2.8 head build q's

[jibberjive]

I gots a couple questions for you people with experience rebuilding the heads as I'm a noob in that area. If I picked up 2.8 heads with ~90k mi and had them rebuilt with supertech springs/titanium retainers and either 2.7 or inconel exhaust valves:

1. What other parts do I need to replace and how many will I need (I assume stem seals/30, guides?, keepers?, whatever else there may be?)? I'm building for longevity and reliability, but don't want to replace what's not necessary.

2. Say I were to rebuild them with the stock springs/retainers and I were to pull the heads again at a later time to install new springs/retainers. Which of the seals/gaskets are one time use and would have to be replaced again (head gaskets, valve cover, cam tensioner seal, cam seals and plug, whatever else)?

3. If I weren't to disassemble and rebuild, how effectively would I be able to clean up the heads, or is it not even worth trying if they're not disassembeled?

4. Anyone have a cheap full set of 2.7 exhaust valves and/or 2.7 intake cams?

5. How much do oversized intake valves really help?

I have more I'll add when I remember, but thanks in advance!

[generationjdm]

Honestly if these are for a pjk04 or RS6 build i would save your money as theres really no point on all the valve train work on a turbo setup that starts dropping power far before 7k. I think your better off having some small work done to your 2.7 heads instead.

[wdbdy2000s4]

I agree with Gen. if you're putting in rs6s and building the head, I'm assuming you're getting rods. Why have a car that can rev to 8200+ if the turbos can't hold boost?

[jibberjive]

Well, here's my situ, I either take apart my 56k mi engine with no issues that's had oil changed every 3k, treated with autorx, etc, no issues whatsoever and replace all the seals/bearings in the bottom and head (I'm installing rods, balancing the crank, etc). If I do that I would see if the rings/cylinder/pistons are in good shape and just reuse the rings if so. I also would likely not do anything to the heads cause I wouldn't really need a valve job at this mileage and I can't really clean them without disassembling them anyways.

OR

I find a cheap higher mileage motor since I'm replacing all the seals/bearings anyways, and do piston rings and a light hone (another couple hundred bucks). I figure I'd want to do a valve job just to be safe with that motor, and since it's obviously the same price for 2.8 as it is for 2.7 heads ($600+ just for labor) I figure I might as well either find a cheap set of 2.8 heads or go pull my own for a couple hundred bucks more. I figure if I'm spending $600+ on just labor, I may as well get the springs/retainers so I can upgrade in the future if I choose to (NOT planning on it), and if S4's keep their low value and I should choose to sell my car in a few years (again NOT planning on it) I can part it out and sell the whole engine completely built, or maybe seperate the heads and it'll be worth alot more with the built heads. Plus I'll then have a brand fresh built motor with 0 miles on everything rather than a stock longblock with rods and 56k mi on the heads. Then I take my 56k mi great condition motor and sell it complete and untouched to recoup most of my costs.

So it's basically a swap for a stock 56k mi motor for one with built heads and 0 miles, but alot of effort and selling on my part.

[jibberjive]

And I would probably only rev to 7500 or wherever the turbos drop off, like I said, it would just be for reliability insurance, ease of potential upgrade, and resell value.

[generationjdm]

they drop before 7k

[Das General]

they drop before 7k

You are incorrect on that.

ASP dyno'd their old/original RS6 setup and held strong all the way to 7k

[generationjdm]

You are incorrect on that.

ASP dyno'd their old/original RS6 setup and held strong all the way to 7k

Whats that little red line doing? power did start dropping at 67-6800rpm and i though they this was the hybrid straight rs6 with the large comp wheel, which might be the reason why the car didnt start spooling until near 4k

[Das General]

That is the tq. Torque peaked early. But the power is still there. You aren't going to shift your car where you torque starts to drop. You shift when your HP drops, which with RS6's, is past 7k.

[generationjdm]

That is the tq. Torque peaked early. But the power is still there. You aren't going to shift your car where you torque starts to drop. You shift when your HP drops, which with RS6's, is past 7k.

I no what the line was, just playing with you. The tq dropped like a ton of brick right after 5200.. Like i said this wasnt the base RS6 turbo, im mean look at the boost, gt2871s come on like that haha Alexs car is making 9lbs before this car

[Das General]

Yeah the TQ is garbage. That car seems to make 9psi around 3700 rpms.

BTW that car (one dyno'd) got rolled all over by Jackson's K04 car.

[317ssayzarc]

Check the exhaust valve guides... Intakes will be fine

[generationjdm]

Yeah the TQ is garbage. That car seems to make 9psi around 3700 rpms.

BTW that car (one dyno'd) got rolled all over by Jackson's K04 car.

Deb, so what have we learned by this dyno graph? I'm glad you found ths chart as it proves everything I've been saying for a long time..

[Das General]

I've never really been an advocate for RS6 turbos. You should know that by now...

[generationjdm]

I've never really been an advocate for RS6 turbos. You should know that by now...

I understand that, but heres the proof that just because you have a large comp wheel on a small turbine side doesn't mean anything.. Heres another lesson probably the most important one. If everything isn't working together IE good/proper manifolds,dps and proper gates you will not spool really good even with a turbo like the RS6 which is tiny compared to a gt2860rs you will get out spooled and make less power down stairs as this graph clearly proves the point.. Watch what Alex's car does for spool which will be bounds and leaps over this one.. Even if he makes the same boost or less his car will make way more power at less boost rpm verse rpm. Greg Just hit near 20lbs yesterday before or at 4k on his first base tune and no timing on the gt2860rsss

[jibberjive]

like I said, it would just be for reliability insurance, ease of potential upgrade, and resell value.

If I work this right it shouldn't cost me much, if any, more than not doing it

[Das General]

If I work this right it shouldn't cost me much, if any, more than not doing it

It gets costly.

[jibberjive]

And I don't want this thread to turn into a debate on spool of RS6's vs GT's or spool of larger heads vs. anything so let's please get this back on topic or start a different thread.

[jibberjive]

It gets costly.

I know for sure, but I'd have a low mileage engine to sell and some other parts from the other engine to help recoup

[jibberjive]

So...

I gots a couple questions for you people with experience rebuilding the heads as I'm a noob in that area. If I picked up 2.8 heads with ~90k mi and had them rebuilt with supertech springs/titanium retainers and either 2.7 or inconel exhaust valves:

1. What other parts do I need to replace and how many will I need (I assume stem seals/30, guides?, keepers?, whatever else there may be?)? I'm building for longevity and reliability, but don't want to replace what's not necessary.

2. Say I were to rebuild them with the stock springs/retainers and I were to pull the heads again at a later time to install new springs/retainers. Which of the seals/gaskets are one time use and would have to be replaced again (head gaskets, valve cover, cam tensioner seal, cam seals and plug, whatever else)?

3. If I weren't to disassemble and rebuild, how effectively would I be able to clean up the heads, or is it not even worth trying if they're not disassembeled?

4. Anyone have a cheap full set of 2.7 exhaust valves and/or 2.7 intake cams?

5. How much do oversized intake valves really help?

I have more I'll add when I remember, but thanks in advance!

[Das General]

I know for sure, but I'd have a low mileage engine to sell and some other parts from the other engine to help recoup

Yes, you can certainly recoup some of the costs and a low mileage motor is very appealing.

[generationjdm]

These are comparisons on exactly what your asking. More doesn't mean better is the point. I would take a properly ported 2.7 head over a stock 2.8 any day of the week

[Das General]

If you are looking for an old 2.7 head, I will have a good conditioned one ready in a little while.

[jibberjive]

These are comparisons on exactly what your asking. More doesn't mean better is the point. I would take a properly ported 2.7 head over a stock 2.8 any day of the week

Any input on questions 1,2,3 or 4? Edited: or question 5? (about the aftermarket oversize intake valves, not the 2.8 intake ports)

[jibberjive]

If you are looking for an old 2.7 head, I will have a good conditioned one ready in a little while.

More just looking for the exhaust valves and cams if someone just has them laying around at a killer price. Don't want to pay to ship the whole heads, and if it's expensive I'd just get the supertech exhaust valves instead.

[generationjdm]

Any input on questions 1,2,3 or 4? Edited: or question 5? (about the aftermarket oversize intake valves, not the 2.8 intake ports)

i have some cheap intake cams, cleaning the heads while togther is a waste of time, you should changes the valve stem seal, wait until u see how hard it is to put the keepers on. If you knew you would leave them alone.. JIBBER just have some one clean up your stock heads, have a nice valve job, clean the bowls up and touch up the exhaust side and port match the comp side..

[317ssayzarc]

Deb, so what have we learned by this dyno graph?

That that sucker could use some cams/headwork!

[koolkoreanked]

wow I'm a be pissed if my power band looks like that. It stops making power after 5. I mean the tq fall right on it's face. Is that dyno of a full rs6 setup?

[jibberjive]

i have some cheap intake cams, cleaning the heads while togther is a waste of time, you should changes the valve stem seal, wait until u see how hard it is to put the keepers on. If you knew you would leave them alone.. JIBBER just have some one clean up your stock heads, have a nice valve job, clean the bowls up and touch up the exhaust side and port match the comp side..

Thanks for the input. I'm thinking of using the 2.7 heads, but if I have them do a valve/port job it'll be $650+ just for labor before the porting (already got a few quotes). I just don't feel right about spending $700 in labor when I could have upgraded, completely built 2.8 heads for another $1500 - ~$400-500 for selling the stock heads = ~$1000 (I guess that is a big number ha). I figure the reliability, resell appeal and upgradeability may outweigh that cost, but maybe not. It's more of a personal dilema.

[jibberjive]

So say I were to not touch the 2.7 heads other than replacing the cam seals, cam plug, cam tensioner gasket, headgaskets, and valve cover gaskets, then 6 months down the road I were to decide to get a valve job and replace the valve stem seals. Would I need to replace any of the above gaskets again (are any of them one time use)?

[A4 Meets 27t]

How much of an improvement would it be to just slap on the 2.8 heads and not really touch them?

[jibberjive]

How much of an improvement would it be to just slap on the 2.8 heads and not really touch them?

You can't just slap them on because the exhaust valves on the 2.8 aren't made to stand the temps of the turbocharged engine. The 2.7 exhaust valves are sodium filled, so at very least you need to swap in the exhaust valves from the 2.7, but you can use all of the other stuff.

[Wizard-of-OD]

You can't just slap them on because the exhaust valves on the 2.8 aren't made to stand the temps of the turbocharged engine. The 2.7 exhaust valves are sodium filled, so at very least you need to swap in the exhaust valves from the 2.7, but you can use all of the other stuff.

It has nothing to do with the valves but more the coolant ports.The big port cylinder heads have smaller cooling ports than the small port version.I always recommend to anyone if you are building a 400+awhp motor to at least run inconnel supertech or similar exhaust valves.
Running stockers is a recipe for disaster.

[A4 Meets 27t]

So even if I was to run the 2.7 heads should I get inconnel supertech or similar exhaust valves? Or at that point, port match the cooling ports with inconnel supertech or similar exhaust valves on the 2.8 head? Thanks for the help.

[Wizard-of-OD]

So even if I was to run the 2.7 heads should I get inconnel supertech or similar exhaust valves? Or at that point, port match the cooling ports with inconnel supertech or similar exhaust valves on the 2.8 head? Thanks for the help.

No no
You cant port match the coolant ports...they are casted into the head.

It is really up to you the end user.

Do you keep 2.7 Heads (small port) & install supertech exhaust valves or do you purchase 2.8 V6 heads (large port) & install supertech exhaust valves.

There is no 2 ways about it,the large port heads will net more gains in the long run.If you are worred about the intake manifold then run the 034 transition phenolic spacers until you can afford an RS4 intake manifold.

[koolkoreanked]

what exactly happens if you run the 2.8 heads as is?

[317ssayzarc]

Get ready to drop exhaust valves

[generationjdm]

what exactly happens if you run the 2.8 heads as is?

get ready to run out of coolant real quick also

[02alltoad]

so let me see if im understanding this, if i put 2.8 heads with 2.7 exhaust valves if i make 400awhp+ the valves will break? im not trying to be a smart ass or anything, im just wondering why this would happen, 1,700+ bucks for valves is a bit of money.

[wdbdy2000s4]

the stock 2.8 produces less heat then the 2.7t so there is less cooling in the big port heads. When you couple turbos with the limited cooling of the 2.8 head it's bad.