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Gunna swap cams on 383/177 set up

740 Views 12 Replies 4 Participants Last post by  ericnova72
I’ve decided I cant help myself and I’m going to swap cams on my Weiand 177 powered 383.

I feel like the current cam, a retro fit crower 238/240 .555/.559 on a 110 lsa, is just robbing power potential and I feel like with almost 20 degrees of cam overlap im getting a lot of exhaust reversion. Plus, im having to really spin the blower to get any PSI out of it.

I know psi is just a measurement of what isn’t getting through the engine, but I would like to spin the blower less rpm and get the same pressure or more.

The two I’m looking at are Howard’s cams but open to other suggestions. Both have an overlap of just 2 degrees.

One is 235/233 .544./.540 on a 116LSA and the other is a 225/235 .525/.536 on a 114LSA.

The motor set up is a fully forged 383 with 200cc runner heads, rings gapped for boost, carb motor in a 95’ Silverado. Curious on opinions?
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Discussion Starter · #5 ·
Got a couple custom cam recommendations. All pretty close to each other. All were a 114 LSA. I messaged one company, I won’t mention the name, and they were in line spec wise with everyone else. A little more duration, in the 230’s at .050, then the others but they cam only was $800 bucks! I’ve seen some awesome builds from them but man that seemed pretty steep comparatively.

Questions for the gurus and this is stemmed from a gentleman I’ve come to really trust on another forum. He says that boost being blown out the exhaust is a myth generally speaking on a supercharged engine. Boost levels of about 15psi or less, the cam overlap doesn’t have nearly the affect it does on say a turbo engine running 20 plus psi. In his opinion, and others online from different posts I’ve read through, the 110lsa on an 8-10 psi motor is possibly better. The supercharger makes up the torque in the lower RPM range and the tighter LSA helps in the upper where the supercharger starts to run out of breath.

Im just conflicted on if it’s really worth $800-$1000 bucks and the time to change it. I was thinking much of the boost is getting “blown out the exhaust” but if that’s truly not the case, then how much power is there really to be made?
 

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Discussion Starter · #7 ·
There is way more to cam timing than just the duration, lift and LSA numbers. Think about the lobe shape and what's happening at the crank position.
Trust the guys who make a great living.....not the joe blow internet know it all.
Definitely, and I’m inclined to believe the custom cam guys, but understandably they won’t weigh much into whether or not their cam will make more power than the current one. One did say his would make way more power below 4k rpm, which with my current traction issue, may not be a good thing 😂
 

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Discussion Starter · #11 · (Edited)
What would you expect them to say?
"Well, for $800 the best I can do is less than you have now"
I figured it was worth a shot to ask, but I knew the answer would be vague at best!

Honestly I need to start working on getting the power to the ground better. I’m looking into some adjustable shocks for the front and rear to help with the cal tracs I have installed. 20 hp would be achievable by swapping to a smaller blower pulley. Right now the 177 is 2.15 overdriven producing about 8 psi. Swapping to their 2.85” upper pulley would put it at 2.45 overdriven and I would guess about 10 psi. I hate to spin it that much but with the meth injection maybe the inlet temps won’t be so bad. I can’t find any solid info on max rpm but I have my redline set to 6250rpm. Which would put the blower speed, overdriven to the 2.45, at 15,300 rpm at redline.

One thing I haven’t done is check fuel flow. I have a nine boost referenced regulator right now. Th me AFR gauge never goes lean, which I would assume it would do if I was running out of fuel volume?
 
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