Got a Stroker?

Rickyll7

Member
Dec 16, 2005
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I was curious to see what kind of numbers are being posted by people who have a 5L stroker with similar mods to those listed in my sig. I am preparing to pull my motor in a week and slap my heads on a Sean Hyland Motorsport stroker short block after the heads get a once over by Patriot. The pistons are 28 cc and should crank out a compression ratio of about 8.7:1, give or take about 2 tenths of a point.
I am realy interested in seeing any dyno sheets or just numbers with respective rpms if possible.
Any good ideas or comments are appreciated, Thanks!

edit:
Red 98 GT Coupe 5spd
Patriot Performance Stage II Heads, Comp Cams XE268H, BBK Tuned Length Shorty Headers, PI Intake, Demolet CAI, Magnaflow catback, Bassani o/r x pipe, Accel Coil Packs w/wires, ASP Pullies, SCT Eliminator Chip.
 
I just dynoed mine last week. It made alittle over 325rwhp with 23-24 degrees of timing and a 12.8 air/fuel. Had I gone with 10.5:1 compression and more aggressive tuning I'm sure it would have been more around 340rwhp.
 
306 Stroker bored .020 over. Don't have it in yet so I want to see your numbers :D . I've ordered stuff from SHM before for myself and clients. There is nothing wrong with their stuff. Their shipping sucks, I've never had anything show up on time, but their products are good.
 
Rickyll7 said:
Wow, awsome numbers! So what else would you all recomend for me to do next? A centerforce dual friction is already in the works with 24 lb injectors.

If I were you i wouldn't waste my money on 24#'s. If you are going blower or turbo 24's aren't enough if you want to make real power, 450+. Get 42's or 55's and be done with it. It you're staying N/A you don't even need the 24's just keep the stock 19's. The centerforce is a good choice though, I have one and love it.
 
I am not a fan of strokers as big bores make the power and more reliable.
First let's look at the stock modular bore and stroke. The stock bore is 3.552'' and the stroke is 3.543''. That stroke is HUGE already. A 351W has a 3.5'' stroke from the factory. They have an extra 73+ CID on the modular motors. This puts it in perspective on how extreme the stock stroke already is.

Now, combine that with a stroker kit and your piston starts leaving the bore. This is VERY bad at high RPMs as the piston becomes extremely unstable. Stroker motors just don't last. The HP/TQ gains are so minimal as well because the valves are still shrouded. The only time you want to use a stroker is when you have a turbo setup as turbos don't really like to rev high either and can benefit heavily from the slightest torque band increase. The reason these are so popular though is because you can use your stock block and you don't have to resort to using the more expensive aluminum block counterpart like you have to in a big bore.

Big bores are what make the REAL power. We're not just talking about HP either. They make great torque and LOVE to rev (which is just what a modular motor needs). Big bores increase the bore from 3.552'' to 3.7''. This is done by taking an aluminum block, boring out the sleeves that are already in it, inserting new, stronger sleeves and boring them out. There are 2 versions of big bores. One is the dry sleeve which doens't cost that much and can handle roughly 20 PSI on a blower. This is the one you want for a mild blower application or NA application. The other one is a set sleeve where they actually bore out the sleeve of the cylinder and insert a new heavy duty sleeve in. It is called a wet sleeve because the coolant is touching the sleeve; this allows for cooler temps. The wet sleeve can withstand basically anything you can throw at it. Aluminum blocks can be either wet sleeved or dry sleeved. Iron blocks can only be wet sleeved. As you probably guessed, wet sleeving is very expensive (about $1k more than normal dry sleeving).

Now, the reason the big bore benefits is this. On the stock motor, the valves are shrouded. This means that the cylinder isn't big enough to support the heads. Basically, the combustion chamber is bigger in diameter than the cylinder. Big bores fix this problem by unshrouding the valves. THIS, my friends, is the secret to why big bores are making the power and lasting as opposed to strokers. Remember this when you want to increase displacement. Oh, and don't even both with the 324'' big bore/stroker blocks as the rod ratio is all fudge up and they are just a problem waiting to happen
 
Rickyll7 said:
So how long have the strokers out there been lasting on the street? And what exactly happens to them to cause them to fail.
People who don't like strokers never had one. I've had mine for two years. I blew it up a couple times at the track before I switched to Modular Powerhouse and got my fuel system straightened out. It has run great for the past year on the street and on the track. A big bore may be better, but there is nothing wrong with a stroker and it will make more torque than a stock stroke.