and heads on a little MG 4 banger done when I built it to Stage II factory specs. Fastest 4 banger MGB I've ever seen short of the supercharged ones.

Jeff- is there a four wheel dyno in Buffalo? I need to find one and there aren't many in the US.

theres one at ride-revolutions in johnson city, tn.

frickjp · Jan 29, 2006

syoung said:
I've had a couple engine extrude honed- Had the carb bodies, intake and heads on a little MG 4 banger done when I built it to Stage II factory specs. Fastest 4 banger MGB I've ever seen short of the supercharged ones.

Jeff- is there a four wheel dyno in Buffalo? I need to find one and there aren't many in the US.

Rumour has it, yes. North of the city in Tonawanda, the 660 foot boys talk about it all the time. I'd actually have to see it before suggesting it's a goodplace to go. I've been looking for an excuse to chuck a truck up and see what it does.

bryno · Jan 30, 2006

Just did it!

Well, for better or worse (I don't know which yet) I just went ahead and ordered the Hedman 39800's. If they don't install without a knock-down-drag-out, all I will be out is the shipping to return.

But if they do work, you know they are going to sound mean!!!

And with or without the Jet-Hot the have got to improve the performance.

So I am going to just do it. Unfortunately, my local 4-wheel dyno can't handle anything greater than 6'2", so I won't have the baseline like I planned. The 4-wheel dyno's just aren't very common.

Anyway, I am sure that someone has an actual baseline dyno of a stock DII at the wheels (mfg 188 bhp/250 lb/ft). I might be traveling to Houston once the 4.6 is installed as there is another 4-wheel dyno down there.

Bryno

bryno · Feb 2, 2006

Well I got the headers in today and the 4.6L yesterday and I am busting at the seams to put it together. I have just eyed the headers to the engine bay as it sits and it looks like it just might fit. The steering linkage that is a known issue on the DI looks like it is just out of the way enought that the shaft connector (lack of a better word) will pass in between the two sets of pipes.

I am going to try to get this changed out this weekend. However, the wife and kids may have other plans. If not, I will be installing next weekend. Will post picks as I see things are fitting or are not.

If there are any wise-words-of-wisdom for the 4.6 short change, please bring them on. As I am only doing the short and keeping existing ECU in place, I imagine it wil be faily simple, just time consuming. Replacing all gaskets and the tappets & head bolts of course and have the RAVE CD for torque settings and the like.

-Bryno

frickjp · Feb 2, 2006

bryno said:
If there are any wise-words-of-wisdom

Use your existing wiring, and you're in.

lgoldd1 · Feb 2, 2006

Hey Bryno, Sounds like you have some fun lined up in the near future. You'll dig the sound. Just curious though, why didn't you opt for the 39806's w/HTC? They really do keep the heat down. The factory gaskets are good, but I used "dead-soft" aluminium exhaust/collector gaskets. I also use grade 8 collector flange bolts and "double-nut". Tighten, get'm hot and re-tighten them and they will stay tight longer. Good luck, Lee

bryno · Feb 3, 2006

Hey Lee,

I will be having fun as soon as I get to my workshop. I am having a lot of work done on our 1924 home and it is taking most of my spare time and I don' have much).

I opted no to do the Jet-Hot now as I am still not sure how well these will fit. As I have found on this forum, no one is fessing up to having a successfull install on the DII with these or any headers. So I decided to do it the cheap route. If it goes on well, I will pull the headers down the road when I do a valve job and 3 angle grind. That way I can spread the expense.

I think the High Temp coating are golden, so I look forward to it down the road.

Do you have the HTC? What has it done for you?

I have the metal exhaust gaskets and will heed you advise on the bolts.

-bryno

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