454 making 525-550hp
 

I have a merc 420 in my Formula 242. It has TRW2399 pistons, crane 132561 cam, dart single plane intake, Holley 800, EMI tunder with 3inch taller/long tails. I run 62mph@5000rpm now with a 23p mirage. I would like to hit 70. I have been told I need 525-550hp to get there. Do I just put a 177 on it? Can I just cam it? I have searched a bunch and the results are vague on the builds people get with 454s. I know this may not be accurate, but on desktop dyno i got 516hp with only a swap to a 741 cam.

You will need to add 150hp to it to get to 70. I would think that a blower would be the easiest and most cost efficient way to get there.

Thats kinda the way I am leaning. I can pick up a 525sc blower/carb setup for $2150 shipped. I am thinking I might make more than a 525sc as my compression is a bump higher. FWIW The previous owner had a 530hp motor in it, he claimed low 70s.

From what I have personally seen, at those speeds with a single engine it takes about 20hp to pick up 1 mph

you'd need to work over the cylinders pretty good(porting) and at least a cam in the 230,236,ls112 range w/ around .600" lift and compression in the mid 9's.thats whatI did to get 527hp,517tq from old 420's.I also ran a victor jr. w/ a bolaw's 950 carb.

Sounds like a $10,000 project to me before all is said and done.

Could I mill my heads to bring the compression up and throw this roller cam in?

http://www.summitracing.com/parts/hr...make/chevrolet

I rather see you run an hp500 efi cam,,230,236 or put a 741 in,,do you have dry exhaust?

well we could start w/ some profiler oval ports.:D

I have EMI Thunder with 3" additional rise.

http://i880.photobucket.com/albums/a...65182309_o.jpg
http://i880.photobucket.com/albums/a...82904155_o.jpg

I helped oso member wayne272 on a build like that. Hotter crane flat tappet than you have, #134561 236/246 114LSA, same pistons , same heads. His heads i believe had the 2.19 mag valves, as his was a 454 mag originally, i believe the 420s had 2.25 intake valves. Anyhow, 177 blower of a 525sc, single 1050. Made 575hp at like 5400rpm, and 600ft lbs with 4lbs of boost. Ran good in his 31 Bullet. Nice little budget build.

I think I am gonna pull the trigger on that 525sc setup. I assume if I would have to swap valve springs, would that also be a good time to put inconel exhaust valves in?

yes and yes.

also upgrade to a bigger oil cooler.

I was thinking of a bigger oil cooler. I have the combo steering/oil cooler now. Can I just plumb in a second cooler? or would you just get a new larger cooler?

You need this. (B&M 250)
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[ATTACH=CONFIG]546548[/ATTACH]
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And 1 of these. http://www.mrcool.us/skin/frontend/d...ct-Listing.pdf
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[ATTACH=CONFIG]546549[/ATTACH]

Is it for sale?

what he said... a 250 would be a better route than a 177.

I would say, its winter time soon. Wait for a 250 to come up in the swap section. Get everything else ready for it and then put it on when it becomes available., much better then a 177. Or find a 671 blower shop setup. 177 end up being like little heat pumps, you start spinning them to make boost and they heat up and since you are staying with stock steel heads they turn out to be not that efficient.. The 250 would run much cooler and you wouldn't have to spin it as hard to make the same HP. And when you wanted to you could always swap the pulley and make a little more :) You are obviously ready for an upgrade, do it once and do it right so you can enjoy the new found HP. Afraid the 177 will leave you short. The 250 gets you where you want to be. Good luck with the project!

Imo, the 250 isnt a big enough upgrade from a 177, it is a better starting point however.

Even a 250 on a 454 making 5-6lbs of boost, will be 60+ percent overdriven, where a 177 will be 100+ percent. Imo, these small blowers work great on the street, where full throttle torque from idle to 5000 is the goal. Running 5000+ for extended periods in a boat, a larger blower like 671, 871, or 420 b&m is a better fit.

I love the idea of a 671, but they seem out of my price league. And how much taller than a 250 are they? I won't cut my hatch.

Quite a bit taller. The 250 is low profile though. And would be my choice over the 177 like the guys here said

That's why I was saying the 250 over the 177. I know not much of a gain. but better. the 671 is another large upgrade cost and height wise.

Here is an old picture of my former Top Gun when I had the Chiefs. They were 671s but they were tall.

Yes, I was going to put them in the swap shop this week.

[ATTACH=CONFIG]546574[/ATTACH]

How much did those coolers bring your oil temps down?

Hey wayne, what would you say the cam upgrade and 177 install gained you over the stock 454s in the bullet ?

To be honest I was running I was running 2"x4" power steering coolers on my original Merc 420's. No temperature gauges. When I re-powered to ~600HP engines I put the 3"x18" on. I have never seen temps over 180*F after the cooler delivering the oil to my bearings and I run over 5500 RPM's for miles.

Would putting a 250 blower on a GenV block with forged internals, aluminum heads, and 9.5:1 compression be too much? I'm just conceptually asking here as I plan out my motor. Or would you pull the pistons and lower the CR ratio?

Hey guys,
I'm new to the forum and this is my first post. I cant seem to start my own discussion but This one seems somewhat comparable to what I'm doing. I have a 1989 Formula 242 LS. The boat originally had the 454 magnum (365) with GIL exhaust on it. I pulled the motor this season and had it completely rebuilt. I threw a Cam in it, punched it out 30 ,,new DART heads, bigger carb ,new exhaust ,,the whole deal. It came off the dyno making 526HP with 558 ft/lb of torque.
My question for anyone out there is what I should be looking at for a prop. I had a 21 pitch Mirage plus with the original block and it ran perfect...58 mph-61mph on a good day. My motor at peak performance now turns at 5300 RPM. I have plans to change my prop but I'm wondering if a 23 mirage plus 3 blade may be a bit small. Should I be looking at a 25 pitch Mirage plus?
I'm told these old formulas like the 3 blades, but any information would be helpful.
Thanks

The 25p Mirage+ is a monster to spin. Many folks use a Mirage+ 23p and have it tuned with a bit more cup to a 24p. But to get you in the ballpark BBlades rents props for trying out for $50. You can rent the 25p and if the motor or boat struggles with it then find a 23p and have it tuned.

Run your original prop and then base from there. Your original engine ran 4800 RPM's?? New power hopefully 500 more RPM and then tweek from there.

Joe, I picked up 10mph in the bullet.

Ended up being a $10,000 project.

http://i880.photobucket.com/albums/a...46907571_n.jpg

Your finished project looks great. Trusting that the power levels are what you are looking for. This would have been an interesting project using this as your platform.
http://www.crateenginedepot.com/LSX4...33-P50880.aspx