stroker questions

[Ieatcamaros]

My brother wants to build a 331 this winter. I have never built a stroker before. I haven't read anywhere that they require any "special mods" to get them running. My question is do they require any block mods or a different oil pan or pump? He wants to get the one from dss. I know they have a good rep. Thanks for any replies. Also, what do you guys think of an aluminum flywheel for a manual tranny? I know they have the steel insert but I was concerned about the pressure plate bolts staying torqued.

[stang_racer20]

The 331 you might get away with free and clear. For my 347, I had to notch the lower cylinder walls for my rod bolts. If you are really concerned talk to a tech at DSS. I would recommend a 7 qt. pan and a high-flow pump as well. Its always better to be safe than sorry. As far as the flywheel, aluminum would probably be fine. I personally would get a steel one though cause their just a little stronger.

[Ieatcamaros]

Stangracer, are you satisfied with your 347? It looks like you have her built pretty good. And does that cam have good vacuum at idle? I didn't really like the aluminum flywheel, but I just wanted some input from you guys.

[302 LX Eric]

The 331 kit will not clear the block. No biggie though. Just clearance the block (notch) and you're set.

Just a side note, you may want to buy a short block assembly from DSS as it is more cost effective than doing the work yourself...I've 'been there, done that'.

Manual tranny and aluminum flywheel work just fine. No issues here.

DSS has a good rep. That's where I got my kit from (w/Probe SRS pistons).

Go with a Canton 7 qt. Extra oil, great pan, and looks cool too!

E

[stang_racer20]

Originally posted by Ieatcamaros
Stangracer, are you satisfied with your 347? It looks like you have her built pretty good. And does that cam have good vacuum at idle? I didn't really like the aluminum flywheel, but I just wanted some input from you guys.

Well actually I have yet to drive it on the road. I need to make all kinds of adjustments to my PCM, cause its not running right yet. So I am getting the Tweecer RT if you've ever heard of it. However, I have started it up and it sounds really nice, just idles bad and runs very lean yet. I'll let ya know how I like it otherwise in about 2 weeks when its drivin'.

[Ieatcamaros]

I wondered if it was worth it to buy a short block or do the work myself. Since I have never built one, I should probably buy the short block. So the next time, I will know what to notch for clearance. I had planned on using a 7 qt. pan anyway. So there is not a special oil pump and pickup necessary? I will probably end up putting a turbo on it. Anyone have any recommendations?

Eric, what rear tires are you running to get that 60 ft in your sig?

[stang_racer20]

yes u will need a special pickup because the pan is deeper. if you order an oil pan package, it should come with a pickup and maybe a dipstick as well.

I too thought about getting a lightweight aluminum flywheel a while back. But my '90GT is a street/strip car...and I was told that for street/strip applications like mine, aluminum flywheels aren't the best choice, especially with a manual trans. When shifting between gears...the alum. flywheel doesn't carry the inertia of the steel one. Therefore the RPMs drop in between shifts...significantly faster than a steel flywheel, which can make street driving more difficult. I'd like to hear from anyone that does run an aluminum flywheel though...how they like it...if they drive their car on the street at all, etc.

[Dave_mustang_50]

Dss recomends a 7qt oil pan for the low comp 331. Like stang racer 20 said, I`d call a tech too. They can answer all of your questions. The 331 is rated for 650 hp, but they told me it would handle alot more. Its just their conservative rating. They actually talked me out of an r302 block. Hope this helps

[302 LX Eric]

Originally posted by Simi Stang
I too thought about getting a lightweight aluminum flywheel a while back. But my '90GT is a street/strip car...and I was told that for street/strip applications like mine, aluminum flywheels aren't the best choice, especially with a manual trans. When shifting between gears...the alum. flywheel doesn't carry the inertia of the steel one. Therefore the RPMs drop in between shifts...significantly faster than a steel flywheel, which can make street driving more difficult. I'd like to hear from anyone that does run an aluminum flywheel though...how they like it...if they drive their car on the street at all, etc.

There was an excellent article a while back in MM&FF about the differences of steel vs. aluminum flywheels. Good information and I think it helped clear up some misconceptions.

I have one on my car and as far as street driving goes, it makes no difference as compared to my old steel one.

At the strip, it's just about the same to launch, except that it doesn't have the same 'hit' when you release the clutch at a given RPM. Easy to rectify by merely raising the RPMs (and we're not talking a whole lot here).

In almost all cases, your car will pick-up ET & MPH with an aluminum flywheel. Think about it this way...many people ditch the stock driveshaft for the lighter aluminum version in order to rid the driveline of rotating mass, or in a similar example, we put on lightweight racing wheels, as opposed to the heavy stockers, again, in an effort to reduce rotating mass. The same holds true for the flywheel, or lightweight pistons, I-beams, etc.

The most noticible downside to reducing rotating mass is the 'hit' to the tires when you drop the clutch at an equal RPM. If you've got 200 pounds of metal swinging at 5000 rpms vs. only 100 pounds of metal at 5000 rpms, the energy released upon the tires will be greater with the heavier driveline. However, as soon as the 'hit' is over with, the engine has to start working again to bring up the rpms through every single gear. This is where the lighter weight driveline really comes on strong. In a very heavy car, you would want a heavier driveline to help get the car rolling off the line, however my Mustang is relatively lightweight and I have absolutely no problem roasting the tires at the drop of a hat. In fact, I struggle just to keep the tires from spinning while launching the car at the track on drag radials.

The article in MM&FF had more technical girth to it than my simple examples above, but I think you see what I'm saying.

Hope this helps,
E

[jonnyk]

I agree with the above except for the blanket statement that a "331" will not fit in a stock block without clearancing. Mine does. It depends on the rods mostly, my Scat I beams fit fine but I know the Eagle H beams need clearancing. That would be something to check on with your machinist once you get going.
I also have an aluminum flywheel on the street and the manners are perfect...the bigger motor doesn't seem to notice the change in inertia, and it freewheels nice on the bigend.

[302 LX Eric]

Originally posted by jonnyk
I agree with the above except for the blanket statement that a "331" will not fit in a stock block without clearancing. Mine does. It depends on the rods mostly, my Scat I beams fit fine but I know the Eagle H beams need clearancing.

Wow! That is surprising! I have 4340 Forged Steel H-Beams and they hit the block pretty good upon first hand assembly. I just assumed that I-Beams would hit as well. FWIW, my H-beams are 5.315".

Thanks for the info, jonny!

E

302 LX Eric & jonnyk...so do you two recommend an aluminum flywheel for a mild street/strip combo such as mine. My mods are in my sig. Just guestimating...but I think I have around 320hp on motor...and then whatever a 150 shot of juice will give me on top of that. Are you guys running the 28oz. flywheel?

302 LX Eric- so did you "actually feel a difference" when installing the alum. flywheel? Or did you do any other mods at the same time. Did your 1/4 mile times improve at all? I still have the steel drive shaft but plan on upgrading eventually. I've read articles that stated that an alum. driveshaft did not improve people's 1/4 mile times at all. Maybe with the alum. flywheel & driveshaft it would?? Let me know what you think.

[stang_racer20]

i am not sure off hand if this makes a difference between manual and automatic, but i know i had to do this for my auto. but the flywheel balance depends on what you have done. a stock mustang is set up for a 50 oz. balance. a mild to med. modified street-strip car should probably go 28 oz., an ALL out race car like nascar uses neutral balance type stuff. just remember though your dampaner, crank and flywheel/flexplate all have to be the same balance or itll run terrible, if it runs.

[jonnyk]

A 331 will probably be closest in balance to 28 oz, although mine was closer to neutral (had I known before I bought everything I would have balanced it neutral too) since my pistons are really light (396 grams w/o wrist pins). You'll probably want to go with a 28oz imbalance as the balancing machine work will work out cheaper (mallory slugs for neutral balance get expensive really fast). Lower external balances (smaller numbers of imbalance) typically mean a smoother running engine with less vibration passed through the bearings. As mentioned above, you have to match the engine balance, flywheel, and balancer, or the offset in balance will cause the engine to shake itself to death.

As for the driveshaft comment, I've read in other threads that the reduction in weight from the stock driveshaft is MOSTLY offset by an increase in driveshaft diameter, meaning it takes more force to spin it on it's axis because the mass is further from the center. That's why most people don't feel any gains with the FRPP shaft. If you found a nice 3" aluminum (stock diameter) driveshaft I'm sure there would be gains to have.

With that being said, yes I'd recommend an aluminum flywheel on the street. It's a little easier to get the car off the line on street tires and with a stroker you won't feel a torque loss anyways. People get quite carried away with "lowend" torque I find...all you need is to get off the line and then it's all topend.