Limits of Stock Internals

B5 S4/ RS4
#1

We all know that this is a topic that has been brought up time and time again. But with further advances in tuning, turbos, fueling, etc. I feel that it is something interesting to discuss. While it is hard to have a fully accurate range of the limits of the stock internals, what has everyone pushed their car too and when do you see power becoming too much for the stock bottom end?

I am running K04’s on an aggressive E85 tune, and recently down 475whp/450wtq on a Mustang AWD dyno. For me, rods are next on the list just because I know that I am playing with fire when pushing the car to over double the factory power levels. I know that Wicked bent a rod a few years back running a K04 car on C16, so I would be interested in hearing others’ stories and feedback.

#2

Great question

I guess it will all depend on how that power is delivered but it will be interesting to hear what people think. I always thought the B5 was good for right around where you are…basically 500 = trouble. That is based on no science or experience though…just forum chat that I’ve heard thrown around.

A retarded tuner can spaghetti your rods at 350 whp though of course. Goes without saying. The B7 RS4 motor can handle 550-600 whp on STOCK internals but I’ve heard of revo bending rods with just a tune due to silly timing parameters. They recently did the same to a B8 S4. So having a good tuner is key. Big power from a proper tuner can be safer than less power from a poser.

#3

I’d think timing would damage pistons, an overly aggressive boost spike/profile down low would do the rods in

#4

Most people on these forums are afraid to inform others of their mishaps in fear of making their tuner, or engine builder look bad. I find that to be a mistake, because it doesn’t help others make wise decisions when looking for a reputable performance shop. If you are trying to cover up a shops mistake, or even the fact that your car is having major problems after you repeatedly bragged about how good your tuner/shop is, just because they offered you a free set of spark plugs, or some other minute service for your car, you are a fool. I built my car myself, minus the tuning, so I don’t have that problem of trying to make my mechanic look good when I’m the one spending my hard earned cash.

I feel that we would have info to go on, if so many shops weren’t bribing naive naive customers to keep everything hush, hush.

My car has made 539whp on stock internals. I didn’t get the torque readout, which definitely would have given more insight of the capabilities of the stock…

With 539whp I bent a rod while going wot. A month later I got a new block, because my crank was also damaged. I put my car back together and it drove fine for about 3 months before one of my rods bent again. I then decided to put in some RPM rods and a new tune with e85. I haven’t had a rod problem yet. KEEPS FINGERS CROSSED.

#5

I agree with Faw, its all about the delivery.

I have gone way over 500 on stock block but it was after 4000 and the rods were tweaked when it got torn down to be built.

On big turbos with slow spool I think 600 might work, I have really wanted to test this but can’t justify killing a good 2.7

#6

I certainly agree with this, and from my observations it is the torque that will have a larger effect on the rod strength than horsepower. You see a lot of guys running around with 605’s on stock internals, but these turbos don’t hit like a K04. With such massive amounts of torque down low, I would think that a high power K04 car (450wtq+) would be more susceptible to a bent rod than a 605 car that makes torque at 4000+ RPM.

I agree with you about people covering up for shitty work, but I tend to disagree with some of the earlier comments about how it depends on how you are tuned. If we are taking about bending a rod due to power/torque, I feel the tuning will have a minute level of influence. You can only do so much to manipulate the power curve, especially on K04’s. The difference becomes if you are timing the car so aggressively that it has consistent levels of knock. A detonation which leads to a complete rod breakage or other bottom end failure could certainly be related back to the tuning.

On another note, F.A.W what are your thoughts on the RPM rods thus far? They are local to me and I have talked to many individuals who find them to be identical to Rosten rods. I have been meaning to take a trip to their warehouse to check out the rods in person.

#7

They are not identical to rosten, they are a Chinese rod, rosten are Japanese and finished/machined in Norway. Rosten are a slight margin ahead of their budget counterparts in regards to QC and material control, Geir Rostens wife is Japanese and her family has ties to the foundry.

Fwiw I would run the rpms, same as ie, vast, eagle and so on with proper fitting and confirmation on the bolts being legit they are all capable of 1000+ HP

#8

Interesting, thank you for the insight. I knew that the others were made in China, but I was under the assumption that Rosten was as well.

#9

They are referred to as that, even I have done it. I am technically the north American distributor for rosten yet I no longer control sales. I have met the man, seen the operation and was responsible for bringing rosten to the American and Canadian markets in 2007. I am only saying all this to let you know I am intimately familiar with operations and actual metallurgical contents of the various offerings.

I no longer sell rosten, last few customers looking for them I sent to other dealers who buy direct from Geir, who I setup as dealers. I get no kickbacks either. The market for rods tanked around the time ie and vast started laser logo basterdizing the market. Actually it was theory dealers selling “made in usa” rods for dirt.

The retail price on rpms are less than my cost on Rostens. I personally run Rostens yet if I was in the market for some personal rods I would not hesitate to buy some rpms, check them out, if true machine them and run them to the moon.

Btw - pauter are down right legit. If you can afford 1300, do it. Best mass avail rod imho.

#10

I really appreciate the information, and your insight is truly invaluable. If I were going to bore the block, I would certainly be spending the extra money for Pauter/Mahle. Seeing as I just want a little more security for my K04 car, I will certainly take a look at RPM. Thanks again!

#11

tell us a little more about your K04 in an intro thread in B5 S4 maybe. I miss the days when people realised the K04 was excellent lol.

interesting info from snow trooper. Good to know.

What’s the cost for rpm rods for a B5 S4? Is there a piston option recommended, and a guestimate on cost there too?

#12

I think rpms are 400 bucks with arp bolts. It’s laughable because the bolts cost 2 something. I know of 4 people running them with solid results. Matt Dangers info from arp that the bolts are genuine made me want to try them. 170 rods that hold 800chp so far that I know of… ::slight_smile:

#13

For pistons stock are first choice for most builds. Mahle had some nice overbore stuff too.

#14

If you are upgrading pistons, I would only go with Mahle. I have actually witnessed other pistons warping in the block, something that I have never seen from Mahle. If you ever have the chance to see their facilities, their setup is truly amazing.

#15

The Mahle pistons that I saw from aritoshed on AZ and an allroad guy on QW looked really nice. Can’t go wrong with Mahle quality.

#16

[quote="_F.A.W,post:4,topic:3639"]
Are 2.8 rods the same as 2.7 rods?

#17

No, just the crank

#18

[quote=“jibberjive,post:16,topic:3639”]

When will you post some updated info about your build?

#19

As far as tq snapping rods goes, you really need to control your tq onset and you can get the big top end hp like snowtrooper is saying. I’ve done a few stock block 605 e85 cars and it certainly gets dicey trying to milk out all the power while staying withing the limits of the stock block, since e85 k04 files can easily break rods.

#20

[quote="_F.A.W,post:18,topic:3639"]
I honestly don’t have anything to update, my car hasn’t changed since I got it running over 7 months ago. It’s still just my daily driver, 15psi, stock fuel pump and damaged tranny. When I get some time and funds that can go towards the car I plan on installing the fuel pumps I’ve had on my floor for over a year and rebuilding the tranny, hopefully before the end of the season. That really is it, no secrets going on over here.