I've been researching and planning my next sb400 buildup, and this is what I believe will give me good streetability, plenty of low end torque and great hp up to a redline of about 6200rpms:

Vitals:
-Stock 400 5.56" rods and 3.75 crank ---balanced rotating assembily, arp bolts
-AFR 195cc heads, race version (1400$) ---moderate port blending work
-Hypereutectic pistons, chrome moly rings ---10:1 compression
-Hydraulic roller cam kit ---232/232 duration at .05" lift, 110 LSA, .550/.550 lift. kit also comes with pushrods/springs
single pattern, about 280 advertised duration
-Holley stealth ram intake, 58mm throttle body ---port matched to heads, 1205 intake gasket
-30lbs injectors, electric fuel pump below tank, heated 02 sensor in collector.
-GM tpi computer, speed density, painless wiring harness

I'd really appreciate any feedback on any part of this setup that doesn't match well or wouldn't hold up. I'm expecting 500hp/torque at the flywheel, more is always better though :yesnod: Thanks guys!

edit

I run 3.55 gears and a doug and nash 4+3 transmission .68 overdrive. More stats are in my sig webpage. My comp XE274h blew up, it was good though, I have also tried an isky magnum 280 and its not as streetable. This is with my current ported brodix street heads not my planned afrs.



[Modified by inqbus383, 10:57 PM 4/15/2003]

 

I ran the Comp XE-274 on my first go around(not much smaller than the cam you posted) and felt it ran out of rpms too soon. went with the XE-284 on round two. Pulls easily to 6500,but I run a carb and high rise intake that will allow the rpms.
What gears do you run,and do you have an OD trans?Maybe you'd best stay smaller in the cam.Just my .02 worth.

 

I would invest in longer rods. The rod/stroke ratio is not good with the stockers. Get some 5.7 or 6" rods and I like your combo.

 

Can't comment on the rest, but doesn't the Holley Stealth Ram come with it's own computer, no need for the GM computer

 

Yes holley likes to sell their stealthram with the holley commander 950 computer, wiring and injectors. I don't need the 800$ computer since I already have a gm computer to use. I plan to buy the manifold and fuel rails alone from thunderracing.com

Here is a similar buildup:
http://www.carcraft.com/techarticles/68999/index.html

 

TTT

 

Is that an EFI friendly cam? I would ask holley either to recommend you a cam or ask if that cam will work well with their fuel injection system. If you have already considered it, just disregard this.
That sounds like a very potent combo, actually very similar to one I've been planning for a long time(406+ci, 195cc heads and edelbrock or holley efi)

 

Yes, that cam should work fine with EFI. Not the stock chip though. Apparently its important to have a lobe separation angle of 110 or greater and not excessive durations. Of course, you can make anything work with efi, it is just more difficult to tune a radical cam.

 

Not sure if you can use 6"ers in a 400 sb but I def would get some better rods than stock, just to be on the safe side. Sounds like a great combo though.

Idle is the hardest thing to tune with a big cam, I have learned that from my formula and I am only running a LT4 hot cam in a 350. Using more adv and longer pulse helped smooth it out some.





[Modified by Fevre, 3:34 PM 4/16/2003]

 

Yes you can use 6" rods. Have seen many kits for sale with em. Just makes the small base circle cam even more important.

 

:cool: Learn something knew everyday. :cheers:

 

Head flow is always very important when building for horsepower. While the AFR 195cc will probably get you in the neighborhood your looking for, why not consider the AFR210cc ? The 210's will step up the intake valve size from a 2.02 to 2.08 ;) .

A fellow forum member (Grumpyvette) has installed the Stealthram with some really impressive dyno results afterwards :yesnod: . The Stealthram system was going to be my original choice, but I needed something that could be port matched to a 1206 which led to a lot of time & research searching for the right pieces :) .

500hp/tq will certainly be entertaining when complete :smash:

:cheers:

 

I think the newest Chevy High Performance has a 406 buildup where they talk about the small base circle cam. I don't recall if they used 6" rods or not though.

 

I've been researching and planning my next sb400 buildup, and this is what I believe will give me good streetability, plenty of low end torque and great hp up to a redline of about 6200rpms:
Vitals:
-Stock 400 5.56" rods and 3.75 crank ---balanced rotating assembily, arp bolts
-AFR 195cc heads, race version (1400$) ---moderate port blending work
-Hypereutectic pistons, chrome moly rings ---10:1 compression
-Hydraulic roller cam kit ---232/232 duration at .05" lift, 110 LSA, .550/.550 lift. kit also comes with pushrods/springs
single pattern, about 280 advertised duration
-Holley stealth ram intake, 58mm throttle body ---port matched to heads, 1205 intake gasket
-30lbs injectors, electric fuel pump below tank, heated 02 sensor in collector.
-GM tpi computer, speed density, painless wiring harness

I'd really appreciate any feedback on any part of this setup that doesn't match well or wouldn't hold up. I'm expecting 500hp/torque at the flywheel, more is always better though Thanks guys!
**************************************** **************

These are my answers to your build up1:)

They usually refer to a .030 over bore as a 406. I bought a used 3.875 stroker short block motor. I just wanted a quick fix and get on the road because I had blown two motors in a 3 month period. It's funny in a way the motor that only lasted me three months also had an Comp Cams XE274. Well anyway the guy had been running the 393 ci stroker over 7000 rpm with a hot SR cam. My plan was a quickie rebuild - just run a hone up and down each bore to give a new surface for the new rings to bite into. It was a short rod externally balanced motor. Never again will I ever deal with motors with those two bad items. Externally balanced means heavy cheap junk parts. Your having to spin an extra 20 lbs of mass. So to accelerate and decelerate is hard on parts (bearings & the whole drive train)

The bores were worn out of round in just two years do to the side thrust imposed by the short rods angularity. Yes this was a poor mans race motor. It was a budget kit stroker short block from somewhere.

My first question is what's wrong with your Brodix? They probably have similar cfm as the AFR's. I learned when I built this 383 I now use that strokers with roller cams don't even follow the same rules as a 355 ci with a H-Flat cam. The TQ and vacuum is so much higher that you don't have to worry about baby heads. I would have 215 cc at a minimum. I'm also unclear why people have such a fixation on AFR heads. When others flow more and cost less.

Your cam dictates your needed compression ratio. With 232 and 110 lc I would plan on a true 10.5 to 10.7

I have mixed feelings about Hyper pistons. On one hand they served me well for years and they have better piston to wall properties. Which in the long run makes for less blow bye, better MPG, and horse power. On the other hand. Just put some heat and mild detonation to them and they fall apart. They are way above stock or cast pistons.

Unless you have super free flowing exhaust starting with heads exhaust port cfm. I would buy a split duration cam. Crane Cams makes a HR right in your range. it's something like 232/238 112 mid .500 lift with 1.5 rockers. Something like that would make a 406 have a broad torque curve

 

Gkull and all: Thanks for the replies!

Currently my block is .020
over and that makes a 404.5.

My brodix heads are the street heads, they flow very poorly and only have 170cc
intake runners. I think they max out near 220cfm as opposed to the afrs 220
cfm out of the box. Plus my brother wants my heads for his van and is willing
to pay me decently for them. I figure I can get the street 195s to flow nearly
290cfm with some porting as the competition version which is only slightly more
cnc'd flows 282. Afr also makes 210cc heads but they flow nearly the same
numbers, and I've seen many small block dyno tests using the 195s that made
well over 500hp/torque at 6000rpms or less, which is where I want to keep the
peak hp. As it was, I'd run to 6000 rpm consistently. I figure with the
better heads I'll want to run up to 6500 which I'm not sure would be great for
the stock 5.56" rods and crank. Do you think I need to upgrade both the
rods/pistons and the crank? Or would the crank probably hold up. If I do get
rods, which ones would you recommend? I was thinking probably forged 6" rods
with a max price of about 550$. I dont think I need anything too exotic
considering the stock ones lasted so well and Im not planning on revving over
about 6500rpms. If I get new pistons, I will probably go with forged since the
longer rods will require a more difficult piston design and theyre not that
much more expensive.

I agree with you on the 232/238 cam duration, I dont think the extra 6degrees
will hurt and I've read that on a similar setup it helped considerably. I also
agree that this cam could use slightly higher static compression, especially
since I'll be using efi with a knock sensor.

Update: I purchased a hydraulic roller from crane, 230/238 duration at .05" and 294/300 seat to seat, around .530/.550" lift, 112 lobe separation. I also got their needle bearing thrust button and a steward stage 2 water pump.

 

I would never again have anything to do with a short rod motor. Inqbus - Eagle and someone else makes forged rods for around $300. Oliver might make a street forging.

RPM is what kills motors - Not the HP level.

That's a nice cam for "405 ci"

If the 195 and 210 cost nearly the same I would go with 210 cc and the 2.08/1.6 valves. Roller motors have so much vacuum and smooth idle that you won't know that it's nearly a race motor by the sound of it idling

 

I would say two things:

1) Either go with a cam that is designed for EFI, or have them ground that cam on a 112 or 114 LSA, Comp Cams makes a nice TPI roller cam (XR276HR)

2) Definately go with an aftermarket ECM, if you are going to make that much power you will save time and money with the tunability of an aftermarket ECM, as opposed to sending a chip off 15 TIMES until the guy gets it right.

just my .02

Josh

 

Gkull: I'd go with longer rods if that was all I need to do. I wouldn't buy any rods that I'm going to need to replace later, probably 550$ for callies or something comperable. But the added cost of new forged pistons, rings, balance job, short base circle cam make it just too expensive. I don't think I'll be taking it over 6000rpms really, and I know its been to 7000 rpms many a time with no problems, and no excessive cylinder/ring wear due to the geometry. I figure there are two possibilities, either it holds together with the short rods and possibly makes a tiny bit less power. Or the unlikely, it throws a rod and ruins the block. If breaks I'll just need to buy a new block core and get it machined, and then buy a new stronger rotating assembily. Blocks aren't that expensive, and I think the rods will hold together anyways. We'll see how it goes!

mean8t: I purchased a hydraulic roller from crane, 230/238 duration at .05" and 294/300 seat to seat, around .530/.550" lift, 112 lobe separation. I agree, and didn't want anything less than 112 lsa. I have the equipment to burn the chips myself, so I'll try that with the computer I already have before I shell out for an aftermarket ecu.