I see that you removed the rubber lip that goes around the perimeter of the engine compartment to seal the top of the engine from the bottom. It's a flap-like gasket that sits in a groove. I take it you're going to replace it? I may do that to mine as well. How did you remove it, and how difficult was that to do? Do you know how difficult it will be to install a new one? Where can it be obtained (other than from a dealer) and at what price?

Thanks for your thoughts.

Are you on the beta test list for Mega Squirt II? Those PC boards aren't readily available for sale yet. Will you go crankfire w/ EDIS? This conversion makes twin plugging pretty easy, from what I can gather. If you do go the MegaSquirt route, PLEASE, let us all know, as there are quite a few of us that want to go this route as well.

Yes, EDIS and I will be one of the MSII pioneers even though its likely to be a few months before I am to that point though.

As usual, all will be well documented. :D

As far as the engine compartment gasket goes, you can pull the rubber right out of its groove. Even the stuff that turned rock hard came out pretty easily.

Can't wait to hear how it goes!

The moment the MSII kits go up for sale, I'm buying.

I finally had a chance to work on my stuff this weekend.

I spent about 6 hours port matching my heads and porting my carrera manifold.

Concidering the casting seams and roughness I can see why the carrera manifolds benefit so much from extrude honing but it wasn't anything that couldn't also be taken care of the old fashioned way.

I remembered to take a few pics so enjoy . . .

Here is a shot of my workbench as I prepared to scribe my heads for the detail work.
http://forums.pelicanparts.com/uploa...1110170124.jpg

The phenolic spacers for the manifold can move around about 0.02" so I decided to make some shims to keep them properly located.
http://forums.pelicanparts.com/uploa...1110170244.jpg

I used the mill to add some precise notches for the injectors.
http://forums.pelicanparts.com/uploa...1110170388.jpg

Here is a before and after shot of the blending and port matching hand work.

http://forums.pelicanparts.com/uploa...1110170533.jpg

http://forums.pelicanparts.com/uploa...1110170619.jpg

And here are a couple shots of my manifold that is now free of its casting seams and roughness in all critical areas.

http://forums.pelicanparts.com/uploa...1110170736.jpg

http://forums.pelicanparts.com/uploa...1110170754.jpg

I can't add much to the rebuild of the motor, but I did replace the rubber seal Rob 930 asked about.

Just like 350HP said, it pulls right out of the channel. Easy job. Reinstall is pretty tough if you don't want to mess with the metal channel the seal rides in.

There's two ways of reinstalling that I considered:

1. Spread the channel open and pinch the new seal in place by crimping the channel closed, little by little as you go around the engine bay. I thought the end result might be a ragged-looking job. So I decided to go with #2.

2. Leave the channel be and simply spray the seal with silicone spray to make sliding the seal into the channel a little easier. Even with the silicone, it was a bit of a struggle. Lots of shoving and inching the seal along. Takes a bit of time and patience. Especially when the seal has to turn the corner(s). :mad:

Good luck.

And BTW, nice job keeping this topic alive 350HP! Slowly but surely it's coming together! SmileWavy

Please don't forget to post measured flows.

I will have some measured flows soon, but I imagine some of you would be interested in seeing my DIY method of doing so . . .

http://forums.pelicanparts.com/911-engine-rebuilding-forum/213275-diy-flow-bench-post1830890.html

I posted on this thread earlier. What size were your intake ports before you did the machining and flow work? Mine are at 35mm+ from Andial way back when, and what started as a clutch and oil line/gasket freshening is now a full rebuild/upgrade. My 3.2 Motronic EFI showed up today, so doing somewhat similar things. My damn heads got done quickly and were re-assembled with all new valve train with a CIS assumption 4 weeks ago, so I didn't open them up anymore. Advice? I am not looking to win dyno wars. Looking for driveability with what should be an easy 100HP boost over where I was, with boost coming on earlier.

The stock 930 ports were officially 34 mm, but in reality they were more like 33 mm.

The carrera manifold and spacers are 40+mm so even with 36 mm ports you will want to do some port matching since port flows do not like meeting sharp edges like several millimeters of port mismatch.

Don't forget about the injector notch and the gasket area right above it.

Your DIY Looks very good. Remember the short side radius, its the ONLY place besides basic port matching that does anything to speak of. Smooth it out, increase the radius as much as possible. For extra but almost nothing, swirl polish the intakes, back cut the intakes, exhaust, radius the exhaust valve edge and finally incut the exhaust face. I suspect that most of this valve work is next to less than 1/2 percent total, but thats what the racers do.

ToyCollector, I'd go ahead and remove the valves and open the intakes correctly. With as much money as this stuff costs, why cut corners on something like the ports, JMHO. :)

Thank god for a good roomate who does not mind me bogarting the dinner table and a portion of the living room for my project. :D

http://forums.pelicanparts.com/uploa...1113160695.jpg

I also just recently received my new super cup bump sticks and titanium retainers from John Dougherty.

http://forums.pelicanparts.com/uploa...1113160839.jpg

I have also recently acquired most of my other internal engine goodies from wayne and EBS. Right now I am just short a new set of exhaust valves and head studs from having everything I need to put the engine together. After that the remaining big items are the turbocharger, intercooler and fuel injectors. Confidence is high that I can get this wrapped up sometime this summer.

http://forums.pelicanparts.com/uploa...1113161111.jpg

Your clearly are NOT married. Or if you are you will soon be unmarried.

Already unmarried, but thats what allowed me to finally get started on my lingering project. :D

But to return to the subject of my 930, I have the result of my intake flow tests.

I took one before measurement and have calculated a flow improvement of almost 40%. That makes sense since the new ports are about 45% larger than the old ones.

My current calculated flows of >255 CFM @ 25" vacuum and 0.45" valve lift are also very respectable.

Compared to other numbers I have seen thats about as good as it gets for heads using 49mm intake valves.

The CFM numbers may vary depending on the equipment used and what is used to guide the flow into the port but the main purpose of this whole experiment was to determine that all the head flows were evenly matched.

I am happy to report that all the heads except one are within 1% of each other, and one is only off about 1.5% off from the rest.

I will be looking to see what is different about my oddball so I can try to correct it.

As usual I will keep everyone updated on my progress.

Tonight I broke out the internal calipers and went in search of the differences between the worst and best flowing heads.

I was pleased to discover that all major dimensions and curvature profiles were the same but I was perplexed as to why the flows would be so different.

Upon further visual inspection I noticed a very subtle difference of the short side radius where it meets the valve seat.

It appears that there is a minor difference in the castings resulting in almost a millimeter difference in the location of the port and a corresponding increase in the length of the short side radius. I guess its enough to cause the measured 1.5% flow difference.

I have attached a picture below to show the difference and I will be spending some time in the shop tomorrow trying to match them up.

Its hard to see it but if you look carefully you can see it.

http://forums.pelicanparts.com/uploa...1113624588.jpg

That just goes to show where the most important area to improve is, ie the short side radius. Hog as much as you can off this side and you will get even better flow, only limitation is running into something, like a valve seat or in some cases water jackets (not a problem common with Porsches). Just a smigen of a sharp edge on this surface can hurt flow by as much as 40%!!!!!

By the way that is one BEAUTIFUL finish in those ports.

What are the low and mid lift numbers on the intake and exhaust? What are the ports opened up to? That number at 450 lift corresponds to about 270cfm at 28 inches which is right with the top head porters in the country with larger valves.

Eric Hood

Its likely that my apparatus might be reading a few percentile points too high due to the boundry layer effects in the measurement tube. Even if that is the case the numbers are still very respectable.

I haven't measured the exhaust flows yet since I still need to build an adapter that will allow me to suck the flow out of the exhaust port but I should hopefully get around to that this week sometime.

I am planning on retesting my tweaked heads tonight so while I am at it I will get some numbers for 0.25" and 0.1" lift.

The intake ports have been opened up to 40 mm and the exhaust are still close to the stock 34 mm.

I suggest forgetting all the numbers at 0.4" and higher. THe really important numbers are at 0.1" , 0.2" and 0.3", thats where ALL the action is at, ie area under the curve. Getting 10% better at 0.1" lift is much better than any improvement at 0.45" lift. The reason is that the flow at 0.1" and higher is for much much much longer time than the flow at 0.45". And furthermore Porsche heads flow very well at low lifts, ie they are in need of duration, not more lift. All of the Porsche heads I have flowed indicated that the HP limitations of the engine are NOT related to head flow, but to rpm limitations.

I am happy to report that after tweaking all my intake port flows are now within 1% of each other. :D

As long as I was testing I decided to take several readings at different valve lifts. I figured a graph would make it easy to see how the flow curve drops off as valve lift increases.

It looks like my new super cup cam intake valve lift of 0.49" is going to be well suited for the flow characteristics of my modified heads.

http://forums.pelicanparts.com/uploa...1113878537.gif

Since your the real science type of guy I would suggest that you do some calcs or use an engine sim program to do them for you and check out what the flow above 0.4" gives you. Basically NOTHING (execpt extreem valve train wear) unless your willing to rev the thing to 12000 rpm.

In terms of numbers its like 5% more flow, but for only 1% of the time, ie 0.01 times 0.05 equals 0.0005 which is pretty darn close to NOTHING. TO put this in HP numbers, say you end up with 400HP the extra lift will give you about 400.2HP, if you are lucky.

I am not a true expert on this subject but Dema Elgin of Elgin Cams is. I would also talk to him for real answers about your cam and heads. He is also a racer as well as a world renown mfg of camshafts. He is usually available and will actually talk to us peons if you give him a call. He is at http://www.elgincams.com/

A higher lift cam gets to 0.4 inches faster and stays open longer than a lower lift cam will.

True, but check out the calcs. Marketing hype is still marketing hype. Only a world class racer pushing for everything at ANY cost might ask for the last 0.2HP, but some wiser ones opt for relialibity.

I also know of another tradeoff that adds even more hp, compression ratio. That extra valve lift will limit the compression ratio enough that you may even end up with a net loss of power. These ain't chevy heads. Chevy heads can flow at very high valve lifts because of their poor design.

If you haven't bought your cams yet, hear the Elgin guy out and then make a decision.

Are those numbers still at 25 inches?

The following two quotes are from Demas class notes,

• In a performance engine, the intake valve is lifted past its point of maximum port flow.
• This increases the amount of time that flow is maximized, limited by the port.

No, those numbers are for 28" and should be more accurate since I made some scientific calculations about how big the boundry layer is in my flow measurement tube. Since most of the other flow numbers I have been finding on line are for 28" I have been adjusting my flow numbers to that reference pressure for comparison purposes.

Since the boundry layer is about 1.25 mm thick where the pitot and static ports are located in my 50 mm measurement tube the actual flow area was only 90% of the total area I was initially using for my calculations.

The latest numbers should be very close to the actual CFM numbers my heads are moving.

Those numbers will support the hp you are looking for no problem.

Eric

The flow numbers given will support a fantastic ammount of HP, but at RPMs that the Porsche will not operate at. I would suggest picking your max RPM eg 8500 and work backwards. IE cut the lift back until you start to see a decrease in HP. You will be amazed at how low a lift you can live with and give up nothing. The only other way to actually utilize all that air is to increase displacement.

an analogy. If you have 3 horses that want to leave the barn at the same time, you give them 3 doors for mininum exit time. If you add 5 more doors, you still end up with 3 horses, no more. And consequently you wear out 8 doors instead of 3.

This is forced induction Jack. I don't have to spin crazy revs to shove air past my closing intake valves.

This is true only if the head is limiting the power, in this case the RPM and or displacement is limiting the power and the heads are a distant 3rd.

Another good reason not to wear out the valvetrain needlessly.

Put another way you already have 8 barn doors open, 3 horses normally aspirated and 5 horses forced induction, why the need for more doors? And furthermore why not add more force?

PS note, the engine breaks at 5 horses.