I'm sure this has probably been beaten to death, but what is the largest stroke you can "safely" take a 400 block. Since I'll be buying the rotating assembly, I wonder if I should save for an aftermarket block too. I'd like something in the 427/434 range with about 600 hp/ lbft torque.

Also, is it possible to internally balance a 400+ sbc ? Pros/ Cons ?

TIA :)


[Modified by SmokedTires, 1:25 PM 8/5/2002]

 

I used a Dart/Rocket block for my Sbc 427, but there are guys who have put a 4.0" crank in a production block. Some even say they have been able to do it wout filling the bottom of the bores. I guess it's a matter of core shift, production year of the block, type of rods and rod bolt/screws used, and a little luck. Personally, I think I wouldn't go more than a 3 7/8" stroke in a production block, unless you are comfortable with filling it - which is perfectly fine as well.

Yes, you can internally balance a 400 SBC. You'll most likely need a slug or two of heavy metal (mallory), so it'll drive the cost of balancing up a little, but you gain some of it back since neutral balanced dampers and flex/flywheels are typically cheaper than 400-style dampers and flex/flywheels. My 4.00" crank is internally balanced and I use standard neutral weight dampers and flex/flywheels. Either way works just fine.

 

Thanks for the reply Monty. Your 427 has been a big inspiration to me. I know someone that I can get a 400 block from. I've also read everything on you 650hp 427 with the Dart block. Since I'll have to buy the rotating assembly, I figure I might as well go 400+ since it's not much more than a 383. I also have a Fluidampr on my 350 which I hope to be able to use on my next engine. I think I just got a magazine lately on block filling that I still need to read more on. :cheers:


[Modified by SmokedTires, 2:28 PM 8/5/2002]

 

JR Motorsports has some nice internal balance 406 short blocks at pretty good prices. Not as cool as a 427 SBC, but pretty cost effective I think.

-Greg

 

I'll say 3.875 without filling the block,,and without major grinding! That will get you to 426 with 4.185 piston. Small base circle cam required!

 

I would not do anything over a say 415 with a 3.875 stroke. Stock block is a no win. You can make some power out of a 396 4.030 bore Dart is the the only way to go in the the tall decks. The costs like you don't see is the tall cam and it's custom only because of the bearing size.

I bought a 4 inch hogged out stroker RR pan. Money gets big when you start thinking long rods and JE pistons.

It really comes down to the your rearend gearing and what your trying to do.


[Modified by gkull, 8:21 AM 8/6/2002]

 

Thanks Greg, I'm saving the site in my favorites. Bill Mitchell also sells 427 sbc short blocks. :)

Autoxer thanks for the info. :yesnod:

George what do you mean when Zyou say it's comes down to your rear gearing ? I have 3.90 gears, so what do you think? The 396 is with a 350 block?

 

I wasn't thinking and forgot about your OD tranny. If you have a good 350 block go 396. If you have a 400 block go 415 ci. If you want a hot rod. The Dart blocks can go with even longer strokes like 4 - 4.250 stroker cranks.

If you really want a show and go car. If you have a blower everybody will come and look at your car at a show. You can't beat something like here on the forum DHylton's Weiand single 4 barrel street blower. Get the 177 ci. For the money it's the most bang for the buck. Or if you don't care about seeing everything out the front window get a 6/71 type blower like Norval.

 

George I like the idea of the 177 blower. I should be able to reach my 600hp goal with one of those shouldn't I ? Since I need to buy a forged rotating assembly, could I go to a 383 with the 177 ? Would a 383 + 177 ci blower put me at 560ci SBC ? I'm thinking JE -16cc pistons for 3.75 stroke with 6.0 rods :rolleyes: .

 

You need to get the blower pistons. The tops are thicker and the first ring is futher down. It doesn't cost anymore to build a 396 with a 3.875 crank. A blower should be able to make 600 RWHP but it would take an over 1000 cfm carb to do it. A blower is much cheaper than building the same power N/A.

What I was trying to say about the 4 inch stroker oil pan is. there are lot's of hidden costs that you don't think about. 7-8 quart with clearanced pan rails run $300-$500. Then you have too, like in my case machine up a 1/2 inch aluminum spacer to space down the steering for deep oil pan clearancing. Block grinding. Small base circle sleeved gear cams.

If you really think about it the amount of power you could get out of a L-82 355 ci would be enough. An L-82 is a good 4 bolt block and forged crank. Just throw in a set of better 6 inch rods with blower pistons and turn the pulleys up. I'm sure that your wife would even see the logic in it when your saving so much money. :yesnod:

 

George I started running numbers last night on DD2000. What is a typical boost rate for a street blower ? I was using 10lbs on DD. I did achieve the 600hp goal with a roller cam, 210 AFR heads and the 177blower. I will be playing with this some more :yesnod: .

My wife always seems to see the logic in saving money, it's just me that has a hard time with it :crazy: .

 

You need to get some good graphs on static C/R and boost vs octane required. 8-12 pounds is a common street machine with 92 octane and boost controlled timing retarding.

 

SmokedTires, you will need to change your thinking a little if you go with a blower. 1. You'll need to change your gearing... roots style blowers make tons of torque down low. Those 3.90 gears need to be change to 3.55's or a little lower numericaly. You'll want maximum engine speed around 6000-6500 RPM or you'll over-speed the smaller street blowers. The steet blowers are red-lined at 14,000 RPM...typical they are over-driven between 2.15 up to 2.46 : 1
If your turning 6,500 RPM engine speed your turning 13,975 RPM blower speed with a 2.15 : 1 ratio!!!
2. You don't need large heads such as the 210's, AFR 195's will be adequate. I'm running Holley 185's in my set-up and the 144 blower will only make 5 lbs. of boost because of the good air flow.
3. You probably won't see more than 8 lbs. boost with the 177. Boost is realative to a number of things. The better air flow in/out of the engine will show less boost on the gauge. A stock engine with stock heads and mild cam will show a higher boost reading because the air will "stack-up" in the manifold and give a false reading. If you want to get into the 10 lb. boost range you'll probably need to go to a B&M 250 Blower.
4. You need to get your compression down to 8.0 : 1 or less...Weiand suggests 7.5 :1 as ideal. I'm running 8.3 but I'm not running that much boost either.
5. You'll have to cut a hole in your hood to run a roots style blower... even without the air cleaner my Holley carb sticks out of the stock hood about 4 inches...but then again who'd want to hide his polished blower...
6. Buy a blower cam, they are designed to keep the boost in the engine rather than letting the boost go out the exhaust valve on the overlap. A good roller cam will net you around 40-50 HP over a solid lifter cam. Keep your HP peak around 6,000-6,200 RPM...remember your now limited by blower speed.
7. Figure on spending $$3200-3,500 on the blower and carb...$2,000 blower, $700 new blower carb, $140 K&N air filter and housing, $200 braided lines, $200 misc. also additional pulleys to add/lower boost will run you $75. each
8. George, thanks for the free advertising :lol:

9. If you get serious about the blower don't hesitate to ask qustions...Deen

 

Thanks for the great info Deen. You guys always teach me something on here that I didn't know or think of before :yesnod: . A buddy of mine was showing me the benefits of destroking an engine and the power that can be had. It was truely amazing to see the results on DD2000 with a 302 sbc and a supercharger. I'm starting to look more into the centrifugal superchargers too. I think it'd be really cool to have a 144 or 177 blower, but it'd have to fit under my current hood, otherwise I'll go the centri supercharger road. Hotrod Mag just did an article on the new Vortech where the carb is totally enclosed in a sealed box that looks intriguing :D .

I have a lot of saving up to do before I make a move, but this gives me time to do lots of research before I make a final decision ;) .

With a blower motor, is it a better idea to increase the exhaust valve size instead of the intake size?

Thanks again for the great info, you guys are the best ! :cheers:

 

I've learned allot about blower motors this past week. My friend brought his Vortec intercooled 355 down for the car show. RWHP of 484 with mild cam 7.8 C/R Sportsman II heads with 2.05/1.6 Max rpm of 6200 at sea level boost of 13 Speedpro computer with 4 barrel type 1300cfm FI on a Weiand team-g single plane.

He told me that the only things he would change is to larger aluminum heads with thermal coatings because he is only able to run 22 degrees of advance under boost on pump gas. I ask him about Deen Hyltons idea of small valves and less than 200 cc intake ports. He said that you would be throwing away a 100+ hp. It makes sense because if you figure out the total volume of a centrifical superchargers air plumbing with an intercooler having 30-50 cc larger intake ports is a very small change in the total system volume. His next heads are going to be one of the larger 18 degree with 2.15 or larger intakes.

Yes, blower motors need all the exhaust flow they can. I saw a couple of blow threw the carb designs at the car show.

 

One of the main concerns I have with stroker small blocks is the inability to get enough head flow in a small block head. SBChevy heads are getting better, but I think you're still limited to a maximum of 2.10/1.65 valves. And then, I think it needs a Jesel shaft-mounted system (aka megabucks), at least in the case of the big Brodix head.

The reason for this concern is because I have also noticed a desire in stroker small block builders to want rpm's too. Air flow does become a concern with so much cubic inch displacement, especially if using forced induction.

One possibility is to use the Dominion 4-valve heads, that still uses a pushrod system. Pretty ingenious design that has been dyno proven to provide big power increases over even the best 2-valve aftermarket heads.
That is expensive too. I think when I looked into it, it would have been around 7 grand for a set of those heads. Not sure that's worth the investment, unless their prices come down closer to reality.

Of course, you folks (Monty and others) who are running the big inch mouse motors would know best, and can probably advise based on experience.

 

I didn't say not to get bigger ports/valves...it's just not as important (to an extent) with a blower. It gets down to how much money do you really want to spend? I'd like to go to a roller cam to pick up the extra 40 HP but it's not worth it to me to spend another $1,000 for the roller setup when I can spend $600 on nitrous and instantly pickup another 200-250 HP. Same thing with the heads...the Holley heads were realitivly inexpensive ($1300 for the complete top end minus the roller rockers and carb)...I could have made more power with bigger ports and valves but I can do the same thing by changing blower pulleys for $75 bucks. I can already blow the street tires off in first and second gear now w/o the NOS. :)

 

I'm going to go against the grain here and say that based on my personal experience(and it's limited to just my own engine and what I've seen work for the guys at Fast Times) big valves and big intake/exhaust ports are still beneficial in forced induction applications on big cubic inch small blocks.

I don't know how significant the difference between a supercharged/blower and a turbo would be. I'd guess that the Roots style blowers and turbo's would act similarly since they can build torque/boost at low rpms whereas centrifugal style superchargers don't make big torque/boost until higher up in the rpm range.

My theory is that with a more efficient intake system, using larger, less restrictive valves and ports, you can make more power with less boost, which increases reliability and reduces chances of detonation - especially on pump gas. My Dart 18* heads have 255cc intakes, and 2.180" intake and 1.65" and low end torque and throttle response have never been a problem, either naturally aspirated or forced induction.

As MoMO mentioned, it's hard to have too large cylinder head on these big small blocks. The long stroke is going to provide plenty of "pull" on the intake charge to get the velocity up even with a big valve, big port combination. I think in the case of a 410ci+ small block, bigger is indeed better.