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Old 03-22-2006, 07:40 AM
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Engine

If I just put poptop pistons in my car and up the cam size, will that really boost my hp&tq. What could I do to really increase the ft pds of tq?
How does my Compression ratio effect my power?

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Old 03-22-2006, 09:19 AM
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What did you start with and what do you have now and whatg is it you want to get out of it?
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Old 03-22-2006, 02:50 PM
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Gigo

Not enough information to assess your setup; what engine, what do you want to get out of it? what heads are you running. what kind of drivetrain are you running behind the engine. what gears in the rear.
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Old 03-27-2006, 07:21 AM
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In about a year I would like to rebuild my engine. I would like to have more tq than hp. I would like to have about 450hp & 500 to 550 tq. I like a lot of pulling power. I have an 89 mustang 302cc. I was told that it has a 351 crank in it. I can tell that the cam is not stock because it has a lope that rocks the car back and forth. I don't know what size heads I have. The reason that I asked about the Poptop pistons is because i know that if I have those then my compression ratio can be around 8 or 9 to1. I don't want to have to rev it high to get that strong pull. Where is the best place to shop for after market engine parts.
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Old 03-27-2006, 02:13 PM
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Ford Motorsport catalog
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Old 03-27-2006, 07:24 PM
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big torque SBF

The biggest stroker kit I know of is a 347 CID kit for the 302. A 351W crank wont fir in a 302, as the main journals are way too big, and the counterweights and rod throws would be too massive as well. It would require a lot of machine work to fit it in.
It would be possible to get 450 HP out of a 347, however, you arent going to get it building a torque motor with out a turbo or supercharger of some kind, I fear. A torque motor is generally classed as an engine that has its peak HP below 5500 RPM.
If you are really interested in building a hefty torque engine, the best way would be to go with a 3.85 stroker kit in a 351W, which a 3.85" stroke will garner 393 cubes with a 30 overbore. The 3.85 stroker is probably the best bang for the buck with the 351W engine, as this crank is designed to be run with stock 351W rods with stock 289/302 pistons.
You would also need some decent breathing after market heads to accomplish it.
I would go with Twisted Wedge, 1.94/1.60 Edelbrocks, or World JR. 1.94/1.60 heads.
Depending on the CC of your combustion chamber as to what your compression would be with popup pistons; IE:TRW .440" dome pistons.

CC combustion chamber on 302

53.5 63.2 58.2 69 60.4
gasket thickness
.028 12.85 11.00 11.85 10.13 11.46
.036 12.47 10.75 11.55 9.91 11.17
.047 11.99 10.35 11.15 9.62 10.79

As you can see there are a lot of variables involved in compression, and this holds true with any engine. However, the larger the displacement, the more effect and addition or subtraction of unswept area will have on the compression ratio. As far as compression goes, higher compression really starts to shine on the upper RPM limits where the cylinders breathing time is extremely short. You could make a good living 347, with a max of 9.5:1 compression, with after market heads, intake should be either EFI, or a dual plane with a 4 bbl in the 500-600 CFM range. You should get close to slightly 400 HP and 400 Lb Ft of torque in the useable power band. Ive run some figures through my desk top dyno and with the cam I have in my 351W, which is a 230/230 degree, .510/.515 solid lifter cam, I was coming up with about 375 HP at 5500 and hi 300's for torque.
As a rule a cam of more than 230 degrees @ .050" in a hydraulic, or 240 degrees @ .050" in a solid lifter, you are getting into cams more designed for higher RPM, and not torque. These generally, in a normally aspirated engine would be the upper limits in a torque cam, as their normal power band is from 2000-6000 RPM,

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Old 03-28-2006, 07:44 AM
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engine

So you are telling me that there is no way that I can have a 351 crank in a 302? Like I said before, I am big on tq. If I got a 347 CID kit, could I build it for more tq rather than hp?.If I got my cylinders bored that would suck more gas right?

Another question? When I go to the autozone to get my plugs I give them the year and make of my car and they always seem to give me the wrong size plugs. They give me plugs that are longer and wont even thread into my heads. How can I tell what size and brand heads that I have with out pulling it out.(or when I get ready to pull it out)?

Also, a bigger lope sprays more gas into the cylinders right? Would I need that if I got popup pistons?. Why would I have to get my engine bored if I got the 3.85 stroker kit? (HOW MUCH ROUGHLY WOULD THAT KIT COST ME?)
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Old 03-28-2006, 10:21 AM
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torquer SBF

You could get near or even over 400 HP with a 347, but it will take a bit of work, to do so normally aspirated.
As I mentioned, the 351W crankshaft, while having its mains on the same centers as the 302, has much larger journals, and it would require a LOT of machining to cut them down to the 302 journal size, the 302 journals are around 2.25 inch in diameter and the 351 journals are 3 inch. The 351W crank also has much beefier rod throws, and it would require a lot of machining inside the block to allow them to clear, so as it stands now, the 347 stroker crank, which has a 3.4 inch stroke is about as big as one can go without a lot of serious machine work. There are also other things to consider, such as rod length, piston deck heights etc. With the 347, youre at the upper most limits with those things now. The only other alternative with a 302 block would be to get an SVO block from the factory or after market that would allow you to go with a bore larger than 4.06". And you are back to spending a bunch of bucks then.
You dont have to bore out the 351W when you install a 3.85 stroker crank, however, when people build those engines like that, the engine usually needs a clean up bore job anyway, and that is why they advertize the engine as being a 393 with the stroker kit, as normally the engines takes a 30 over bore to clean it up. With the stock 4 inch bore, the engine displaces 387 cubic inches.
The 3.85 stroker cranks go for around $400- 500. That is the biggest single outlay of money in the operation, as you can use your stock 351W rods with it along with stock 302 pistons. So its a pretty straight up engine build and economical as well. Additional costs will be approximately $100- 150 for the pistons and another $100 or there abouts for your bearings, rings, and gaskets. As I mentioned previously, you can build a 3.85 stroker for under $1000, unless you want to put aftermarket rods and some super whiz bang pistons in it. I would recommend getting the entire rotating assembly balanced before installing it in the engine. This should run you about $150-200 at the most, and you will still come in at around $1000 total expense on that part of the engine build. Your cam, valve springs, and lifters would run you another $200, approximately. Since you arent building a super high RPM engine, go with the recommended springs your cam grinder goes with. I would also install a high volumn oil pump while youre at it.
As for your heads, Take of a rocker cover and see what kinds of markings are on the head in the valve spring well.
Here is a samle of realistic engine setup for street in a 351W. I have a 351W in an 88 F-150. Engine mods include, 40 overbore, flat top 9.4:1 compression pistons, with TFS Twisted Wedge heads out of the box, custom ground Camresearch solid lifter 230/235 degree @ .050". .510/.515 lift 106 degree lobe separation, Edelbrock performer intake, 600 CFM 1850 series Holley carb body mounted on an 83310 series 750 CFM base plate,Mallory ignition, 1 5/8ths primary tube headers with 3 inch collectors.
This engine dynoed in real life at 398 HP @5500 RPM and delivers over 400 LB Ft Tq from 2500 to 4500 RPM. This should give you some good perameters to work from. This is a torque engine, and I shift at max RPM of 6000. I have played with this engine on my pc dyno, and with the 3.85 stroker kit, the engine would still have the same peak RPM but the torque figures below that are abundantly higher, well into the 400 Lb Ft range. Dont take this as meaning that you couldnt get a lot more torque and HP out of a similar setup.
Lift and duration of your cam govern how high the valve will lift and for what length of time the valve will be open. Generally high torque cams will have a high lift with not so great a duration. As one guy told me many years ago, lift helps torque and duration gives you RPM. The higher a valve is lifted and or the longer the valve is open, the more fuel and air the cylinder is capable of drawing in. So any modifications in either area are going to allow the engine to take in larger amounts of fuel on each intake stroke. That being said, its not uncommon, though it doesnt actually make sense, that an engine with a cam thats maybe 10-15 degrees larger than stock, along with the coordinated lift, will often give better gas mileage than the stock cam, with all else being equal or the same as was when the engine was stock.
At one time I had a 70 Ranchero with a 302. Before I did any mods to the engine, it got about 15-16 MPG. After putting a Crane HMV 260 cam, 1 1/2 inch primary tube headers with 2 1/2 inch collectors, an old 66 289 Hi Po iron intake and 480 CFM Ford 4 bbl on it, I was getting 17-18 MPG on the highway. This was with the stock 3.25 gears and C-4 tranny. On the cam, I went from a stock 184/189 duration with .368/.381 lift to a 204/216 duration and .456/.484 lift.
As for your spark plugs, it sounds like you dont have the origional heads on your engine, which is why you are having trouble with getting the proper plugs. On stock heads, Ford has used only two basic plugs. So it sounds like your engine could have aftermarket heads on it. My Twisted Wedge heads dont use a plug that is anywhere near what the origional factory plugs would have been for the 78 heads that were origionally on my 351W. For some reason, it seems that a lot of the aftermarket heads will use a plug that would have come out of a Chevy engine, and being that most aftermarket heads are using Chevy valves, even for the Ford engines, that wouldnt surprise me at all.
I would also think that somewhere on the ends of your heads there would be some kind of identification as to the manufacturer, if they arent stock Ford heads. Find out what kind of heads you are running, and if they are aftermarket, get ahold of someone that sells those heads and find out what the proper plug should be.
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