Need inputs on my 2789 Oxy project

[Der_Butzelmann]

Hi guys.

I need some input on my 2789 Oxy project. The main things I need help with, is deciding how big the valves with matched ports will need to be in the heads I allready have, or suggestions for other type of heads for this engine. Both the 48X40 CE`s and the 50X40 910`s were found too big and then way too big for my intentions by "the pro`s".

The rest of the list has more or less been decided and purchased, but inputs on the rest is also of great interest.

This engine will stay NA, and will be used in my fiberglass buggy, for track and some strip, and will probably not see any street at all.

The thoughts with the engine is to have a ( stupid ) big engine, that will not be on its peak when it comes to power output, for a longer lasting engine life.

The more bottom-end power there is, the better it is also, since the local track is "short", with hard turns. I have been told by several engine builders that the cam I have chosen will work fine, especially since the engine is this big. Smaller heads, carbs and exhaust then a typical race setup will make more of the wanted power range, I think.

Tell me what you guys think about this set up:



2789 OXYBOXER FOR MY BUGGY


CASE: WBX 2,1 DJ, Modified for aircooling, cam lubing mod, maby shuffle pinning also

HEAD STUDS: 8mm molys with std. T1 case savers, or 10mm molys with time-serts, both for a ”bolt on” combo

HEADS: Sauer Aircooled “T1 looking” twin spark heads, 40X35 with wbx stud spacing ( needs work! How big valves ?)

CRANK: T1 Type, Scat Pro Comp, Super Lite, Knife Edge, T4 Mains, Porsche Journals, Wedgemated

FLYWHEEL: 200mm Wedgemated

CLUTCH: Not sure, but probably Kennedy Stage 2/3 and a good disc ( which one ? )

CYLINDERS: 101,6mm with cooling fins

PISTONS: Speed Pro ( Chevy type ) Coated Hypereutectic Noched Flat Tops. Measure 35mm from the bolt centre and up

RODS: Porsche 912, slightly clearenced, weight matched

CAM: Engle FK-89

ROCKERS: 1,4:1 With needle bearings

LIFTERS: T1 type Scat Lube-a-lobes in Rocky`s bushings

PUSH RODS: Moly(?) ”cut to lenght” type. ( Bugpacks? )

STATIC COMP. ESTIMATED: About 10-12:1 or higher

INLETS: Modified Type 3, short ones ( CB ? )

CARBS: HPMX 44 with Pipercross foam filters and homemade linkage ( yes, they are a bit small )

FUEL: 98 Octane pump gas / E-85 or Methanol , did`nt really decide that yet, but Methanol would be best I think

TRANNY: 4 Speed 091/1 ( sideshift, not midshift ) modified to frontshift, and maby with a limited slip diff

SHIFTER: Gene Berg

EXHAUST: Merged Collector ( cant remember how big it is. 1,3/4” / 1,1/2” ?? with a ”full flow” carbon silencer from a motorcycle

IGNITION: WBX or the 009 copy with the ignitor

[Stripped66]

You plan to run really small heads with a really large engine and a really large cam...that's not a good combination. Either get larger heads to work with that cam (like the CE's those "pro's" told you were too large), or get a smaller cam to work with those heads.

The duration of the camshaft determines the RPM range of the powerband...it doesn't care how large the engine is. The idea that "large displacement engines like larger cams" is only because the increased displacement contributes torque to the lower-rpm range where a large-duration cam loses torque. You're building a race engine that should have lots of low-RPM torque, but you're running a cam that takes that torque away. Whoever recommended this to you should be kicked in the shins. Run a FK-7 or FK-8...ultimately, your heads are going to limit your redline, so why choose a cam that's making most of its power after your redline? The FK89 will only take away the torque and power you could be making at low RPMs...

Ditch the 912 rods. They are a weak design, and eventhough you plan to keep the RPMs much lower than their "limit" on a Type 1 engine, you are hanging huge, heavy pistons onto them. Get a strong H-beam with 3/8" ARP2000 hardware.

The 44 HPMX's, despite being a low-quality carb, are probably capable of delivering the airflow to your small cylinder heads. If you run larger valves with larger ports, you'll probably need larger carbs. As far as running E-85 or Methanol, I don't know if the 44's are capable of delivering the VOLUME of FUEL necessary, which is substantially more than gasoline. You better research this one before settling on a CR to match your fuel...in case you find out that your carbs can't deliver enough fuel.

[Der_Butzelmann]

Thank you very much for your reply!

Well, this project list has been changed about 30 times before the project even got started on, and the parts list now is a result of that process, and yes, I got lost somewhere in the middle

I know that a "wild" cam does`nt go well together with small heads, and also not with small carbs on top of that.

The fact that big volume engines are more "forgiving" about the wilder cam because of it`s natural greater low rpm tourque, or that they feel like that anyway, made me hope that there could be a chance this might work out, if the Sauer heads got larger valves in them, and a port`n polish for better flow. The 44 carbs are just what I have for the time being, but some 48 IDF`s or IDA`s are on the wish list, but the engine could probably have been "ran in" with these.

I found out earlier with a quick calculation that the 44`s would limit the max rpm`s at about 4500-5000 rpm`s. So, with a more suitable cam ( Fk 7 / 8 ? ), I could get away with these carbs and the then slightly modified Sauer heads, and hoping for how many hp`s and tourque, roughfly?

Then compared to bigger and better heads, like the CE`s I used to have, ( traded those for the Scat crank ) together with the FK 89 ( or another cam you think? ), and some 48`s at the top?

The answer to this question, that would actually tell the differents in engine performance all together ( roughfly ), will probably be the answer that will make me decide on what to do next.

Maximum hp is not what I want. A very driveable engine with an even more useful powerband from the basement and up is more the thing I seek.

About the 912 rods, you say that they are a weak design. Could you please tell me more about that?

From what I have heard and read, and then based my knowledge on, these rods are very strong and also very popular, in Europe anyway, for use in high performance vw engines during many years.

The fact that the pistons I have chosen are not the lightest ones ( they are going to be a bit lighter soon though ), I had a very simple thought that might be wrong: Since this engine would hopefully not need to see 8-10.000 rpm`s, but about 5-6.000, the rods would still be strong enough an even more than that. (?)

If you know for a fact that these rods are weak or such, please tell me more about it. I would hate to loose a rod or two, even at low rpm`s

[Stripped66]

I found out earlier with a quick calculation that the 44`s would limit the max rpm`s at about 4500-5000 rpm`s. So, with a more suitable cam ( Fk 7 / 8 ? ), I could get away with these carbs and the then slightly modified Sauer heads, and hoping for how many hp`s and tourque, roughfly?

I couldn't estimate the HP and torque without an idea how those heads flow. If 5000 RPM is about what you'll be limited to, then try the FK7...it will certainly give you more torque within your powerband. My friend has that cam in his 2332 and the low-end torque off idle is very impressive.

About the 912 rods, you say that they are a weak design. Could you please tell me more about that?

If these are the '616' rods common to the 356/912, they have the rod bolts integral with the cap. The cap and the rod bolts are what's responsible for pulling those big heavy pistons around...you should run the strongest bolts you can find and that may require you step up to a modern rod and ARP hardware.

From what I have heard and read, and then based my knowledge on, these rods are very strong and also very popular, in Europe anyway, for use in high performance vw engines during many years.

They used to be popular a few decades ago in the US...rods splitting down the beam and bolt failures eventually turned folks towards different rod options.

If you know for a fact that these rods are weak or such, please tell me more about it. I would hate to loose a rod or two, even at low rpm`s

There's a nice pic of a split 912 rod in Keith Seume's "Aircooled Interchange Manual." Go to page 27 on this online book:
http://books.google.com/books?id=NPJVPI ... o#PPA27,M1
The rod bolts are not replaceable, so you you are putting a lot of faith into an old USED part...that's enough for me to never consider them as an option on an engine that I want to last a long time.

[Der_Butzelmann]

Hmmmm...
I`ve got that book myself actually, but did`nt remember that the picture of that broken rod you are refering to here actually was the 912 rod. It looks like the exact same type that I have too. DOUH!

Well, after a quick look on the net, there are not many H- Beams with Porsche journals to choose from. Carillo`s is more or less out of my budget league, so it would have to be something like this:

http://www.thesamba.com/vw/classifieds/ ... ?id=535990

But they are "no names". I e-mailed the seller earlier about info on who made them, since all the names of the companys listed that did`nt make them does`nt really help much, but I never got any reply. That was the reason why I purchased the "very popular" 912 rods I now have when they popped up for sale in my neck of the woods.

So, to put no-named H-Beam rods in my engine instead of the spookey 912 rods would`nt really make so much more sence to me, so I guess that option is out of the window. If nobody else could tell me that these exact rods have been used and tested, and found to be ok that is.

Good suggestions for good quality ( not super race super priced )
H-Beams for Porsche journals are of great interest these days

I have no idea what the Sauer heads flow, but would guess about in the neighbourhood of what a slightly ported 2,1 wbx head would do, if that would be of any help for guessing HP numbers?

The CNC CE`s flow chart could be found here:

http://www.cbperformance.com/cnc/

FK-89 cam charts can be found here:

http://www.vwspeedshop.com/store/pages.php?pageid=3

Anybody wanna guess HP`s, tourque and/or "engine behaviour" with this combo of heads and cam plus some 48`s with 98 pump gas on my 101,6 X 86 Oxy?

HP migt be the "easiest" to guess if you compare the setup with similar ones that are dyno`d I would like to think.

150hp ? 200hp? 250hp? 250+???

[Stripped66]

It didn't occur to me that you're running 86mm of stroke. The rod ratio with those Porsche rods on an 86mm stroke is insane...about 1.57, IIRC.

Those 5.5" rods will make the rod ratio better...they are Chinese-made just like most of the other H-beams on the market. If they spec out, they *may* be as good as the CB Performance H-beams...but of course, they may not. While a low rod ratio may tailor to your RPM range just fine, I could not recommend the weak cap/bolts of those Porsche rods to be capable of handling the forces they'll see just after TDC on the intake stroke. If you're dead-set on them, by all means, run 'em.

Small heads, no flow numbers...150 HP with an FK7, more torque than you'll know what to deal with for a lightweight buggy on a road course.

[Der_Butzelmann]

It didn't occur to me that you're running 86mm of stroke. The rod ratio with those Porsche rods on an 86mm stroke is insane...about 1.57, IIRC.

Those 5.5" rods will make the rod ratio better...they are Chinese-made just like most of the other H-beams on the market. If they spec out, they *may* be as good as the CB Performance H-beams...but of course, they may not. While a low rod ratio may tailor to your RPM range just fine, I could not recommend the weak cap/bolts of those Porsche rods to be capable of handling the forces they'll see just after TDC on the intake stroke. If you're dead-set on them, by all means, run 'em.

Small heads, no flow numbers...150 HP with an FK7, more torque than you'll know what to deal with for a lightweight buggy on a road course.

"Train torque" and about 150 hp in a buggy could be alot of fun on the track I guess
But what do you think about the alternative setup I mentioned above, with CE`s , FK-89 and some 48`s?

At least the ARP bolts in the Chinese rods would be stronger then the used Porsche ones. I wonder if there is enough meat in the small end for putting in the chevy bolts in these rods. ( thats a good thing about the 912`s. lots of meat for bigger than 22mm bolts)
Only one way to find out I guess.

Thanks for the inputs by the way.

[Stripped66]

But what do you think about the alternative setup I mentioned above, with CE`s , FK-89 and some 48`s?

If it were me, I'd ditch the small heads and run that combo. You've got the displacement...let it BREATHE and make some power.

[Der_Butzelmann]

But what do you think about the alternative setup I mentioned above, with CE`s , FK-89 and some 48`s?

If it were me, I'd ditch the small heads and run that combo. You've got the displacement...let it BREATHE and make some power.

Ok. Looks like I`ll put the Sauer heads on the shelf for the smaller 2,4 street oxy for one of my bugs, and go for bigger heads for this current oxy.

Just two more things. What is your guess in HP with the "breathing combo"?

And, what are your thoughts about the Auto-Craft 910 40X50 heads? Would they be way too big for this engine together with the FK-89 and 48 IDF / IDA`s?

[Stripped66]

It all depends on the level of port work in the heads. Off the shelf CNC'd Comp Eliminators may be good for 250-270 HP. Some folks suggest the 48 IDAs can only flow enough air to support about 225-230 HP before you need to bore them out. On a set of Autocraft heads, with some good port work, I'd be afraid that 1) the 48's would eventually choke the combo, and 2) the Autocraft heads may not have the cooling capacity for road-racing, especially over extended periods of time. CE's may be borderline, too.

What type of racing? Short circuit, solo time-trials? CE's may work...but finding a set with the Wasser stud pattern might be a chore.

[Der_Butzelmann]

It all depends on the level of port work in the heads. Off the shelf CNC'd Comp Eliminators may be good for 250-270 HP. Some folks suggest the 48 IDAs can only flow enough air to support about 225-230 HP before you need to bore them out. On a set of Autocraft heads, with some good port work, I'd be afraid that 1) the 48's would eventually choke the combo, and 2) the Autocraft heads may not have the cooling capacity for road-racing, especially over extended periods of time. CE's may be borderline, too.

What type of racing? Short circuit, solo time-trials? CE's may work...but finding a set with the Wasser stud pattern might be a chore.

Maby injection with some massive throttle bodies would be better in this case, if 48`s might be to restrictive, if I would decide to go for the AC heads.

Yes, the type of racing I am aiming for is mainly short circuit solo time-trials and similar, and the local track is actually a go-kart / karting track where there are some "just for fun" track days for street legal cars.

CB do not sell the "magic" CE`s with blank stud holes anymore ( I tried many times ), but welding them up and re-bore for wbx pattern has been done successfully by other guys, so I would go for that in that case.

Big heads, big carbs/throttle bodies and the FK-89 would more or less make the engine a "screamer", and not a low end tourque monster that I would like the most.

I think I need to put on my thinking cap, again

[Stripped66]

I think I need to put on my thinking cap, again

Ultimately, that's what you've got to do.

You can't start with a huge engine, tiny heads, and a huge cam and expect it to deliver power in an RPM range the cam wasn't designed for.

Figure out how much power you want out of this combo and get the heads to match; then choose the cam that delivers that powerband over the RPM range that the heads are capable of flowing.

If you're going to limit yourself to those small heads, you need a cam with much less duration. If you're going to run very large heads like CNC'd CEs or 910's, then you'll need more duration.

[Der_Butzelmann]

I think I need to put on my thinking cap, again

Ultimately, that's what you've got to do.

You can't start with a huge engine, tiny heads, and a huge cam and expect it to deliver power in an RPM range the cam wasn't designed for.

Figure out how much power you want out of this combo and get the heads to match; then choose the cam that delivers that powerband over the RPM range that the heads are capable of flowing.

If you're going to limit yourself to those small heads, you need a cam with much less duration. If you're going to run very large heads like CNC'd CEs or 910's, then you'll need more duration.

Well, I had my thinking cap on for a few hours, and now think I will go for CE`s with about 46X38 valves. About the Sauer heads, they are very small as they are, I agree about that, but my hopes and questions was to get them big ( how big ) enought for this engine, but it will be too much work and too expensive to get them big enough.

Another question is which deck hight to go for. The pistons weigh 712grams now ( will be a bit lighter soon ) complete with rings, bolt and circlips. Just the piston alone with only the bolt weigh 566 grams, which are the same as a complete Cima/Mahle 94B. So that can`t be sooo bad, considering the 101.6 pistons are alot bigger, and "only weigh a set of rings" more than the 94`s.

So, which deck hight would be safe for this combo? What does other 4" oxy guys run?

[Stripped66]

Well, I had my thinking cap on for a few hours, and now think I will go for CE`s with about 46X38 valves. About the Sauer heads, they are very small as they are, I agree about that, but my hopes and questions was to get them big ( how big ) enought for this engine, but it will be too much work and too expensive to get them big enough.

Pat Downs recently posted (on the Cal-Look forum) that CB Performance has CE's that have not been drilled for the head-stud pattern. These would probably be ideal to run the WBX stud pattern needed for 4" bore, rather than welding up a std. head and redrilling the stud pattern.

[Der_Butzelmann]

Well, I had my thinking cap on for a few hours, and now think I will go for CE`s with about 46X38 valves. About the Sauer heads, they are very small as they are, I agree about that, but my hopes and questions was to get them big ( how big ) enought for this engine, but it will be too much work and too expensive to get them big enough.

Pat Downs recently posted (on the Cal-Look forum) that CB Performance has CE's that have not been drilled for the head-stud pattern. These would probably be ideal to run the WBX stud pattern needed for 4" bore, rather than welding up a std. head and redrilling the stud pattern.

I tried CB several times, ( in a period over three years or so ) but they don`t sell them like that they always answer me. I guess I don`t know the right people to get hold of them? Or did they start selling them like this recently, after myself and many others around the world begging them to do so?

I now know of someone that have been able to get hold of these much-spoken-of-but-never-seen CE "blanks" heads, so it seems like it will work out after all, I hope.