Quick question: bored out 3400 w/ LX9 heads???

[bszopi]

No one has broke a 3.1/3.4 crank yet have they?

I swear I thought there was some reason it couldn't be done.

Yet. I'm just hoping I don't break the 3500 crank.

[robertisaar]

Yet. I'm just hoping I don't break the 3500 crank.

consider it a trophy: you'll have the only one in existance! i think....

[2.8-350TBI]

Yeah but then you miss out on the "big bore short stroke" and also the LX9 heads...

Wait, I thought you couldn't put a gen3 crank in a gen 3.5 (lx9) ?

Exactly my point. to accomodate the bigger bores, the lx9 has bores 1.5mm offset from the engine centerline http://en.wikipedia.org/wiki/GM_High_Value_engine

The big bore short stroke works w/ the genIII lb8 crank (shorter than the 2.8 btw) and the 3400 block can be safely bored to 93.5...

[bszopi]

Not really sure why they included the LX9 in that, because its bores are the same as the 3400 (as far as placement goes).

The 3900 has the offset bores, and then the 3500s based off of the 3900 (the LZE and LZ4) are the only ones with the offset bore.

[2.8-350TBI]

Hey brad, props for the ingenuity of bringing a great chevy engine to a great ford body.

And thanks for the correction on the lx9's bore.

I really know this thread is going nowhere now...

But taken that I use the genIII 2500 LB8 crank and put it into a 3500 LX9 block and bore it 1mm over to 95mm ittl be 173 cubes!!! The perfect 2800

[bszopi]

Thanks. It'll be intersting to see how it turns out.

Just a question - How easy is it to get the LB8 crank?

[2.8-350TBI]

Sourcing the crank is the biggest issue...
When theres a will, theres a way, but maybe GM or GMPP, if that doesnt happen, GM China.

Who knows, ill be working all 2010 on sourcing parts for this build, because I really want to go through with it. I assume it would have the capability to rev to 9K+, but I think that the valvetrain is the real limitation here...

Meh, its going to be a built turbo street/strip engine anyways...

[IsaacHayes]

Yeah, valve train would probably be the limit of RPM, that and maybe oiling at some point.

But with a short stroke, huge bore, LX9 heads cam, compression, some strong rods it would wind out fast and far... Some TALL gears would be needed I'd think.

What trans will you use? a 282 doesn't like to shift at 7000k, max input speed is 6200 rpm spec... Auto's don't like high RPM either... what is this motor going in?

[2.8-350TBI]

Its going into a RWD 1985 Nissan 720 pickup. Trannywise, I dont know my options yet, but maybe a T-56/ford 9 inch rear setup can be frankensteined... lol, im daydreaming.

All engine internals will be aftermarket, mainly from WOT-tech, but con-rods and pistons will have to be custom made, and im building the UIM myself. Aftermarket computer (undecided), and a single turbocharger.

[robertisaar]

T56 get run up to 7000 regularly...

[AaronGTR]

Yeah, I was thinking myself that possible problems would be valve train... specifically a timing chain that can handle 9000rpm and the valve springs that it will require... and a transmission that will shift at the speed.

If those too issues can be figured out, it would certainly be a heck of an engine. I'd love to hear what a 60v6 at 9000rpm sounds like!

[2.8-350TBI]

You guys know of any rwd 5 or 6-speeds that can handle 9k rpm???

[robertisaar]

You guys know of any rwd 5 or 6-speeds that can handle 9k rpm???

toyota supra tranny? how fast do they get those straight 6's spinning?

IIRC it's a getrag tranny

[2.8-350TBI]

Its 6-sp a getrag (233), the engine itself is limited to 7500 because of harmonic vibrations though. VERY strong tranny, been tried and true @ 1200hp!

LOL, the AP1 Honda S2000 has a 6-speed and the engine hits 9k, but I dont think the tranny itself is up to the task of holding big power...