Twin O/B Sonic

Very impressive project. Big fan of the Panthers and really like the way yours is coming out and the direction you chose.
Well done.

MILD THUNDER

I'll post my cam card later jay, but 236/[email protected] .630 lift 114lsa.

If you can get the compression down a bit, nothing wrong with a little more compression, little less boost. My heads have been milled a TON. Chambers are now 105cc. With my flattops, valve relief, and headgasket I used, I'm almost 9:1. Dynoed on pump gas, and been running pump gas this summer with 5.5lbs of boost. No issues. I have another friend running 9.5:1, 3.5lbs of boost on a 580ci on pump gas making 850hp for years. He bumps the boost to 6psi with a race gas mix and well over 900hp

The extra compression will work well with the smaller blowers your running. A little work on my heads, and going from the 250 blower single carb, to the 420 blower twin carb, so far I've gained 5mph on top, and that with 1.5lbs less boost. (was running 7lbs with the 250's)

MILD THUNDER

I actually came out around 8.8:1 static on mine. 468CI, GM crank, manley rods with arp 2000 bolts, Pistons are JE Flattops with -3cc relief. Speed Pro plasma moly file fit rings (woulda liked total seal gapless, but...) Dart 308CC rect port aluminum heads, isky springs, morel lifters, crane roller rockers, 420 blowers with 850 holley's. In the boat, idle at 750 in gear all day. I only pulled to 6200 on the dyno, not sure where it would have peaked, but didnt really care to push it. I dont plan to exceed 6000 in the boat, so its just a number. I may have done a little better with slightly less duration, but for a budget build i was impressed with those numbers out of a 468ci. There is also a hideous port mismatch on the intake side, that i just didnt have the time to address. But it works.

Id guess Jason, that your JimV heads flow better than mine. If you can knock that compression down a bit by milling the pistons, or a little chamber work, and run a thicker headgasket (the quench factor isnt that crucial with the blower), I think you'll be making some real nice power.
You'll love the blowers. Just dial in the AFR in the boat, keep water temp cold, use good gas, and enjoy the blower whine at wot! .

Rookie

Thanks Twin O/B, I appreciate that.

Rookie

Thanks for the cam specs. That is a tough looking engine with the Black Blower! Just plugging the specs into my desktop dyno that cam seems to make nice power N/A also. Decent cruise, maintain some fuel consumption before getting into full boost.(oxymoron)

I forgot that you were running 308's. My heads flow [email protected]" With the increased flow in heads I might lose some boost. Which might not be a bad thing. Jim has a thing about flow/restrictions and heat with a blower setup. But I think you already know that.

This is the cam we are looking at. It is on a 112 though. Input...

jeff32

great work! did that on my stinger 260 !

MILD THUNDER

Jims cam would probably work well too. Little more lift, little less duration, and the 112lsa is still blower friendly. I am by no means a cam guy. But I know you want the wider lobe separation, (112-115 LSA), anything less and your blowing boost out the exhaust valve and wasting power.

The blower will usually move the rpm band up a couple hundo. For example, if say N/A the engine peaks at 5500, bolting the roots blower on might make it peak at 5800-6000 or so.

What you say regarding boost is true. Cam choice, cylinder head flow, exhaust flow, all play a part. You can take a basic 454/330HP engine, slap a 177 blower on it, and make 5lbs of boost and not drive the blower very hard. Then you take your engine for example, good flowing heads, high lift long duration cam, and take that same 177 and bolt it on, and maybe only make 2psi of boost. Boost psi is just a restriction. Same goes for Cubic inch. A 540CI will normally require a larger blower than a 454. However, if your 454 is modified well, and breathes (makes same HP) as that 540 N/A, well then you also need a larger blower. Most guys will say, well, you got a little 454/468, no need for a large blower. The blower itself has no idea what size engine its on . A 250 blower can be just fine for a 540CI with lamo heads and a weak flat tappet cam. But a stout 540 with nice pieces is gonna do much better with a 10-71, etc. a 454 making 800hp, or a 598 making 800hp, should, in theory, be moving the same amount of air. This is why I suggested the 420, or a 871 for what you have. However, with your extra compression, thats gonna help you with the smaller blower. Now, if you had say 8:1, and wanted to run 8lbs, with your heads, cam, etc, You'd probably have to spin the blower close to 2:1 ratio. 12,000RPM blower speed on those B&M's just ends up #1 creating tons of heat, #2 the blower lives a short life.

I was turning my 250 1.86:1. My 420's are turning .93:1 now. The rotors are turning so much slower, my charge is probably much cooler now, and the blowers should last a long time.

Heres a couple good build articles.

http://www.superchevy.com/technical/...r/viewall.html

http://www.hotrod.com/techarticles/e...r/viewall.html

http://www.chevyhiperformance.com/te...e/viewall.html

MILD THUNDER

Fun idea......when your ready to dyno, I'll come up, and bring my blower/carb/pulley/belt setup.We can see what effect the larger blower twin carb setup does vs the smaller blower single carb setup. It be a really cool test, and easy, since my blower will bolt right on your intake. Four bolts and a fuel line and we're all good! nobody does fun stuff like that anymore!

Rookie

I'm in, that would be great. I have single dominator plates, dual quad plates, 4 4150 carbs and 2 dominator carbs. Looking for front offset dominator plates now. #93153 Just in case you have seen any. I plan on obtaining some data. I still need to get my lazy ass down to DMPE and get these checked out.

You guys should head up to HotBoat in a couple of weeks. A lot of BS'ing and cool boats.

http://www.holley.com/data/Catalogs/Weiand/118.pdf

Rookie

Next will be sanding, filling in hook, sanding/sharpening all edges, fixing repairs and spraying gel coat. I will state that laying on your back sanding and filling is not fun. I put this experience right up there with bailing hay the old fashion way on a 102*F day.

The bottom of my hull was a mess. Chipped and missing gel, globs of filler that was never sanded from previous owners to cover damage.

Just a few pics to start with.
1st pic is showing hook after I had sanded as much of the high spots of original gel down.

2nd pic is the bottom of the V looking towards the drives/water pickups.

3rd pic is sanding the sides of the chine and damage before filler