1CAMWNDR

iTrader: (21)

OK so a 4.125" stroke and a 6.125" rod is doable and the revs should be kept below 7,000 right? Would the 6.125" rod allow a 1" compression height?
So if I was interested in a low rpm torque motor and used a 4.25" stroke; what rod length can I get away with? 6.0"?
<img border="0" alt="[burn out]" title="" src="graemlins/gr_burnout.gif" />

Chicago Crew UnderBoss

iTrader: (1)

Since this topic is right on point, can you guys enlighten me in regards to my MTI 427 stroker Motor being built as we speak, that utilizes a smaller but max. bore for a LQ4 (4.060) with the larger 4.125 crank.

I don't know the length of the rods for my engine build, but i am sure the Colonel and some others here would know. I am assuming it is the same rod length used in the MTI 422 motor.

I have been told that MTI that my car will make a ton of torque down low, but will max power around 6500 and that my A4 tranny will shift around 6500 also.

What are the pros and cons of my bore and stroke and rod length combp, as it applies to this thread, and will my engine wear out quicker than if i went with a 4.00 crank instead.

Thanks for the educational lesson.

MTI 427 C5 Roadster

SStrokerAce

iTrader: (2)

Good question MTI 427 C5 Roadster,

The funny falacy with stroke length from what I have seen is that people think that a longer arm will make more TQ down low. In reality there is not going to be any difference if the Cubes stay the same. Your going to make a ton of TQ down low because you have 427 CUBES!!!!

My guess is that you have a 6.125" rod or a 6.000" rod, either one will be o.k. Engine wear and life has alot more to do with use, power, and engine RPM, if you are nice to it, it should last a good amount of time for the power it will make, if you beat on it (think Thunderchicken from GM High Tech and MTI) 50,000 miles is going to be a little too far.

Bret

NoOne

Well now I'm interested in this.

I have 6.125 rods in mine and want to build a 427 Iron block but want to do it as cheap as possible meaning keeping the rods I have now.

Right now the motor is 8.5:1, I am thinking with the bigger motor I can go up a point in compression to 9.5:1, run less boost and stay on pump gas at around 600rwhp.

Can this be done with the 6.125 rod? The bore right now is stock and I think I was told you can go 4.030 on a iron block?

The heads are not cut at all and have stock sized LS1 5.7 liter combustion chambers.

Chicago Crew UnderBoss

iTrader: (1)

No One:

From what SS Stroker states above the 6.125 rod length would be fine for your 427 LQ4, but i have no other knowledge about that.

However, i do know for a fact that the 4.030 overbore is certainly fine and recommended as the max. bore which is safe and acceptable for F/I applications. I am running a 4.060 bore as i am building my motor for N/A and not F/I.

Good luck,

MTI 427 C5 Roadster <img border="0" title="" alt="[Big Grin]" src="gr_grin.gif" />

Pro Stock John

iTrader: (34)

FWIW, 4.000 stroke x 6.125 rod setups are common. You can still run a ~9:1 piston OR a high compression piston.

4.030 bores for iron blocks are very common. LPE uses that bore for their SC'd truck setups all the time and uses JE for their pistons.

Less common rod that is sometimes used is a 6.200 rod. ARE has used them in some motors, perhaps the 393ci big bores?

SStrokerAce

iTrader: (2)

</font><blockquote><font size="1" face="Verdana, Helvetica, sans-serif">quote:</font><hr /><font size="2" face="Verdana, Helvetica, sans-serif">Originally posted by NoOne:
<strong> Well now I'm interested in this.

I have 6.125 rods in mine and want to build a 427 Iron block but want to do it as cheap as possible meaning keeping the rods I have now.

</strong></font><hr /></blockquote><font size="2" face="Verdana, Helvetica, sans-serif">What rods do you have now? Are they stock or aftermarket? how much power do you want?

Bret

NoOne

SStrokerace:

They are Lunati Pro Billets.

SStrokerAce

iTrader: (2)

how many miles? and at what power? how much do you abuse them?

If anything get them magnafluxed before you put them in another engine, they should work.

Bret

NoOne

SStrokerace:

Around 15K miles, ALOT of abuse <img border="0" title="" alt="[Smile]" src="gr_stretch.gif" />

680hp for the entire 15K miles.

SStrokerAce

iTrader: (2)

If it's me, I'd buy new ones. The problem with metal is it's like a woman, every little thing you have done to it, it will remember. So all that 680hp worth of abuse is, just that abuse that will bite you back.

Now they still might be good. You need to have them checked out and magnafluxed and they should be good for some more hard miles!

Bret

Brian Tooley Racing

iTrader: (13)

John,
I like the answer Billy Glidden once gave when asked the same question, "you have the block, you have a crank, make the piston the way you want, put a pin in it and the length that connects the piston to the crank is the length you need" Not to tangent here but, I have a customer with a SBC 422 I built,it has the 3.875 stroke, we built the piston and then connected it with a 5.85" rod. It has TFS Twisted Wedge heads (remember these?) and it runs 9.60's in the quarter on MOTOR. I used to theorize rod length/angularity to death. I think Billy is right on this one. Design the piston close to the way you want, generally with 1.200" or better pin height and then find the closest length rod that fits it, finish moving the pin to fit the rod and call it done. Good luck.

SStrokerAce

iTrader: (2)

good point Brian. That's my thoughts now too!

I wonder if Glidens pistons were designed for the sneeky pete bottle in the gas tank!

Anyways, here is a good aticle on this.......

http://www.motortecmag.com/archives/...AUG010201.html


Bret