Dyno day is getting close

[CGT]

Thanks for sharing your results cgarb.

[cgarb]

Thanks Randy, no offense taken. I consider my engine a well prepped ordinary Joe engine. I'm just lacking some of the exotic parts. Yes, this is a sickness.... haven't even made a pass in my car yet and I'm gathering prices for what I'm doing to it next...lol. I was seriously debating steeper valve seats, but I shot down the idea because of longevity concerns due to it being a bracket race style engine. Thanks for the example's though. I see what your saying about the combination chamber, my engine made most power at 38 degrees.

[groberts101]

Hey man, nice build. I can't help but wonder how in the heck there is a 100 hp difference in your motor and Randy 331's motor? They're both very similar builds. Both 421's, solid roller cams, really close on compression ratios, high head flows and all that. I'm not knocking your build, because Lord knows I couldn't come anywhere close to either your's or Randy's builds as far as power is concerned. Just curious as to how a couple of specs being different in small amounts could cause that large amount of power difference.

Maybe cgarb won't mind me throwing a few thoughts in on this.

1. I have an aftermarket block (dart shp pro) it's likely the stronger block is worth a little power.

2. I have more comp ( his 13.8 vs my 14.8 ) and I got my comp with a custom piston to match the vortec chamber, with custom valve notches based on my cam choise, so my dome is most likely lower and and it has a nice spark plug relief. I can still run extended tip plugs. And I got that comp in a chamber I consider better than the profiler. I have 31* total timing on my 421 and I tried more on the dyno.

3. Not only is his cam an old grind, it's a slow lobe. 40* vs 32* intake on mine, and I have higher rocker. I have .100" more intake lift with a ti valve, more ex duration and lift too. My valve speed would be faster.

4. cgarb most likely still has 400 main size, I have 350 mian and 2" rod journals, so I'd have a bearing speed advantage.

5. My custom piston has gas ports, acumulator grove, contact reduction groves, and .9 mm .9 mm 2 mm ring pack. My short block with the cam and belt drive in it would rotate over at under 10lbs.

6. Mine has steeper than 45* seats. I'd bet that would put power on his engine if done correctly.

7. My Braswell is probably bigger. It's 1.59 v x 1.79 t.

8. But the big difference is induction tract. I welded the pushrod area and widened it and did a lot of CSA work. I'm running a modified 2970 intake, so my whole intake tract is sized for more rpm, and that shows by where both of our engines made peak at.

And I don't want this to be taken as negetive to cgarb because it sure isn't intended that way, but my first atempt at this type of build wouldn't run as good as this one does. I think his engine runs good and I'd say he already has Ideas on how it could be better.

An observation,
cgarb HP/cfm = 1.98
My HP/cfm = 2.46

Randy

Awesome post.. thanks for sharing.

[RevTheory]

Agreed! Thanks, Randy

[Casper393W]

This is a prime example of how many small things add up to be a big difference in the overall picture!

I think for me the biggest surprise I have seen was going from a factory block 302 block that was girdled and all of the tricks... Switched to the new Boss 302 block and picked up right at 20HP.....to me that kind of gain is huge just knowing that the bores are staying put and having better ring seal

Andy

[Frankshaft]

This is a prime example of how many small things add up to be a big difference in the overall picture!

I think for me the biggest surprise I have seen was going from a factory block 302 block that was girdled and all of the tricks... Switched to the new Boss 302 block and picked up right at 20HP.....to me that kind of gain is huge just knowing that the bores are staying put and having better ring seal

Andy

I think the biggest gain is coming from more accurately placed lifter bores and cam tunnel.

[Casper393W]

I believe you are on to something... Stock 5.0 blocks are flimsy to say the least! Nothing like having a 500hp ticking time bomb....