Have a 2 bolt 400 block. Putting it together a drag motor. Will be a 406 with either a C.A.T. forged crank, or a SCAT series 9000 cast steel crank, with Eagle H-beam rods, and Speed Pro Forged pistons. Anyway I would like to run an NX nitrous kit with around a 200 shot. However with the OEM 400 block I know they have weaker wall than other blocks. Also I dont have the caps, so Im gonna buy steel Milodon caps anyway.

I dont look for the motor to last forever but, I would like the motor to last at least 9 months to a year without needing freshened preferably with the block staying together. Would see only track use, once ever other weekend or so.

To get to the point, how well do you think the block would stand up just as is being bored .030? One of the solutions I was looking at is Hard Blok. I dont want to fill it all the way, cause the car MAY see the drive to teh drag strip a few times, if I dont get my hands on a trailer right away. So I would like it to remain minimally streetable, although with the compression I wanna run it wont be able to use pump gas anyway.

Anyone have any experiance Hard Blok? THe add in Summit for their half-fill says the ride would remain streetable with it. How much stronger would it make the block?


Also I was reading in Lingenfelter's book that using longer rods, can reduce pressure on the cylinder walls. I would imagine its true, but would it make a noticable differnece if I used a 6.0" rod rather than a 5.7? I know most issues with rod length are negligable.

And how much would it help if I used a dual stage kit. Like 75 off the line and then 125-250 later in the run? Would that be just as ET effective and be better on the drive/powertrain?

 

I haven't seen much problem with the 400 cyl wall. The 4-bolt blocks were prone to crack from the outer main cap bolt holes to the cylinder wall. This is why the 2 bolt blocks are preferred.... especially with splayed 4 bolt caps.

I wouldn't recommend a cast crank for a race motor with nitrous.

Definitely use a longer 5.7 or 6" rod. I only use the stock short rods in a pick-up truck.

If only running on the strip, the Hardblock will help wall stability. It's use will depend on the total HP you plan on having. A mild 350hp motor with 200 HP juice will probably be fine without it, but a 12.5:1 high rpm motor (5-600hp) with a 200 shot will be pushing the limits of a normal block. 200 with a TRW piston is also borderline in my opinion. I have seen a lot of these motors in budget circle track applications run well & last.

 

I know I shouldnt use a cast crank, but man its hard to justify, spending DOUBLE the money for a forged one. A brand new top of the line SCAT cast crank with the 400 mains I think is $330. I cant find a forged crank of any brand for less than $600. I was thinking that it would hold up as long as I didnt spin it over 7.1-2k But I know Im reaching. I'll try to talk my dad into buying me a forged eagle crank or something. The pistons arent a big deal, I was already thinking the TRW's were borderline and I was gonna upgrade to Ross.

The motor would be anything but mild. Im gonna be using a Herbert Peformance roller nitrous cam. int/exh @.050= 253/261, int/exh lift = .598/.625, Lobe C = 112*. Or maybe a little meaner one. Heads I havent quite decided on yet. MoTown 220s are leading the race right now, topped off with a Team G and 850 Double pumper pro built carb. I was looking at 12.5-13.0 compression. But I was thinking of backing it off a bit down to around 11.0 if that would help cylinder pressure and reduce wear on the block any?

And I wasnt planning on putting anything shorter than a 5.7" rod. Its just that I find new 5.7s for sale cheap on E-bay and Racing junk al the time. The 6.0"s are a little harder to come by.

So the hard blok sounds like it would be a good idea?

 

My $.02

 

Ok the MAIN advantage of the 400, is the fact that I have a good one sitting beside my Camaro right now. Because I was originally planing on a lage displacement stroker. Like 434. But then with the masses of machine work and the expense of the large stroke crank, and pistons short compression height pistons I decided to back it off, so I could use a cheaper crank, and make up teh differnece with nitrous.

As for going with an aftermarket block cause you say it will amount to the same price.

Using rough numbers even with a steel crank $600, Rods $500, Pistons $500, RIngs and Bearings $200. Thats $1800. Now that i have my entire rotating assembly accounted for I would still fall, $300 short of the World Products block. Thats a good chunk out of my machine work. So for my rotating assembly and most of my machine work I could have a nice useless bare block. Honestly I respect your opinion alot, but its really its just not an option at this point. The only block switch I could see, is if someone wanted to trade me the 400 for a nice 4 bolt 2% nickel 1% tin 350 block. By the way how much more Nitrous could the 383 handle?

So back to it, how much would the Hard Blok increase the durability of the block?

Will the SCAT last a the approx hp/torque my set-up would make turning high 6k to low 7k RPMS, or do I need to get a 4340 crank period?

And how much easier on the powertrain would it be if I used a dual stage kit?

 

FWIW we split the cylinder walls of a 4 bolt 400 block with hardblock in it. The number 2 cylinder developed a 3" crack towards the cam bore.
Motor never went above 6700 rpm,had a T trim making roughly 14-15 psi. Cola crank,Eagle rods,JE slugs.

That motor lasted less then 9 months with every 2 weekends of racing,and 2500 street miles at most.

 

Well the 4 bolts are weaker, than a 2 bolt splayed. But thats on a charger. Didnt you tell me before that he had a nitrous motor and it was fine other than a bearing problem?

 

I'm curious. What was the bore on this motor?

Rich Krause

 

My guess on the bore is 4.145"-4.155"

The reason they made Bowties is so you can build a awesome 400 block.

Bret

 

 

Ok so I'm gonna have to buy a steel crank. I'll survive that I guess. I suppose its just cause Ive never actually seen any, not even a cast OEM crank break, that I find it hard to swallow that extra price for the steel one.

As for backing off the RPMS, I had already been thinking about it. I had just been thinking that with the bore stroke combo of the 400 upper 6k would be where it would easily make the bigest hp numbers. Problem is that even coming off the line at like 3200, which isnt as hard as Id like to come off. And I back the shift points down to around 6300 or so to save the engine. That doesnt leave me much of an RPM band to work with. I suppose coming off the line on nitrous at 3200 would be just as good as 4000 N/A though.

If I were driving it often I wouldnt have a hard time backing off power goals. But because Im a 19 year old college student I cant afford insurance regularly on two cars, and teh Z isnt reliable enough to drive everyday. So I'm limited to a race only car, which Im not against in teh first place, but I would really like to see 10's out of this project, therefore its hard to back off power figures.

Add the 12 lb, 10 lb hammer thing made me

 

Rich,it was a .030 over high nickel 400.

 

You should listen to the 383 proposition a little more closely. That 400 block is worth some cheddar, and if it's machined I can guarantee you it's worth as much as a 350 core + machining. The 383 is more durable, and if you're stuck with a factory block it has a much better chance of holding together.

I'm not aware of Scat 9000 cranks failing below 750hp one way or the other, so I'd be tempted to lean that way, but OldStroker definately knows more than I do. Anyway, unless you're going to have the heads done by a competent porter, I would go with the Pro Topline heads, without a doubt. Dollar for dollar, nothing out there flows like those.

About the TRW pistons... I wouldn't use those in anything, period. A good set of Hypers is every bit as durable, if set up properly, and a hell of a lot lighter. Those TRW pistons are so heavy... might make a good ashtray though. I'd look into one of the Eagle/SRP rotating assemblies on ebay if it were me. And it'd be a 383

 

Well I'll put my 400 up for trade on the board for a 350 block (or a big block ) and see if anyones interested.

But what kinda power loss would I be looking at in backing off from a 4.155 bore to a 4.040? Using the same set-up with mo-Town 220 heads?

 

Thanks. Food for thought, confirm my idea of building up my mtor for next year as a "10 over", thouh it's an LT1, not a 400.

As far as cranks go, I just got off the phone with Callies. A 4340 forged "Dragonslayer" crank is <$800. Same material as their high-end cranks, just lacks a few of the more labor intensive finishing steps and is a bit heaver as the center two journals aren't drilled.

Rich Krause