370,377, 396,OR 422 CID 8-71 Blown SBC?

[ProStreetLuvr422]

I have been doing alot of reading lately.

Most of what I read is old Issues of Car Craft, Chevy High Performance, and Hot Rod Magazine.

I would like to build an 8-71 Blown E-85 SBC based on a Motown block, AFR 215-227 CC Aluminum Heads, a BDS intake manifold, a Blower Shop Air to Water Intercooler, forged 8.25-8.75:1 CR pistons, 5.85-6.0 forged rods and a (112-114 LSA) Hyd. Roller cam (expected output 580-670 HP).

Potential Combos:

I) A 4.03 bore with a 3.625 crank (370 CID)

II) A 4.155 bore with a 3.48 crank (377 CID)

III) A 4.17 bore with a 3.625 crank (396 CID)

IV) A 4.165 bore with a 3.875 crank (422 CID)

Which would you pick and why?

How big of a "Blower Cam" would you run?

[John_Heard]

Assuming you're going to run the same boost on all of them, the 422.

"No replacement for displacement" (except for boost)

[CDR Performance]

...of what I read is old Issues of Car Craft, Chevy High Performance, and Hot Rod Magazine...

Please remember these guys are try to support magazine sponsors and sell you parts.

If you going to a large air heater. You will need a BBC snout on your sbc crank and dual key ways.
Keeping the motor under 4.100" bore will help keep the head gaskets in place.
Stroke depends on the app. 3.500" stroke is nice allow good piston selection even a little room for a rod choice.
Rod is the lowest on the priority. Pistons need to survive.
3.750 stroke is the max that I like on a standard deck with a standard height cam tunnel.
It already requires a small base circle....
Might as well do a solid roller. Cheaper than Retro lifters.

Of course a 4.100 bore X 3.500 Stroke SBC (380ISH) and a single 80mm turbo could fit under the hood and make 1000hp.
To each.............

[ytnova]

I would agree with all of the above and I would only add this. More cubic inches would require less boost to make the same power. More boost means more heat. I am not reallly sure you need a intercooler if you are going the e85 route also.

[Moparious Maximus]

I dont know much about E-85, but unless this is a street motor it kinda looks to me that you are low-balling the HP, even a 6-71 on a sbc will make over 1000hp if you want it to.

The 3.48-3.50 cranks let you run the 6.0in rod and still have plenty of room for the ring stack, we are putting together a 4.155 x 3.5, 380" blown alky motor. We chose the 3.500 crank for rigidity, rod/piston room and blower motors really dont care about cubic inches much, the bigger they are the harder it is to keep them happy. You might think the longer arm might help make some low rpm torque but really, a blower motor doesnt need any help on the bottom end.

We also run a big 572" 8-71 motor, it makes awesome power but its hard on parts.

HP is all in the pulleys.

[CDR Performance]

You can make more power with an intercooler and e-85 than without.

[ProStreetLuvr422]

Forgot to mention this engine will be a "Training Wheel" Pro-Street/Strip 11-10 Second combo. I will up the boost and/or add a N2O injection system as is necessary.

After weighing your collective ideas a 377 SBC(4.155 bore & 3.48 inch crank in a Motown or Dart Little M block) sounds like an optimal combination.

If I restrict RPMs to around 6500 could a Hyd. Roller fit this bill?

Knowledge is power and saving $$$ is King.

[CDR Performance]

Hyd roller maybe but why. We run solid rollers on the street with thousands of mile a year and Zero issues.

MYTH, You need to adjust your solid roller cam at every stop light.

Go for the 3.500 Stroke, if your buying new it doesn't cost any more.

[Moparious Maximus]

Limiting the rpm to 6500 would be crippling it in my opinion, a short stoke blower motor is not even in its happy place yet. Spin it to 8000 at least, thats where the power is.

On a std blower, the rotor rpm should be around 9,000 to 10,000 rpm at the shift and the stripe, much faster than that they just aint efficient anymore, any slower there is still power to be had.

[ProStreetLuvr422]

Sorry about the million questions and thanks for all the responces.

It looks like most of the aftermarket engine blocks start at 3.98 bore and offer either 350 or 400 mains.

A 350 finished bored to 4.10,5.85-6.0 rod, and either a 3.625 or 3.75 inch crank with 350 mains should build me a 383 or 396 SBC would these be better or worse than the 377 SBC?

Hot Rod Magazine made 825 HP on pump gas with a 8-71 Blown 454 BBC could I do the same thing with a 396 SBC and a 20% overdriven 6-71?

{(Blower CID X %UD/OD X 25.58)/ Engine CID-14.7} calculations based the above formula suggest even assuming a 2 PSI loss from the Intercooler suggest 15.2 PSI of boost.

[CDR Performance]

If you're staying in a standard height block with a std height cam @ 3.750" stroke you have to run a small base circle cam.
A standard or larger cam is better. No to mention issue with pan and then rail clearance.

If you do a tall deck with a raised cam you have more options. But you are still going to run a small block head.
Tough to fit a big block sized motor through a small block head.

An 8-71 on a small block has a lot to offer, as long as it is a good unit. (no b&m or weiand street blower) Maybe a Littlefield or ???

Please do yourself a favor step away from the CC, HR, and other rags. Most are optimistic at best and often run on happy dynos. Even at that a dyno is a tool for tuning, it is just a high tech torque wrench.

[ProStreetLuvr422]

Would I gain anything by picking a BBC over a SBC to setup as a Blower Motor; for instance a 435 (+.040 over 427 or 454, steel 3.766 crank from a 396/402/427) , 483 ( 502 with a 4.52 bore not the 4.468 bore and a 427 steel crank) ,511 (427 Tall Deck Block or Aftermarket Block 4.31 inch bore and 4.375 stroke) or a 526 (4.375 bore and stroke based on a tall deck aftermarket block)?

In short would a 435 BBC be better than a 377 or even 434 SBC?

[John_Heard]

How about you telling us what your budget is? Are you going to be racing somewhere where they have rules?

[Moparious Maximus]

BBC's have stronger bottom ends, so I could see it possibly being a little cheaper because you can use factory block, crank and heads, and they have a better port layout.

Im with John on this, how much money do you want to spend and how many ponys do you want, its all relative.

There are guys out there with 2500hp blown SBC's or there are the people that have fits keeping a 1000hp blown BBC togeather.

The variations are endless, build what you want, but build it right.

[ProStreetLuvr422]

I would like to have less than (in the engine around $6000-8,000) and $32,000 in the whole Car or Sedan Delivery.

If I do all but the Blower setup myself with help is this possible?