Carrera 2 replica engine for the Ghia - Choices

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RHough
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Sun Jul 10, 2016 12:30 pm

I need a reality check.

What rpm should I limit the engine to? Is a 6800-7000 rpm recline unreasonable for a well built Type 1?

One of the considerations for the 92x74 was based on the BMW R75 engine. Both are air cooled pushrod engines. The R75 was 57 HP @ 6400 the same lower end was good to 7000 the small 32mm carbs were the limiting factor for rpm. That works out to 150 HP for the 1967cc VW.

If it is foolish to expect high rpm with reliability, someone slap me.

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Wed Jul 13, 2016 4:12 am

At high RPM you are trading safety margin for HP.

Trading a few HP for a fat wide power band is usually a better plan on the street/for AX.
The Fuhrmann Carrera motor made good power for its day but didn't possess an ideal powerband for AX.
You can build a T1 today that will eat its lunch with a parts catalog, care and knowledge...
...and be (comparatively) zero maintenance, for the ~cost of a tune up on a type 571.

A well set up dry sump will help, a lot, but everything else must be absolutely correct too.

Extended high RPM use makes valve springs a consumable, an oil spraybar setup supposedly helps greatly.
If they let go at high RPM things will break...
Drag racers tend to just replace them on a schedule.
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Wed Jul 13, 2016 8:26 am

#2
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#1
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#4
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#3
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Wed Jul 13, 2016 8:36 am

I don't know what to make of this.

The crank was seized in the #1 main bearing. The oil passage to the #3 rod was full of bearing material. The #3 rod was NOT seized on the crank it wasn't even tight ... just a melted bearing.

I don't see how the rod bearing failure could have caused the main bearing failure.

All the rod bearings wanted to stay on the crank. The rod bearing OD is smaller than the rod ID. Like the bearings have shrunk.

Does it look like the engine was starving for oil? What would pound the rod bearings like that?
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Wed Jul 13, 2016 11:46 am

Piledriver wrote:At high RPM you are trading safety margin for HP.

Trading a few HP for a fat wide power band is usually a better plan on the street/for AX.
The Fuhrmann Carrera motor made good power for its day but didn't possess an ideal powerband for AX.
You can build a T1 today that will eat its lunch with a parts catalog, care and knowledge...
...and be (comparatively) zero maintenance, for the ~cost of a tune up on a type 571.

A well set up dry sump will help, a lot, but everything else must be absolutely correct too.

Extended high RPM use makes valve springs a consumable, an oil spraybar setup supposedly helps greatly.
If they let go at high RPM things will break...
Drag racers tend to just replace them on a schedule.
Let me put it another way. The 1968 92x74 engine with the W-120 cam had a wide powerband. Huge torque (compared to stock) from 1500 to ???? At 6390 (tach tell-tale) it went flat ... not like slowly running out of air power loss 'might as well shift' high rpm limit. It pulled strong right up until that point then a sudden change in engine sound (waaaaa to honk), loss of power, and OMG "I hope I didn't break it" sort of deal.
The engine specs say it should be making good power to 6800 or so. The engine ran fine after the high rpm episode. My first thought was valve float, but I was assured the dual springs on the L5 heads should be good to over 7000. If it had a rev limiter I would suspect that, but unless the Pertronix Flame Thrower has a built in rev limiter that is undocumented ignition cutting out is not likely. It could be a harmonic on the intake or exhaust ... maybe a reflected wave off the bottom of the air cleaner covers. I set the shift light to 5800 until I had time to find out why the engine flat refused to rev over 6400 ... then the failure after never seeing over 6200 on Saturday and only 6120 on the blip to downshift before it locked up on Sunday.

The #4 rod bearing is unmarked, there is a wear pattern on the #1 & #2 rod bearings. All the rod bearings have lost their spread (their OD is now smaller than the ID of the rod caps) They still preload but they are distorted.

I'm looking for advice on a parts combo that will let the engine reach its 6800 rpm power peak if that is possible.

I'm going to replace the crank. For 7000 rpm do I need a super crank or will this from CIP be good enough?
http://www.cip1.ca/ProductDetails.asp?P ... e=C13-8121

Do I want/need this DPR crank: http://vwparts.aircooled.net/DPR-DELUXE ... t1-rod.htm

The rods were "Race Prepped" http://vwparts.aircooled.net/OEM-Connec ... e-rods.htm

Scat makes a CroMo I-beam rod with the VW journal and 5.394" length http://vwparts.aircooled.net/SCAT-5-394 ... 5394-3.htm

Next step are the H beam rods.

Pistons are AA - full skirt 92's with thick wall cylinders - should I consider slippers?

At 135 HP and 130 ft/lb do I need a supper gland nut? I'm having a hell of a time trying to get the 1.5" nut of the crank to look at the #1 bearing ... 1.5" sockets are more than the price of a gland nut. 36mm I could have used my handy axle nut/gland nut tool but at well over 400 ft lb (200 lbs of me bouncing on a 18" 1/2" breaker bar) the nut won't move.

I'f I put a new crank and rods in it and keep it under 6000 I'll be back where I started. Great power band and good drivability. But I want it to rev to the limits of the cam/head/intake combo ... 6800.

I'm going with the HD aluminum pushrods from ACN to replace the "set to zero lash cold and clatter hot" CroMo push rods.

Should I be looking for lighter valve spring retainers as well?

I don't have plans to go endurance racing with this engine, but It should be able to live through a few track day weekends of 15-30 minute sessions and a half-dozen autocross events between teardowns. If there is a weak link inside the cases that makes the Type 1 unreliable at 6500 - 7000 I'm ready to do almost anything to make it reliable. Should I can the AS41 case and start over with aluminum?

I didn't think I was getting a budget engine.
So far a rocker stud failed at 2 hours. "Those never break".
"Pounded rod bearings is normally detonation. What ignition timing?"
"The rods you got are better quality than the 4340 I-beams, because if they are a VW rod (311), then we ONLY use our race rods (shot peened, race balanced, race sized, etc)."

I've never heard of detonation causing rod bearing failures, particularly with no evidence of detonation on the pistons or cylinder heads. If the race prepped VW rods are better quality than the CroMo I beams, why are the CroMo rods listed more expensive? Why wouldn't the build information include the prepped rods rather than the CroMo rods?

I don't want to sound like I'm whining, I just don't want to have to rebuild this engine 5 times to get a combo that works (if my goal is even possible). If it comes down to 5500 RPM engines live forever, 7000 RPM engines need bearings and valve springs every 5 hours I might be able to live with that.

Cheers,
Randy

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Wed Jul 13, 2016 12:43 pm

Unless you have gotten it apart, there is no evidence of detonation posted yet, so they are making stuff up.
Detonation leaves other evidence, and a seized rod bearing from det is unusual.
As to the vw rods, they are also making up stories, They are not junk, but not as good for your uses as what you paid for.

The scat ibeams are nice, get them with the ARP2000 bolts.
They are heavy, probably better suited to a turbo motor, but they are good,
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by FJCamper » Wed Jul 13, 2016 3:54 pm

Hi Randy,

You are talking to "high RPM" central here. All experience, no theory.

In 2000, I was training my son Barret for road racing. I'd done the usual go-kart training with him when he was little. By 2002, we had a 1970 Ghia with a 4.86 rear end out of a drag car, and a "mule" engine for him to just get around the track on.

It was a deep-sumped aluminum case, cast counterweighted crank 69mm stroke, "race prepped" stock rods, out of the box Mahle 85.5 pistons, an Engle 110 cam, some overkill AJ Sims heads, HD aluminum pushrods from Aircooled, and a pair of AJ's Kadons with 30mm venturis. 11:1 compression. No balancing, just assembly.

The 4,86 final drive transaxle forced us to turn 7k just to do 100 mph. Early on, Barret didn't yet have the killer instinct the most predatory drivers do, but he wasn't afraid of breaking parts.

Listen to this engine at 7k plus.
http://www.youtube.com/watch?v=u1d3Swrn-YI

That's on a 009, Hall-Effect ignition, and a Blue coil. Hear any misses?

Anyway, we did bearing swaps every year for almost 3 years, and the little mule engine just kept on cranking.

My point is, we were either so lucky it was crazy, or just reasonable care and the right parts combo can take the punishment.

FJC

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Wed Jul 13, 2016 6:06 pm

Here are the full size photos: https://goo.gl/photos/DaFeEDMJd2CBuJXm7

After I got the flywheel off and managed to knock the #1 main bearing off the journal ... it looks like the crank was either bent or flexing.

If anyone sees cause of failure in the photos, please chime in before I repeat the mistake with new parts!
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Wed Jul 13, 2016 8:01 pm

Missed the earlier post with inline carnage pics, can't see the rest from work...
Almost looks like #1 was too loose or picked up some trash, started spalling, and then came apart then welded.
Did the thrusts look OK?

Its not out of the realm of possibility that it simply swallowed some metal swarf left over from machining, but its hard to tell given the damage. (Or RTV if it used RTV, right, FJCamper?)

I would be inclined to clean up that crank and make some measurements to see WTF if anything odd was going on there clearance or ovality or such.

Also: What brand of bearings for mains and rods?
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Wed Jul 13, 2016 11:48 pm

Piledriver wrote:Missed the earlier post with inline carnage pics, can't see the rest from work...
Almost looks like #1 was too loose or picked up some trash, started spalling, and then came apart then welded.
Did the thrusts look OK?

Its not out of the realm of possibility that it simply swallowed some metal swarf left over from machining, but its hard to tell given the damage. (Or RTV if it used RTV, right, FJCamper?)

I would be inclined to clean up that crank and make some measurements to see WTF if anything odd was going on there clearance or ovality or such.

Also: What brand of bearings for mains and rods?
No idea of brand on the bearings, should they be marked?

The flywheel side didn't look bad, the crankshaft side was blueish. Cam thrust looks fine to me. I'll grab the Micrometers tomorrow and measure what's left. The only odd looking thing is this damage pattern on the crank. Bearing crooked in case for 50+ hours then failed? Crank flexing somehow and loading edges?

I don't have much experience looking at damaged VW parts but both the #1 and #3 pistons look like they had almost zero squish. The carbon patterns on #2 & #4 look different than #1 & #4.

Is there anything I could have done to cause this? I'm *not* looking to assign blame, only trying to learn about the Type 1. The more I read the more I'm convinced this engine should have been good to at least 7000 if not 8000.

The rod bearings don't look oil starved so what can cause them to loose their spread and fall out of the rods?
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Thu Jul 14, 2016 1:58 am

Bearings are usually stamped with a mfr logo, at least.
Some may be inked on and may have cooked off..

Its probably just the picture but it almost looks like someone, somewhere, dropped the crank ~on end and bent it, making #1 run crooked. Could have happened in China.
That would explain the weird wear/burn pattern on #1 (>really, that explains everything), and should be measurable.
An engine "assembler" probably would have missed that.

FWIW I basically beat my t4 almost as hard as you have described every day, >80K miles now, just far less cam, so no point taking it over 6k. Just changed to 10W30 oil, no low hot oil pressure in 100+ degree temps, and I run a T1 cooler on my T4 for AC clearance. There's no reason a properly built motor won't last.
My current daily doesn't really even qualify for that.

Mine was almost all used parts down to the main bearings and a $25 crank/rod set off TOS I inspected and dropped in, ~zero wear, factory rod bearings looked almost new, and the OG mains with >400K miles on them were in spec with the newer crank. (high end of spec, but in spec) The only new or fresh things were the cam/lifters, cam bearings (dual thrust) and fresh heads from HAM, and the cut to length CrMo pushrods, which make no funny noises.
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by FJCamper » Thu Jul 14, 2016 9:32 am

Hi Randy,

Take the crank to a shop and ask them to check it for straightness.

Your photos seem to show either a bent crank or a warped case. I just can't imagine how the builder managed to torque the case (while test rotating the crank assembly) without feeling restriction.

When you build a Type 1, and you have the big case nuts all the little nuts torqued, and it turns over smoothly and easily, you know you have a good low-end build.

The over-square Boxer engine was designed to rev.

There is revving and there is revving. I was always impressed with Ferraris until one day I saw one with it's heads removed, and the crank being rotated by hand. The little pistons just barely bobbed up and down. Talk about a short stroke! It took all the magic out of it for me. Sure you can rev to the Moon if you have tea cup pistons and just enough stroke to lift the piston half its height!

We are using a 74mm Chinese crank in this historic sportscar build, but with 85.5 Mahle pistons. I have used the AA pistons, and they are acceptable, but much heavier than Mahles. We balance our own rods and pistons in house.

Whatever I'm gaining with the Mahles, I'm losing with the chromoly I-beam rods. They are strong but heavy. The only mitigating factor is a con rod is a reciprocating part, and the weight & balance penalty is not as great as if they were rotating parts.

Be advised heavy imperfectly pistons and rods can warp a crank at 7k plus.

The Type 1 case tends to promote crank bending once specs are exceeded. Remember, our Type 1 cases have four bearings, but only three are really load bearing. Thrust, Center Main, and #3. The cranks tend to bend on the ends, with the 2 and 4 cyl end the most common,

FJC

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Re: Carrera 2 replica engine for the Ghia - Choices

Post by RHough » Thu Jul 14, 2016 11:00 pm

FJCamper wrote:Hi Randy,
...
We are using a 74mm Chinese crank in this historic sportscar build, but with 85.5 Mahle pistons. I have used the AA pistons, and they are acceptable, but much heavier than Mahles. We balance our own rods and pistons in house.

Whatever I'm gaining with the Mahles, I'm losing with the chromoly I-beam rods. They are strong but heavy. The only mitigating factor is a con rod is a reciprocating part, and the weight & balance penalty is not as great as if they were rotating parts.

Be advised heavy imperfectly pistons and rods can warp a crank at 7k plus.

The Type 1 case tends to promote crank bending once specs are exceeded. Remember, our Type 1 cases have four bearings, but only three are really load bearing. Thrust, Center Main, and #3. The cranks tend to bend on the ends, with the 2 and 4 cyl end the most common,

FJC
Bingo! (maybe)

"92mm x 69-76mm Hypereutectic Thick Wall Machine In Piston & Cylinder Set, Fits 90.5/92mm Case and 94mm Head, AA Brand, Type 1, VW9200T1K is a great quality Piston and Cylinder Kit for engines that do not exceed 6500 RPM! These use a 90.5/92mm Case and 94mm Head bore, for a super thick cylinder wall thickness at the top, but minimal machining at the bottom!"

I shot myself in the foot ... I wanted the Thick Wall 92mm for longer engine life. I never noticed the caution to keep the RPM down. The AA cast pistons are heavy? Too heavy maybe?

#1 & #3 pistons have suspiciously clean squish areas. Like the pistons were very close to the heads. What would the engine do or sound like if the pistons went to zero squish but not quite piston to head contact?

I had repeated instances of sudden power loss and engine noise during short WOT runs. I thought it was valve float. The RPM Tell-Tale read 6390 RPM more than once. Are there any symptoms of crank flex that a driver could pick up on?

Why would they state the AA pistons were for engines that do not exceed 6500?
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by Piledriver » Fri Jul 15, 2016 1:25 am

The AAs are hypereutetics.
(Other than their "true forged" 94s. which are 2300 series aluminum with ~zero silicon content)

Thats a Very Good Thing for their intended use.
...You simply aren't using them for that.
A tight deck will give the "bare" squish area carbon pattern, what's more disturbing is all 4 should look ~like that.
If they don't, somethings up.
Deck is not something you guess at, or want terribly uneven.
I would not run that tight on a motor intended to run 7K+, particularly with stock rods.

OTOH, the one on #3 probably "kissed" the head when the #3 rod bearing died, and knocked off the carbon there.
(The sharp "edge"/transition gives that away, usually there's a narrow but gradual transition area)
Also, you are running too rich to have that much carbon build up that soon.

You can probably score//drop in Mahle 92mm pistons.
If forged Mahle 92s are available, they will need more clearance than the std mahles, but any of the T1 92mm Mahle pistons will be fine for your intended use.

The forged ones are very soft and may not last 20K in DD use, forged 23xx alloy slugs are better suited to high compression drag/boosted engine use.
(ring grooves wear out, ring seal goes away)

One option you have at this point is to use Mahle "B" (78-82mm stroker) pistons with longer H-beam rods.
If you intend it to run over 7K, that is a very good plan.
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Re: Carrera 2 replica engine for the Ghia - Choices

Post by FJCamper » Fri Jul 15, 2016 9:03 am

Hi Randy,

The piston RPM limits are to keep the piston from literally breaking apart. AA pistons are not inferior. They just have some limitations. Hypereutectic means they expand (and contract) in a even, controllable fashion and have less expansion than just common cast pistons.

BTW, Mahles are not true forged pistons, but still excellent.

Way back in the day, Road & Track used to list piston speed for its road test cars as a central item in engine design, cited literally as feet per second. https://en.wikipedia.org/wiki/Mean_piston_speed

A secondary gotcha is the wider the piston, the more likely is the piston to "rock" and slap one edge or the other against the head when at full compression stroke, even with proper 40-thou deck height. This is because there is more length on each side of the wrist pin pivot point.

True racing pistons have the wrist pin centered to minimize friction between the piston rings and the cylinder walls. Street pistons have a deliberate wrist pin offset to minimize piston slap and run quietly. I don't know if AA offsets their big pistons or not. I suspect their 1600's are just standard replacement parts. And offset or not, your big pistons can slap.

Your carbon patterns on the piston crowns are very telling.

One way to interpret them is the builder got the deck too tight, and at high RPM one or more of the pistons were slapping, and thanks to the standard VW rods as they stretched a few thousandths, each slap would be like a hammer blow to the rod bearings.

The bearings flatten, then try and spin. While flattening is taking place, the weight of the pistons is also leveraging the crank at its center main, bending it so that cyls 1# and #3 are still in the straight plane, but #2 and 4# are not. Your #3 journal photo seems to indicate it was oscillating at some point as it rotated.

You can have the rods measured for stretch, the crank checked for straightness, and the case line bored.

Building a "homage" Carrera 2 engine is going to be problematic without a set of forged pistons. I've stuck to the original Carrera 1500 and 1600 displacements because I can get the RPM's with the Mahles.

The best we can do is clone the spirit of these giant-killer engines rather than make a mechanical clone.

FJC

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