tahoe

What are you thought on this concept for an all bore 401?

LSX cast iron GMPP block
4,20 custom pistons, copy of stock but obviously larger diameter.
Reuse ALL stock parts such as crank, rods, plus all the bits and pieces.
(If you are looking beyond DD use, replace the rods)

Top it off with a stock set of L92 heads with L92/L76 intake.
The L92 heads should flow well on that big bore I guess.

This would, depending on cam choice, make a very strong DD.
For a tow motor also keep the stock heads for that BB oval port kind of low down Tq.

What´s your opinion on the benefit of an all bore motor,
as well as the cost of doing one compared with a stroker 402/408?

BR//

tahoe

Ok since there are no takers, here is my analysis of the non stroker 401.

Bore only 401, parts needed
LSX GMPP block 1900 Dollars
Custom pistons 800 Dollars?
Total 2700 Dollars

Stroker 402/408 parts needed
6,0 liter (iron) block (800) Dollars
Stroker rotating assembly with pistons (eagle) 2800 dollars.
Total 3600 Dollars.

This is just to show cost of the big part in each way of going to 400 ci.
It seems to me that by spending aprox 1000 less, you can build on a LSX block
reusing crank and rods from the stock motor.

It would be great to be able to buy a bored/honed block to 4,20 with a set of matched pistons for the stock rod length.

Any sponsor that like to comment?

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Hennytime

iTrader: (33)

so you plan on using stock rods on a high rpm, big power motor...let me know how that goes

silver-mod-o

iTrader: (15)

I could see doing that and using stock SIZE stuff but not factory, off the shelf internals minus pistons... thats just asking for trouble...

you have to consider the amount of added weight those huge bore slugs will be, and the rods and crank needed to keep them in check. I wouldnt try it on guts designed for 346ci....

99C5JA

The rods I could see being an issue, but isn't the crank on these motors considered to be very stout?

tahoe

I never said this would be a high rpm motor, there is actually, for some of us, a middle ground between drag racing engines (track or street) and showroom stock.

For my use, it would be a tow engine, max rpm no more than 5500 rpm.

//

silver-mod-o

iTrader: (15)

I understand your reasoning, but the charecteristics and physics involved in a stroker make the Tq to make it be associated as a "high torque, or towing" motor... the shorter stroke and bigger bore will be more advantageous in an application that called for higher Hp rather than Tq... the stroke length helps the Tq numbers... not ci displacement alone.

bottom line is, while its a good idea, I dont see it being ideal for what you are wanting to make it.

Hennytime

iTrader: (33)

from the sound of what you want, go with a longer stroke, itll cost less in the end and will get you more under the curve power

3.4camaro

iTrader: (1)

an all bore 401 would be badass for a high rpm road course car. You could spin that guy to like 9000 with a dry sump!!

tahoe

So what you are saying, is that a 5,3 could be spun to 9000 rpm with a dry sump?
same stroke......

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tahoe

As I understand, the standard stroke 401 would have mechanical advantages over a stroked 6.0, i.e. less piston rock and better (stock) oil control = no oil consumption.
The compression height would be same as stock, with the possibility to use the proper length piston skirt.

As for power under the curve, I feel that a big block 427 has the potential to create a reasonable amount of Tq under the curve!?
A CBB 427 has 4,25 bore and 3,76 stroke,
not far from what I suggest 4,20 bore and 3,62 stroke.
This is 1,27 mm diff in bore and 3,55 mm in stroke.
The diff is there, but the different displacement must come from somewhere.

For the stock stroke 401 being more expensive than a stroker 6.0, please explain.



//

Specialized

iTrader: (15)

Theyre saying that you're going to want to get upgraded rods at least. That will run you between 500-1400 depending on what you buy. Then machine work. You have to take all of this into consideration.

tahoe

I see no need to upgrade the rods, they are plenty strong for stock rpm and the Tq a Na 401 can produce. It might be a good idea how ever to upgrade the rod bolts.

As for machine work, there is no more machine work in boring a LSX to 4,20 than taking a 6,0 to first over size. Ok a bit more time consuming, but nothing to offset the 1000 dollar head start compared with the stroker.


//

njc.corp

i see what and where u are coming from-but i am pretty sure that new lsx block was intented for racers+hp junkies and to be strong-imo

so spending that kind of cash on a block defeats the pupose if u have no intentions to gain cubes,power,torque ,its a all out war block that needs punishment-etc etc-

i am pretty sure a mild ls1,ls2 would make a nice tow vechile-

to me it seems like buying a brandnew car and then putting second hand seats on a zero kay car-

this is my thought only----

silver-mod-o

iTrader: (15)

for that matter a bored .030 6L block (370ci) with the right cam and heads will make a VERY stout tow rig.... a lot of your choice wont be in the engine config, but in the cam profile and choice of heads IMO

-Trans gearing, final rear gear ratio, tire size etc etc etc.... all play a huge part in making a vehicle optimal to tow with.

tahoe

Ok thanks for the discussion and input.

I agree that there are less expensive ways of creating a strong Tow/DD motor, but I havn´t been proven wrong yet when a bore only 401 is compared with a 402 stroker.

I will post before and after dyno charts what ever route I choose.

//

Hennytime

iTrader: (33)

let him do his high rpm designed 5500rpm tq bore motor with stock rods....

tahoe

Yes, it my money, not yours!

sr71bbjr

iTrader: (52)

The crank is fine...I would most def. throw in a billet rod though..Howard makes great rods at a affordable price..Would be a good solid roller motor..Titanium valved heads,and a sheet metal intake..9500 rmps sound good to me..

3.4camaro

iTrader: (1)

I'll prove you wrong.

All things being equal, a 401 all bore will NOT make as much torque as a 402 stroker because of the lever size on the crank during the power stroke. A longer stroke puts more turning force on the crank, because the lever arm is longer.

On the flip side:

All things being equal(i.e. piston speed), a 402 stroker will NOT make as much HP because it can't spin as high as an all bore 401. This is because each rpm in the stroker is making the piston move an extra inch or so compared to the all bore, and there is a magic piston speed(i think 4800 ft/min) that you can't or don't want to go past. Look at the F1 engines: V8's with like a 2.3L displacement. They don't make a whole lot of torque, but they can spin to 20,000 rpm because the stroke is so short. This equates to about 1500 HP NATURALLY ASPIRATED!

Bottom line, if you want to tow something, go 402 stroker. It WILL make you happy.