I'm trying to decide on a stroke combo. Virgin stage II 4.1. Will be 90% street, fully ported GN1s, stock ported intake, 3200 lock-up with 200R4. I'm thinking about a 224-224 hydrolic roller? Should I go to a 4" bore? Would like comments on the cam as well. I'm thinking that I would like to keep the rpms at 6500 through the traps? Which crank and rod combo would give me the best street piston, not only brand but size/length. Longest skirt and the best compression height (center of pin to top of piston. Also trying to get an ideal stroke and rod ratio...being better than 1.55:1. I'm looking for a nice low stress motor combo...3.75, 3.625, 3.590 or 3.4? Maybe a crank stroke that I can use an off-the-shelf rod with? I think there's 5.965, 6.0, and 6.35 rod lengths available? I want to put some miles on it. Help me out! Thanks
Guys with 4.1 stage street motors (or gals)
- Thread starter turboclam
- Start date
i ve got a nice brand new set of forged diamonds (8 in all) with a 1.640 comp height if you can use them,im also considering selling my 224/224 hydralic comp roller with a .587" lift. $250 shipped for the pistons and $250. for the cam- im building a stage2 4.1 and will be going to a larger cam. matt 347 680 8642.
turbodave231
Moderator
- Joined
- May 24, 2001
Both a 3.590 or 3.625 stroke is a good choice for the engine you are looking to build. There are many lower cost (import) 3.625 cranks available today. Some are better quality than others. I have used a 3.625 from Dan at DLS with good results. Crower makes nice cranks for Buick V6 engines and TA perf is a vendor selling Crower cranks. Crower cranks are not for a budget build, but what Stage 2 parts are cheap?
At far as rod length, go with the longest rod possible. The longer the rod, the less rod angularity........ which translates into less stress on the rod. If you go with 6.5" or longer rods, you end up putting the pin bore into the oil control ring groove. This isn't a problem, but it forces you to use a support rail below the oil control ring.
Dave
At far as rod length, go with the longest rod possible. The longer the rod, the less rod angularity........ which translates into less stress on the rod. If you go with 6.5" or longer rods, you end up putting the pin bore into the oil control ring groove. This isn't a problem, but it forces you to use a support rail below the oil control ring.
Dave
rod length---IMO
Since he is looking for more of a street eng. I would recommend a short rod. A 3.625 crank and 6.5 rods makes for a short skirted piston which makes them that much harder to keep quite. I recommend J&E pistons since they can be installed @ a much tighter piston to wall clearance as compared to Diamond.
Since he is looking for more of a street eng. I would recommend a short rod. A 3.625 crank and 6.5 rods makes for a short skirted piston which makes them that much harder to keep quite. I recommend J&E pistons since they can be installed @ a much tighter piston to wall clearance as compared to Diamond.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
I have these pistons for sale if your interested. I changed these out because they were fora 3.625 stroke and I have a 3.59. They were way down in the hole and compression was calculated to only 8.04:1 . With the correct 3.625 stroke crank, compression would be 8.5:1 .
See attached picture.
See attached picture.
Attachments
Thanks for the comments guys! I guess it's coming down to building a stroke out of a good street piston. Trying to get a long skirt and a 1.25 or better CH but still get a stroker of some kind in there. Thanks for the info about the J&E pistons, I also have read about how the forged pistons change a little versus the hypers or cast. Keep it coming...
My 0.02 cents.
I'd look at what your HP goal is under full track boost and work backwards within budget.
Really figure out what YOU want out of the motor and don't get fixated on specific parts or "possible" HP numbers as you uncover the potential of your stage motor. You don't want to end up with a high maintenance race motor in a street car that is not built for the power.
Pistons won't be noisey unless you have a crappy machinist. I'd even consider a less than 224/224 cam and keep the rpms well under 6500 and take advantage of some low end torque. We're talking about staying well below the range of hydraulic roller cams and having big-block like spoolup characteristics.
Pick a builder/vendor on here with experience with stage II's and get parts through them. You're not going to loose $ ordering through them and can use the advise.
I'd look at what your HP goal is under full track boost and work backwards within budget.
Really figure out what YOU want out of the motor and don't get fixated on specific parts or "possible" HP numbers as you uncover the potential of your stage motor. You don't want to end up with a high maintenance race motor in a street car that is not built for the power.
Pistons won't be noisey unless you have a crappy machinist. I'd even consider a less than 224/224 cam and keep the rpms well under 6500 and take advantage of some low end torque. We're talking about staying well below the range of hydraulic roller cams and having big-block like spoolup characteristics.
Pick a builder/vendor on here with experience with stage II's and get parts through them. You're not going to loose $ ordering through them and can use the advise.
turbobitt
Well-Known Member
- Joined
- Feb 14, 2002
The pistons are JE's. Valve reliefs are cut for stage 2 heads To make a long story short, I ordered these from Ken Dutweiler about 8 or 9 years ago and installed them without checking them. Well I finally tore down my engine for freshening and decided to measure stuff to see if there was any wear since I street drive this thing. Well much to my surprise these pistons had a calculated compression of 8.0 to 1 and not the 8.5 that I thought I had. If my stroke was 3.625, then the piston would have been near zero deck and compression would have worked out to be 8.5. I just ordered a new set and they look identical execpt with a shallower dish to give me 9.0 to 1.
If anyone is interested, these are for sale but without pins and support rails. $325 takes them.
Allan G.
Just FYI...I've been running a 3.590 stroke with 6.5 rods and 4.20 bore Diamond pistons with a CH somewhere around 1.20. .007 deck clearance. Stage 2 heads with a 222/218 HR cam. Lots of low-end with a T-76 BB. (Want some real burnout fun? Try it with a 60-1 first. 
)
It's a little rattley at cold startup, but quiets right down. Nice, smooth engine on the street. S2's run cold, too. You might need a 180 t-stat.
)It's a little rattley at cold startup, but quiets right down. Nice, smooth engine on the street. S2's run cold, too. You might need a 180 t-stat.
I run a 3.8 Stage 2 block with a 3.625 crank on the street all the time in my GN. The car is primarily a street car. It's not noisey at all. Runs nice and cool. I use Carillo Rods and Diamond pistons. I also run a 215/220 Hydraulic roller cam with a 70HPQ ball bearing turbo and a 3200 9/11 converter. The car hasnt seen past 8psi yet but on the street, it doesn need any more boost to say the least. I run E85 though 160lb injectors too.
