View Full Version : Camshaft For Turbo'd 400

05-08-2005, 06:04 PM
I'm looking for a cam for my 400 poncho that im planning on turbocharging. A while ago i was talking with a guy i work with(whos into impos) and he said that a cam for a turbo you want lower duration and lower lift... Is this true? Also this is the cam i was looking at
Comp Cams Part# 51-224-4:

Comp Cams Hydraulic Flat Tappet
RPM Range | Dur @ .050 | Lift w/ 1.5 | LSA
1800-6000 230 236 .488 .491 110

Would this be a good cam, or would you suggest something else, and what?

05-08-2005, 08:14 PM
1. Where do your heads flow best at? A turbo isn't as sensitive to smaller lifts- but you want to make the most of your combo, right? I flow all mine first, keeping in mind cam choices or possible custom grinds.

2. Definitely try to stay with a split-pattern cam with more lift on the exhaust, as the Poncho exhaust ports aren't the best (but not the worst).

3. I'd try to go with a wider LSA to minimize overlap. To know how high to go , as in 112-116, you want to first define where you want your power band.

05-09-2005, 04:22 AM
thnx for the info. I'm looking to be more top end, but still have some good low end. I'm gonna use poncho heads, casting 66 if i can find em, if not i think im gonna go with 6X-4. They have large cc to drop the cr down to around 7.3:1. I'm planning on getting them ported and polished and all. Was also gonna go with 2.11 Intake 1.77 Exh Valves.

This is the other cam i was looking at:

Comp Cams Hydraulic Flat Tappet
RPM Range | Dur @ .050 | Lift w/ 1.5 | LSA

1800-5800 224 Int/Exh .476In/Exh 110

05-09-2005, 06:52 AM
A 114 lsa would be a much better start. Here's the specs on my small block 383 twin turbo as spec'd from Precision Turbos. I do have decent heads, not great. This cam supports over 1000 hp and idles with 19-20" of vacuum, which is what I wanted. This is a hydraulic roller.

lift intake .577" 1.6 rocker

lift exhaust .541 1.5 rocker

duration @ .050" 224

lsa 114

overlap 4 degrees


07-07-2005, 05:14 PM
Yeah more lsa with less valve overlap so you don't push everything right out the tailpipe.

Also If your having the heads done let the shop that is doing them know it will be turbocharged because with a turbo engine you will want the exhaust seat to be a little wider because of the heat so the valve wont burn.