anyone try a stroker?

mmathews

Registered User
has anyone used a stroker kit on their 3.8? also, how much can you bore out the block?
 
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We've been building strokers for years but they have not been overly popular on this site due to having to forgo the forged crank and use a cast 4.2L truck crank.
 
Hmmm.... you mean one of those 3.8 blocks which have recieved a 4.2L truck crank, 6.125 Scat H-beam rods and custom forged pistons.
I think I have seen one somewhere. ;)
 
Is there no forged option? And what kind of compression is it making? How bout some other info. How much hp gain? Any problems?
 
Is there no forged option? And what kind of compression is it making? How bout some other info. How much hp gain? Any problems?

I built David's motor as well as several others around here so I can offer you some insight about the swap.

1) There is no forged crank option in the 4.2L stroke. If you really want to spend the money, billet cranks are available but they are expensive as you can imagine. We have not had any reliability issues with the cast crank as of yet. Be aware that they are not cast iron, or even nodular iron, but cast steel. They are much stronger than a garden variety 350 Chevy crankshaft.

2) Compression is a matter of how much boost you make and what your design intentions are. We build the compression ratio to suit the customer. David's is 8.5:1, but he also runs 21psi on pump gas. On lower boost applications or racing applications we have run as much as 9.2:1 but I do not recommend any higher than that for forced induction. This has nothing to do with the crank design but more a matter of general engine building principles.

3) HP produced is primarily a function of cylinder heads/cam package and blower design capabilities. We find that on average the 4.2 doesn't make more power than a similarly set up 3.8L unless displacement is a limiting factor for HP. In our case, particularly with an M90 on the motor, the blower is the #1 limiting factor for HP. The 4.2 does make on average about 20ftlbs more torque.

4) I would say no, there are not any known problems at this time. I would say that the bigger displacement makes the motor more pump gas friendly at any given boost level, so that may be considered a bonus if you have the tuning capability to take advantage of it.
 
great info! i am just kickin some stuff around. i am not gonna be the guy that rips a motor apart weekly. i really only wanna do it once. or once in awhile. i love to drive my car. i rarely hit WOT. if i do though, i don't wanna worry about breakin stuff. i want it to be smooth and powerfull. reliable. i really wanna be able to whoop just about any car that pulls up beside me too. within reason ;) so, would this be a total package option? or just not worth it for my situation? and any other advice is greatly appreciated!
 
great info! i am just kickin some stuff around. i am not gonna be the guy that rips a motor apart weekly. i really only wanna do it once. or once in awhile. i love to drive my car. i rarely hit WOT. if i do though, i don't wanna worry about breakin stuff. i want it to be smooth and powerfull. reliable. i really wanna be able to whoop just about any car that pulls up beside me too. within reason ;) so, would this be a total package option? or just not worth it for my situation? and any other advice is greatly appreciated!

A built bottom end is just a foundation to build on. To be fast and reliable you need a bunch of other stuff to go with it. The heads, cam and blower are going to dictate the power potential. The supporting stuff like valvetrain, fuel system, exhaust system, air intake system, engine cooling system, intercooler and tuning are equally important.

David
 
What??

must be nice to have money:rolleyes:

What does money have to do with it? I completedly trashed my entire bottom end on the last failure on the my 3.8 and was going to have to get new rods and pistons anyway, so why not get the 4.2 kit.

Not really much more money since I was going to get all new forged items for the 3.8 anyway

Machine work, heads, larger valves, MPIII, 25% OD, Snow injection kit, Long tube headers, etc; are already done, so this was the next step for me.

Have a great day!

Smitty
 
What does money have to do with it? I completedly trashed my entire bottom end on the last failure on the my 3.8 and was going to have to get new rods and pistons anyway, so why not get the 4.2 kit.

Not really much more money since I was going to get all new forged items for the 3.8 anyway

Machine work, heads, larger valves, MPIII, 25% OD, Snow injection kit, Long tube headers, etc; are already done, so this was the next step for me.

Have a great day!

Smitty

Sorry didnt mean it that way I was just saying that maybe the set up would cost lots of money and would be nice to have the money to do it;)
 
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