he he... our first victim. There are several options. Some port the stock LT1 heads with great success. But another option is the AFR 210s or these Trick Flows. I'm particularly intrigued by these Trick Flows which seem to be a great value.

All heads should be cleaned up a bit and the bowls blended at a minimum. I would eliminate all of the sharp edges and raise the compression to take advantage of the overlap on that cam.

Look at what your target head gasket thickness should be and have the heads milled to get your Dynamic Compression Ratio around 8.4:1

You may want to talk to Nightrain66 or Skaradom or Bret Bauer.

 

i highly doubt a single head choice from TFS would run AFR anywhere.
those 2 have been head to head for years,and both doing well. the TFS isnt for everyone,especially with those large combustion chambers.

 

ok, though with the size of the combustion chamber, what would be the compression ratio on your generic 383 crank? figure on normal lt1 gasket and everything i suppose.

 

If your building a 383 you will need new pistons and you probably are going to want to deck the block!

so you pick the pistons you need to give you the proper compression!

if i put these heads on my 383 here is what i would end up with!

Bore Size: 4.03"
Piston Size: 4.028"
Stroke: 3.75"
Deck Height: 0.005"
Piston Ring Land: 0.3"
Piston Dome/Dish: 5 cc
Head Gasket Bore: 4.125"
Head Gasket Height: 0.039"
Cylinder Head Volume: 64 cc
Cylinder Volume: 783.826 cc
Gasket Volume: 8.541 cc
Deck Volume: 1.045 cc
Total Volume: 862.474 cc
Engine Displacement: 382.66 cid
Compression Ratio: 10.97:1


So with that said you would end up right where you would want to be with a 383, if you built it approx the same!!

 

thank you for your informative and energetic answer.

 

Get a Dynamic Compression Ratio calculator... you'll figure it out quick and fairly accurate. If you stroke the engine, you'll have nearly the same Static Compression Ratio. It depends on the amount of stroking, head gasket thickness, etc......

 

No way. Stroking increases the Static Compression Ratio, all other variables the same.

 

yeah... I think that's the point.

The larger combustion chamber in these heads makes a stroker pump-gas friendly without hoggin' out the chamber on stock heads to compensate.

350-->383 means a 10% increase in total displacement... so to keep the samp C/R (if that's your goal), you'd need to increase the combustion chamber size by the same 10%.

A 396 or larger stroker gets even worse. Obviously a thin 0.020 gasket isn't ideal for a high-hp application as well... so many bottom end rebuilds shoot for a 0.005" deck-piston height, allowing a more substancial gasket (like the Felpro unit) while maintaining quench heights from 0.040" to 0.060".

Typical response to this is to dig out a bit of the chamber... making the deck height even thinner. For a high-pressure engine like a nitrous monster, or a high-boost situation, this seems like the ideal head to use. Not only do you get the larger cc's nessesary, but you don't thin the combustion chamber's roof to do it (and even make it thicker!).

Good deal for boost and exotic strokers for sure.

For my 383 build-up though I think I'll stick with a ported LT1 casting though, since I'm only looking for ~430rwhp (~500? fwhp) NA and 600 rwhp on the bottle. If things change though, this would definitely be an option I'd look at.

 

steve in seattle, so your saying that the trick flow heads here are overkill for your horsepower goals? what cam along with what flow number from the stock heads are going to make 500hp so easily?

 

no not really. It's not the hp numbers you need to look at, but the combustion pressures and what your engine goals are.

I'm only building a 383 and looking for 11:1 compression, which isn't too bad on stock LT1 heads. If I can get the LT1's to flow ~270cfm, then 540 fwhp sounds about right (2hp/cfm is typical for V8's).

So with LT1 castings going for ~$200, and a decent porting job running anywhere from $600 to $1500... it's really dependant on how much you plan on porting the heads out (ie. how much will you spend).

Seeing how I have a set of LT1 castings in my garage, I'm wagering I can clean them up a bit, and have local guy port them to 270 without breaking the $1200 these heads cost. Obviously I could sell the LT1 castings and get these at ~$1000... but I honestly think it'll be a bit of a toss-up in my situation.

For race-gas compression ratios, boost, or heavy nitrous applications my position would definitely change.

Now the only thing I have to consider is if the ported LT1 heads will be fine with a 150 shot on an already stoute motor. Reading what others have done I'm not convinced this will be a problem.

Cool product, but unless I opt for a 396 instead, or find people with head failures at ~700 fwhp I'm not sure it's more than just an option... although the deck thickness is appealing...

 

Wow, I just re-read the specs, and you can put 2.05 intake valves in these TFS heads and not have to change the seats.

Wouldn't this alone be a big increase in flow?

Never thought my initial post would initiate this kind of response

 

hmmm... that price is looking better, I just noticed these are for assembled heads with SS valves, and large double-springs.

Considering the target of these heads though, I'm supprised they arn't shipping with 7/16" studs though. I guess this brings up a few questions:

1) will 7/16" studs be an option?

2) will proper LT1 guide plates be used (GMPP)? or will we need to swap them out since standard SBC guideplates do NOT work in LT1's without "massaging".

3) what springs are used with these heads? (Maker / part number) Any estimates on total lift possible as shipped?

4) what valves are used with these heads? are these 0.100" longer valves? are there lash caps? Are these Manley Race Flows? or cheaper street-valve replacements?


I know it's a bit much to figure out now, but if anyone knows the details on these please speak up!

 

Those are good questions for Artie to answer.
I am very interested as well.

 

I don't know. For the price sounds great . Need to see some real #.

 

So assuming stock internals what kind of compression ratio would you see with the bigger chambers?