Looking to build a 396 fully forged.

Current setup:

Strong running LT1 with stock ported heads ( Int 194 neck down Ex 160 SS valves) (no flow numbers), intake and cam (xe 224/236 114lsa w/1.6rr)58mm tb. 30lb SVO inj, GSS340M pump, Hooker LTs 2 1/2" true duals. (383rwhp/340rwtq) M6 342 1.8 60ft 8.2 1/8 12.7 @ 110 more in it just scard to grenade the rear + driver error

Love the setup just looking for more.

Plan of attack:

Try and keep it short and to the point.

Build the 396 forged and use my stock ported heads for now.
Get a good size cam for later (AFR heads 220cc, n2o or blower ATI D1SC 14 - 16#)but install now N/A power.

Looking to get into the 11s or more n/a and spray a small 100 shot to go quicker, until I can save for the blower and fuel system.

This is not a daily driver and would be willing to do solid roller, for more HP. Looking to see around 430HP on the low to about 470 w/heads??? CR 9.1 N/A

Looking for 4bolt main bare block.

Have ordered the forged eagle (I think) 396 crank, forged rods (not sure on size) and JE/SRP forged pistons. sorry local engine builder helping with that part.

Cam: looking at the CC ex 248/254 .562/.580 114lsa 4 degrees adv springs to support.

Max rpm 6500?? at this rpm should I say hydro?

Boy is this a bunch of loaded questions... heheh

Always value your inputs and Thanks!

 

The only problem I see with possibly changing heads later is using the new bottom end with old heads. I'm assuming the pistons you're planning on with the 396 build will be matched to the final heads you use as far as CR goes. What will it be temporarily with the stock heads? Will this have an adverse effect on performance? Or are you planning on changing pistons again? By the way use the longest rods possible. Gives your pistons a much longer life. Less side loading.

 

A blower and/or nitrous with a 3.875 stroke kinda limits how long a rod is practical. You might want to consider a piston compression height (CH) well over an inch for the high cylinder pressures. 6 inch rods only give you about 1.06 CH with a 9.00 decked block.

5.85 gives about 1.212 which should help the blower pistons live.

My $.02

 

Listen to the Old Stroker! I also prefer short rods for a SC or nitrous setup. These motors develop huge cylinder pressures and the ring lands need to be beefy to support the ring package. It's also my opinion that a shorter rod is beneficial at decreasing the chance of detonation. By moving the piston away from TDC faster, peak cylinder pressure is less and the chance of detonation is decreased. This latter effect is probably small, and I really can't quantify it, but I believe it is real.

For a 3.75" stroke (383), use a 5.7" rod, for a 3.875" stroke (396) a 5.85" sounds good. The rod ratio is somewhat extreme, but there have been thousands of motors built with these sorts of ratios that work fine. OTOH, if I were building a high revving NA motor, I would use a a 6" rod or longer. The lighter pistons, among many other characteristics of a long rod motor, are a big advantage here.

Rich Krause

 

I have a 3.750 stroke and 6" rods and still have a CH of 1.125. With a 26cc inverted dish I have a CR of 9.4. Long rods are better, sorry guys.

 

Thanks for the info on the rod ratio, as Im not sure on what rod to get.... (leaving it to my local engine builder) that stuff is way above me.

Does any one know what the stock head chamber cc is? I'm trying to get the CR around 9:1

Moreboost

 

anyone?

 

Well bad news my local shop said they had a 4bolt bare block and it turns out its not!

Does anyone have one sitting around? Is the 2bolt block strong enough to handle the boost?

Thanks again

 

Converting a 2-bolt to a 4-bolt block is a basic operation. Any decent shop should be able to do it. You want to upgrade the main caps anyway, even if the original block is 4-bolt, so in either case new caps have to be fitted and the mains need to be align honed.

Rich Krause

 

My local shop is quoting $500.00 for parts and labor, does that sound like to much?

would a two bolt hold up?

 

Depends on what parts they are using. A good set of steel main caps can run in the ~$250 range. You need a 4-bolt setup for what you are proposing.

Rich Krause

 

Ok thats what I was thinking. Hmm will I'm in hawaii so finding a block and shipping to Hawaii and shop work..... ACK!

ebay maybe? hehe

There is a bad block at the shop now, I think the block has a bad cylinder, scored... Should I take a chance on it? The guy want $400.00 for the block or $600.00 with heads........

 

Do one thing, do it right, do it well.

NA, NA + nitorus or supercharged. No cross breeding. You'll end with a retard.


for a blower i am thinking 8.5:1 on the street.

NA i'm thinking around 12:1


this is dependant upon the gas you have available and the cam you choose of coarse

 

One thing i noticed is your cam choice as of now, if you only want to spin it to 6500, which 6700 is pretty much the most you want to spin a hyrdaulic roller without a hydra rev kit. Anyway, that cam with that much duration is going to make peak power wellll above 7000, which the rotating assembly will handle it, but the valvetrain wont. Id say go for a cam in the low to mid 230s on the intake and low 240s on the exhaust side. that will peak out at around 6500 or 6600, still well in the hydraulic roller range, just get some springs with goood pressure and that can handle at least .6" of lift.

 

Moving more to the side of solid roller, 6500rpm maybe 7000 but I dont thing so.... If I can get to where I need to be at a lower rpm all the better....

Cams lsa is 114 and 4 degrees adv for this cam..... I hope that will lower the power band in the correct range.