Engine Experts-331 or 347

rd · Mar 11, 2009

If the stars align properly next month, I may be able to get a 302 stroker kit. (If my f---ing renters move out of my house so I can move in and sell this place....) Sorry for venting here.

I am headed toward DSS at this point. Couple questions.

If I want a play toy engine that can go to 6500+ rpm down the dragstrip a few times a year, what crank, rods and pistons should I get? It will get 2-3k street miles a year maybe.

I am thinking forged crank, h beam rods, forged pistons.

I was thinking 347 but is a 331 less potential trouble?

This will be a na motor, with up to a 100 shot once in awhile, with a C4, 2500 ten inch converter, 410 gears, etc. I have AFR 185 heads for it.

Thanks for the input.

brytell · Mar 12, 2009

why dss? Do they have better costumer service than chp?

I believe the 331 can rev higher than the 347. The stroke is a little shorter. The 331 has more top end power. So i heard. I need to race one. LOL On my 347, I'm revving to around 5000rmp and i think the power is dropping off there. Keep in mind that I have a stock intake manifold with the tb ported to 75mm and stock heads ported also. Once i through in that trick flow cam and the edelbrock intake, it should raise the rpm range. Holla!

Go forged all the way. I should have, but its all good. I can always upgrade.

dcurtis · Mar 12, 2009

Depending on you power goals you could save a few bucks and get a cast crank, you will break a block before the crank.

5spd GT · Mar 12, 2009

Go with a 347.

PM or Email Rick 91GT on this site. His website is RNH Performance -Street and Race Engines, Custom Fabrication. He has built several engines for guys on this site and helped me with my own engine.

A 347 with the heads you propose and a shot of nitrous are going to be pushing the stock block limits.

dcurtis - Where do you live at in Arkansas? I did not know you lived in AR.

Jaym14 · Mar 12, 2009

The old thinking was that a 331 generally has more longevity than a 347. This is for numerous reasons, many of which are valid, but typically only apply to the DIY in the garage engine build. If your going to compare professionally built motors with race oriented components and blocks than a 347 should last just as long. Performance wise, the numbers will be virtually the same. A 347 has the potential to rev just as much as a 331. The final performance of your engine (which ever you decide to go with) will ultimately be decided by the quality of your components and assembly. That being said, if this is going to be a DIY build, using a stock block, then I'd highly recommend the DSS 331 stroker kit.

Not sure about your budget, but you might want to look into having them just build you a fresh engine. Mine is a DSS 331 Stroker w/ their level 10 bullitt block. The entire long block was delivered assembled and ready to go. 10-7-1 compression 400HP N/A. Price is very reasonable.

347HO · Mar 12, 2009

dcurtis said:
Depending on you power goals you could save a few bucks and get a cast crank, you will break a block before the crank.

Here's the physics you're dealing with.
The more air and fuel you get in the combustion chamber, the more power you'll make... period.
This means 347ci = more potential power than a 331ci.

I suggest you talk with people who race/own 347ci sbfs. You'll find many shifting at 6800rpm and crossing even higher. You HAVE to pay attention to details when building the setup.

If your only choices are 331 or 347... it's 347 hands down.
In this economy, you need to shop around. 5spd suggested one source, and I suggest you try Jim Woods @ fordstrokers.com

strtrcr50 · Mar 12, 2009

First off, I'd recommend you really start looking into dss before you buy a motor from them. Second, I'd say go with rhs or fordstrokers.
331-347, the longetivity supposedly is no longer an issue. Do a little reading on piston dwell. There is a reason why they still make 331s.

1FOX2NV · Mar 12, 2009

i would stay away from DSS way to many poeple have been screwed by them with junk motors
i have both strokers 347 in my GT and a 331 in my coupe and i am much happier with 331 the 347 uses oil and my 331 does not
i would not go with forged internals the cast kit is fine for what your planning
my 331 is the cheaper kit puts 420 to the wheels and runs 11.50's all day long
with no power adders
my 347 is all forged was a waste of money i think but oh well
thats just my .02 cense

rd · Mar 12, 2009

Thanks guys. I am planning to buy the balanced kit, probably including the block, although I have several 302 blocks. I actually have a 68 302 block, but I really don't want the hassle of having to deal with the block machining and clearancing separately, if I can afford it. I had planned on the cleaning, checking and assembly being done by me at home. I was headed to a 331, but the 1/8 mile guys say go 347 and don't spin it as high. Still not sure. I do want an assembly that will live at 6500 to 7000 rpm once in awhile, for insurance, and because I seem to run both 1/8 and 1/4 distances regularly. I am asking here, and will probably have more questions, as a reality check.

This will be a 28 oz motor. The short block I currently have was built in 87 by a local shop, has a stock 78 crank and rods from a Tbird, TRW forged pistons, the stock 78 Tbird damper, and iron GT 40 heads. Not balanced. It turns about 6100 or so at the stripe with 4.10 gears, and I don't really dare to try any more rpm. It runs high 12s on motor. I have not sprayed a full 1/4 pass with the 100 jets I have in it. It has run 7. 87 in the 1/8th on spray.

I just want to get a motor that I can play with into the low 12s or better over the next few years. It will be balanced, etc. Probably use the Performer RPM I have.

Good info in the responses!

5spd GT · Mar 12, 2009

PM Grn92LX on here.

He has a stock block 347 that he shifts at 6800-7000 RPM.

It was built by Rick @ RNH Performance.

fordfan89 · Mar 13, 2009

I`m running a 347 with a stock block. I had the machine work done and put it together in my garage. I have an Eagle cast crank, Eagle I-beam rods, and SRP flat top pistons. I am very pleased with this set-up. It`s putting 385hp and 400tq at the wheels N/A. I haven`t had it to the track yet so I don`t know what times it will run.

dcurtis · Mar 13, 2009

5spd GT said:
Go with a 347.

PM or Email Rick 91GT on this site. His website is RNH Performance -Street and Race Engines, Custom Fabrication. He has built several engines for guys on this site and helped me with my own engine.

A 347 with the heads you propose and a shot of nitrous are going to be pushing the stock block limits.

dcurtis - Where do you live at in Arkansas? I did not know you lived in AR.

Tiny little clarksville

5spd GT · Mar 13, 2009

dcurtis said:
Tiny little clarksville

I live an hour from there. I pass through about once a month.

Great place for State Troopers.

FastDriver · Mar 13, 2009

rd said:
Thanks guys. I am planning to buy the balanced kit, probably including the block, although I have several 302 blocks. I actually have a 68 302 block, but I really don't want the hassle of having to deal with the block machining and clearancing separately, if I can afford it. I had planned on the cleaning, checking and assembly being done by me at home. I was headed to a 331, but the 1/8 mile guys say go 347 and don't spin it as high. Still not sure. I do want an assembly that will live at 6500 to 7000 rpm once in awhile, for insurance, and because I seem to run both 1/8 and 1/4 distances regularly. I am asking here, and will probably have more questions, as a reality check.

This will be a 28 oz motor. The short block I currently have was built in 87 by a local shop, has a stock 78 crank and rods from a Tbird, TRW forged pistons, the stock 78 Tbird damper, and iron GT 40 heads. Not balanced. It turns about 6100 or so at the stripe with 4.10 gears, and I don't really dare to try any more rpm. It runs high 12s on motor. I have not sprayed a full 1/4 pass with the 100 jets I have in it. It has run 7. 87 in the 1/8th on spray.

I just want to get a motor that I can play with into the low 12s or better over the next few years. It will be balanced, etc. Probably use the Performer RPM I have.

Good info in the responses!

I've seen pictures of the extra main webbing in the older 302 blocks. I think you should build that block up. Forget DSS. They're great at marketing, but you can find cheaper and higher quality stuff out there. A 28 oz balanced motor with the right valvetrain parts will run your rpm goal. I will also stick a vote in there for Rick. He's a very active member of these forums, and has been very helpful to people that aren't his customers, let alone those that actually are.

1slo5ohh · Mar 14, 2009

Rick at RNH Performance definitely worth talkin to .. he is building mine now and he has definitely been great to deal with

7upstang91 · Mar 14, 2009

331 is for torque. and the 347 is for horsepower.

Wallzy · Mar 14, 2009

Today 04:56 PM
7upstang91 331 is for torque. and the 347 is for horsepower.

This statment is incorrect - HP and Torque are directly related. You can make more HP and TQ with more cubic inches. With more ci you need to look at longer duration camshafts as well as bigger ports in your heads. Problem is that your mean piston velocity will be higher in the 347 but you are still only at 3600ft/min at 6300 RPM (vs about 3400 w/331). Just keep in mind that blocks start splitting around 500 hp to the ground and it might be easier to run a blower unless you decied to find a nice block.

Walz

enyawix · Mar 14, 2009

351 more power for each dollar spent

qwik347 · Mar 15, 2009

u can't go wrong with either one. i went 347 for the extra torque. i went with chp street fighter kit.

Engine Experts-331 or 347

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brytell

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dcurtis

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347HO

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rd

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