Advice on to port or not
 

My car is a 94 993. I am installing PMO ITBs, John D's DC 43 cam, springs and retainers from John D, Electromotive TEC3r ecu, custom headers 1 3/4 w/ equal length 27 inch primaries, 42 lb injectors and a LWF.

I plan to refreshen the head and while so doing, I am debating on whether to port the head or not. The mechanic who will port the head has had extensive experience with Evo's, STI's etc. He uses a flow bench and according to him he has a tool to measure velocity.

He wants to combine both volume and velocity for max results. I have reading up on velocity porting done by Ninemeister, Racetech etc. and am wondering if this is the correct path to take. It is prohibitive in terms of cost to ship my head to the US to have it done.

The car has 65k kms on it. Any advice is welcome.

Where are you located?

I would not let anyone touch my heads unless they had a lot of Porsche experience.

You could pay this guy a lot of money to experiment on your heads and still not get the optimum result.....

Based in the Phil's. Yeah thats why I am skeptical on doing it. But he claims he can improve flow nos and velocity. Still waiting for more inputs. Read somewhere that 993 ports are fairly large already. But with the itb's and cam, maybe the stock ports are limited? Targetting somewhere around 350hp.

imo, you are right to be skeptical. Flow benches are simple tools. ...crude by today's standards of CFD, high-speed visualization of mixing & burning, and actual testing of results. --actual power output, measured, rather than just the obvious result of measuring more air-flow thru a bigger hole. (surprise)

Stock 993 ports (with bigger valves) support power to about 330 BHP.

Its VERY easy to destroy cylinder head flow unless one really has a lot of experience with Porsche heads so I'd be very careful here. This isn't something for one to learn on your dime unless you can afford it.

Hi Steve, heard about your eye operation. Hopefully all went well. I was operated 3x on my right eye because of detached retina!!

So going back to the head, my question is, why is a Porsche head so different? Just wondering and searching for the reasons...

I've thought about doing mine while I had them off the engine.

Steve, what about just polishing the casting but not porting/reconfiguring the port shape?

That should be ok, right?

Zero benefit to doing that on the intake side: polishing exhaust ports helps to limit carbon buildups.

Advice on to port or not
 

I'm curious Steve,

What would they charge to port the heads on a 95 3.6?

RS valves cost?

Titanium springs cost?

What kind of money to do something like this?

http://i250.photobucket.com/albums/g...9/DSCN0357.jpg

I would contact Steve W. or Xtreme heads in fla. about doing your heads with bigger valves etc. i am doing mine with Xtreme (closer for me) and getting coatings on pistons, heads, bearings and headers. As much as you are doing you might go a little bit further, get maximum flow and heat protection to get to the goal of longivity,

You can call me for pricing and further information, but if you are using stock or RS cams, porting your heads will not make a big difference, commensurate to cost. We don't use titanium valve springs as I think thats a poor choice of material for that application. We do use Ti retainers since the OEM sintered metal ones do fracture from time to time with catastrophic results.

I will tell you that your exhaust, as pictured, will cost you a lot of torque & HP with an engine in that configuration. :) :)

Advice on to port or not
 

Hi, Steve:

Thank-you for your reply.

Oh that engine is from the Timmins website.

I was just curious what the going rate was to add RS valves to the heads.

Is it even worth to add lumpy cams and larger valves to a stock 95 3.6?

Oop's yeah I meant titanium retainers.

Thank's in advance.

You are quite welcome,...:)

One usually adds the RS intake valves at valve job time since the seats must be remachined to fit. Labor rates vary widely but the RS valves run about $140/each.

One can use RS cams with the OEM single-throttle intake systems for good effect.

Advice on to port or not
 

'Great Thanx'

This info is very helpful. :cool:

Steve, what is the recommended exhaust for that configuration with headers?

Thanks

X-Treme cylinder heads is the place to go, Bill probably is the number #1 guy in the States to go for Porsche cylinder heads,cheers.

camlob,

I am no where near Steve's level but have been around performance engines for a long while. The heads as Steve said will support 330 plus HP as they are. The port area is quite large by today's standard. If you were increasing the engine size to say a 3.8 or plan to wind it past 6500 then some minor porting could get you some gains. Increasing the valve size with the ports as they are is a nice bump with a really good valve job. I saw some very minor work done in the bowl area that pick up 10 CFM across the board with NO change in the port entry area. Also to copy Steve the 3.6 manifold flows very well the throttle door not so much, attaching the intake to a bare head increased the flow, the tuned length is also spot on. Each port handled 280 CFM@28" H2O and were all within plus or minus 3 CFM as shipped. To put that into perspective you need about 210 CFM to make 330 HP your heads stock flow about 245 but you do not have enough cam lift to get there.

Stay tuned,

PFM

So if 210 CFM is possible for 330hp then the stock 245 CFM = 384hp? As I mentioned in my first post, I am getting a DC 43 cam with 12.44mm lift. So with the ITBs and the cam, the stock head should suffice. In ninemeisters head thread, he mentions that his billet heads have stock sized ports and valves. So his work must be somewhere else like in the bowl area, my guess.

Thanks for the info on the stock flow nos. I think it wont be cost effective wise to pay $1k for doing the bowl area only. Thats how much they charge here for a port job. I am inclined to just cleaning the up the head.

camlob,

Good luck, spend that cash as you see fit but BIG power will not come from porting these heads unless other things change too.

PFM