You two guys together? I don't see anything coming out of that equation, except horsepower. :bunnydance:

MildThunder,

Great thread with some great data.

I have 420s to put on 461s. Probably 15% underdriven.

These were originally setup for 5200 peak with the stock Mag cam 224° single pattern. 0.510" lift 115.5LSA. Not sure when this cam runs out of steam on a blown application.
088 heads. I'll do some mild porting and clean up chambers. 8.6:1 comp but I'll be decking the blocks for quench of 0.040" or just under. New pistons as well...old blocks frost cracked when I got them, so have to bore replacements. Looking to keep the 8.6 area.
​​​​​
I'm looking for 700hp around 5600. Will need to spin up my 25 pitch Rollas. (1.32gears). to use the HP.

How did you find the higher rpm running?

I'm 100% on max reliability, but want some performance potential as well.

Timing, always a critical factor. Interesting to note where the egts really start to impact the valves when retarded.

The B&M BBC intakes are untouched for port matching...and are more of a modern Roval port. I'm hesitant to port match to the park a dump truck sized 088 rec intake ports. It's a lot of welding back up to fit a roval port on a new aluminum head...lol.

I suspect the un-port matched intake man ports were a restriction. Hoping it reduces some boost pressure, with some better flow from the mild port work.

Knock sensor, can they be setup to retard a Daytona Sensor Ignition system?
​​
Mild Thunder, always enjoy your posts, thank you for taking the time to archive the data.

Art

We did 650 at 5400 on a 468 with a B&M 250, touched up 188’s, 500 EFI cam, and twin 800’s through CMI split tops (Stainless Marine in the boat). My buddy didn’t want it pushed hard so RPM was capped there; there was definitely more in it.

I’d call it a very budget-minded effort.

420s should make this an easier effort and be much more reliable.

TomZ, thanks for some real world examples
These were originally forged crate 454HO 390hp at crank.

420s added with twin 750DPs. Dyno'd in 1992 ish at 650hp.15% underdriven. Not sure RPM, but I assume 5200. It was the peak HP for crate engine 390hp...and also the 5200 chip in the rev limiters.

Has Gen 1 (assumed) Stainless Marine exh with dry to tip.

I'll check springs and make sure they're up to revving a bit more as well to 5500-5600 if they need to use the prop 25 pitch.

Any thoughts on where the 224° hyd flat cam 0.510" lift 115.5LSA with 088 2.19/1.88 valves will peak for HP?
​​​​​461 CI.
​
I want to run the smallest cam I can get away with? Without jacking up the pumping loss of pushing the exhaust out...with the shorter single pattern style cam.