Scat’s Super Budget Small Block Chevy Rod

[Robert_McDonald]

Just how good – or strong- can a rod costing as little as $25 a time be?

Text, Photos and Drawings,

By

Robert McDonald

I have to tell you we backed into this test the wrong way and it was far from a pretty site. The cookie (well in this case the engine) crumbled like this. About three years ago I built a low cost engine for a good friend of mine. For this I had a used set of Bow Tie heads on which I did a quick week end porting job. The intake was a single 750 Holley on a Bow Tie single plane intake. For a cam a dual pattern Comp solid flat tappet grind (part # 12-678-4) from their Xtreme Energy series was used. I picked this cam because it works well with a moderate nitrous system. With the intake delivering 282 degrees advertised duration (244 @ 50) and the exhaust 290 (252 @ 50) ground on a 110 LCA it needs to be timed in at 6 degrees of advance for a nitrous application. Assuming a good flowing exhaust port in the heads this produces very effective valve event timing for a typical 150 -200 hp nitrous system. If you intend to use a cam like this or any of Comps Xtreme flat tappet cams be sure to follow the break in procedure to the letter as these are pretty aggressive cams.

Scat’s low buck rods are available in two bolt style configurations. The cheapest is the through bolt design as per the stock rod. Shown here is the slightly more expensive cap bolt version. It is less problematical to clearance the shoulder on these for a stroker application.

The bottom end of this 350 was almost stock in that it used a forged Chevy crank, Ross forged pistons and a set of those $199.99 a set Scat rods. Augmenting the power was a semi home built nitrous system that I originally jetted for about 175 hp increase. This engine proceeded to power a 3000 lb car down the strip for about 3 years. Then my friend asked if I could rebuild it – sort of an extensive freshen up if you like. This I agreed to do.


The rebuild was a pretty straight forward deal. It involved a complete teardown and a hot tank clean. From here the bores were re-deck plate honed to just clean up some very minor bore wear. The only components changed in this rebuild were the bearings, rings and gaskets (all from Jegs at $128 for full bearing set including cam bearings, rings $213 and FelPro gaskets at $107) The bearings were Feral Mogul and I used the ‘H’ grade for the rods. The rings were Total Seal’s gapless regular race grade ones which feature a standard tension oil control ring. With everything cleaned up and the block repainted the whole thing went back together in just a few hours.


I was looking forward to this test as the only real change here was from regular rings to Total Seals gapless top ring set. Since three years had gone by I could not lay my hands on any dyno figures from the original test but was sure the engine originally did not quite crack the 500 hp mark. After an hour of break in for the rings and bearings we got down to testing in earnest. Remember all the carb jetting and timing requirements were already sorted from previous testing. The first pull yielded 506 HP! Better yet the torque seen was 460 lbs-ft which for a 10.5/1 350 is nothing short of excellent. So, for an engine I probably put together for a couple of grand total, things were looking good. Now was time to hit the nitrous.


With the bottle warmed to deliver 900 psi the engine was started and brought up to 3000 rpm where it produced some 380 lbs-ft. Hitting the button promptly caused the torque to climb to well over 700 lbs-ft and the test was under way. Just as the r’s hit the 6000 mark the whole engine disappeared in a giant cloud of smoke. I hit the kill button fast enough to have got a red light on a pro tree. The two big dyno fans cleared the smoke in seconds and revealed the source of the problem. There was a ragged hole the size of a fist in the pan. With the aid of a flashlight the reason for said hole could be seen. The bottom three quarters of a rod was hanging down in the pan. I was more than a little disappointed here as a very good motor had just turned into mostly a pile of junk. But I still wanted to see what the output was before its demise so I walked over to the printer and grabbed the printout.


Much to my surprise the last figure was at 5900 where the number recorded was 738 hp! Even more amazing is at the 6000 and 6100 point where the rod had already gone through the side of the pan the engine still recorded almost 600 hp. Now this struck me as very relevant here because I had originally jetted the nitrous system at 175 hp so this engine should have had no business producing the output it did. Curious, I call my friend and asked if he had changed the jetting. “Yes” was the reply “I put 300 horse jets in it”. “When” I asked. “About a week after you originally built the engine” he replied. “And how many runs do you think you have done over the last three years with this setup?” I asked. There was a long pause here and I wondered if I was going to get an answer but finally it came. “About 700 or so I guess”.


When that Scat rod initially broke I was a little ticked off but as the enormity of 700 runs at 750 (or possibly more) hp sank in I realized that this must be one heck of a connecting rod to have lasted so long so far out of the operating sphere that Scat recommends for their use. So here’s what I think of the Scat rod after our totally unintentional destruction test.


Firstly you can pretty much rest assured it will have a very long life in an engine of 500 hp and rpm up to 7000. Secondly the fact that it is about the same as stock weight even though it is 0.300 longer means minimal to zero balance problems with stock type cranks. Lastly this 4340 (that’s considered a top grade steel for rods) rod comes with a bushed pin end which is a far better deal when it comes to assemble and dis-assemble.


I would give this bargain deal of a rod 5 stars on the GFN scale of value for money and functionality but for one thing. Scat is one of the biggest suppliers of stroker cranks in the world and they made a rod that is not stroker clearanced at the bolt shoulder? Sure you can do it yourself on an offhand grinder in two minutes but why? As things stand I would recommend these rods to any one building on a tight budget. They are so far superior to a stock rod that it’s not even worth considering using a stock part. My GFN score for this speed part is 4.7 stars.