Racing porting and reliability question

[sdusablon]

Newbie looking for experienced feedback

I am looking at buying an 84 911 fitted with an 87 3.2 engine and which has had a "major racing porting" (stage 3 ?) done to it.

Owner says that the car has been fitted with a performance chip, Dansk 85 mm exhaust, RPM increased to 7200, etc... (Vertex kit (spelling probably wrong))

If the work has been done properly, would it still affect the reliability of the engine? Could a good PPI done by a reputable shop determine if the porting has been done properly?

Thanks for any feedback

[Randy Webb]

1. No, but if the guy did that, then he wanted to either race it or drive hard on the street. The use pattern may well have reduced engine life.

2. The PPI would have to be very hardcore -- only a head flow expert could just look and see how effecitve the porting was. Most experts would not guess but would determine the flow of the heads on a flow bench -- so the heads would be removed.
So, in a word, no.

Advice: try to find out who did the work, and what components were used. Post that info here, and I'd bet a bunch will reply - esp. to the parts issues.

Also, see how many miles are on the car after the work was done.

As always, drive the car extensively, and see how well it performs for power feel, cold starts, hot starts, etc.

[ChrisBennet]

Stock 3.2 heads flow very well. If the motor is running the stock injection (which the chip implies) I would wonder why big bucks were spent on improving a head (that already flows enough for 300hp) if the rest of the system was not improved to take advantage of it?
If the rev limit was raised, make sure the rod bolts were replaced with ARP or Raceware. The stock rod bolts aren't really strong enough for 7200 rpm use.

-Chris

[Bill Verburg]

I agree w/ CB. The rev limit stock is 6k for constant operation w/a max permissible speed of 6520. The rod bolts followed by valve springs are the weakest components which will limit acceptable rpm limits.

Porting per se doesn't cause any issues(unless it was improperly done)

[sdusablon]

Owner says that he used a Vertex kit (spelling more than likely wrong) to perform the porting. This was the 3rd car he has done a race porting to.

Car has been used for 2 seasons (approx. 6000 miles) since the porting was done.

He also installed Koni shocks in the back, rebuilt the transmission with new bearings, synchro and dog teeth.

Thanks for the feedback so far.

[ChrisBennet]

So he did the porting himself using some sort of kit from Vertex?
-Chris

[cstreit]

As has been mentioned... Porting by itself has very little performance value in a 911 motor... Unless the cam has been switched and the motor is run to higher RPMs.... Neccessitating better valve train and possibly rod bolts...

So, unless other work was done, I'd be suspicious of the guys knowledge and wonder about the quality of the work.

[Randy Webb]

Everything above + you may want to contact Vertex and ask about their kit.

I'd probably move on to a different car....