I currently have slp ceramic shorties, loudmouth exhaust, tb bypass, k&nCAI, trick flow elbow, pcm4less tune, 160 thermostat, 3.73 gears. This summer I will be adding a 58 mm tb, ported lt-1 heads (2.00 intake valves, 1.56 exhaust valves) with a port matched intake manifold, the flow numbers for the heads with the intake manifold are 245 intake and 191.1 exhaust.

I will also be installing a GM 846 cam with 222/230 duration and .543 intake lift/.563 exhaust lift and 112 degrees separation. With the cam I will be installing crane gold race 7/16" roller rocker arms(1.6 ratio non-self aligning), thunder racing 7.200" hardened pushrods with GMP guideplates and last but not least some 30# injectors...Will this set up give me 400 hp?

 

Would I have to get a new timing gear set like the GMP extreme duty set with this set up?

 

400 on the motor could be possible. Your still giving up almost 25 cfm on the heads though and that is were all the power is. Who ported the heads? I had Llyod Elliot do mine and we got 270 cfm. The etreme duty timing set is cheap insure from breakage. I am running one also. If you do go that route call Sam Taylor Buick ask for Jason. I paid 210 shipped for the timing set. Using comp pro mag rockers would be a better choice than the aluminum but that is my .02 and preference. I have had bad luck with Crane stuff so I stick to Comp mainly. Ditch the shorties and do the Hooker longtubes to get full potential out of the head work and cam. 400 is possible.

 

If your going for 400 Rear Wheel......No....
The heads are a hair shy of great flowing and the cam is a little small for rear wheel power.

Now as of flywheel, you figure 350 - 360 RWHP would make an easy 400.....

So in that case.... I would say your motor would have 400 with that setup...probably closer to 425 or so.... But not rear wheel..........

 

Thanks guys, I would go with long tubes but I have to pass emissions here Thats what I was hopeing for 400-425 hp at the crank.

 

I live in Dodge county and we don't have the emissions, yet! Check to see if they do just the sniffer. If they have to do a visual you may not pass cause the long tubes will move the cats further back from the stock locations. Otherwise you may as well stick with your Mac or slp headers. Just make sure the primary tubes are 1 3/4 to help it flow.

 

Yeah I at least got the 1 3/4" primaries...now I just can't wait to start working on my car this summer...how long does it take to put new heads, intake manifold, valvetrain and camshaft in?

 

An LT1 can make 400 at the flywheel with stock heads and a healthy cam. (And the usual bolt-ons.)

 

A good weekend to do it and do it right. Give yourself time and double check your work. I would say it took me about 16 hours total to do my assembly on my engine. I am bummed out though cause I am going to wait till April to put the engine in. I took my time, I HATE doing things over. Better to do it right the first time.