Basic specs of current setup:

70 over 454
steel rods
13:1
Alcohol
EFI with 2000cfm TB
Super Vic manifold
Dart Pro 1 325cc, running them out of the box
roller cam with 304/312 adv., 272/280 at 0.050", 192/199 @ 0.200", 110LSA, lift is 0.690", springs are ~230# on the seat and 650# open

Keeping in mind that the use of this motor is bracket racing, with the primary goals of reliability and consistency which would you choose for winter mods to get some more hp out of it next season. I can afford one but not both.

1. Port and mill heads for more compression and better flow. Put in a bigger cam.
2. 4.25" stroker crank will increase displacement from 469 to 498ci and increase CR to ~13.6:1 w/o any head work.

Any and all opinions welcome.

Rich

 

My old 469 used a 11-613-5 cam. .638/.638 lift. 270/280 duration at .050". Oval port, iron Merlin heads. Victor Jr intake with an 850 DP on alcohol. Best time was mid 10's at altitude.

When I built the 540, the cam changed a couple of times but it's now a 11-740-9. Induction became a tunnel ram with 2 850's on alcohol. Heads are out of the box Canfield 310's. Car now runs mid 9's at altitude with a race weight around 3075 pounds.

I'd love to do some port work on the heads or pick up some 345's but I'm making enough power now to run the ET's that I want.

Answers to your questions.
1. Cheaper than an engine rebuild but watch the piston to valve clearance. It could cost more if you have to strip the engine down to get the pistons flycut.
2. 29 more CID is 29+ more HP plus a bunch more torque from the increased stroke. Go with .250" longer rods too.

13.6 is a magic number for alcohol but it will also run in a low 8:1 compression engine and if you can do it, 15:1.

Injection and CFM doesn't mean the same as carb CFM. My two 850 carbs make 1700 CFM. I plan on installing two 4.1" toilets on my car this winter. 1800 CFM each for 3600 CFM.

 

Thanks, the leakdown was 4-6% when I checked it last week. So, if I can avoid a teardown I'd like to do so. I already have long rods (6.535"), and there are off the shelf pistons that ought to work. Sounds like your cam at 321/336 286/298 .748 .748 112° is about what I need.

Rich

 

My engine idles very smooth at around 1000 rpm once it's warmed up. No rump rump type idle. The wide LSA makes a smooth idle. I do however use race mufflers or I would need ear plugs just to fire the engine up.

My cam starts making power just over 4000 rpm and peaks out around 7400. I usually launched at 4500 but now launch at 6000 and cross the finish line at 7200. My rev limiter is set to 7800.