Too much of the piston falls out of the bore. Many of them eventually fail overtime due to too short cylinder length. We already know this.

With stock deck height your figureing 1.050 c/d? what do you think of that?

We have motors built for the street, motors that arn't expected to be back in the machine shop every year.

 

Fraser
I guess as a site sponsor I was inquiring to tap into your vast knowledge of building engines of this type. It wasn't a reflection of your ability or questioning you at all. I am building a 454 LSX engine right now and I am looking into the combination of using a 4.125" stroke crank. If it doesn't work for you then it may not work for me. I want a serviceable engine but it will not be a DD. Several of these engines have been built using this combination but as you may know these engines, (LSX blocks) haven't been out for any length of time so we can't look into a database to find out how long this combination will last. It does appear however that the LSX block has an aprox. .020" taller deck height than the aluminum variant. If minimum square decking was applied it could add to your number. Not much but some. Thanks for your reply.
D.J.

 

Don't think i'm giving you an attitude, its not my intention, theirs a whole list of variables.

Being the LSX deck height is 9.260 not going to help the issue I covered, its good that you can design pistons for xyz C/D then machine the block for XYZ deck height.

The most recent LSX motor we built here had it decked to 9.240" anyway.

 

Hmmm.... a 496 LSX wouldnt be bad either....

 

Chicago Crew UnderBoss,

After actually receiving and working on these new LSX blocks I will no longer run that much stroke (4.250) since the true cylinder length of the LSX is still only 5.500-ish. At PRI it was checking like 5.750 or so but unfortunately the real deal LSXs aren't that nice. I can still see running a 4.000 with no problems or a 4.100/4.125 deal NA only. The pistons just start getting too short to make a reliable power adder deal after this.

Now the tall deck LSX will easily do 480 inches when it comes out and also the ERL or the Warhawk. I think 440-450 inches though with a great block like this will easily still make extreme power. Look at the LME 454 deal with the TFS 235 heads already almost hitting 600 at the wheels. I know we have a few that should make over 600 easy with around the same 440 inches and some very nice heads. You can make 600 at the wheels with a hot LS7 easy already.

Anyway Hope to talk to you again soon and the block is still a big move forward for the LS1 market and the big bore cylinders very nice and actually stay put under real power. GM should have come out with this block a long time ago but I sure wish it had the longer cylinders it seemed to have at PRI.

 

It's all about the piston design vs cylinder length but you are right that there is a limit depending on the app. I've done some crazy strokers with the right skirts that were 4.100 stroke in the stock cylinders and they are still running fine after a long time and several years and I've seen quite a few 4.000 inch deals smoke like crazy with shelf parts.

I'm fixing two of these right now for a sponsor and have redone maybe 20 more like this where they ran the wrong skirts for the cylinder length and the stroke among other problems. You do have to know what you are doing when you are pushing the limits. OTOH we redid a 4.250 deal in an iron block that another shop built and was all wrong as far as I was concerned but yet it ran great for years and was even a pretty fast low 10 second street car. It did smoke though but not extremely bad.

I won't run that much stroke (>4.125) in a cylinder this short as there just isn't enough real estate witha regular piston to make it work right. Maybe a 2 ring piston would do it but that's not really a street engine there again so it's out of the running.

 

Now thats why Erik built my 408 for me.

 

ERIK,

Thanks for the update and very informative info on running a big stroke on the new LSX motors. YOU DA MAN! Looking forward to getting one of these LSX monster's built in the future, but right now I am on a holding pattern and just enjoying my current set-up!

 

I cant believe that is all that motor is making. i would have thought that 455 ci would make some more than that. If not i am gonna keep my 402 ls motor. It made 523rwhp and 637rwtq last year i havent even had it on the dyno this year but it only went 6.19 last year and this year it has been5.84 on the same hit just some more compression

 

Yeah, basically 4.20x bore by 4.500 stroke on an ERL LS2 block. Topped off with CNC'd LS7 heads it made 700bhp NA and 920bhp with spray.

I'm pretty sure Gray posted a thread after the dyno runs.