Alfred's Holy Grail - Low RPM High Torque RV8

[4Runner]

No turbos on this one; but I am very much looking at a screw or a roots. I understand how boost works... There is very little exploration in that. The stroke and other elements are very interesting to me; yeah, a billet crank is not in the cards; I will be saying this a million friggin times: this is to explore the extents of the what is possible, or at least semi-rationally plausible.

I will likely end up with a 4.6 crank and an M122 (or hopefully a screw blower), along with a home built (very long runner) custom intake and custom headers. (I know how to tig weld... my Dads' got an awesome set of tools!)

Not sure you need the long intake runners when you have a pressurized intake charge. Also Whipple or Ken Bell superchargers are more efficient at lower rpm’s. That’s my thoughts on the matter.

 

[p m]

I will be saying this a million friggin times: this is to explore the extents of the what is possible, or at least semi-rationally plausible.

That reminds me a bit of this -

Please don't jump in with a bunch of second hand opinions, I'm looking for actual first hand experience.

 

[DiscoClay]

Yeah...well... At this point; rational, experiential guesswork is welcomed ;-P

I am working on a new gig but I need to get this 4.0 disassembled so that I can make my own measurements. I am digging to see if I can make a SBB350 crank clear the cam and block. I can mod the pan and notch the sleeves (SBB350 = 3.85" / 97.79mm). I may need to call D&D but I didn't get happy vibes from him (he's prol done with tire kicking callers .

Has anyone explored doing sleeves larger than 96mm?

 

[DiscoClay]

Not sure you need the long intake runners when you have a pressurized intake charge. Also Whipple or Ken Bell superchargers are more efficient at lower rpm’s. That’s my thoughts on the matter.

Boost does nothing to the runner length equation Long runner = low rpm / short runner = high rpm. Same with headers, btw. If you want to shift power lower, use long runners and long primaries. Richard Holdener has some great dyno runs and discussions on his channel about this. Also, Dave Vizzard has a really good unequal long primaries header video (with the calcs) that shows how to balance the pressure pulses for (typical) American V8 firing orders. TLDR:a couple primaries remain the same, some are slightly longer and some are slightly shorter.

While Richard has a TONNE of vids about the boost/manifold stuff. This is not the main one I am thinking of, but he talks about it right here:

 

[DiscoClay]

Buick Wildcat (300 and 340) specs, for the mildly curious:
credit to the teambuick boys: https://www.teambuick.com/reference/300-340_engine_specs.php

 

[DiscoClay]

I should drop some 4/4.6 specs in here.

The 3.5/3.9/4/4.6 deck height is 8.960" (your results may vary). This being only 0.060" (60 thou) shorter than sbc means small block chevy rods are a real option. Also, custom (low compression height) pistons can be made from SBC forgings for (not cheap but not batshitcraycray) prices.

The deck heights:
Rover V8: 8.960" (227.58mm)
SBB 300: 9.543" (242.39mm)
SBB 340: 10.187" (258.75mm)
SBB 350: 10.187" (258.75mm)

So.. this is why I am thinking "if I can make the crank throws clear the block & cam, then mod the pan...and make deck spacers (~1.00"/25.4mm or more) and bore for 96.52mm extended sleeves... That gives 350 cubes / 5.7L of under-square displacement. With a very mild cam (VERY necessary in this application) and tack on about 3psi of boost above ~1800rpm and p00f [shift gently] you've got about 400ftlb of torque in the ~2800rpm range (~200lb-ft@ ~1400rpm)

So.. IF all that worked (lots of ifs) then a fairly short rod ratio is going to be best for low RPM torque. This means a 1.25-inch deck spacer would be handy (consider a sbb350, with it's ~10.2" deck, ~6.4" rod, and 3.85" stroke gives a 1.65:1 rod/stroke ratio). The drawback is that increased side load on the cylinder. So.. maybe as low as a 1 inch deck plate with a shorter rod (sbc 6.2, etc) and a tight compression height.

(for more on the affects of rod ratio: https://www.hpacademy.com/technical-articles/rod-to-stroke-ratio-explained/ )

Here are the SBB 350 block and crank specs (again, thanks go to TeamBuick: https://www.teambuick.com/reference/350_engine_specs.php):

 

[DiscoClay]

I stumbled across a little snippet that indicates the stock deck RV8 (same deck as the sbb215) will *at least* support a 3.75" stroke:
https://www.leylandp76.com/technical/tech-headflow.html ...this is Dan Jones' EXCELLENT data dump on head flow.

That would give a 96mm sleeve (I hear this is the bleeding edge, and 94.75 is much safer) a 5.5L/337cu displacement.

 

[DiscoClay]

This Dan guy is a wealth of info Here's a few comments on the 340/350 crank:

Leyland Car Owners - Buick cranks to P76

 

[DiscoClay]

That site has some great old info from ~18-20yr ago.

Check out this casting cross section that shows the danger of boring for 96mm liners as well as a clear shot of the crank - cam clearance consideration:



It seems the Darton MID solution might be a good fit for the RV8... And that would allow a 4.00" bore. Of course it's a $7500 experiment

 

[DiscoClay]

Maybe I'll weld up a 4.6 crank and stroke it, otherwise it's a bunch of cutting, grinding, and welding on a 340/350 crank or one of those unfinished Castings. I wonder if the rough castings will go out to 98mm? Doesn't look like it without using the Darton MID process.

Here is a rollup of the generic crank differences (NOT including snout & tail shaft differences, which are significant!):
[please let me know if this has errors and I will correct them]

Engine​	STROKE​	BORE​	MAIN JOURNAL DIA.​	ROD JOURNAL DIA.​	Displacement
Buick 215	71mm / 2.80in	88.9mm / 3.50in	2.30 (2.2992)in / 58.42 (58.39968)mm	2.00	3.528L / 215.3cu
ROVER 3.5	71mm / 2.80in	88.9mm / 3.50in	2.30 (2.2992)in / 58.42 (58.39968)mm	2.00	3.528L / 215.3cu
ROVER 3.9	71mm / 2.80in	94mm / 3.70in	2.30 (2.2992)in / 58.42 (58.39968)mm	2.00	3.946L / 240.8cu
ROVER 4.2	77mm / 3.03in	94mm / 3.70in	2.30 (2.2992)in / 58.42 (58.39968)mm	2.00	4.275L / 260.9cu
ROVER 4.0	71mm / 2.80in	94mm / 3.70in	2.50 (2.4995)in / 63.5 (63.4873)mm	2.1875	3.946L / 240.8cu
ROVER 4.6	82mm / 3.2in​	94mm / 3.70in	2.50 (2.4995)in / 63.5 (63.4873)mm	2.1875	4.552L / 277.8cu
BUICK 300	86.36mm / 3.4in	95.25mm / 3.75in	2.50 (2.4995)in / 63.5 (63.4873)mm	2.00	4.923L / 300.41cu
BUICK 340	97.79mm / 3.85in	95.25mm / 3.75in	3.00 (2.9995)in / 76.2 (76.1873)mm	2.00	5.575L / 340.2cu
BUICK 350	97.79mm / 3.85in	96.52mm / 3.8in	3.00 (2.9995)in / 76.2 (76.1873)mm	2.00	5.724L / 349.31cu

 

[DiscoClay]

Those buick guys.. heh heh, Passing more info on here, to memorialize; Specifically: the rare-ish aftermarket cam grinds from the New World Kenne-Bell cams for the 215/300/340/350 SBB: https://www.teambuick.com/reference/library/v8_cams_kenne-bell.php

 

[DiscoClay]

I spoke with the guy that makes the cast stroker cranks; he confirmed that his crank's can be finished out to 98mm stroke. To clear this swing, at least one of the oil gallery casting areas needs to be ground down, which requires sleeving it; he said this was an easy and straightforward (and reliable) process. He said the rods need to be well thought out, of course (i.e.: $$$) for clearance. He build and ran a reliable 5.3L using 98mm of stroke with 94mm tophats in a crossbolted block.

Also, TAperformance, in Arizona, specializes in Buick speed parts and makes a custom Rover V8 aluminum head! It looks very interesting and is very expensive. They did some nice upgrades and it's worth drooling over. They also make roller cams, and sell them ground or blank: https://www.taperformance.com/proddetail.asp?prod=TA_2150

 

[special ed]

Also, TAperformance, in Arizona, specializes in Buick speed parts and makes a custom Rover V8 aluminum head! It looks very interesting and is very expensive. They did some nice upgrades and it's worth drooling over. They also make roller cams, and sell them ground or blank: https://www.taperformance.com/proddetail.asp?prod=TA_2150

TA performance only makes a long nose billit not a gems bosch nose profile. I had to take their blank and have it custom profiled to run full roller in Annabelle. Calling 8 different machine shops to find one that would even look at it.

I was thinking about this yesterday as i was driving Annabelle to a car meet. I am glad i have a high rpm cam in it. and the real torque is around 3000-4000 rpm. R380 and 4.71 gears if the cam i had was running in the stock rpm range with low end torque would be atrocious. You really want a much higher rpm range with a manual transmission and big gearing. That said that low rpm torque would be great only if your running an automatic transmission. Also you probably want to think about torque converter strength and stall speeds.

Everyhting affects the next piece of the puzzle.

 

[DiscoClay]

TA performance only makes a long nose billit not a gems bosch nose profile. I had to take their blank and have it custom profiled to run full roller in Annabelle. Calling 8 different machine shops to find one that would even look at it.

I don't know the actual lengths of the 3.9 and 4/4.6 cams. I will be using a '97 4.0 GEMS (NAS) as the basis for the build.

I was thinking about this yesterday as i was driving Annabelle to a car meet. I am glad i have a high rpm cam in it. and the real torque is around 3000-4000 rpm. R380 and 4.71 gears if the cam i had was running in the stock rpm range with low end torque would be atrocious. You really want a much higher rpm range with a manual transmission and big gearing.

The lowest gears I've ran in a disco was 4.11's with 32" muds and a 4HP24 behind a Navistar Powerstroke HS2.8VNT (the modernized 300tdi)... It's low end torque was something to behold. From 0-20mph it surprised many folks A real Crosswalk Commando But seriously, while it was certainly no speed demon, it was torquey as hell and could climb like a boss. It ran circles around Alfred.

That said that low rpm torque would be great only if your running an automatic transmission. Also you probably want to think about torque converter strength and stall speeds.

Everyhting affects the next piece of the puzzle.

I'm running an R380 with stock gears and 32" tires. This puts Alfred at 2000rpm @60mph. I spend most of my time between 25mph and 70mph (with a upper bellcurve in the 35-55 range, which means 1500-2500 with occasional visits up to ~4K max.).

 

[DiscoClay]

I am homing in on the following:

• 4.6 crank
• Custom very-long runner intake (of my own design)
• M122 eaton or similary sized whipple/screw supercharger with intercooler
• Custom long tube 8-4-2-1 exhaust (of my own design); to maximize low RPM scavenge **AND** give a nice Euro~flat-crank exhaust note (ish).
• Lots of coils (8)
• A fully sequential injection ECU (very useful below 3000 rpm)
• Capacitive Discharge Ignition (very useful below 3500 rpm)

I am looking at various rod and piston combos. I am interested in modern thin-ring pistons. Not sure about rods yet but now that I don't need to bend the laws of physics, I will sort out a strong combo for low rpm boost.

I'd still love to do a stroker, just to see what can be done.. maybe when my *next* startup is successful...

 

[DiscoClay]

Depending upon how the intake comes out, I may make a few and see if anyone is willing to buy one or two. I may experiment with a non-blower version of the very-long-runner intake [heretofor known as the VLR intake or the VLRLR intake ;-P] as well. Not sure yet.

I really want to use a whipple/screw supercharger (quieter, more efficient) but I will probably end up with an M122.

The M122 will probably be the choice because it's large and cheap (compared to a screw). I am interested in low RPM power without a lot of noise. Not only is the blower quieter the slower you spin it (to a certain extent) but it's also more efficient (drag is based upon velocity).

Of course a screw blower would more easily make low rpm boost but I don't expect much of a difference.. and certainly not ~$2k-$3k worth of diff.