Is this short block a little overkill?
 

I was kinda wandering if my short block is a little over kill for 1000 flywheel with 15-17 pounds of boost with twin turbos.Im using a 400 block that has been sonic checked with splayed 3 center 4 bolt billet caps and studded front 2 bolt and hard blocked to bottom of freeze plugs. Ross pistons with Total Seal filefit rings(1/16,1/16,3/16) with SS top ring and Ross .990 X 2.930 piston pins.Callies compstar 6.8 rods with L19 bolts.4 inch stroke scat forged crank.This will be driven on the street as well as raced occasionally thoughts?

Over kill? Not in my opinion, but that’s just me.



GTO George

The short stroke will help... So will keeping your RPMs below 5500....

There is a general rule of thumb that most people in the Pontiac realm seem agree on. You will be hard pressed to find anyone to recommend pushing the factory Iron blocks much over 700HP. 700HP seems to be the consensus where factory cast iron blocks split. I think its got more to do with rotational weights, RPM, detonation and bad tuning than 700HP alone, but Ive been flamed for my thoughts and I have learned to just keep them to myself. (Kind of like being a conservative in a "progressive" world)

So based on that, NO, your block is NOT over-killed for 1000HP, Its actually under-killed because its expected to exceeded all expectations of survivability past 700HP.

I'm building a 496 stroker (4.5" stroke) and intend to run 10-15 lbs of boost. I started doing my build with a 1972 455 block. I had the 3 center splayed mains, added steel front and rear mains and filled it with Hard block to the bottom of the freeze plugs. After spending some time on the forums I became convinced that my build was a ticking time bomb so I stopped talking myself into keeping the 455 block and just bit the bullet and purchased an MR1 block... (money I didn't have but could not afford not to spend)

You're not running the long stroke like I am... so that short stroke will help with survivability.

If you are hell bent on using that cast iron block, I would go as light weight as humanly possible on your Pistons, Pins & Rods and build it to do all you want it to do by 5500RPM and the tune must be right. Even then most would suggest you are still on eggshells.

Since I went with the MR1, my goals have shifted slightly. I plan to run more RPM and more boost than initially intended (because I can) Looking at 6500RPM target and 15-20lbs boost, with a Luhn Perf LS firing order cam, HP should be some place on the moon. <--- and it WILL BE a daily driver!

Good luck with your build...

The problem with boost is you are never happy and you will want to turn it up, so I don’t like the stock block even with the mods. If you actually stay around 1,000 or under the crank should be ok with a lite rotating assembly. I don’t take me engine to 7,000 rpm.....mainly under 6,600 with the torque of a Pontiac. I also like aluminum rods.....BMI.


GTO George

Honestly I think we can all agree that more engines have been destroyed by bad tunes then anything else.My deal is there is available parts to easily deal with the 1000 flywheel I’m looking for.To me It’s about the tune then block and I’m not sayin it doent have its limits but once everything is prepped and given a chance to live it’s likely to put a smile on ones face this is sopost to be fun right Ha!Im running a Holley Terminator X and working with Holley as we speak to run Gen 4 Ls knock sensors in the extra holes were the motors mounts are located(5 hole block) will see.When done I plan to share the entire tune to help others.Oh and I will also be running flex fuel it’s time to bring these dinosaurs to the future Lol.

I know nothing with regards to boost, so I am just throwing this out there.

I did not see any mention of securing the engine/trans in the car. It is my opinion, as you get into these higher HP/TQ numbers that the engine torque puts a ton of pull on the drivers side engine mount and can focus too much pressure on the side of the block at that point and cause unwanted flexing/stress on the block which can inturn cause distortions and out the window go your internal clearances and cause problems.

Would it make sense to suggest an engine/transmission plate to secure the engine to the frame? Or is this a given at these HP/TQ levels?

A lot depends on which year of block you've used -some are better than others. I also believe that a short stroke light weight rotating assembly is essential for durability (not too light on the pistons/pins for high boost though), and like George I much prefer ali rods- not any ali rods though- if you have a 1000hp combo, use a set of ali rods spec'd to 1500hp or more. My own ali rods are spec'd for 2500hp Top Meth cars- yet my engine will never make more that 1500hp. I just drifted off the question sorry, JMO.

You will be ok for the street.

Buy yourself an e85 tester and be strict about it . Ive been getting really low % from 50 to 60% lately. Found 1 station that has 90% . Most are low..

Agree Charlie we got E-85 everywhere I live one has to be careful especially with winter blends.Ill be running flex fuel so that should help to keep things in check ive got a ton of LS tuning files to get me up and running.Ive spent a lot of time thinking this over but I’ll get there the only time I will be on 93 pump is just in those rare accounts...Guys I appreciate all the opinions helps to see things in a different way!

Valvetrain seems to be the expense that has me stuck in Flat HHD lifter RPMs.