2276cc, 12:1 CR, Roller-Cammed Daily Driven Oxyboxer

[helowrench]

Were you able to detemine what was truly causing the wear in the lifter bores?

I am investigating a roller cam build for a daily driver and trying to determine whether it is within the scope of my possibilities.

Rob

[Wally]

I've been having major tuning issues with the EFI to get it to run through the RPM range under full power.

Jason,
The times that that happenend to me, it was always the spark plug wires running to closely to the alternator or the regulator of the alternator (or the pick-up of the crank sensor (even though its shielded).
It presents itself only at higher rpm's under load, so it may seem a trivial thing, but I thought to mention it anyways
Walter

[Stripped66]

Were you able to detemine what was truly causing the wear in the lifter bores?

I am investigating a roller cam build for a daily driver and trying to determine whether it is within the scope of my possibilities.

Rob

IMO, the first issue was the tall pushrod cup height of the ISKY lifters creating enough of an angle between the lifter and the pushrod. I feel that has been satisfactorily addressed with the Crower lifter modified for Pauter. Almost a drop-in with Rocky's roller conversion and a much shorter pushrod cup height.

The second issue was that at least 2 of the lifters were arguably not machined properly...like the radius on the side of the lifter wheel was too small, so the wheel actually wore a groove in the bore.


Rocky probably has a better handle on the mechanism of wear, so he can add his two cents if he's interested.

[Stripped66]

I've been having major tuning issues with the EFI to get it to run through the RPM range under full power.

Jason,
The times that that happenend to me, it was always the spark plug wires running to closely to the alternator or the regulator of the alternator (or the pick-up of the crank sensor (even though its shielded).
It presents itself only at higher rpm's under load, so it may seem a trivial thing, but I thought to mention it anyways
Walter

I appreciate the advice, Wally...it actually wouldn't be the first time I had a crank trigger-related problem with Electromotive. The first time was a completely bad crank position sender. The second crank sensor worked great, but I pitched it into the trigger wheel when my sensor mount broke (right before I pulled the engine last summer). I had to replace that sensor and it could certainly be that the replacement sender is shite like the first one.

Currently, my spark plug leads don't run near the alternator (they are on the top curve of the fan shroud), but they do pass near the lead to the crank sensor. I could try propping the spark plug leads up and out of the way...if this was the cause, I'd still be confused as to why the ECU datalog freezes up when this occurs (instead of logging the "jumpiness" in the crank position signal).

[Wally]

Yeah, well, electronics work in mysterious ways sometimes
Let us know if it made any difference.

[Stripped66]

Yeah, well, electronics work in mysterious ways sometimes
Let us know if it made any difference.

FWIW, I did rearrange the lead to the crank position sensor so that it is no longer near the alternator lead (and it was far enough away from the spark plug leads)...however, no change.

*But* I am thinking about buying another sensor just for the piece of mind of ruling this component out.

[TomiSe]

I had similar problems, when I pumped up the compression ratio from 10:1 to 12:1 and changed to E85 fuel. The engine just would not rev past 5000 rpm. I tried everything from new sensors, plugs, rewiring, foil wrapping the signal wires, no help. Finally I changed the ignition modules and the problem was sloved. I suspect they were damaged by heat, so I also made a bigger cooling plate for them. That's cheap and easy test, if nothing else helps.

[Stripped66]

I had similar problems, when I pumped up the compression ratio from 10:1 to 12:1 and changed to E85 fuel. The engine just would not rev past 5000 rpm. I tried everything from new sensors, plugs, rewiring, foil wrapping the signal wires, no help. Finally I changed the ignition modules and the problem was sloved. I suspect they were damaged by heat, so I also made a bigger cooling plate for them. That's cheap and easy test, if nothing else helps.

There is no ignition module with this Electromotive set-up, and coil failures are very uncommon.

I can get the engine to redline, I just can't do it at WOT

I won't be touching it for a few weeks...I've got to go back to Vegas for 2 weeks to jump through a few last academic hoops. Once I get back, I'll find some time to sort this all out.

[Unkl Ian]

Stripped' : If you were going to do another Oxyboxer,
knowing what you know now, what would you do ?

1.9 or 2.1 block ?
Larger stroke ?
Bigger bore ?

[Stripped66]

Stripped' : If you were going to do another Oxyboxer,
knowing what you know now, what would you do ?

1.9 or 2.1 block ?
Larger stroke ?
Bigger bore ?

Pauter big block

The first change I would seriously pursue would be 4" bore. I'd stick with the 2.1L block, but definitely increase the bore to 4+". I didn't consider this route from the start because I was using a set of 94mm Super Squish pistons, and because I didn't feel there was a streetable 4" head available at the time. With the JPM heads (albeit expensive) and DRD's new cylinder head, I would definitely increase the bore.

As far as stroke goes, I would not increase the stroke unless I could run a larger main bearing diameter. If I was limited to the 411 main bearing, my next oxyboxer might look like: 76mm stroke, 4" bore, lots and lots of boost (and more boost for good measure). I'd even consider modifying whatever heads I'd use for water-cooling, if keeping the engine streetable was a goal. I can't lay claim to any of these ideas, as other folks are working on similar builds...but I can agree that they are d@mn good ideas!!!

[Unkl Ian]

101.6 x 76 = 2465cc

Yes, streetable is my the goal, normally aspirated.

Jeff Denham runs some big NA motors 101.6 x 90 and larger.
Still not sure how 4"(101.6mm) barrels can stay round, in a Type 1 or 5,
when there isn't much room for fins or airflow between the cyl. Bore spacing is only 112mm IIRC.

Unfortunately, Nickies are not in the budget, and I'm not brave enough
to try the Chinese "Nicasil" Aluminum cylinders.

[Mr. Electric Wizard]

So, did you ever get the engine tuned to your satisfaction?
I'm curious to know how it's running?

[trapnm]

Any update on this build...I am on the cusp of starting my T4 build and have been contemplating an Oxyboxer build instead.

[Stripped66]

I've been working to convert the cooling system over to a 911-style shroud. It hasn't been without hiccups...

First, the features on the rear of the case are a little bit different than a Type 1:


That required modification to the mount for the fan housing:


I had planned to run my stock-style EFI endcastings backwards, but the inlets hit the shroud before they would seat. I needed to raise the manifolds up to allow them (and the intake "T") to clear the shroud:









Manifold mocked up with spacer:


Spacer next to shroud:


And the whole mess clearing the shroud:


Slowly getting there:




Relocating all of my oil lines:



New intake plumbing:




I need to replace 2 -AN hose ends that are leaking from the swivel seals before I start the engine. I still need to connect the throttle cable to the TB; haven't yet given that much thought.

[Stripped66]

Update:

With the Christmas/semester break, I found about a week and a half to work on the cooling shroud. Unfortunately, I've been suffering from bronchitis/asthma/allergy/something since Thanksgiving, and the persistent coughing led to a broken rib (snapped in half) , and possibly one more that is presently undiagnosed. This was a painful week.

Also, I'd like to thank local VW enthusiast and racer Scott Sain for providing me the garage space to do the work (as I have no garage). He's definitely one of the coolest folks I've met in the hobby, and is the personification of southern hospitality.

I had two major tasks to accomplish; one was adding the oil drain to the 3/4 head (I used to have this when the car was N/A, and had it welded up when I turbo'd it), the other was to continue development on my Bergmann shroud.

I had a chance to look at the wear patterns on my Pauter lifters. If some of you recall, a few summers ago during the changeover to forced induction, I was not happy with the wear I observed on the ISKY lifters I was originally running. These were a tall pushrod cup lifter; the pushrod cup actually stuck out of the case at full lift. The benefits were running a short pushrod, but we did not consider the increased pushrod angle would reflect enough force into the lifter to cause it to want to "lever" in the bore and cause a diagonal wear pattern. Again, this would probably be fine for a race-only engine that saw limited miles over the course of its short life, especially since the short pushrod would be advantageous; but for a street/daily-driven engine, this isn't what we wanted to see.

Rocky rebushed the lifter bores that summer and we opted to run the Pauter roller lifter. The pushrod cup is recessed into the body of the lifter, closer to the stock pushrod cup location. After 5000 miles on this new set-up, I'm much happier with the wear patterns. There is no more diagonal wear as observed with the ISKY's. The wear pattern on the Pauter lifter is isolated to just the top and bottom of the lifter, indicative of the shear load during both valve opening and valve closing. The wear is consistent across all 8 lifters, on both sides of the engine, suggesting that the oil supply to both banks of lifter bores are also consistent. I've posted a few pics below; excuse the graininess of my cell-phone camera, as I tried to capture the location of the wear patterns just behind the roller wheel on the top and bottom of each lifter (you can kind of see a "dull" patch on the lifter in the 2nd pic; this would be the wear pattern I'm describing). Overall, everything looks good, all roller wheels roll nice and tight, and valve clearances have be consistent over the past year and half. I expect the next 5000 miles will be as trouble-free as the last.







Now, on to the modifications to the Bergmann shroud. One issue I've found with the Bergmann shroud is it's poor fit, gaping holes around the cylinder heads (notably, behind the exhaust port fins). To address this, I made simple deflectors that attached to the heads and interfaced with the inside of the shroud.







The goal was to prevent air from flowing past the cooling fins and simply out of the gaps in the shroud. The deflectors were mounted to the outside of the exhaust port fins, closing a major gap in shroud, and to the head to direct airflow down onto and in between the fins. This is not the most elegant solution, short of reglassing the shroud, but relatively easy.

Another criticism is the lack of airflow around the underside of the cylinders and heads. Several other folks have suggested solutions to aid the control of airflow,

sumtihg worth considering (no im no guru)

i always had at the back of my head,
911 style fan and shroud, you could try the super cool tins

mod it like sum1 did here in the forums to have the center part form like a pyramid/deflector for the air to move to the front and rear cylinders

should it help? datalogging would judge that,

but from my newbie mind.. it seems ideal seeing that this would make the exit of the air only below each of the 4 cylinders?

As for bergman's shroud, lemme make an illustration real quick.

ok, see how the airflow is forced into the fins and goes all the way around each cylinder? That's how most aircooled engines are. Does Bernies shroud do that? doesen't look like it

And, of course, if you evaluate the Klaus 911-shroud, controlling airflow around the undersides of the cylinders and heads is one of the unique features that sets their shrouds apart from the rest:




The stock cooling tin, in its complete form, controls airflow down the sides and around the underside of the cylinders and heads. The Bergmann shroud does not; it just dumps air on top and down the sides of the cylinders and heads with no mechanism to direct airflow to the fins underneath, and no mechanism to control plenum pressure. Air isn't simply going to loiter around the underside of the cylinders and heads and cool off like goth kids at the mall.

So, after initially dismissing Ralf's suggestion, I decided to buy a set of Type 3 "cool tins". I should have stuck to my guns because that was a mistake and a waste of money (sorry Ralf); the Type 3 tins simply require too much modification to fit my engine case and interfere with my pushrod tubes. On a type 1 case with standard diameter pushrod tubes, this might be an option. Oh well, lesson learned (again).

So, with a large sheet of aluminum, snips, and some safety wire, I constructed some tin of my own:

fitting the tin around the cylinders:


The tin divides the airflow down the middle. Holes are cut into the underside to provide an exit for the cooling air. If this restricts airflow too much, I can always snip away at the underside to open it up:


And fit into place:




I also extended the tin along the side of the head fins and wrapping around the underside. These fit sung alongisde the head when the shroud is placed on the engine. Hopefully this will direct air across the underside of the head:





After reinstalling the Bergmann shroud with these new tins, I removed the original diverters that I previously installed. I want to start with a new baseline as these new tins and deflectors are going to affect the pressure in the shroud, and likely the air distribution as well. I have only driven the car about 20 minutes since finishing these mods (returning home from Scott's house yesterday). Right off the bat, I noticed that the 1/2 cylinder bank was running warmer than before and the 3/4 cylinder bank was running cooler. This was to be expected; given a fixed supply of air, cooling down one side will result in the other side warming up. Cylinder #3 was the hottest cylinder :-k, but I think the reason for this is that the #3 injector is pissing fuel and running that cylinder rich (this was evident from the top-end tear down). Cylinder #4, which usually is the hottest, was running about 10 degrees warmer than cylinders 1 and 2 around 45 mph or less, and about 15-20 degrees warmer than 1/2 at 65 mph. Cylinder 1 and 2 were within 5 degrees of each other. So far, this appears to be a much better baseline to work with when I go back in to reinstall diverters inside the shroud.

These are just preliminary observations from very little driving, but the results are promising. I need to replace the #3 injector (or just get a new set from RC Engineering...these Siemens injectors are not too impressive) before I do any further development because the #3 CHT is simply not indicative of the tune of the cooling shroud. Once that is fixed, I'll begin concentrating on equalizing air flow between the two cylinder banks.