mumzer

what was required to fit the intake manifold? is the bolt pattern the same? is there enough material in the manifold to fit it with head simply by porting, or was it necessary to cut and weld?

Second, if you have any lenght of service information with the non coated ports, what was your experience? thanks

mumzer

and a follow up question also...any idea what the combustion chamber volume on the head is?

fast951

The 2.7L head will not work with a 2.5L block. The water outlet/jacket does not lign up with the block. Most people use the 2.7L head on the 3.0L block where everything matches.

Also the inlet ports of the 2.7L head are oval in shape, so you'll have to modify your turbo intake runners to match.

For a 2.5L block, modify your stock head with bigger valves. Much cheaper and works as well, if ported correctly.

mumzer

sorry...it is a 3.0l

Danno

Most of the gains in a head P&P job is at the valve-seats. Get a fully-contoured valve-seat cut with variable radius curves. These curves are tuned to the flow velocity differences between the long and short radius bends in the port. Using a 104mm bore block will also allow you to unshroud the tight areas around the intake-valve to let you flow more. And of course, undercut the valves since there's a ledge on the exhaust valves that really limits flow at low cam lifts (Hans & Frans strikes at Porsche again.... <img border="0" alt="[nono]" title="" src="graemlins/nono.gif" /> )

We can actually install larger intake valves with 7mm stems to take advantage of the increased flow in 3.0L engine...

PorscheG96

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Danno:
<strong>Most of the gains in a head P&P job is at the valve-seats. Get a fully-contoured valve-seat cut with variable radius curves. These curves are tuned to the flow velocity differences between the long and short radius bends in the port. Using a 104mm bore block will also allow you to unshroud the tight areas around the intake-valve to let you flow more. And of course, undercut the valves since there's a ledge on the exhaust valves that really limits flow at low cam lifts (Hans & Frans strikes at Porsche again.... <img border="0" alt="[nono]" title="" src="graemlins/nono.gif" /> )

We can actually install larger intake valves with 7mm stems to take advantage of the increased flow in 3.0L engine...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Whoa...about two sentences into your post my brain went poop and I find the rest beyond my comprehension. Where'd you get data for all this?? Yikes! <img border="0" title="" alt="[Eek!]" src="eek.gif" />

mumzer

</font><blockquote><font size="1" face="Verdana,Tahoma,Arial,Helvetica,Geneva">quote:</font><hr /><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">Originally posted by Danno:
<strong>Most of the gains in a head P&P job is at the valve-seats. Get a fully-contoured valve-seat cut with variable radius curves. These curves are tuned to the flow velocity differences between the long and short radius bends in the port. Using a 104mm bore block will also allow you to unshroud the tight areas around the intake-valve to let you flow more. And of course, undercut the valves since there's a ledge on the exhaust valves that really limits flow at low cam lifts (Hans & Frans strikes at Porsche again.... <img border="0" alt="[nono]" title="" src="graemlins/nono.gif" /> )

We can actually install larger intake valves with 7mm stems to take advantage of the increased flow in 3.0L engine...</strong></font><hr /></blockquote><font size="2" face="Verdana,Tahoma,Arial,Helvetica,Geneva">danno. s there a readily available bronze guide that we can retrofit? our valves are stupidly porky...i dlove to see a lighter stem...

Danno

"Whoa...about two sentences into your post my brain went poop and I find the rest beyond my comprehension."

Heh, heh.. Imagine a standard 3-angle valve-seat cut. Start at one point on the valve-seat, say... the part that's closest to the spark plug. Then as you work your way around, the seat changes into a 5-angle valve-seat. About 120-degrees around, this changes into a 7-angle valve-seat cut. After 180-degrees around, it goes in reverse back to a 3-angle cut near the spark-plug. This is just for illustration purposes as the seat will have curved surfaces and the shapes of the curves will change as you go around the valve.

"Where'd you get data for all this??" Ancient Chinese secret! If I tell you, I'll have to kill you! Actually we're working with some folks with lots of F1 and Porsche Motorsports experience .

"s there a readily available bronze guide that we can retrofit? our valves are stupidly porky...i dlove to see a lighter stem..."

Yup, we have an undersized bronze guide that can be used. Also a nickel-bronze valve seat that conducts heat 10x faster than steel. They're slightly softer, so they can actually be forged by the valves to remove high & low spots... I'm giving you a call... <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" />

Rich Sandor

Okay, since the topic is 3.0L Turbos with 2.7(s) 16 valve head, here's my question:

With the doubled valves, what else do you need to modify? Do the Chips need to be customized to take advantage of 16 valves? Would you run the same cam belts or timing chains? I'm guessing there's lots of extra stuff to add, besides just a reshaped plenumb. (or whatever it's called)

There's no way you could take a regular 968, put a 2.7S 16V head on it, slap on a K27, and have it run just like that, could you? Cuz a setup like that.. whoa mamma.

Danno

"There's no way you could take a regular 968, put a 2.7S 16V head on it, slap on a K27, and have it run just like that, could you?"

Hmmm that actually won't work because the 944S is a 2.5L with 16-valve head while the 944 2.7L has an 8-valve head.

The trick with all these head-swapping scenarios is to get the proper match with coolant port near the front. The 944/951/944S all used the 100mm-bore 2.5L blocks and can swap heads easily. The 944S2/968/944NA-2.7L all used the 104mm-bore 3.0L blocks (short-stroke on 944NA gives 2.7L).

Here's a comparison photo of the heads:

<img src="http://boards.rennlist.com/upload/Heads951944s944s2.jpg" alt=" - " />

I don't have a photo of the 944NA-2.7L 2-valve head, if someone could post one, that'd be great!

Since mumzer has a brand-new 104mm-bore 3.0L 968 block, his choices of bolt-on heads are the 944S2/968 16-valve heads or the 944NA-2.7L 8-valve head. Since he's going to be turbocharging the beast, he's going to use as many 951 parts as possible. This means the 951 intake-manifold, which will only fit on the 944NA-2.7L's 8-valve head.

"Do the Chips need to be customized to take advantage of 16 valves? "

Assuming that you're going with an S2 or 968 16-valve head with the 951 DME/KLR/AFM electronics, yes, you will need custom chips for the engine. Our 2.7L and 3.0L Turbo chips are wildly different from the other 2.5L Turbo chips. The additional re-tune option is typically required to go back & forth with dyno-charts about 1-2 times.

"Would you run the same cam belts or timing chains?"

Sure, those will work just fine. Personally on a street car, I would advance the cams a couple of degrees to get more mid-range torque. Otherwise these cars will tend to be revvy with a peaky torque curve. But advancing the cams will sacrifice some top-end power as well. A better solution would be to retard the exhaust cam and advance the intake cam a couple of degrees to get more mid-range yet not sacrifice too much high-end HP (requires twin cam-gear conversion).