It’s been almost 1 year since I received my RPM rods. When I received them I wrote about their appearance out of the box.
This post is a bit of a follow up. So far I am happy with them, especially for the price. However, I have only 2 miles on my motor so I can’t comment yet on longevity.
Shortly after I received the rods I went to a friend’s machine shop to end balance the rods. I had been under the assumption that the reason these rods were so inexpensive was because they would require final machining and balancing. As it turned out all rods were already within 1g of one another and required no machining.
One thing you will want to check is wrist pin bushing clearance. Mine were all fine except 1, which was a bit tighter. I ran it because it didn’t seem overly tight and I was told that it felt normal and the bushing would break in. We’ll see how it goes. If you assemble them and they are too tight then you can have a machine shop open them up.
As I mentioned in my previous post, the RPM rods come with ARP bolts & assembly lube. I want to point out that the torque instructions that RPM includes for the rod bolts is incorrect! They incorrectly list the bolts as 3/8″ when they are in fact 5/16″. The proper torque, according to ARP, should be 32 ft/lbs and not the 50 ft/lbs listed by RPM.
I believe these same H-Beam style connecting rods are being sold by several other vendors. One includes Nick Audilee @ ProjectB5. The pictures he has show on his website are identical packaging & wrapping. He prices his at $650.
I have discussed off-brand connecting rods with several people in the B5 S4 community and many believe all H-beam rods come from the same Chinese source that supplies IE, VAST, Rosten and a few other companies. I found one source, Racing Parts Maximum (RPM), that sells these rods for $390 shipped with ARP 2000 bolts. I ordered them last week and yesterday they arrived from California.
A visual inspection shows these rods are very similar, if not the same. We will see how they work out in the engine. If they fail, oh well.
The rods came with a calibration sheet from RPM that included crankshaft and pin end weights. I will be rebalancing them myself to verify.
The RPM rods also come with ARP 2000 bolts. These bolts cost $140 if sourced independently so it is a big savings to have them included. There has been some speculation on the forums that these bolts were Chinese fakes but they have ARP markings and appear to be quality. A rep from ARP confirmed they were authentic.
I weighed two of the rods (without bolts). They were 522 grams and 523 grams.
This post has some comparison rod weights:
- Stock 2.7T rod/no rod bolt: 529 grams
- Pauter standard 2.7L rod/no rod bolts: 530 grams
- VAST standard 2.7L H-beam rods/no rod bolts: 515 grams
- VAST custom 3.0L stroker H-beam rod/no rod bolts: 479 grams
- Rosten Connection Rods/no rod bolt: 542 grams
- IE Connection Rods/no rod bolt: 555 grams
So far, so good. I’ll post more info after they’re balanced and installed.
The car got a few new parts over the past 3 weekends. WOTBox, ER intercoolers, new charge pipes and a larger fuel pump.
A few weeks ago I installed my WOTBox. It’s a hardware based 2-step launch control.
It wires into the clutch & accelerator pedal and cuts the ignition at a predetermined RPM when you have both pedals to the floor. The install was very easy and the color instructions that N2MB includes are wonderful! I haven’t been able to get the thing to work correctly though.. When it’s set up it incorrectly cuts the ignition when the clutch pedal is out. But I think I’m setting it wrong. I learned last night that there’s a secondary rev limiter “hidden” in Motronic that you can enable. I’m trying to find out more about it and see if it’ll build as much boost as the WOTbox.
Next up was the replacement charge pipes. The first set of charge pipes I was sent didn’t fit well at all. I think they were meant for another car. At first I couldn’t get a lot of sympathy about the poor fitment. A few months later I saw some install photos of the pipes on another person’s car and could tell an obvious difference. So I emailed photos of my pipes and the fitment to the actual guy who fabricated them at Vast. He immediately shipped me a replacement set.
Old pipes, the meth nozzle rubbed right into the timing cover.
New pipes. They fit sooooo much better.
At the same time I was installing the charge pipes I also installed the larger ER intercoolers. The install was annoying and I ended up cutting more than I probably needed to. They fit alright, better than the RS4s. It was still tight on the passenger side with the AC condenser very close behind.
I ran some intake temp logs last night and it showed a measurable improvement.
The old RS4 intercoolers + meth dipped to ~15* above ambient and rose to ~30*
The new ER intercoolers + meth stay a little flatter. They dip to ~5* above ambient and rise to 15*.
So an improvement of 15* up top. Not bad, I guess. Not really worth the $$ I spent on the ICs but I might spend some time revising my “custom” shroud setup.
Finally, the most recent install was a Walboro 255lph pumpthat I did Saturday @ Chris’ bonanza. Between the heat, my allergies and the gasoline everywhere it was a pretty miserable task. I didn’t tighten the top lid down enough and it leaked all over the place on the way home, so I spent some time Sunday making sure everything was tight. The good news is I have enough fuel now.
Pink is before on the stock fuel pump. Too lean.
Red is the Walboro. Getting better.
A few months ago I picked up a set of new K04 turbos from a guy in Philly. The turbos had been dropped but I was confident that they could be repaired.
Got a spare driver’s side K03 from from my friend Brad and installed the wastegate actuator on my K04. It bolts up and fits the same as the K04 wastegate actuator. Below is the new driver side K04 with the K03 wastegate actuator installed (left) next to the old driver side K03 (right).
I took the turbos to my friend Rick, owner of BTF Racing. He looked them over and verified the repairs were fine. He said the sloppy welds on the turbo outlet weren’t a big deal. I had him run a tig around one edge of the outlet.
I also asked him to test the K03 wastegate to see if it would work as a replacement for the bent K04 wastegate. He adjusted the wastegate and said that the K03 wastegate actuator had a different spring rate than the K04 but they were close and I’d be fine.
I picked up a new South Bend stage 3 OFE clutch & RS4 Pressure Plate from some kid in DC for a few bones. The pressure plate needs to be reset so I’ll have to find someone with a press I can use.
I picked up a set of 2nd hand but never installed K04 turbos. They have apparently been dropped. The driver’s side turbo needs a wastegate, the current one is bent. The passenger side needs to have the compressor outlet TIG welded, it is cracked.