I was curious about anyone running high horsepower Nitrous systems on the 351C and 400. If the block has 4 bolt mains, main cap girdle, hard block added, and really good machining and ARP studs, what's the limit on boost? Say if you c.r. is around 10.00 to 12.5 to one. Mine has all of that plus customs pistons and old but never used Aluminum Superods.

I've asked this question before my self. not how much can you spray? but how much do you spray? about a 150 shot is the concensus I got as the safe point. It's been tough for me to build for this class because most the other small block in our class are built for around five hundred horses and then spray the dog $hit out of it to make about 800 pony's depending on the weight of their car.

The Cleveland that was in my heavy '70 Ranchero with at least 12 to 1 compression saw between 175 & 225 nitrous shot. But you have to remember that this was mid to late 80's NOS nitrous technology I was using in the early 90's. So the limited nitrous plate jetting (only three stages 125, 175, 225 hp) that came with the system was on the rich side from the factory (I guess for safety). So it's a good bet that the "advertised" HP numbers when using the 175 & 225 hp jets actually resulted in lower HP gains by an unknown amount.

The first weak link with nitrous & RPM's was the cylinder walls, grouting the block almost to the top cured that problem. Next weak link was the head gaskets, copper head gaskets & O-rings cured that problem. Next weak link was the factory rods........ouch........only thing left of the short block that was reusable was the crank. Factory crank + nitrous + RPM's = still a decently stout piece. But factory rods + nitrous + RPM's = "hey, why are the bearings still good but the middle of the connecting rod is missing".

A friend had a '67 Mustang back then (mid 90's) with a Cleveland/clutch-Jericho combo. It had a stock offset ground crank & chevy rods, don't remember how big it ended up being (370's to 390's cubic inch range maybe). Simple grouted 2 bolt block, really nothing fancy like 4 bolt mains or a main girdle. Factory 4V CC heads with intake port stuffers & the exhaust port floor filled with home made steel weld-in inserts. He never really did say how much nitrous he used, but wild guess is it might have been in the 250 hp shot range to hit the 6.15 to 6.25 ET's he was running (decent times back then with basic factory iron block/heads).

did the copper head gaskets get water in the oil? my friend has a brand x small block with 636 hp and two stages of nitrous. and those gaskets are not working out fo him.

The very first time I used coppers they leaked water because I listened to some of the local "experts" that said (A) the spray on sealer was the way to go, and (B) the coppers didn't need a re-torque after the first heat cycling.........both dead wrong.

The spray on sealer (forget which brand) was useless, too thin to fill any scratches in the deck surface. And copper head gaskets (hell any type head gasket truth be told) need to be checked for torque specs on any race engine after the first few heat/cool cycles. The best sealer I have found is the GE silicone with aluminum in it (forget the part number) comes in a calking gun sized tube.

The shop installing O-rings in the block needs to know what their doing too. The O-ring needs to stand out of the block a given amount. Too little & the O-ring won't embed into the copper enough. Too much & you might have a hard time getting the copper to fully seat on the deck surface. A shop that knows what there doing can install the O-ring wire just right so it's hard to tell where the seam is. A crappy shop might cut the wire too short leaving a giant gap that could leak & say "it's good enough".

I almost positive that the copper headgaskets need a very smooth AR on the surface of the block and head to seal perfectly.

copper is notorious for water sealing problems. SCE has a Titan line 'with built in coolant and oil seals'

http://www.scegaskets.com/Shop/Control/fp/SFV/32777/seo/1/search/cleveland/sfv/32777/field/1/prods_per_page/96

old school tricks include aluminum spray paint on the gaskets, more modern is copper spray.

copper gaskets are supposed to be anealed before use, i'm not sure if the Titans are annealed or not but they have sealant on them like FelPro Print-o-Seal, possible that some old school copper gaskets are not annealed as sold.

http://www.steamengine.com.au/ic/faq/annealing-copper.html

http://www.headgasket.com/preinstall.html



"Enlightened statesmen will not always be at the helm" ~ James Madison