Stroker Questions

[Eagle]

Personally, I would rather buy a motor from a junkyard.

 

My thinking is that someone started working on this, and then for some reason they stopped. WHY? Is it cracked? Are the cylinders scored (maybe not a problem since you would be replacing pistons anyway, but depends on how badly scored.) Are the cylinders out of round? (Again, maybe not a problem if you'll be boring for new pistons, but ... how bad?)

[yxmj]

If you want to start slow and source a block first...why don't you read on the stroker page a bit and see what block(s) the guys over there suggest to start with....and find one of those....my suggestion would be a block in the same casting as a 2000 xj....i choose this for the reasons stated on the site.... :dunno:

 

. :MJ 1: .

[Jackrabbit41]

Personally, I would rather buy a motor from a junkyard.

 

My thinking is that someone started working on this, and then for some reason they stopped. WHY? Is it cracked? Are the cylinders scored (maybe not a problem since you would be replacing pistons anyway, but depends on how badly scored.) Are the cylinders out of round? (Again, maybe not a problem if you'll be boring for new pistons, but ... how bad?)

Thanks I guess I better start looking

[Limeyjeeper]

Having built 2 Strokers and bought my last one. I would always go with 258 crank, 4.0 rods and forged Keith Black Silvolite 2229 pistons. Stay with a stock or mild cam, stock springs, mildly ported head (Doesn't need much, the 4.0 doesn't respond that well to porting except at higher revs), 99+ intake, header, +030 or +060 bore. Make sure your head hasn't been decked. A lot of the refurbs have had crazy amounts of metal taken off. That will get you in trouble. I learned that lesson second time and bought a new Alabama/Promaxx head. that way you know what you are dealing with, but pricey. I kept the deck stock, standard head gasket and it ran fine on 91. If you want 87, then deck it a bit to get the CR down, but be careful not to get to a place where you will need to change the rod length, that is a PITA to deal with.  I have used the Dino poor man's stroker recipes to great effect. The wilder you make the cam the more likely you are to lose the no 6 cam lobe. (Happened to me once, not pretty) Got my pistons dished by Leigh performance. IMHO the more exotic you get with a stroker the more likely you will have tuning or valve train issues. Keep it simple and you will have a very reliable setup. Mine have all been HO engines. Not as familiar with the renix setup, but I believe the renix responds as well or better to a stroker. I do like the idea of the Edelbrock head but that is big $$$$. Your toughest challenge is getting a good straight 258 crank. I have always used my own block or a low mileage block. A bit more money but less concern about them already been bored. Make sure the block is the right year for the vehicle it was pulled from. Finally whatever you think it will cost you add 50%. just how it always works out. Never done a stroker for under $1,500. Pistons $250, crank $250, injectors $200, machining $200, head $400 - $800. Block $150. Soon adds up.

[mvusse]

I kept the deck stock, standard head gasket and it ran fine on 91. If you want 87, then deck it a bit to get the CR down, but be careful not to get to a place where you will need to change the rod length, that is a PITA to deal with. 

 

Decking, whether it be the block or the head will increase the compression ratio, not decrease it. To lower the compression ratio, you have 5 reasonable choices:

1 - shorter rods,

2 - shorter pistons,

3 - more dish in the pistons,

4 - thicker head gasket, or

5 - increase the combustion chamber size.

 

These all affect static compression. Dynamic compression (the important number) is affected by all of these as well as cam timing.

 

The stroke length of the crankshaft also affects compression ratio, but custom grinding a crank to destroke a stroker is prohibitively expensive and counterproductive.

[johnj92131]

<snip>   Make sure the block is the right year for the vehicle it was pulled from. Finally whatever you think it will cost you add 50%. just how it always works out. ,snip>.

 

First block I purchased was wrong for the Comanche. Check the casting numbers.  Second block is fine. Also, SCAT has a new 258 crank for about $450

[Limeyjeeper]

QuoteQuoteQuote

 Decking, whether it be the block or the head will increase the compression ratio, not decrease it. To lower the compression ratio, you have 5 reasonable choices:

 

My bad, you are correct. Decking will push up the CR not down as it decreases the combustion chamber volume. I always try to get about a 9.2:1 that seems to keep the pinging gremlins away. My first stroker had a CR of 9.6:1 never got that running right even with 93. It did have a big valve head which I think caused a quench problem which is tough to tune around. You have to be realistic, the PCM will only adjust fuelling to a certain degree and the MAP sensor adjustment only helps with cold or  WOT tuning because the PCM uses the O2 sensor to manage fuelling off WOT and uses pre-programmed maps, which on an odb1 PCM cannot be played with easily. I have found the MAP sensor mod is the best bang for the buck to eliminate pinging on acceleration. I am currently at 5.4v on mine. Probably needs a little bit more on 89 octane. The alternative is a HESCO adjustable fuel regulator to get the fuel pressure up a bit, Bottom line is that stroker's can work really well or be a bear to get running right.