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RickBuonauro
04-11-2013, 10:56 PM
I have a 290 hp, 350 GM crate engine with a performer intake, patriot headers, and magnaflow mufflers. It's a daily driver '55 bel air, only about 20 miles per day. I'd like more horsepower, but I don't want to sacrifice drivability. I was considering going the cheap route, and just getting a set of iron vortec heads. But it's tempting to spend more on expensive aluminum heads, in the hopes for tons more power. But how much horsepower gain could there really be over the Vortec heads, 10-20 horsepower for an additional $1,000? I don't know. Thoughts, suggestions, advice...

Run-em
04-12-2013, 04:34 AM
Aluminum heads will allow you to increase compression & still run pump gas. Take that into consideration also.

chevynut
04-12-2013, 09:14 AM
There's no replacement for displacement. ;)

A lot of it depends on how much you want to spend on your engine. Heads are definitely a key to unlocking horsepower if your camshaft allows the increased flow capability. But....

Are you really looking for horsepower, or are you wanting more bottom end torque? What is your gearing? That might play a bigger role than horsepower.

Remember horsepower = torque x RPM.

56-210Sedan
04-12-2013, 03:47 PM
In my opinion there are two key places to develop your best power good flowing cylinder heads and cam combination, now not to leave it out but a good intake and carb set up fall in this mix as well (air flow is your winner) i am all to familiar with budgets specially tight ones but even in your shoes i would look a going the aluminum cylinder route, dollar for dollar you will be money ahead IMO an now with that said you have your choices dart,brodix,edelbrock,afr, etc.... do some research but for the money and the better flowing head i would suggest AFR do some shopping and you get them for 1300 dollars want them now 1400 and up, have fun and good luck.

chevynut
04-12-2013, 04:14 PM
Again, if it was me I'd decie what I'm trying to accomplish. If you want more "seat of the pants" "power", I think you're really talking about torque. That's why a BBC or other large engine feels so "powerful" at all RPMs, because of the torque. I'd be looking at my gearing as well as my engine to get what I want. You can get more torque to the rear wheels with a gear ratio change. The engine will deliver more power at a given speed because it will be turning at a higher RPM. Of course you have to balance that with the way you use your car.

My point is that if you have an engine that produces 300 ft-lb of torque between 3000 and 4000 RPM, they're going to feel exactly the same in that range regardless of peak horsepower. I think too many people get caught up in peak horsepower numbers even though they rarely use their engines in that RPM range.

Here's the curves for his 290 HP engine...

http://www.crateenginedepot.com/Assets/images/12499529_dyno.jpg

Now here's a ZZ4 with 355HP

http://www.crateenginedepot.com/Assets/images/24502609_dyno.jpg

Note that at 3500 RPM, they both have similar HP at 230-250HP, but the ZZ4 has 405 ft-lb at that RPM while the 290 HP engine has about 325 ft-lb. The ZZ4 is going to feel a lot more powerful when driving around town at 3000-4000 RPM.

An engine built to perform at high RPM can feel like a dog at low to medium RPMs.

Rick_L
04-12-2013, 05:54 PM
"But how much horsepower gain could there really be over the Vortec heads, 10-20 horsepower for an additional $1,000?"

I'd think the power difference between some AFR 195s and a Vortec would be 35-50 hp. Chevynut showed you the difference between a 290 hp crate engine and a ZZ4 at 3500-4000 rpm. I think the AFR heads would do the same over the ZZ4 heads or Vortecs, which have similar potential.

Also don't overlook what Chevynut said about gearing. Combine some performance gearing with an overdrive transmission, especially a T56, and even a stock 290 hp engine will do better than you might think, and still cruise nice and get some mileage.

I'm surprised I don't see more builds with a 4.56 rear gear and a T56 trans. In fact I've never seen one. Gear life would be short, but it would be like adding 75-100 hp to a mild small block.

55mike
04-13-2013, 08:08 AM
I've been running AFR 190's for years. HUGE difference on my 355 vs the old L98 aluminum heads (same ones as the ZZ4 has). AFR claims 70 HP more.. I can't verify that claim, but, I do know the power is certainly there, and the quality is superior (no more smoking due to sloppy valve guides). BTW.. As I understand it, the new AFR heads are even better! Since you are using the 290 HP engine, and you want to step up the power and keep it also drivable, you might also consider (besides heads) a bump up in the cam shaft. Even a "mild" Xtreme Energy cam from Comp Cams with good heads would have the potential to really wake it up and not sacrifice drivability.

JT56
04-13-2013, 07:09 PM
I've been running AFR 190's for years. HUGE difference on my 355 vs the old L98 aluminum heads (same ones as the ZZ4 has). AFR claims 70 HP more.. I can't verify that claim, but, I do know the power is certainly there, and the quality is superior (no more smoking due to sloppy valve guides). BTW.. As I understand it, the new AFR heads are even better! Since you are using the 290 HP engine, and you want to step up the power and keep it also drivable, you might also consider (besides heads) a bump up in the cam shaft. Even a "mild" Xtreme Energy cam from Comp Cams with good heads would have the potential to really wake it up and not sacrifice drivability.

I run the AFR's too. Mike good to see you post!

Joey