Mongo510

Hey fella's I am building an engine using an LS2 block and want to use a 4.8L crank.
1. Are they pretty much equal in strength between applications?
2. What about the reluctor when using a 0411 pcm? 24? 58?
3. Flex fuel vs gas crank?

I've been building SBCs for 45 yrs and am a bit overwhelmed with all the differences.

Thanks for your input.

Mongo

thunderstruck507

iTrader: (18)

for 0411 you will want the 24x reluctor crank

not real sure the goal of using the 4.8 crank though?

gnx7

iTrader: (28)

You can spin a stock 3.622" crank to 7500rpm without issues. Above that you should go solid roller cam to control valve events. Unless you are class limited..... I don't see the point in destroking unless you want to rev it to stupid silly RPMs. You are just going to lose torque from less cubes.

Mongo510

GNX7, Losing torque is the goal!

Here is what I am doing
LS2 block, sleeved to 4.125"
Callies rods
Diamond pistons
LS3 heads
CM solid roller cam, shaft mounted rockers, brand undecided.
Dry sump
Intake is undecided at this time
5.5" tilton flywheel- clutch assy--11#'s total
TK0-600

Any suggestions on which crank to use? Vehicle model? are they about the same performance wise?

This is going into a Lotus 7 clone with a total weight of about 1600 #'s
Car will be primarily a track car with occasional street use( If it is managable on the street)

Heck, this may well be undrivable on the street, but should make for a hell of a ride!

Mongo

Orange Juice

iTrader: (3)

That will be an insane ride, love the Lotus 7.

EmmaBrooks

According to GM all LS cranks are cast with the exception of the LS7, LS9 and LSA cranks, which are all forged and 3.622 and larger in stroke. So it wouldn't matter what casting to get, they are all going to be cast.
Have you considered an aftermarket? There are some that make a shorter stroke. I know Callies does.

Mongo510

I have not found a forged 4.8L crank except billet. Any ideas?

Mongo

wait a minute, I just checked Callies and the may have something.

gnx7

iTrader: (28)

The LSA 3.622" forged crank is a steal at $550 new. Downside is the flywheel bolt pattern is funky.

You could effectively kill some bottom end torque by running a single plane intake manifold... a plastic style unit hits an airflow wall around 6500-6800rpm and flatlines. Only a single plane or ITB/Harrop style intake will flow well above that.

I can tell you that the TKO600 doesn't like high RPM shifting above 6500rpm. It's also notchy and a very old design. I do realize you save about 65lbs over a T56 Magnum..... but the Magnum I have personally shifted at 7800rpm making 1200rwhp all the way up to 5th gear and it is like a velvet glove compared to the TKO hohum unit. That weight is also in the middle of the car. That would make it very streetable. Plus 5th gear is .80 so you stay in your powerband.... and 6th is .63 so you get decent overdrive.

Another option is a dogbox.... The G-Force GSR is bad *** and I've had one... but they are about 3x the cost of a Magnum once you add all the necessary bits. They are internal shift rails and very compact. Plus they are only about 65lbs and can take high RPM shifts to 10K if you needed.

My buddy is selling a Tex Racing T101A 4spd dog box setup for LSx. PM me if interested. External shift rails.

I bought the motor out of this Bonneville record setting LSx S10. My intentions are to run a 4" stroke crank (441ci). It came with a highly modified Magnum 4.8 crank and Howards billet rods that I don't plan to run.
http://www.lsxtv.com/features/interv...at-bonneville/

It was shifted at over 9500rpm and made 625rwhp with a single plane AllPro intake/heads.

Mongo510

I realize the TKO may be problematic, But it has had all internal mods performed, and with the extremely light clutch assy it may be okay. This car will not be drag raced so ultimate speed shifting is not needed. If it becomes a problem I may have it faceplated or have dog gears installed.
I may be interested in your rotating assy. PM me with more info.

I have always run high rev motors in light weight cars. I have a 352"destroked 400 in my 240Z,and a 322 " destroked 400 waiting for assy sometime on the future.
I also have an LQ9, but decided to go with the alloy block for weight savings in the Lotus.

uxojerry

Callies has a 3.370 Dragon Slayer crank in stock. I would think cathedral port heads, shaft rockers, and a low lash solid roller? Please do a build thread for this when your ready. Good luck! My favorite kind of build.

dogsballs

Callies used to do the lightweight race style short stroke magnum xl cranks in 3.300

You need to read up and google david mizell's 346 motor, which was a destroked ls2 spinning to 9k

EmmaBrooks

Callies can make any stroke you want, it just has to be in the Magnum series. SCAT is making cranks now, but the price is astronomical for a forged crank. No one shelf stocks a crank though that is a shorter stroke.

MileHighSierra

Wow, an LS3 based engine in a Lotus 7? I'd love to learn more about your build if possible.