87 GN engine rebuild

[Holdenbr]

So we got onto the engine and a valve had gotten stuck and ground down a lobe on the cam shaft
Found a new block with Pistons and cam shaft.
What would I gain boring it out 30 over? Original was bored 30 over.
Would the gains be worth the cost?
What else should I consider?
Don't want to break the bank but looking for 400 plus hp.
Have new high pressure fuel pump and injectors along with 60 mm turbo now.

 

[TURBOTIMMER]

So we got onto the engine and a valve had gotten stuck and ground down a lobe on the cam shaft
Found a new block with Pistons and cam shaft.
What would I gain boring it out 30 over? Original was bored 30 over.
Would the gains be worth the cost?
What else should I consider?
Don't want to break the bank but looking for 400 plus hp.
Have new high pressure fuel pump and injectors along with 60 mm turbo now.

IMO, the only benefit of boring the block is if you already have pistons for it. Otherwise, take as little out as possible. 400 hp is easily obtainable with a stock shortblock and will live a long time if it's tuned correctly. You have everything now to get to that hp level as long as you're not choking the turbo down with a stock air cleaner assembly and exhaust. Only thing I would consider is adding alcohol injection.

 

[Reggie West]

If you have a new block with the Pistons set up for it go that route. I'm guessing you need to clean up the cylinders to build the motor. Go 10 over and save the meat between the cylinders. You won't gain anything by going 30 over.

For 400 hp I would spend the money on 2 steel main caps, forged pistons on stock rods, a 206/206 roller cam with the correct springs and TA rockers. Double roller timing chain and a good front cover with oil mods and a high volume pump.

You can port and polish the heads if you want but it will be overkill on a stock turbo. The turbo will run out of air literally. A light pocket port will help and be cost effective. Use ARP studs on the heads they are cheap insurance.

Good luck.