/4 shortblock assembly + HP limits, case, crank and rods....how much abuse?? Options

[Mueller]

Let's say we take the stock heads and cylinders out of the picture and use heads/cylinders that are overkill and robust....

what is the next weak link in the motor?

are the rods going to fail once we start hitting the 200+hp mark?

will the stock crank turn to putty at 7000rpm?

what about the case??


at what HP range before it cannot hold everything together and gives up scatering it's internals all over???

[Jake Raby]

The case is good for 250HP with the correct work (not pinning- don't need it)
The case is hellaciously strong!

The crank is super strong, I know of a slat flat racer that turns a destroker to 17,000 RPM! I don't like the stock 2.0 rod journals as they are way too tiny to hold bearing stresses, we only use them on bus engines and 2056 low ball engines, everything else gets TI, Buick, or a certain Honda size that we save for our high revvers.

The weak point is the stock rods. They are too heavy, 750-800 gr!!!)

too short and because of the weight they snap rod bolts. The stock rod is good for 130BHP,(with better bolts) but not for a super high revver. I'm not fond of the Pauter rods at all, every one I have seen has had an issue and caused a failure. The stock length rod is inadequate for any added stroke, it creates a powerband that is totally out of whacjk for a stroker.... The Ricardo rule laughs at those rod ratios!

I'm working on rods now that can be bought for the same price as rebuilt stockers. They have an H beam design, various big and small end sizes. One of them is a 100% stock replacement with ARP 2000 bolts..... Another is a stock replacement that is .300 longer, the way it should be!

I started making my big power when we tossed out the stock rods and opted for H beams with TI characteristics.

The other weak link is the stock lifters, they weigh in at 140 gr....

Its all in the combo!

I would have to say that weak link #1 is rods, especially 2.0.. I have 90% MORE 2.0 rod bearing failures than I have 1.7/1.8 rod bearing failures. Odd thing is that we tear down more 1.7/1.8s than we do 2.0s because the cases are BETTER for what we are doing with them....

BTW, Higher RPM does not need more oil pressure! The centrifugal force of the crank will feed the bearings much better at high RPM... Just keep the mains fed and the crank will do the work for you. Extra pressure just pulls down HP and bumps up the flow of oil to the valve covers through the pushrods.... Thats why guys have oil pressure problems on the track!

Too much pressure and using a stock windage tray will put atleast a quart in each valve cover and the tray keeps it from GETTING BACK TO THE PICK UP TUBE!

It doesn't take extra parts to make this engine good, it takes extra thought- more later when I don't have one hot on the dyno!