13 sec 2.8/3.4 rev monster?

JamesCurtis · Post by **JamesCurtis** » Mon Apr 11, 2005 3:06 pm

Is there any reasonable way (without ghastly amounts of $$) that you can make the 2.8 rev past 7000? I am starting to lean towards building a boat anchor that will put me in the 13's instead of swapping in a 3.4 dohc. I'm just wondering if there is enough aftermarket out there to make a 2.8 that will spin 7 grand all day long without puking out its innards. Obviously this takes money, but that's what this thread's all about. Analyzing the boat anchor & its potential. Also, I would like to do a turbo setup, I'll be back later to post more questions, I have to get to class. So say I got the true leo intake, 2.5" exhaust behind the turbo (maybe 3"?), hogged out heads, and a turbo cam with roller rocker arms & performance springs (haven't done alot of research). Would I be able to do this on 10 lbs of non-intercooled bost? And does anyone know of a good book to read on turbos, I'd really like to read more about them.

Kohburn · Post by **Kohburn** » Mon Apr 11, 2005 3:37 pm

its easier to make one to widthstand the forces of 8000rpm than it is to make one that will breath well and make power up there.. if you don't want to go dohc you can go 3100 or 3400 - those engines are still pushrod and still breath well not to mention the reinforcing cast oil pan that bolts to the crank carriers.

with work, boost and $$$$ it can be done - probably easier and cheaper to do a swap though

Shaun41178(2) · Post by **Shaun41178(2)** » Sun Apr 24, 2005 2:05 pm

stock rods can handle what you have planned for it.

The rods have been proven to hold up to 7k rpm.

Its the small bearing journals that usually are the problem. not a lot of surface area and its easy to push that think layer of oil out at high rpm allowing the rod bearing to touch the crank.

HV oil pump is a must.

JamesCurtis · Post by **JamesCurtis** » Mon Apr 25, 2005 1:46 am

Hey guys, i'm starting to think that a turbo engine is out of my skill level and out of my price range. I've decided it's just gonna be a high-winding n/a engine til' i get the $$ somewhere down the road. I should've mentioned forged pistons, but that pretty much goes without saying when talking about forced induction. One thing i'm wondering about now is how much different is a nitrous setup (engine wise) than a turbo setup, as in internals. Do they like different grinds, high revs, etc. I remember hearing somewhere that nitrous really likes exhaust. Oh well, time to go do some more research

The Dark Side of Will · Mon Apr 25, 2005 5:50 pm

N2O and superchargers both like cams and heads that favor exhaust because they naturally produce a lot more exhaust volume relative to intake volume than N/A and turbo engines.

Kohburn · Post by **Kohburn** » Tue Apr 26, 2005 8:18 am

yeah I was gonna say you can basicly tune it for NA then "slap" on nitrous and it'll be happy

(slap meaning you do it right so you don't blow the shit out of the engine)

JamesCurtis · Post by **JamesCurtis** » Thu Apr 28, 2005 2:18 am

Good thing you cleared that up kohburn, and to think, I was just about ready to slap the engine real good with a Nitrous bottle and call it good :la: Nitrous sounds like the best thing for me. One of these days I'll have a turbo car though..... one of these days

JamesCurtis · Post by **JamesCurtis** » Fri Apr 29, 2005 7:32 pm

and to think, I was just about ready to slap the engine real good with a Nitrous bottle and call it good

wow, talk about dry humor. I really shouldn't be posting that early in the morning with no sleep...

loudias · Post by **loudias** » Sun May 29, 2005 11:16 am

you could always destroke it to 3.1 (2 . 8 crank and pistons with the 3.4 bore) but then it wouldn't be a three point four now would it... You'd also have to get the v8 connecting rods...to play it safe.

ZeroC · Post by **ZeroC** » Sat Jun 11, 2005 9:24 pm

loudias wrote:You'd also have to get the v8 connecting rods...to play it safe.

Christ I Hope Your Kidding ...Im Guessing A Shop Did Your Last Engine Build Right ?

Aaron · Post by **Aaron** » Sat Jun 11, 2005 10:59 pm

loudias wrote:you could always destroke it to 3.1

Now what purpose does that serve? The engine already doesn't have issues reaching 7200rpm, and with a new intake manifold and cam timing has gone to 7500rpm, and I will be revving mine to 8000. Destroking will just take away power.

loudias · Post by **loudias** » Sun Jun 12, 2005 2:23 am

um

you never heard of the magic rod length to stroke ratio?

supposedly 1.75 is the perfect ratio.

a 3.4 (5.7" rod and 3.31" stroke) has a 1.72 ratio which makes is close but on the torquey side. a 2 .8/3.1 (3.1 with a 2 .8 stoke and 3.4 bore) has a ratio of 1.906 which makes it a revving machine.

It's all about what you looking for. Torque or horse power...and it starts with your bottom end.

So I guess you've also never heard of de-stroking a 454 to a 427 in order to get more top end horse power?...and a 350 to a 327?...and a 302 Ford to a 289? It all depends on what you are looking for.

To get the right height with a 2 .8 crank, 6" rods are almost perfect. That gives to a high spinning 2.0 ratio.

donk_316 · Post by **donk_316** » Sun Jun 12, 2005 11:50 am

ZeroC wrote:
Christ I Hope Your Kidding ...Im Guessing A Shop Did Your Last Engine Build Right ?

Dont post about things you dont know about.

Early style small block rods with the 2" main journal size with minor big end narrowing will fit into a 660 giving you a better rod (assuming you go aftermarket) and a 6" length (again, assuming you go aftermarket)

For 289 USD raceparts.com sells the Small journal 6" H beam rod set of 8

Detroked DOHC:
May sound like a bad idea , but like buddy above me has stated destroking is the easiest way to get a motor to rev fast and hard with no loss of high end HP and effectively moving the peak Hp numbers higher into the powerband. A dohc destroked theoretically hits its max HP at 7000 not 5500 rpm. The loss of torque is bugger all and who cares about low end torque when your building for all out RPM HP.

Dont think of it like its a 3.1 now and it will act like a 3.1 Pushrod engine in the way it revs and behaves....think of it as a destroked DOHC with a shorter stroke and that can rev to the moon and back quicker than you can imagine. Its not for everyone....its for who wants to be the fastest. Now turbo charge that destroked DOHC and guess what your comparing too?

Aaron · Post by **Aaron** » Sun Jun 12, 2005 12:11 pm

I know what destroking does. But I just don't see the point when with bolt ons it will already pull hard to redline, and far past that in some cases. The enigne already revs high, and can make power up there.

donk_316 · Post by **donk_316** » Sun Jun 12, 2005 1:32 pm

Aaron I have sent you a few PMs but i dont think they are getting through.

loudias · Post by **loudias** » Sun Jun 12, 2005 4:30 pm

Well the original post was about a pushrod motor so where destroking a dohc 3 .4 may not make much sense, a pushrod 3. 4 might if the goal is high revs.

Aaron · Post by **Aaron** » Sun Jun 12, 2005 5:34 pm

loudias wrote:Well the original post was about a pushrod motor so where destroking a dohc 3 .4 may not make much sense, a pushrod 3. 4 might if the goal is high revs.

I agree, that would help the pushrod motor go up higher. But I doubt you will get a 3.4 OHV to rev to 7000, making power the whole way, without some sort of custom intake manifold and camshaft, and headers wouldn't be abad idea either. Those, in addition to a destroke, can get you to make power at 7000. But, for all of the work, time, and money it would cost, a stock 3.4 DOHC would still make more power at the same RPM, with limitless untapped potential.

The Dark Side of Will · Mon Jun 13, 2005 1:04 pm

loudias wrote: you never heard of the magic rod length to stroke ratio?

supposedly 1.75 is the perfect ratio.

Lots of people have said this... have you ever read a good technical explanation to support that claim?