Garage Storage Organization and Garage Cabinets

shinjin · **Changing the heads on standard V6**

Does anyone have information about changingthe standard head (SOHC) to a 24v or DOHC. Are they interchangeable?

Ondonti · 07-25-2007, 07:45 PM

Tim_K · 07-25-2007, 08:48 PM

Hooo, boy.

We know about it, but read a little here and figure it out on your own first, noob.

Shadow24V · 07-25-2007, 10:13 PM

i just grabbed a whole 24v SOHC motor instead....

but in a nutshell, YES they will bolt on....as for everything else fitting or working....thats another story

87turbodance · 07-26-2007, 07:40 AM

There are a few threads on this already. Stuff bolts up but you'll likely need a stand-alone computer and custom exhaust manifolds or headers. Timing belts are still unknown. So, in theory .. yes they bolt up... but no one has gone through the steps to actually try to make something run.

kreel · 07-26-2007, 07:59 AM

I'll probably be attempting this feat throughout the winter. It depends if I can find some time to go down to the US and grab a pair of heads (stealth heads are rare and diamante's are non-existent here in Winnipeg). I was already planning to use Megasquirt, forged pistons, custom headers, and a custom intake with the SOHC...so I might as well take it one step further and attempt the DOHC conversion. From looking at my duster I imagine that the alternator must be moved to where the AC is, fan moved to the other side of the rad (this is a maybe...depends on how crazy you want to get with headers), and a couple coolant lines modified.

Is it worth the effort? Well, the heads flow quite well. They can rev higher than our SOHC heads can. Even non-TT heads are pretty awesome. Here's a link to check out some numbers Stealth 316 - 6G72 DOHC-Turbo Head Info.

**c2xejk** · 07-26-2007, 11:11 AM

Quote:

Originally Posted by kreel

Is it worth the effort? Well, the heads flow quite well. They can rev higher than our SOHC heads can. Even non-TT heads are pretty awesome. Here's a link to check out some numbers Stealth 316 - 6G72 DOHC-Turbo Head Info.

I have said it before and I will say it again. With proper porting, the 12-valve heads can flow very well. Probably better than 99+% of the people here need.

Ported heads are a lot eaiser to install than swapping to any of the 24-valve heads...

If you check out pro-stock drag racing, they run 2-valve/cyl engines and make peak power at 9K RPM... I could port some 12-v heads for the 3L that could make there peak power close to 8 or 9K RPM...

That said, most people couldn't take advantage of that kind of peak power band... So most would be better off targeting an RPM band more usefull...

kreel · 07-26-2007, 12:24 PM

Quote:

Originally Posted by c2xejk

I have said it before and I will say it again. With proper porting, the 12-valve heads can flow very well. Probably better than 99+% of the people here need.

Ported heads are a lot eaiser to install than swapping to any of the 24-valve heads...

If you check out pro-stock drag racing, they run 2-valve/cyl engines and make peak power at 9K RPM... I could port some 12-v heads for the 3L that could make there peak power close to 8 or 9K RPM...

That said, most people couldn't take advantage of that kind of peak power band... So most would be better off targeting an RPM band more usefull...

I agree with you 100%...ported SOHC heads will meet almost everyone's needs. Why might I attempt a DOHC conversion then?

1. In stock form they flow quite well.
2. *Highly* doubt I'll be making power at 8k RPM...but if I do I know that they can rev that high
3. Personally, I'd love to learn more about porting...but I'm not willing to spend countless hours trying to get a pair of SOHC heads to suit my needs. I'll probably end up spending countless hours on a DOHC conversion as well, but at least it won't be as tedious as "port some, flowbench it, compare results, repeat, etc"

.
4. I want to do a bunch of custom stuff already. No harm in throwing one more thing on the list

5. It's something cool and unique to try.

Once I 100% know that I'm going to try this I will document the whole process, costs, modifications necessary, etc and build a website for it.

Shadow24V · 07-26-2007, 08:07 PM

if you want to see fitment, look at my install thread here: 24v swap and my updates thread here: 24v updates for what i did for an SOHC 24v which has smaller heads than the DOHC.

Ondonti · 07-26-2007, 08:23 PM

Ed does the 12v heads though

Shadow24V · 07-26-2007, 08:58 PM

i agree that porting the 12v heads would be the most economical and easiest way to achieve your flow needs. getting into the 24v stuff has cost me a year of downtime (most of it due to school so only 6 months out of 18 was i working on it)

87turbodance · 07-27-2007, 09:09 AM

I know some people will disagree but I believe multi valve heads are they way to go for a street / strip car. They give you the best of both worlds - great low lift flow combined with great velocity with the ability to flow more than enough air then a 3.0 will need. If you setup 12V heads to flow at 8000 rpm you WILL lose velocity in the lower RPM ranges unlike the 24V heads to some degree. I like to debate this subject so lets hear some more opinions. If you want a car that will run 12's but still can still be driven by your wife to the grocery store without too much bitching then the 24V heads are your ticket IMO

**c2xejk** · 07-27-2007, 11:36 AM

Quote:

Originally Posted by 87turbodance

I know some people will disagree but I believe multi valve heads are they way to go for a street / strip car. They give you the best of both worlds - great low lift flow combined with great velocity with the ability to flow more than enough air then a 3.0 will need.

Not possible... At a given CFM, for a given area, the velocity will be the same. (CFM = cubic feet per minute. So if you fix the area (ft^2) then you can calculate the average velocity (ft/min...)

Quote:

If you setup 12V heads to flow at 8000 rpm you WILL lose velocity in the lower RPM ranges unlike the 24V heads to some degree.

On the 12-valve head, yes you would velocity at lower RPM, but that is not to say that your hp output would be lower than stock.

On the 24-valve not suffering the same problems, not possible. No matter how many valves you have, if you have tuned the ports to a particular RPM range, then that is the range that they will flow the best.

Too many people are taken in by the standard hype... 'The port is bigger so it will flow better.' 'It has bigger valves so it will flow better and make more hp.'

Multil-valve engines help when the bore area limits the valve size. So if you have a small bore, long stroke engine, multi-valves would likely be advantagous. The problem is the 3L engine is a large bore, short stroke engine. Worse, it is (stock) a low-rpm engine...

If you wanted an "ultimate" 3L engine in the stock RPM range, one of the best things you could probably do is go to a smaller intake valve...

Quote:

I like to debate this subject so lets hear some more opinions. If you want a car that will run 12's but still can still be driven by your wife to the grocery store without too much bitching then the 24V heads are your ticket IMO

24v heads are not magic... If we are talking a 3L, a 12 second 12v would be as "driveable" as a 12 second 24v...

**c2xejk** · 07-27-2007, 11:53 AM

Quote:

Originally Posted by Ondonti

Ed does the 12v heads though

I believe the potential of the 12v heads are heavily underrated... Espeically considering the 3L has a big bore (compared to it's stroke.)

87turbodance · 07-27-2007, 08:45 PM

My point being that for some people it's easier to bolt on a set of heads which are known to flow better then to modify a set of heads through porting when you don't have the knowledge or experience to make any real improvements on a head. 90 % of people out there wont have the time or know how to make a set of 12V heads flow the same as the 24V heads available IMO The 12V heads have potential but not right out of the box