LT1 Based Engine Tech 1993-1997 LT1/LT4 Engine Related

Will LT1 heads flow enough for a 396?

Old Jan 14, 2004 | 01:21 PM
  #1  
onebad96T/A's Avatar
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Will LT1 heads flow enough for a 396?

Im currently buildind a LT1 stroker motor (3.875 stroke .30 over bore) using Eagle's Forged 4340 3.875 crank, 6" Scat I beam rods, SRP Forged 12.2 to 1 w/ a 58cc head, the block will be decked for a little more CR, studed main caps, also will be O-ringed, and this is my short block.

This is what im left with:
Comp 306 cam 112lsa
LT1 heads Ported by Lloyd Elliot flowed decent 270cfm @ .600 lift
w/ 2.02/160 valves, Crane dual springs, Comp 1.6 RR's, comp lifters, comp push rods.
Ported intake to match the heads and a 52mm TB, 30# inj

Can i make these heads flow enough to support my short block by doing some more porting and go to a bigger TB? Or will i have to invest in a set of LT4's and have them ported or even though about the new Trick flow heads. And i know i will need a bigger cam if i go to a bigger size head 195cc+.

But the question is that can i make these LT1 heads work and the 306 cam and make decent power 400 to 410 RWHP i know i can make more with a better head like a AFR or TFS i just dont have much more money because of what i have spent on the short block, unless i sale my heads, intake and valve train and invest in a solid roller set-up and maybe come across some AFR's down he road or even a CNC ported set of LT4 castings, this is not my daily driver and dont mind letting it sit for a few months if i have to.

What everyones thoughs, comments, .02 cents, etc..
Old Jan 14, 2004 | 01:31 PM
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That combo should hit over 400rwhp with a dyno tune.
Old Jan 14, 2004 | 01:34 PM
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I'd expect around 420-430rwhp with that cam and those heads in a 396. But I'm just guessing. Look at some of the 383 strokers on this board, they are pushing 410rwhp with just a hotcam.
Old Jan 14, 2004 | 01:41 PM
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onebad96T/A's Avatar
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I will try what i got unless i sale the heads and then i will got to a solid roller and AFR heads
Old Jan 14, 2004 | 02:51 PM
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Those heads have plenty of potential to feed it to your needs, a good tune will help.
Old Jan 14, 2004 | 03:10 PM
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Why are you going to oring the block? Waste of money unless you have a big power adder.
Old Jan 14, 2004 | 05:09 PM
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judging by that list, id say your cam is the weakpoint, not the heads.

get a bigger custom ground cam.
Old Jan 14, 2004 | 05:40 PM
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Originally posted by got_hp?
judging by that list, id say your cam is the weakpoint, not the heads.

get a bigger custom ground cam.
Nope. Those heads are borderline on a 396. You might be able to have Lloyd take another whack at them and dig a little deeper. Or an even better option is a set of AFR 220s.
Old Jan 14, 2004 | 05:43 PM
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Originally posted by got_hp?
judging by that list, id say your cam is the weakpoint, not the heads.

get a bigger custom ground cam.
I agree too. He might be able to get a little more out of the heads with Lloyd doing them, but I think he should go with a different cam. That 396 monster can handle more than the 306 cam.
Old Jan 14, 2004 | 05:47 PM
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They'll feed it, but it'll run out of air up high in the powerband. The intake runners just aren't going to be big enough to feed a 396 huffing at 6500+ rpm. They should be good below that though.
Old Jan 14, 2004 | 08:25 PM
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Originally posted by Josh-'97 WS6
Nope. Those heads are borderline on a 396. You might be able to have Lloyd take another whack at them and dig a little deeper. Or an even better option is a set of AFR 220s.

yes......that cam isnt big enough for the 396 to outdo those heads, so at this point the cam is the weak point.

if he gets a bigger cam, then the heads/intake will the limiting factor.

and lloyd already worked on the heads, i doubt hes gonna find much more flow in them.
Old Jan 14, 2004 | 08:39 PM
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Originally posted by got_hp?
yes......that cam isnt big enough for the 396 to outdo those heads, so at this point the cam is the weak point.

if he gets a bigger cam, then the heads/intake will the limiting factor.

and lloyd already worked on the heads, i doubt hes gonna find much more flow in them.
Cams do not "outdo" heads. Cams are chosen based on the desired rpm range and the characteristics of the components being put together (heads are just one of those).

Those heads in their current state will make for a torquey street 396, however, top end horsepower will not come to fruition without additional airflow. Unfortunately, this is a common scenario on most strokers. A bigger cam will only "band-aid" the horsepower issue and will make for a "peaky" engine that will fall short of it's true potential while sacrificing torque.

This technical write up by John Baechtel will give you a good basis on how to build a powerful, torquey engine that will be awesome on a street/strip application, including a breakdown of camshaft timing. In a nutshell, a huge cam isn't always the answer.
http://www.westechperformance.com/pa...ng/hpvstq.html
Old Jan 14, 2004 | 09:13 PM
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Originally posted by got_hp?
judging by that list, id say your cam is the weakpoint, not the heads.

get a bigger custom ground cam.
yep, all that money into a short block only to throw in an off the shelf cam....spend a lil bit extra and get a custom grind taylored to your car!! my $0.02

Steve
Old Jan 14, 2004 | 11:10 PM
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Remember BIGGER CUBE Engines can afford alot more Duration with cam specs, So in theory this is like running a REALLY SMALL cam in your 396, Considering its not even big for a 355, also Your heads in my opinion will either need to be worked further, or step up to AFR 220 or if u cant afford those try getting a set of the 195's, also the intake should be ported (extrude honed of u got the loot)and u might Wanna Try a TPIS Mono Blad TB 1300 cfm (if this for race) And in Fact u might wanna talk to them about there ported AFR 's and a ZZX cam or at Least a ZZ409. Try To sell Your heads, And almost have the funds to buy AFR's.Go custom with the rest of the Engine as You Did With the BOTTOM END, Go cheap now and Get beat On the street by lesse cars cause u didnt paln your combo well , Also Power Comes From Top End Relaibility comes from the bottom
Old Jan 14, 2004 | 11:28 PM
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I think a 58mm TB would be better, but thats me, especially if you go with bigger heads/cam. I agree, the 396 is gonna want A LOT of air.

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