RKD in OKC

Driver's side cam broke at the gear on 94 GTS with 62,000 miles.

Obviously it needs a valve job on that head, the exhaust cam, and full timing belt job including gears. Will go Porken Tensioner. Have not inspected passenger side for valve damage yet so don't know if that will also need work or not. Weighing options until then.

Some Background
GTS is not an only car, but used as fair weather daily driver (however work from home). Does road trips and group drives. Thoroughly enjoys autocrossing/solo events, but not many track day events. Autocross competition is Nissan GT-R, Shelby Super Snake, and 997 X-51 Turbo, and GT3 RS. All in all sees about 7,000 miles a year.

Last spring it seemed to be losing power, just was not as competitive at solo events. A trip to the dyno showed a little weak and worked ALL SUMMER to finally discover, after installing wideband 02 and Sharktuner, that the LH brain was bad.

Because of loss of power, frustration at not finding anything wrong, and often hearing "Some GT cams would really wake that GTS up," was contemplating more aggressive cams. In fact, the cam plan justified installing wideband and Sharktuner which was instrumental in findng the LH brain problem.

Options Available (so far and in order of expense)

1. Just put it back stock. With some Sharktuning it will have more power anyway.

2. Stock cams with balance, blueprint, porting valve job on both heads. Add $1000

3. Upgrade to GT cams. Add $1800, $2500 if needs valve springs.

4. GT cams with balance, blueprint, porting valve job. Add $2800, $3500 if needs valve springs.

5. Colin's Stage2 cams with upgraded valve springs and injectors. Add $3600.

6. Colin's cams with balance, blueprint, ported valve job and upgraded valve springs and injectors. Add $4600.

What would you do or are there other options?

WallyP

My first suggestion is to do a leak-down test to determine if you really need to pull the head.

I don't think that the 928 engine needs balancing, blueprinting and porting nearly as much as a high-volume production engine such as the Chevy. Not much bang for the buck...

Estimate the number of times in a year that you spend more than five seconds at full throttle. Divide that number into the number of dollars that you will spend on power upgrades, and decide whether it is worth it.

AO

Buzzkill!

heinrich

If you add higher-lift cams, you absolutely need lighter lifters and S2 / 968 springs

RKD in OKC

Plan is to do leak down on heads, then make decision. Borescope shows drivers head has bent valves. One piston has four distinct )))) crash marks for one of the valves.

Spend quite a bit of time full throttle one Sunday a month soloing against Nissan GT-R, Shelby Super Snake. I am typically the fastest Porsche at the event and it is put on by the local PCA.

Haven't priced better lifters and valve guides yet, but I consider that as part of the port and polish thing.

Don't know if different springs are required for GT cams or not. It would up the cost of going to GT cams.

123quattro

Colin's cams, VW lightweight lifters, stiffer springs, injectors, and call it a day.

heinrich

how are you planning on doing a leak-down when your valves are bent?

Herman K

Buy TonyC (great running motor that can be tested) GTS motor so you can drive your car and than take the time to sort out your own.

Right now while you're in some ruf seas all the sea pilots are standing on the shore and giving you advise

I wish you well

heinrich

Is that not what he was asking for? Isn't that what this forum is about?

Gary Knox

According to Louis Ott, in some communications I've had with him, you should at least consider replacing the exhaust cams with S4 cams. I think you've had an offer of free S4 cams, as I recall. That would be a very cost effective way to get better breathing.

Gary Knox

Herman K

Yes, he is asking "what would you do?" this is for Richard the fastest way to get back into the joy of driving his car he is not into wrenching him self.

RKD in OKC

Leakdown is easy. It's a pass/fail thing. No hold pressure = bent.

Oh man, wasn't even thinking the whole nuther motor route.

Who offered the free S4 cams? I thought Sterling said I could pic some up for a couple hundred dollars.

RKD in OKC

I have some concerns with the VW lightweight lifters. They are made by INA who now makes all the hydraulic lifters you get from Porsche. The INA lifters may be lighter, but they are also softer than original stock lifters. When I had my 944 Turbo the INA lifter failure rate was huge. Lindsey Racing worked with INA to try to match the original lifters and INA could not longer produce the harder lifters due to changes in the materials manufacturing process brought on by your friendly EPA. Lindsey's solution is to find some low mileage original lifters or go to their solid lifters on their motors with non-stock cams.

heinrich

Thanks for sharing. Well, you have to do something if you want to run higher-lift cams. Better springs as I said, but lighter something ... lifters, valves, something. The whole point with high-revving cams is float, and heavy assemblies do just that, and you saw what my GT cams look like.

I am about to buy light lifters and have already bought better springs for my new GT cams.

SteveG

You don't mention time factor, but I suspect you want it running/DE reasonably soon, like late March, cuz the Nissan is blowing a raspberry at you? I wonder how available the GT cams are? You might spend some time trying to source those, and the result is not necessarily the most you can get from this engine at this price; it does have R2 rods? IMHUnprofessO, Option 5.