Audi A4R4 450HP CBEA (CR) Build

Rub87 said:

So these pictons have stock 30mm pin and no bushing, is the rod length equal to a stock TDI one with stock block height? Are those chevy bearings also of sputter design or are they non cracked with the coating?

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The Rods are a custom length as well. I should have mentioned that above. The ASB has a different compression height than the 1.9/2.0 series. Also, we are running a fire ring, so this effects required rod length/block deck height.
I do not think the Chevy bearings are sputtered, which made me a bit skeptical, but all levels of tehcnical support assured me they were supperior for longevity and load. There are Chev V8 applications out there running 900-950ft-lbs torque on this bearing, which is in the same ball park for bearing load that we are talking about at the low end, and certainly much more HP/rod and RPM for the upper range PV rating of the bearing. These facts give me more level of comfort in the choice than using the OEM bearing. Time will tell if it was a good choice or not.

Now that's some true TDI porn right there. Are you taking any special steps for not having a bronze pin bushing? Or is that not an issue?

Good to know about the bearings. Does the width or the shell need to be altered at all?

Whitbread said:

Now that's some true TDI porn right there. Are you taking any special steps for not having a bronze pin bushing? Or is that not an issue?

Good to know about the bearings. Does the width or the shell need to be altered at all?

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Well, we are not sure about the long term endurance on no bushing, but all V6 3.0TDI are like this.

The shell is almost a perfect width. These rods have tabs for chev shell. The PD130+/CBEA crank journal will loose about .0035" on radius.

Floating pins held in by circlips (pins are not press fit on either the rod or the piston)? I think I can see the circlip groove in the wristpin bore of the piston. If that's what you are doing, every motorcycle engine is like that, and they don't use bushings. Shouldn't be an issue.

Motorcycle engines usually also don't see 250bar PCP and almost 40bar BMEP.. maybe they can get away witout using a bushing because the pin is 30mm, altough didn't the first 1Z engines also had 30mm pin and no bushin'?

Hard to predict
The bigger 30mm pin will spread the load better i assume.
The Cummins steel piston don't have any bronze bushing either

Not a real comparison to a Motorcycle that spins 16000rpm on a 17mm pin (with much lighter piston ofcourse) but it's truely amazing that the motorcycle pistons holds up for thousands of km with the abuse these components see,and often on cold engine aswell


Louis,how much lighter is the Scitex pin?

The point was that a floating pin retained with circlips and no bronze bushings is a common design on high performance engines. It's not a problem, in my opinion it's a better design than a pressed pin and I must not be alone in that opinion.

A supercharged drag racing engine could see very high cylinder pressures. I don't know how high, but they are up there. And that's on top of the inertial loads.

but the old 1Z had 30mm floating pin with circlips and no bushing and these engines where known for the piston failures when modded..

I think piston quality has improved since 1994 which was the last year the 1Z used 30mm pins.

Even a 7000hp Top fuel piston doesn't use bushings.
They are not designed for lasting a long time though.
But the ring land collapse way before the pin boss breaks on these.

GoFaster said:

The point was that a floating pin retained with circlips and no bronze bushings is a common design on high performance engines. It's not a problem, in my opinion it's a better design than a pressed pin and I must not be alone in that opinion.

A supercharged drag racing engine could see very high cylinder pressures. I don't know how high, but they are up there. And that's on top of the inertial loads.

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yes, a lot of the aftermarket Aluminum pistons for trucks have no bushing. Also, I have looked at cylinder pressure charts for supercharged dragsters and cylinder pressures were reaching 4200psi (286bar), which is above our expected pressure.

Geir, the 30mm OEM wrist pin is a whopping 284g, compared to the TDI 26mm OEM pin at 203g. The Scitex 30mm pin we had designed is 180g..I have yet to verify with my own scale. Non the less, this rotating assembly does way less than a stock 81mm piston wirh 26mmm pin and OEM rod. The CBEA ROD/Piston/pin assembly weighed in at 1488g. This assembly weighs in at approximatley 1360g. So much stronger, yet 128g less weight.

TDIsyncro said:

yes, a lot of the aftermarket Aluminum pistons for trucks have no bushing. Also, I have looked at cylinder pressure charts for supercharged dragsters and cylinder pressures were reaching 4200psi (286bar), which is above our expected pressure.

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the average piston life of a top fuel dragster is expressed in seconds at rated power

Ah rats! I just saw this thread today and scrolled through each page and was hoping to see the finial product by the end!!

Good luck fellas! Looks like some mad scientist work going on...

Thought you guys might like this. Stumbled across it on a diesel truck forum. Figured it might get some gears turning for future expansions to this build .

The piston is a Mahle Monotherm for a 5.9 cummins.

To expand on what Whitbread just brought up, here's some pictures of a Cat C32 monotherm piston - I believe it's also made by Mahle. They are very strong, however they're also quite heavy. Enjoy. Oh, and these engine have two spray jets/cyl. One is aimed at the bottom of the crown, and the second is aimed at the hole in the oil baffle plate.

Here's a lighter, automotive-sized steel piston. Some motorsport application pistons are said to be lighter than aluminum ones for a comparable rating. Both Audi and Peugeot are said to be using steel-pistons in their Le Mans racers instead of aluminum.

thanks for all the piston pics and such guys. I never get tired looking at monotherms.


Here are some updates on the girdle. It is now complete and on its way back to me.









Next week will bring boring to 83mm, honing, line boring crank mains.

Oh yeah I want! Now that is a girdle. Nothing flimsy or weak about that gem. Lovely engineering in that piece and Bravo on an excellent addition to the TDI power world.

1 <3 this thread

v8 coupe said:

Oh yeah I want! Now that is a girdle. Nothing flimsy or weak about that gem. Lovely engineering in that piece and Bravo on an excellent addition to the TDI power world.

1 <3 this thread

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Thanks! it is a good chunk of metal..but very nice finishing. Passanger Performance did the CNC machining and grinding for me. Dave is very particular about his work and likes stuff to be perfect.

One other update. The car past the government structural integrity inspection this week. I will get some pics. Its looking good.

It is on to government mechanical inspection next week.

Then I bring it home and take it all apart again for the project. So much crazyness.

TDIsyncro said:

thanks for all the piston pics and such guys. I never get tired looking at monotherms.


Here are some updates on the girdle. It is now complete and on its way back to me.

Next week will bring boring to 83mm, honing, line boring crank mains.

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Louis.
Are those main bearing caps OEM units that was just modified on the top to align with the girdle?

I was just thinking,when you are linehoning the block,the bearing caps has to be grinded down slightly in height,so you can hone back to correct diameter.

The girdle looks like it has an integrated spacer with a set height,so how are you going to compensate the height when the caps are being grinded down in height?

Or maybe you grinded the caps before you machined the girdle?

Anyway,that girdle looks VERY beefy

Looks Awsome as usual! Cant wait for results.

Can I order a girdle?

Hi Geir,

yes..its beefy. lol They are OEM units. There is no need for stronger billet mains with extra stiffness and mass that this girde supplies. I had the main caps precision ground down for line boring process prior to fit up with girdle.

yes, if anybody wants one pm me. looks like there will be about three more being made at this point..including one for a T5 and a D24TCI.

OEM main bearing caps are retained and rewoked. Depending on the success of this design, in future we may consider trying different caps altogether that eliminates the need for the spacers.

On some other deep-skirt blocks with suspended main bearing caps, they use up to 6 bolts to hold each cap -- 4 longitudinal and 2 transverse. In the VW R4 design (almost 40 years old), you have 5 main bearings, each with 2 dinky bolts that have the sole task of withstanding full peak firing pressures that can exceed 250 bar in some tuned cases...

It's somewhat of a testament of the original engineering but also speaks of the potentials for improvement. The main bearing caps will move about (however minutely) in 3-dimensions due to inertial- and gas pressure forces transmitted from piston --> con rod --> crankshaft journal. This ladder frame attempts to somewhat constrain those movements and stiffen-up the bottom end. A ladder frame / crankshaft bed plate is state-of-the-art practise in engine design. All contemporary VAG V-layout Diesels do something like this.

TDIMeister said:

A ladder frame / crankshaft bed plate is state-of-the-art practise in engine design. All contemporary VAG V-layout Diesels do something like this.

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V6 TDI:



V8 TDI:



V10 TDI:



V12 TDI:

Now thats looking like the older Cooper Bessemers but alot smaller

TDIMeister said:

OEM main bearing caps are retained and rewoked. Depending on the success of this design, in future we may consider trying different caps altogether that eliminates the need for the spacers.

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Correction. there are no spacers between the OE caps and the ladder frame. Those steps are integral to the frame and were machined-in that way from one thick chunk of steel. My bad.

TDIsyncro said:

Hi Geir,

yes..its beefy. lol They are OEM units. There is no need for stronger billet mains with extra stiffness and mass that this girde supplies. I had the main caps precision ground down for line boring process prior to fit up with girdle.

yes, if anybody wants one pm me. looks like there will be about three more being made at this point..including one for a T5 and a D24TCI.

Click to expand...

Agree,no need for making a billet cap when you modified the OEM like you did here.
This design looks very good,i especcially like that the girdle goes across the whole bearing cap,not just supporting the bolt holes.
The whole purpose of this girdle is to hold the bearing caps steady so they don't start "walking around"
And prevent the bearing cap from bending and pinch the bearings

One month later - any new progress?

The engine is out of the machine shop. Work that was completed on it:

Block - Line bored mains, Bored and honed for 83mm pistons. Used a torque plate and gridle all fully torqued for this process
Crank - ground to perfect size, matched with rods
Rods - Sized for desired clearances on rod bearings and wrist pins
Piston Bowls are resized, and now need valve reliefs and ceramic coating to complete
Block needs firing rings, water/oil passage oring grooves, and gas ports CNC milled into deck surface..that will proably be a coupe months off, I am getting low on money. Time to focus on making money for a couple months, instead of spending it.

The chasis is coming together. The 6 point roll cage is finished today. These are pics from earlier this morning (not quit finished). To do the job properly, all the interior had to be removed, but certain items had to be on hand for test fitting..such as the dash, door cards, kick panels, and roof liner.
We have gone with 1.75"x.120 DOM throughout. There are substantial connection points thoughout the system between the roll cage and th unibody, such as the main mounting points, plus A pillar, B pillar top and bottom, rocker panels, and rear subframe.
As you can see, I left the miles of wire alone. I will have to do a quick inspection prior to reinstaling the interior to check for any damaged points, though they did take great care not to damage stuff. Part of doing this right, is having the windshield removed.








there are removable door bars, not shown in this picture.






I cant wait to get all the interior back together. I have to customize the roof liner and a few other minor trims, and notch the dash for the down tubes. There were a few mods I did to the ventilation system to fit the underdash cross bar in there with the factory dash.



Jim from Streetwise in Saskatoon here has done all the roll bar fitting and welding. He does most of the race car roll cages and tube frames in our city. He is truely a master at this!

Louie:

Was just going to ask if this was one of Jim's cages...then I got to the bottom of your pictorial post. And, you are right: he has become very good at it.