SB2 Motor

[tyson__91]

Id like to know if anybody is running a low compresion like 10.5 motor with sb2 or 2.2 heads. If you are how does it do whats the power band like how streetable is it. Also what cam and piston are you using for your setup thanks for any info i would need before i go buy some heads.

[907rs]

Tyson, I believe Chris (racerodz) is going to run an SB2 in his truck. Not sure if he's actually run the motor yet, but maybe he'll chime in and let us know about it.

[XcYZ]

I really don't know a whole lot about the SB2 and SB2.2, but you'll need a special cam, valvetrain, pistons, intake, headers, etc.

[Blown353]

I don't see any streetability issues with an SB2 provided it is cammed and compressed to be "street friendly", although the low-end may be a bit soggy due to the intake runners typically being on the large side for lower-RPM usage. Lots of power potential though given the massive flow capabilities of the typical SB2 head.

A very good friend of mine with contacts at RCR (Richard Childress Racing) picked up a 691hp used SB2 from RCR that he's going to put into his '66 Chevelle sooner or later, once he gets around to figuring out how to make room for the dry sump system, fabs a motorplate, and fabs custom headers (the headers are the larger Stahl pattern.) Other problem is that even if he moves the dry sump pump the standard motor mount provision on the drivers side of the block was milled off for dry sump pump clearance, so no using the factory motormounts.

Lots of special parts on an SB2-- the cam because of the journal size, lifters, heads, intake, rockers, headers, so make sure you have a DEEP wallet handy. I think Jesel SB2 lifters are on the order of $1600/set new, although you can get used ones fairly cheaply. I started to put together a parts list once with new stuff and I was knocking on the $30K door in a BIG hurry before I was done with the list.

Very cool and very unusual to see one in a street car. I still think about picking up a used motor through my friend and tossing my Procharger on it for added entertainment.

Troy

[race-rodz]

i am still in the process of collecting parts, my combo is on the far side of streetable, the static comp ratio on mine will be around 12.5-12.8, with a fair amount of cam overlap. the rest of the combo will be a standard small journal sbc block, splayed caps, roller cam bearings and offset lifters, bryant superlite crank, 339 cubic inches. RCR sb2.2 heads/intake cnc ported, 5 stage dry sump, and all the other goodies.

as soon as the parts are collected it will be off to the machine shop, and onto the dyno. the target is 650-700hp, and it should be able to turn 8500-9000 rpm for atleast 86 miles at a time(silver state challenge)

the original plan called for a manual trans, but now things have evolved to a 4L80E, and steve-o will be taking care of up/down shifting.

the combo will have lil torque compared to the forced inducted monsters most guys are putting together, but its also goin into a 2100# "shop truck".

[Y-TRY]

How does SB2 head flow compare to LSx stuff?

[race-rodz]

off the top of my head.........WAAAAAAAAAAAAAAY more.

my engine builder told me he would flow them for free..... just show he could have the data for camparison...as soon as i have some #'s...i will be sure to post them

[ProdigyCustoms]

The SB2 may very well be the most HP for the dollar in a motor for the wise shopper. There are a bunch of Nascar used parts guys selling almost everything you need used. For the most part this is either one race, or qualifying stuff that is perfectly fine. The horsepower, as in any motor, with SB2 is in the heads. SB2 heads flow big block numbers, high 300s is no problem. Using the 2HP per CI, you can see it would be easy to get 750 to 800 from a SB2. There are some things to watch out for though. Intake runner sizes can get huge, remember Nascar guys really do not worry about low end torque much, but camed properly, along with other correct component selection can minimize torque issues A Pump gas SB2 will require a very special dished piston for NA application, and it is almost impossible to build a blower piston with 3 rings, especially for bigger cube motors, for a SB2. The heads range from a small size of 46CCs to a max of 54CCs or so, and do not have much room in them to be opened more then mid 50s, so we are talking serious dish pistons here. If you decide to make some cubes (Hot ticket to make up for the torque issues of the too big heads), then you are looking at more compression issues trying to keep it down in the 11 : 1 range, but it can be done. The cam is a totally custom piece not only to the motor, but in the way the lobes are cut. It requires a short lobe to keep lift down to .700 to .750. Used Jessel rocker set ups are anywhere from 1.6 to 2.2, most being closer to 1.8 to 2.0 range. So it can be hard to find a smaller set of rockers. The intakes that are available are big, so again the low end may suffer, but suffering here may be like driving the old Ferrari because the new ZO6 is in the shop for service.

I spent a lot of time specking one out for Prodigy before the big block decision was made. I do not have my spec sheet and cost anymore (computer crash), but if memory serves, using a new block, rotating assembly, and cam with used everything else, $12k would build a all aluminum 427 CU SB2 that should make a tick north of 800HP on pump gas. You wanna talk about a lightweight, nasty sombitch! Just talking about it makes me think about it again, but right now I am seduced by a 500" LS1 idea. But we ain't talkin $12k either.

If anyone gets real serious about doing one, I can help, and I also have a friend at Bill Mitchell doing one right now for his own PT Camaro.

[MarkM66]

Frank, don't the SB2 heads that the Busch series guys use have larger combustion chambers? I thought those guys had to run like 10:1 or so.

[race-rodz]

i looked long and hard for the biggest chambers i could find, mine are 54's, i have yet to order pistons, so the final comp ratio isnt set in stone. the torque issue will be interesting with my small inch motor, in a lite vehicle. the idea was to have a chance at getting rolling without blowing the tires off or breaking parts....and since my end goal is extended high rpm road racing, the combo should work out well. all totaled up doing as much "value" shopping for used high dollar race parts, my engine should come in at about $8k