86 Stroke Engine Recomendations

[Dougy Dee]

I'm currently accumulating parts for a customers 94x86 stroke engine. Aluminum case arrives tomorrow...

Looking at using A&A slipper skirt with the longer cylinders from Aircooled.net. P/N VW9400-17T1SLF

Also a Bugpack 86 stroke 4340 crank with Chevy journals.

I have a set of 5.4 Carillo Chevy journal rods with 5/16 ARP bolts but I think a longer rod, 5.7, would be better. I have no width restrictions as this is going in to a 'Baja' style street car.

I was hoping for some rod length and bolt size recommendations. In other words "What would saner heads do here?"

The customer has mentioned that he has a DLI Supercharger that he wants to use on this engine. Yes. I have tried talking him out of it!
Have any of you ran the DLI setup that could give some insight in to what I am getting in to?
Input or thoughts on ignition, compression and cooling would also be appreciated.

One of the locals had the DLI setup on his Manx style buggy but it scared him too much to drive it. It sucks to get old....

[Zach Gomulka]

Width "restrictions" should still be a concern if you want the tins to fit easily and correctly (also think about longer head studs, pushrods tubes, etc). An 86mm crank with a 5.4 rod is mathematically feasible when considering piston skirt to crank clearance at BDC, but the rod ratio is a very low 1.59:1. It would however end up only (roughly) .163" per side wider than a stock 1600. 5.7" rods will give you a safer 1.68:1 rod ratio, but will of course make the engine and additional .300" wider per side, total of about .463" per side. KROC uses a piston with a .945" pin height, allowing an 86mm with 5.7 rod to be only .028" wider than stock

[Dougy Dee]

Is that a 94C piston or some custom configuration?

[richie]

Dougy

what are you planning on using for heads? and cam

I have a 86 stroke with 5.6 rods and b pistons engine and tin fits pretty good, I built it that way as I had the rods already[pauters] but would normally go with a 5.7 rod

If you want to use the carillos then why not do a smaller stroke? if it has the DLI set up added it will make plenty of torque so the lack of stroke would be noticed

cheers Richie   

[Dougy Dee]

We're still discussing heads and cam.

Customer is bringing some heads by tomorrow. CB Street Eliminators were mentioned as were a set of BERG 42x37 or so.

FK10 cam. As I recall, could be wrong...., he has Street Eliminator heads and FK10 in his street car...

[spanners]

5/16" rod bolts with 86 stroke would normally need a Rev limit, 3/8 bolts are almost a must on the end of such a long arm, given that the idea is to gun the tits of it, you may get away with them tho in your planned ride which won't won't a full on build,  Richie has a good point on a smaller stroke build, it solves many issues and would be easyer on the rod bolts, and as its Going in a Baha bug, it will be fairly light and won't need a race spec build with big cam, valves and ports killing any low and mid range, assuming it will have Baha rear tyre height, final drive,  R&P and its top gear ratio set up will govern Much of the top end build, Bahas also normally need a 3" engine lift, will a super charger go in still atop the motor?  personly, I think they are a waste of space and belong in the 50's, but that's just me proffering turbos, far to much parasitic loss with them, and with such a big motor, you won't be short of torque anyway, in a Baha, it will be enough to get seriously into trouble even minus blower,
The Street elims mentioned in my view won't be fun in a Baha, to much port area, but 42mm intakes were mentioned on berg heads, now that is a good move, you need gas speed for throttle response, only about a 5/8" exhaust primary for the same reason, An FK 10? Hmmm, about we'd 86c then,  it's a big cam for what the car needs to do, it MIGHT just work, they are run off road often enough, you could soften it of with 1.25 or 1.3 rockers, so much to plan and scheme

[Dougy Dee]

I've been advised it's an FK8 cam. Modest compression, 8-8.5:1 or less.
Stock geared 091 trans. Tallish tires. Planning on Pauter rockers.

Heads are still up in the air. He brought an old school set of 040's welded with 44x37 valves.
He thought they were Berg heads but no machining or stamping with GBE anywhere on them....
Some issues need to be addressed with them.
At one time they were triple springs with the guide bosses seriously trimmed back.
They had duals when I stripped them down and featured a broken spring that has caused problems with a spring seat that will need TIG repair.
I know spring bosses can be had to repair but was wondering whether they need to be welded in or whether the press fit on the guide will be adequate.
I have a set of steel bosses that I had machined to repair a different set of heads. I was planning on relying on the press of the guide to hold the replacement boss in place.
Thanx for the feedback so far...

[Jonny Grigg]

5/16" rod bolts with 86 stroke would normally need a Rev limit, 3/8 bolts are almost a must on the end of such a long arm, given that the idea is to gun the tits of it, you may get away with them tho in your planned ride which won't won't a full on build

What kind of rev limit? I have seen over 8500 on my 88mm stroke motor using 5.7" rods and 5/16" ARP 2000 bolts. The import boys take these over 10-11k using equally long stroke motors. My motor us still making good power at 8000.....

Using 3/8" would be nice but you kinda run out of space with and 86 or larger crank, unless you want huge notches in the cam- which in my mind isn't too great with 450+lb of pressure on the nose at full lift.

Just passing in my experience, not just opinion.....

Cheers,

Jonny.

[spanners]

Wow, thats some revs on a long arm For 5/16 bolts, but if you KNOW you have gen'  ARP bolts, that's some piece of mind at least, given all the copy cat rumours,   and yes, 3/8 sized cam notching can look alarmingly drastic, without a cam drop case,  if your 5/16 bolts do as you say, then I've learned something, As for the imports revs, I'm staggered and have to bough to the achievement, it must require plenty of TI And top quality crank and rod combo's, helps being OHC also of course.
no doubt I have got used to circuit racing hours logs  were we are WOT for longer periods, I like to replace 5/16 bolts after 12 hours, I've seen a dead case after just 2 seasons, or about 15 hours of 8,000 rpm, down changes load everything, most blow ups happen with the unload phase.. Best regards Spanner.