331/347 stroker w/gt40p's, waste?Hp?cost involved?

So I've got the motor and heads already for my maverick project. It's an 86 roller 5.0 engine that had a recent rebuild sometime in the past with keith black pistons, otherwise stock.

I've got gt40p heads for it I'll be running, and can't afford better than that. (I really want afr heads)

I do plan on going with a custom cam, as I believe I've got a local hookup from a friend.

What kind of HP benefits would I see going from say a 302 to a 331 or 347 with gt40p heads.

is it worth iT? streetable?

what's the basic cost on a stroker shortblock?

 

Sometimes you have to do what you got to do. Personally I am not impressed with AFR heads. Ran against many of them with my "junk" Roush 200 heads won some lost a few. For the money I don't see any reason other than a status symbol. Flow isn't everything. Combustion chamber design is a big factor.

 

i'm just going off my friends successes, which is a bone stock shortblock with a custom cam, afr 165's, edlebrock rpm 2 efi manifold, full bolt ons in an 89 stang.

best of 12.1 n/a, 321 at the wheels, and his first wheel up shot. That's my only experience, however, when the time comes, no doubt I'll do my full research.

what I want to know here, is can I put together a BUDGET stroker block on my own, being very affordable, and how much of a reward in hp am I gonna get for 30-50 extra cubes??

 

Well....Yes those heads will work. Although any after market head will be an improvement. I would say they would cost you 60 to 75 hp depending on cam/compression ratio etc.... You can always upgrade after the fact. Git er done and enjoy it!!

 

Call a local machine shop and check out the price on boring cyls, checking and cleaning the block, cutting the crank, resizing rods (cheaper than new but not better. oh yeah when resizing get arp rod bolts), pressing pistons on, installing cam bearings and freeze plugs. Price a rebuild kit and cam from summit or jegs. Then when thats done put it together. It's fun and easy to assemble. The Torque wrench is even rentable. It's probably the cheapest way to go unless you got a machine shop you can use. I would imagine the whole deal would average 6 or 7 hundred if you already had a block to work with.(and a stroker crank)Could be a lot cheaper in some areas and if you know/can trade with someone. Just make sure you use a reputable machine shop. especially not Winger Machine in San Angelo, TX. Never thought you could ruin a crankshaft in a externally balanced engine by balancing it.......
Not sure about power...depends on alot of things

 

The 347 stroker with ported GT40P is how I am going. My mechanic said that is one of his best sellers, and best setups for the buck.

He can do all the machine work for $300-$500 depending on the balancing. I still have to buy the parts.

Aluminum heads are always better for HP, but like Mavowar said, throw them on later...get the stroker going now with those P heads.

Mine is not a roller, but I am researching retrofitting rollers in there, maybe solid lifters, but that may be overkill for what I am going to to with this car.

Like Comick said, make the call. You will be shocked at the performance gains, as well as the reasonable prices for rebuilding.

Personally, I want my machinist to do the machine and prep, and I want to reassemble myself. Never done one, and want to be able to say "I did it!"

But I could easily be swayed to let an "expert" assemble it...

 

doing it yourself isnt a bad thing, if you know what you are doing and what to check. last engine i let someone reputable assemble my engine. right now i am busy correcting what he didnt do properly. nothing really serious, just laziness and lack of being thorough, except for one item that could easily have lost me oil pressure during a run. i usually do all my assembly because i am more comfortable if i KNOW what was done and how. not saying i'm perfect, but its not really rocket science, either. its just patience, test fitting and measuring, & rechecking. takes time and patience. finding TDC & checking your timing pointer/mark is a pain in the neck. so is degreeing the cam in. (at least i think so.) but doing it yourself correctly eliminates questions later when trying to figure out a problem. knowing the engine shop does good work is great. checking the assembly clearances gives you peace of mind as to how that work was done.

 

I have done all of the above except for actually putting together the pistons, pins, and crank. I hear that is pretty easy with a couple of dial indicators, so, like you, I feel comfortable doing this myself and being sure everything is within tolerance.

Plus, my dad used to be a diesel mechanic, so I have some engine building help if I need it.

Luckily, I have heard only good news from the closest engine machinist near me, so I feel comfortable with his work and prices were far less than I expected. Also, after visiting him, he reports that many of the small block in the area he has built and did the 347 stroker kit, with no problems. He tends to use GT40 heads, but said the Ps would just work a little better.

Maybe next Feb (income tax return) I will do the engine. Would like to have final bodywork and paint while engine is out, so some saving up will need to be done between now and then.

 

Let me toss another question out that I feel would assist Jeremy (and myself, and others...)

If my current configuration has 200 hp (a rounded assumption, just for calculation sake), giving me 2/3 HP per cubic inch in my 302, and I bore and stroke to 347, would I expect 230 HP on the new motor (again, rounded just assuming all the same parts being used and just adding the 2/3 HP for the extra cubes)?

I recognize a rebuild will give tighter tolerances, better seals on rings and gaskets, different compression from new pistons...but just assuming that on an experimental basis, we could keep all these factors constant, would I gain only 30 HP?

I think that is part of the question jeremy is asking when he asks "is it worth it?"

I personally will balance my motor, use 10.2:1 pistons up from my current 8.0:1, 1.7 lifters, and a new cam (possibly roller, possibly solid lifter), so my numbers, and probably jeremy's will be better, but just assuming...

 

assuming the cam, intake, heads will not be much less efficient on the bigger motor then yes about the same hp per ci. one thing to remeber is that it doesnt cost much more to get the stroker kit than to just go .030 over on the stock block, assuming crank would have to be cut, rods reconditioned, adding rod bolts, you were going either forged or hypereutectic on the pistons. either way the machine work is about the same (less rod recon), either way needs a balance job. then cost of kit vs cut crank, recon rods, ass & unass pistons & rods, new pistons, etc. on top of which you are getting higher quality rods and often crank, too. i think i priced it out for a friend & it came to about $120 more to stroke it. $120 for 30+ hp isnt bad and the parts are higher quality.

 

Assmbling it yourself is the only way to KNOW it was put together with care and diligence.

 

One word of advice don't get caught up in the I got 10 to 1 pistons. In the end that means nothing. Have yopur machinist cc the chambers get the piston specs and the head gasket crushed height. Many guys running around claiming to have 10 to 1 or whatever but reality is they end up with 9 to 1.

 

Go for the 347. Same price as the 331 kits. As mentioned, it doesn't cost much more to build a 331 or 347 than it does to build a 302 stock stroke. The strokers will rev faster as well due to reduced piston mass (the stock 302 pistons weigh ~700 grams and most good 347 pistons are less than 450...mulitpied times 8 cylinders, that is close to 5 lbs less weight that is slinging around in there). You also generally get better rods, better crank...but still use a 302 block which is fine as long as you aren't real hard on it (nitrous, blower, turbo, 7500+ RPM...etc). Keep the compression around 10:1 use a good cam that's got around 235 duration @ .050" lift....or more, and you'll have yourself a nice running little engine.

 

I had P heads on my 347, ran good. But I felt they were holding me back some. The stock springs are good for only .500" lift so that limits your cam selection. When I figured the cost of a spring upgrade, better valve job and more porting I decided to sell the Ps and put that money towards a set of used AFR 185s. All depends what you want to do with the car. For a cruiser stroker or a performance 302 P heads are great.

 

I've got a set of tfs valve springs on the heads right now.


I suppose this all boils down to cost, as the motor is ready to run as is, and doesn't need a rebuild, so,,....in my case, it may be a lot of work to tear down a motor that has had a recent rebuild just to stroke it.

Maybe a better idea would be to pick up a spare block, and mess around with that on the side, then save for some real heads.

If I don't dump a ton into the interior, I'll have some good money to put into this motor, however, something tells me my interior is gonna eat up some good cash from my budget.

Great info here guys.