Destroked 400 with a 327 cam makes 348 right? basically a 5.7 ltr. But with a shorter stroke and larger bore right? Both are single rear main seal. Would this be easy to do? wont it rev easier and with more torque (then 350, not against 400) because of the larger bore? thanks.

 

Here we go again

 

Spend all that money for a 400 block build, just to get 348 cubes? Also it's the crank not the cam that's in question. It will rev easier for high end power, but as far as torque goes, it will do worse at the low end. The short stroke means less mechanical advantage as the pistons get less leverage on the crank. This means that the engine will produce less torque at the crank. I think the best way to go with a 400 block is a 400 or bigger. If you are going for an all out rev happy race engine, maybe a 377 (350 crank). Usually wantonly giving up cubes is not a good budget performance route.

 

The advantage to having this kind of motor is it has a larger bore and the flow charateristics that go with it ( i.e. the 305 shrouds the valves but this motor would not).

Then you have less rotating mass and higher rev capability. The problem is you have to spend alot more money on the valvetrain to get the horsepower up in the rpm band. if you just stuck with the 400 crank the valvetrain would be alot cheaper for the same horsepower.

 

Yup!

Last time I saw this question posted it got after a lot of bickering.

 

I feel the need to say for others that will read this reply,,, I would NEVER destroke and kill the cubes of a 400 unless there was some cubic inch rule in effect. Now with that out of the way:

You can make similar power with a standard 355 as a destroked 400 w/3.25 crank. Optimal to optimal power, the destroked 400 should deliver better hp to cid, but when you start comparing HP to $,,, you TYPICALLY can spend the money you save by building a standard 355 and put that in the heads (where it REALLY makes the most impact),,, and run circles around the destroked 400.

Now,,, if you’re limited to what heads you can run and the cubic inches,,, I like the destroked 400s. However, you need to know there are subtle differences needed in the combination selection (like the cam and gearing) and to understand why to take full advantage of the short stroke combination - especially if you're talking dirt track racing. Still,,, the difference in power or how much quicker the engine is,,,,, could ultimately come down to tuning, how well the engine is built, and the overall combination.

 

Taking cubes away is like beating yourself in the head with a hammer. Its stupid. The only time it makes sense is in a racing class situation where you are limited to Cubes. It will not help you get higher RPMs. It wont make it rev easier, it wont do anything but take away cubic inches.

 

What is the casting number of this 400 block with a 1 pc rear main oil seal?

Read this thread:

https://www.thirdgen.org/techbb2/sho...hreadid=266018

Catch the basics of where this thread will probably take off.

 

Someone should do a DD graph comparing a 302 to a 327 to a 350 to a 383 to a 400 etc.
All with the same cam etc.
And then post it under FAQs
And this question would never have to be asked again.
It's a lot more meaningful to look at data on a graph, than to have someone try to explain it verbally or in text.

I think it would be worthwhile, cause there is a difference in the power curve when an engine is given a longer stroke. And some guys are curious about that sort of stuff. So give guys a graph to look at.

Somebody.... PLEASE!!!

 

Hey, now there's a great idea!! :hail:

 

when you are trying to go fast with real street tires (and i dont mean drag radials) would you benefit from a shorter stroke because of traction limitations? and once you hook the power would come on strong?

 

delete

 

that link isn't working for me...

 

That was a long shot, not surprised it didn't work.

 

delete

 

still not working but if i shorten the link like this:
http://us.f1.yahoofs.com/users/
i get this message:
The requested URL is a directory, and directory accessing is disabled on this server.

 

It looks like you're posting an attachment in your e-mail. Unless you want to give everyone your mail password, that's not going to work.

 

I have posted this in the past, and luckily (spelling?) I still have it. It's a clear explanation of why a 350 makes more overall power than a 327 everywhere else except above 6,500 RPM.

That was using the same cam, same heads, same compression ratio, etc. on DD2000.

I am going to be building a 400 block with either a 350 crank (not cam ) or a 327 crank simply because the block I have has chunks out of the bottoms of #1 and #2 cylinders. I don't really feel like having it repaired, other than filling it with block filler and grinding the edges smooth.

I don't feel comfortable with the idea of having the piston skirts that close to the bottom of the cylinders and risking their instability by using a 400 crank.

Besides, I don't have a 400 crank, but I do have a 350 crank.

In all honesty, to each his own. If you really want to build an engine like that, and have the funds available then do it. It's your engine, not everyone else's. Just realize that just because it's different doesn't mean it's "better".

If the 350, 383, and 400 engine combos weren't good they wouldn't be as popular as they are. :shrug:

 

Here's another Combo of what everyone had requested. Nothing else is changed except the bore and stroke of each engine.

Just to give you an idea in case it's difficult to see.

The top green line is the 400 torque curve.

The next green line is the 383

Next is the 350

Next the 327

Next the 302

Can you guess what order the red lines are in?

Then above ~ 5,000 RPM is where the opposite occurs.

The top red line is the 302, the next is the 327, etc. etc.

Does this help everyone understand why there's no replacement for displacement? Unless you're only really looking to make more HP above ~5,000 RPM on an otherwise mild-to-slightly aggressive engine (or "dare to be different), there's no reason to use an engine that's smaller or has less stroke.

 

Here i hope you can read it 400-383-250-327 AFR 195 XR-274-12

 

Bastard you bet me while i was cropping it.

 

And here are the specs that I used for all the engines. As I said, nothing was changed, other than the bore and stroke of each engine.

And before anyone asks "why did you use that cam?" or "that compression?"... because that was pretty much all DD2000 Default settings.

 

As you can see from the graphs, engine size does not effect the peak hp that an engine combo makes, its the components. With everything the same except for engine size, peak hp is the same. This does not occur for torque though, bigger engine = more torque, smaller, less.

 

I know mine was built with what I consider "streetable" power at 5500 RPM's or lower. There's just no real need to spin it up that high to get some power from it because the displacement gets the car going pretty quickly!

Now the trick is getting it to the ground without breaking anything! lol

 

Hi all,

I didnt think this would be such a problem. I dont care whats better in sense of power. I DONT want too much power. Let me rephrase. I want about 375-425 (flywheel) with street headers and hsr, prefferably with vortec heads but that has obious problems so im leaning to afr's/trickflow. I wont have a problem getting that with almost any cu in and almost any high power combo.

I believe my stock l98 has enough mid range toque all across the powerband for city driving. I want the SAME power (maybe slightly better) from 2000 - ~5000 but have A LOT more power up high. And a much higher revving engine (7000 would be beautiful)

I thought that a destroked 400 would be better at doing that. I just wanted to know my options.

I want.
1, something different.
2, no more then flywheel 425hp (cause i dont want to upgrade the heck out of my drivetrain)
3, Decent milage (i cruise at 12-1800 rpm all day with awsome milage and still get to light it up and win more cars i see)
4, Quicker revving. Better throttle response. ect...
5. Plus i'de like to be able to have a 350 rev to 7000. I thought a 348 would be easier to do that with.



I thank everyone for their replies, and look forward to more.

 

If you want to rev to 7k, you'll need a flat tappet cam and a strong bottom end. I also doubt you will get L98 low end torque. Odds are your fuel economy will suck. You can get 375-425 horsepower with less than 6k with a well chosen setup on a 350.

 

dont NEED 7000rpm, 6 is even fine. Just want same power now, much more power later

edit * and hopefully around the same fuel economy at low rpms (below 2200). I dont care if it burns twice as much fuel at 5500rmp. its just low end economy i need. i dont mind being really easy on the throttle 95% of the time and just stand on it when its safe on the rare occation.

 

Dont waste your money "destroking" the engine. Spend as much as you can on the valvetrain and heads. Thats where the power is. To get 425 HP, you really cant be concerned with economy. I think you should evaluate the entire situation again and set goals.

 

Look at the graphs with the same components all the engines of differring sizes have the same peak hp potentional. Of course the smaller the engine the more it will have to be revved and the more gas it will use. Also the smaller engines will use more gas because they are not as efficient and lower cruise rpms.

Build a 400 and be done, it will be a much better combo, for everything you wanted.

 

in a nutshell

you build your destroked 400
i build my 400.
they both rev the same. they both have the same max RPM.

mine just makes more power.

 

I think that the graphs that have been posted create a strong argument for strokers, but at the same time they create an argument in favor of short stroke engines. If you happen to be someone who wants more power above peak TQ, at the expense of some bottom end.
Anyone will have to admit that in the graphs that are displayed, the 302 has a pretty flat TQ curve.
But on the other hand, it could be argued that camshaft selection could potentially play a role in extending the power curve where it falls off too early on the larger engines. For example the TQ curve for the 400 with the 236*@.050 cam has the same shape as the curve of a 350 with a 218*@.050 duration cam, only about 50 lb/ft stronger overall. And on and on...

So where that actually leaves you is... If you aren't into playing keeping up with the SBC Jonses and you want an engine that revs higher at the expense of some low end TQ, you can do a destroked 400.
But don't expect to get any standing ovations for it here, cause the TGO guys (or at least the most outspoken ones) don't advocate short stroke engines. Which totally makes sense. And it can be quantified as well, both on the dyno and at the track.
But the thing that can't be quantified is the enjoyment you get when you're redlining it at 7K in third and you still have 3 more gears to go. As long as there's no one there to ruin the moment for you by passing you.

 

Sure but you can do that in a 434 or a 377. Which one is going to be more fun?

 

sure it can.

the enjoyment of redlining at 7.5k with a aftermarket crank 415 still pulling strong > the enjoyment of redlining at 7k with a stock crank destroked 400.

 

"Anyone will have to admit that in the graphs that are displayed, the 302 has a pretty flat TQ curve.
But on the other hand, it could be argued that camshaft selection could potentially play a role in extending the power curve where it falls off too early on the larger engines. For example the TQ curve for the 400 with the 236*@.050 cam has the same shape as the curve of a 350 with a 218*@.050 duration cam, only about 50 lb/ft stronger overall. And on and on... "

Correct here is a comparison with the larger motors getting larger cams 327-400. XR274-XR292

 

As you can clearly see the 400 still makes way more torque and way more hp. I'd go with the smallest engine possible if it was me, i hate going fast.

 

ME Leigh,

I'm at work so I can't do this now, but maybe you could try cams that would favor the high RPM nature of the 302 and 327?

Perhaps a single plane intake manifold as well?

Not saying it can't be done on a 400, 434, etc., but as I pointed out in the last thread, the stock rotating parts of shorter stroke engines are "cheaper" to build simply because things like light weight pistons, H-beam rods, etc. aren't as necessary to hold things together because of higher tolerable RPMs.

I guess I'm saying, in general, show a cam that would accent the particular engines' attributes. 400 for torque, 302 for high RPM... yadda yadda yadda.

IMO, the basic overall design of the 302 bore/stroke combo was never made to produce torque, so why bash it because it will obviously loose to a 400.

Thanks

 

I'd suggest building the biggest engine you can afford. That cost would include the driveline parts needed to support your engine combo, and the fuel to power it.
The thing that's important, is to be aware of what you're getting into in advance.
But still I believe that there's validity to the point that if a guy has the desire to do a destroked 400, he ought to do it, as long as he's aware of what he's getting into, and the pros and cons.
If someones desire to build a certain engine combo outweighs his desire to win races against cars with larger engines, that's his business. It might seem illogical to the majority, but so what. That's why we each have our own car.

 

Sure i could do that but your assumption are incorrect. Stroke length plays a very insignificate role in torque production. It all has do with and is directly proportional to the amount of fuel burned. This means that a bigger engine no matter what the stroke will make more power, plain and simple. Say you build a 350cid engine one with a 4.14 bore, 3.25" stroke and another with 3.73" bore and 4.0" stroke. They will produce essentially the same power all the way up to about 4500rpm where the short stroke engine will make start making more power. THis is because the shorter stroke engine will "breath" better because of the limited time to fill the chamber when rpm's get really high and the ability to fit bigger valves in a bigger bore. Also there is less work needed to overcome the friction force of a short stroke engine.

From your calculations could you please tell me the rpms for the maximum safe piston speed for a 3.75" stroke and 3.0" stroke. I believe its something like 5000fps. I could do the calculations really quick and easy but i'm leaving now.

 

DD2000 is
dd2000 said my engine will make 524 hp it only made 450 hp on the dyno.

 

Yes the numbers are off but it is a very good tool for comparing builds. Infact thats all it really good for.

 

Sounds like you made an error on the model.

 

I think you have to consider what your doing withthe motor / car.

To many people here focus on straight up 1/4 drag racing.

If you are doing road course and shifting gear a 7200RPM you eengine choice is different.


Even street racing is different as its never a real 1/4. Its a mile or more. usually when ever who lifts or run out of RPMs.


-----------------------------------
MotorHead MaMa's
Where Deep Strokers and Big Blowers bare it ALL!!!

Http://viragotech.com/buick/motorhead_mamas.html

 

Nevermind.

Too many of you are too much into the dragstrip competition part of building engines. Not that there's anything wrong with that, but my points that I'm making, and have made are for the average guy/gal that's building a car that's fun for HIM/HER to drive.

Therefore you're completely missing my point(s).

I guess I'm a little too open minded to get into any specifics when I say "the basic overall design of the 302 bore/stroke combo......."

Just forget it. I feel like I'm trying to explain to an eskimo how a freezer works.

 

I gonna try it someday anyway. Still saving up $$ hahaha. I've talked about it before and alot of people think I'm retarded. In an all motor setup, I agree with them, it would be retarded unless you are in some racing class. More cubes = more power. But I'm gonna be boosting this setup and racing top end so its a little different in my opinion. I think high RPM use compliments certain boosted setups (not roots of course). I think you better utilize the power adders if you have a longer powerband. I think the debate in this situation is power loss versus strain on the engine. Sacrafice those cubes and possibly the motor will last longer at higher RPM's. Run a few more PSI and make up for those sacraficed cubes. Weather or not its gonna be worth it, who knows. I'll honestly never know how much power I "lost" versus how much longer the engine lasted because it was destroked (or if it even made a difference at all). I'm just hoping this setup dosnt explode. I know when you push the limits every little bit helps. I'm willing to sacrafice some power if it might help. Two T04E turbos and a 3 bar map sensor, somethings gonna break hahahaha.

 

More .

It will not cost anymore to get a 350 to spin 7k than a 302, or a 400.

 

I'm fully supportive of guys building short stroke motors if they want to.
In fact the jury is still out on what I'm going to do with my next build.
The thing is... Unfortunately, it's too easy to argue the case for a larger engine... MORE POWER so when there's a debate taking place, the big inch argument always seems to come out on top. In truth it's simply a case that's easier to present, easier to quantify. But that doesn't nessecarily mean that's what's best.
I think there could possibly be more subtle reasons why a shorter stroke engine might be a good idea.

So anyway... What are the specifics that you're referring to (above) AJ_92RS?

Edit:
When an engine builder is willing to define his project mission as To Build A Better Engine as opposed to Building A More Powerful Engine, it changes the parameters of the project, and a shorter stroke might become more applicable.
But you'd still have a hard time convincing the big inch advocates. Cause how do you define better? Have a "betterness" competition??

 

It's so nice to see someone ask instead of trying to prove me "wrong". :lala:

The same reason some people swear by big blocks, some people swear by turbo, some superchargers, 350's, 400's, 327's, etc.

Someone who wants to build a 302 isn't building it for torque. If they are, then that does make them a fool IMHO. And MOST people (key word there) don't build 400's (or bigger) for high RPM power. They primarily build them for torque.

Why would people want to build either one?

Some people want that high, 7000+ RPM scream. Some people want that 1/4 throttle blip that sends tires screaming for blocks in protest. It's all what the person wants to build.

Just because they're building something that's not as common, and may spend more doing it, doesn't mean they're stupid. Let's face it... what's one reason we own third gen cars? Because everybody and their brother has a Mustang. So I guess (well I don't "guess") that all Mustang owners think we're dumb for not owning the same car they do.

And regardless of who thinks "the math" doesn't relate to real world, how do you think the displacement of an engine is figured? Or the bearing to rod journal clearances? Or HP? Or Torque? It's all math. Hell, even speed is math.

Anyone who wants to refuse that fact is simply overlooking the details that make or break an engine. Regardless of what they say, piston speed is a factor in how high the bottom end of an engine can spin before things start to propel themselves through either the cylinder head or the oil pan. Once the speed is reached (the "common law" is 4,000 feet/minute and I've heard as low as 3,500), other things have to be changed, and more money spent. Using a shorter stroke is one way around that. Just because their mother's sister's husband's brother ran his stock built 383 to 8,000 RPM (maybe even more than once) doesn't mean it's OK for everyone to do it, nor does it make it OK to do "sometimes".

Couldn't have said it better myself. :shrug:

 

Problem is that old saying. Why spend $2.50 on a salad when BigMacs are 2 for $2

Just cause you get more for the same amount or less, does not mean its gonna please everyone in the same way.

 

I probably could have said it better, but then there would have been some tradeoff in low end torque.

 

Interesting article.

http://www.airflowresearch.com/artic...le03/A3-P1.htm