[GTOGEORGE]

First thing I did after installing my B & M blower was put in a cage then ladder bars. I already had SD rods and a four bolt main....I shifted at only 5,200 rpm. No aftermarket block available at the time but I wasn’t close to maxing out a Pontiac block. When I bought my 8-71 then I bought a IA block. Going fast safety is not cheap.



GTO George

[GTOGEORGE]

FYI, I bought my is block because I broke my factory Pontiac block when I pushed HP near 800, luckily I only broke my frank and nothing else!



GTO George

[JSPONT]

Originally Posted by 455TA

I've got a perfectly good 400 on the stand - I just find it hard to wrap my head around spending $8600 on a new aftermarket shortblock when I could probably build the 400 for half that and it still be reliable under 15 lbs.
I would go ahead and do the midplate before I put the engine in the car. Mine is around 3800 lbs roughly. But it's built well.
Tubular upper and lower control arms, Viking Coilovers. Calvert racing caltracs, good adjustable rear shocks. Subframe connectors, and aluminum body bushings. Gforce Crossmember. Only thing it lacks is a cage and a scattershield but it would get those along with the turbo setup.

You will be fine, plenty of guys running stock blocks at that level. My car has no cage either full interior. I drive my kids to games, soccer, supermarket trips on weekends. It is a real street car, not a race car on the street.

[Tom Vaught]

Your other alternative is to build a throw-away boosted engine.
Just make sure the rings and bearings are good, arp bolts in the rods, basic balance job.

Then install the turbo stuff and go beat on it on the street. If it blows up, build another CHEAP engine. Learn about Boost and Tuning with a carb and have FUN. Save your money for the good stuff down the road. This is if it is a true street car with boost like 70bird has. There is a sharp guy with boost on a street car. (Much like Charlie66) with his deal, having fun!

Tom V.

[455TA]

No Carb here - I used to run a 850 Holley DP, but now I run the FiTech Fuel Injection. It is the 1200 hp power adder system so it will take it all day. Technically my current engine is a cheapy - other than the top end. I bought it for $1200 fresh rebuild with the arp rod bolts and TRW's. Just dont want to mess up the top end if things get bad. lol

[Tom Vaught]

Odds of hurting the top end, with the pieces you describe, is minimal if you have stainless one piece valves in the heads. Higher pressure springs help on Boosted engines too with the boost applying force on the 2.11" intake valves vs NA pressures.

Is the camshaft a flat tappet or Roller?

Tom V.

[455TA]

It does have Ferrea Valves. Has comp 914 springs - Right at 160 lbs seat pressure before break in. It's got a 236/242 Hydraulic Roller, 600/620 lift on a 110 LSA

It also has a good ignition system. MSD 6AL-2 Box with a MSD Pro Billet distributor. I currently have the rev limiter set to 5800 rpm, and I shift at 5500

[JSPONT]

I run 250 on the seat but i have a solid roller. When you add boost you need a little more seat pressure. There is a formula for it. I do not have it handy.

[Tom Vaught]

Here is a example that would get you close"

If the I.D. at the valve seat is 2.11" and the valve stem diameter is 5/16", the area of the valve on it's seat is about 3.5" for simple math.
Multiply that by the boost pressure, 15 psi
so 15 psi times 3.5 gets you 52#s more spring force on the seat (for 15 psi boost).

You need to be over 210 on the seat to allow for the 15 psi boost.

Tom v.

[twooldgoats]

Originally Posted by GTOGEORGE

......., luckily I only broke my frank and nothing else!



GTO George

Damn, that had to hurt!


Jim

[charlie66]

Originally Posted by Tom Vaught

Here is a example that would get you close"

If the I.D. at the valve seat is 2.11" and the valve stem diameter is 5/16", the area of the valve on it's seat is about 3.5" for simple math.
Multiply that by the boost pressure, 15 psi
so 15 psi times 3.5 gets you 52#s more spring force on the seat (for 15 psi boost).

You need to be over 210 on the seat to allow for the 15 psi boost.

Tom v.

The way i do it is valve size times the amount of boost you want to use ..

So 2.11 X 15 psi = 31.65 + N/A roll cam seat pressure 225 = 256.65 seat pressure.

Is this a good way as well Tom? I hope so.. lol

[Tom Vaught]

Your calculation Charlie is exactly correct just we said it different ways.

And Because you posted your calculation in a line form might be a bit easier to understand.
You are just using the Diameter of the Valve and I was using the AREA of the Valve Seat Diameter (under the valve) but close enough.

Tom V.