Bus stroker motor advice based on parts accumulated: 94x?

[travelvw]

I'm building my first stroker motor based around parts I've already accumulated for an all around bus motor: power as needed, "economy", longevity, reliability, and ease of assembly. All parts are new. This is not a bug drag race motor. I will be driving in everything from harsh off-road conditions to long road trips; winter thru summer, with a heavy load. The transmission is super beefed, so no worries there (4th gear@65=3370rpm). I prefer to limit expense based on what I already have, but I also don't want to necessarily limit the build because of it.

*DRD 40x35.5 dual spring heads cut 94mm
*CB solid shaft rockers w/swivel, stock ratio
*AA 94mm cylinders
*aluminum case NOT clearanced, cut 94mm, full flow
*aluminum case NOT clearanced OR cut, full flow
*CB forged flywheel 8 pin and 4340 nut (Kennedy stage 1?)
*high flow j-tubes (I'm not running boxes)
*I do happen to have a set of 4340 forged 5.4" I-Beam rods with ARP Bolts, and a Scat C35 cam, lightweight lifters... probably irrelevant for this build and my experience with Scat stuff is its a marginal step up from Empi junk.

I would like to run cheap gas (87) and mild compression (8:1-ish). I have no crank, cam, rods or carb size chosen as of yet. If AA made thick-wall 92 B's, I'd be all over that! I will be running a single CB Weber IDF center mount for simplicity and reliability. I will not be convinced on dual carbs; I've tried it both ways, so I'm not interested in that argument . I could use the advice elsewhere in the build.

I've personally never been happy with Engle cams (100 or 110) on smaller engines. I have been most happy with the CB Eagle 2280 (valve lift 391, duration @ 0.50": 224) on a 1776 with 044 heads and a single weber 40. I know very little about cams, but I do know they can make or break an engine. I certainly don't want any lump-lump idle (this might be an issue with too much cam and not enough engine?). I'm looking for a low to mid range power band.

As for cooling, I am considering a Raby type 1 DTM, but will probably go with a thing shroud and type 4 cooler. Thanks in advance,

K

[luckystiff]

AA DOES make thickwall 92Bs. i have them in my 2021 in my squareback....
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[travelvw]

[modok]

since you will use a single carb, stay below 240degrees duration at .050 lift.
the 2280 is ok but with a stroker you will want a bit more cam so it isn't all kneckjerk at low rpms and weak past 3500 rpm.

yeah, AA has 92 B pistons, they are slipper skirt
most will say 1 3/8 exhaust is too small, I say it is too small if your using a stock arrangement header. So 1 3/8 j-tubes just isn't gonna be optimal either way

[mark tucker]

thick wall 92's and 82 stroke,.040" deck(piston to head clearance) low lift cam around [email protected] & 1.25 ~1.33 ratio rockers. add the extra oil galy&slot the lifter bores.deburr the lobe edges.

[travelvw]

I don't plan on needing much power past 3500 rpm... probably won't even rev past 4k.

The j's I have look to measure about 1 3/8". Haven't chose the header/muffler yet. Sounds like I'm going to have to move up in size . I don't need anything fancy, as I'll have to customize for clearance and will probably beat it on rocks anyhow.

It looks like 82mm is the "easy" B piston builld... I originally thought it was 78mm.

92mm thick B's are preferred if it fits my heads. I'm guessing they are 90.5mm case, 94mm head?

Thanks for the cam duration advice. Why ratio rockers? I thought they directly relate to the cam and lift and were a "patch" instead of changing out the cam?

K

[[email protected]]

http://vwparts.aircooled.net/Piston-Cylinder-Set-92mm-x-82mm-Machine-In-p/vw9200t1s.htm

are 94mm head, and 90.5/92mm case

while

http://vwparts.aircooled.net/Piston-Cylinder-Set-92mm-x-82mm-Machine-In-p/vw9200t1ms.htm

fit a 94mm Case and head machining bore.
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[mark tucker]

I built a motor for a guys SC ,it tends to see some rpm. as does his bus. do not cut your self off at the knees, it's not any cheeper but it can be disastorious.remember your foot governs the motor.use what you need when you need it. if you need it and dont have it,better hope that big truck has real good brakes&a light load, cause he's fixen to squash the crap out of you.......or pull away from him like he is in reverse.the choice is yours. build it right & it will last.

[travelvw]

Thank you John, I will grab a set of thick 92 B's from you (94x94 cut), and an 82 stroke crank: 2180 it is! Perfect. I'm guessing this takes stock length rods 5.4" for a mild compression motor?...will the 4340 Scat I-beam set I have be a good choice? Does 8:1 compression sound about right to everyone for running cheap gas? My last few engine builds have been 7.8- 8.2:1, and they ran fine on 87. That said, the engine size was much smaller. I don't want to be creating excessive heat.

Any more info on cam choice... particularly valve lift?... what numbers qualify as "low lift", and how does that effect things?

Mark, unlike most folks, I don't need the power band up high. I want it to kick in right away and fade out by 4k or so. I do very limited interstate driving, especially in traffic. Again, not looking to limit myself, but put the power band in the right place for me: very low range to mid-high at most.

K

[luckystiff]

like the guy in the other thread about cam choice don't limit that stroker based on gas thats $0.20 cheaper per gallon. as i said in that thread you're talking $2-3 more per fill up for the ability to bump that cr in the 9:1+ range and use that engine like it can be. i know theres plenty of folks that have and do build low cr strokers. to each their own. theres also guy that build small HIGH compression engines putting out buttloads of power.

the scat c35 is pretty similar is specs to a engle 110. if the objective is to use as much of what you have it may fit into that low cr build range you are talking.

is the case stroker clearanced? if not you'll probably either want to send it to someone to be done so or i've heard several say that 82mm with buick journals and a nice set of H beams puts you in the by hand at home clearance range. cheaper to send the case out for stroker clearancing though...ken....
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[[email protected]]

SCAT rods are outstanding, all the "no-name" rods try to achieve SCAT's level of quality, and rarely do. They are an excellent choice, for another $20 over the generic versions.

5.4" is the proper length for an 82mm crank and B pistons. You will NOT have a loss of low end with a "big" cam because of the stroke increase. One counters the other.

I'd go with dual 2bbls and an Engle 120, and 9:1 CR. Will run very well.
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[travelvw]

Ok, sounds like I've already got my rods. Great!

That's kinda what I was thinking about cam choice: what appears "bad" on a small engine, may work great on a larger engine... something I am not familiar with. That said, a 120 looks to be a little on the mid-to high, even in a big engine... also not really what I'm looking for. Might work better with dual carbs, but I'm running a single Weber IDF... so, what size? 44, 48? I am not running duals, even if everyone else in the world would .

C35 was a typo... I actually have the C45, which is not at all where I want to be on this build.

I will consider upping the CR. Curious as to what a typical ratio is with 82 and B's on a new case, no flycut?

I will likely have the case clearanced locally for an 82mm crank. Thanks,

K

[[email protected]]

With a single IDF do not go bigger than 286 adv duration, which is the Engle W110, or SCAT C35. You need a venturi in the 32-34mm range. The 40 IDF comes with a 28, and the 44 comes with a 36. So in either case you need to make a carb change to optimize everything.
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It's just advice, do whatever you want with it!

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[travelvw]

Thanks again, great info. I will probably go with a single 44 and drop the venturi.

These are the specs on the cam I was most happy with:
Adv. Duration 274°
Dur. @ .050" 222°
Lift @ cam .359"
Lift w/1.1:1 Rocker Arms .394"

K

[luckystiff]

[jfats808]

[luckystiff]

they do also offer chevy/buick journal'd but i think only in maybe 5.5, 5.6 or something like that. so yeah all longer choices.

oddly enough i ended up digging those up because CB was out of the unitechs when i was ordering parts. after dealing with them i wish i would have known that before i bought my crank from CB as i probably would have ordered my crank from them also. great folks to deal with, nice products for a reasonable price, and fast shipping. i ordered my rods on a friday and they were here the following monday....ken....
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[sactojesse]

[travelvw]

[stingah2]

Kevin, if there's one thing about you it's that you are not normal. Normal is boring. I have run duals on everything for 20 years but for what you do I really can see and appreciate that a single is a great choice. I personally like your abnormal build
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