no replacement for displacement????

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Prine said:
I apologize man...really. This forced induction stuff is really out there for some people and I am trying to be as upfront and honest as I can, and felt like you were calling BS on what I said.
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Oh I wasn't calling BS, just questioned the % of hp increase.

The problem is not all platforms are equally blessed with an optimum selection of components that will give you a desirable "doubling of hp per 1 bar of boost"

While this maybe true with some advanced 16V designs (like the DSM and Honda packages) with proper turbo systems other engine families will respond less favorably.

I'd wager if you ran the average 5.2 Dakota (230hp) at 14 psi with a turbocharger chances are it would not provide you with 460hp due to a poor intake manifold (torque design) and other restrictions.

HP estimates from 60% to 100% increase would all be reasonable, depending on the parts.

And its all on a sliding scale, the first 15-20 pounds are great and then you start to run into declining returns...

I actually got the Reliant down to a one to one pressure ratio between exhaust and intake pressure, no mean feet with a crappy flowing 8 valve.

We DSMers have a joke...you know what a 400hp, 600hp, 800hp Supra have in common?....a stack of 12 second timeslips. :snakeman:
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Yup, I've heard that.

If the guy didn't blow the launch I'm not sure I would have reeled him in during the first half of the race. He cut a perfect .500 light while I held back to make sure I didn't light the bulb.

I was out accelerating him at all points of the track till the 1000 ft mark when my old combo just runs out of steam.

Peace!
 
I would have to side with GD on this one. In my experience in my small block Mopar I have found that boost is is good, however the "double the HP" formula for every 15 pounds of boost doesn't apply. It is way better than some of the other "land of diminishing returns" power adders. Especially if you keep moving up in size on your turbo while maintaining around the magic 15 pound mark.


On another subject, if I had to do it all over again with a clean sheet I would go big block. The base HP is important since its multiplied on boost. A big block has several structural advantages. Deep skirt block, stronger crankshaft, and 5 head bolts per cylinder come to mind.

I have had the pleasure to co-build and help sort out 2 LARGE Procharger cars that make way more than 4 digit power. They have a lot of problems and are really hard to harness, IMHO I think they turbo is easier on parts and has more tractable power.


Ebay turbos are tempting, but turbos are like anything else. You get what you pay for, and coming from a guy who had a turbo come unhinged, its devastating! I destroyed a very expensive set up by using a questionable turbo. Never again. Have fun guys its fun!
 
The sand is another place where there is an acception to the rule of displacement. That acception is weight. There has been a lot of guys left sitting there wondering how there 500+ HP LS powered rail just got smoked on buy a little VW 2180 that only makes 200HP. There most all around 2500-3000 pounds and were at 680 pounds. Weight is very important in sand. Way more so than HP or displacement.
 
There are a few people pushing the 5.9 magnum block with half fills right now on some dakota to right around 700rwhp. If you dont have the block and everything already what about going with the new hemi? Can start finding some cheaper now and they can handle some decent hp once you replace internals.

On a stock bottom end my '99 dak r/t made 435rwhp@ 11psi on a small si-trim Vortech. I was using met/water injection for cooling with 91 pump gas. It should have probably made better but was hitting the limits of the stock fuel system. Also just for reference it made 300rwhp with everything being the same except tune and s/c.
Originally was wanting to go boost on my dart but some how ended up trying to do this one n/a and running 13/1 comp (love e-85).


Troy
 
Prine said:
yes....air to water kits like Frozenboost has.

I advocate Water Injection, because of the simplicity, the Lowes/Home Depot "repair" parts...and the effectiveness.

I also advocate (WI) because it does not hinder engine compartment/glovebox/inner fender/mounting.....a simple 1 or 2 gallon water tank somewhere....a electric RV water pump, feedline, a nozzle...a hobbs switch for the pump Power....your in business.
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Most people forget to think about water in a na engine.. Before I got blown I had a 500 inch motor very prone to det.. I put a spray nozzle under the carb.. viola.. pump gas nb...
 
Just my kinda late 2 bits:
A supercharger "fools" the engine into 'behaving' like it has more displacement.
If you calculate the amount of air that your engine moves naturally aspiriated per minute.
We will call this 'Dynamic Displacement'.
Now add the amount of air that the forced induction system slams into the engine to that.
To keep it simple:
360 CUI engine plus a 140 CUI huffer will act LIKE a 500 CUI engine.
Notice I put LIKE.
In reality, it actually will put out slightly MORE, with a properly designed system, especially a turbo.
Why? You get the power of the increased amount of fuel and air BUT you dont have to have larger, heavier pistons, conrods, heavier valves with fatter springs, harsh cam profiles, and the rod ratio is more effecient. This means a far lower mechanical power loss . If you cant make more power, then free up the power that you have.

The assembly spins up faster, too.
THe more power earlier into the RPM band the more effective work over time the engine puts out... or power increase.

At part throttle cruise the engine behaves as though it has lost those cubic inches and mileage goes up!

Forced induction is the way to go, IMHO.
 
turbodart68 said:
I would have to side with GD on this one. In my experience in my small block Mopar I have found that boost is is good, however the "double the HP" formula for every 15 pounds of boost doesn't apply. It is way better than some of the other "land of diminishing returns" power adders. Especially if you keep moving up in size on your turbo while maintaining around the magic 15 pound mark.


On another subject, if I had to do it all over again with a clean sheet I would go big block. The base HP is important since its multiplied on boost. A big block has several structural advantages. Deep skirt block, stronger crankshaft, and 5 head bolts per cylinder come to mind.

I have had the pleasure to co-build and help sort out 2 LARGE Procharger cars that make way more than 4 digit power. They have a lot of problems and are really hard to harness, IMHO I think they turbo is easier on parts and has more tractable power.


Ebay turbos are tempting, but turbos are like anything else. You get what you pay for, and coming from a guy who had a turbo come unhinged, its devastating! I destroyed a very expensive set up by using a questionable turbo. Never again. Have fun guys its fun!
Click to expand...

Prochargers are a serious hoot on a bb.. the instant on torque is a near sexual experience.. I can see the advantage to the slight turbo lag getting off the line for a turbo though.. I dont drag race but it would seem an advantage. Beyond that the procharger has a very predictible power curve all be it exponetial especially after 4K rpm.. but in the interest of harmony.. I sure dont have it all figured out yet..
 
Dave_n_68383S said:
I can see the advantage to the slight turbo lag getting off the line for a turbo though.. I dont drag race but it would seem an advantage.
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Lag with a turbo? 28 psi on launch!

[ame="http://www.youtube.com/watch?v=dYuo5pUqnZ8"]YouTube - Reliant vs Supra at dragstrip[/ame]
 
gdonovan said:
Lag with a turbo? 28 psi on launch!

YouTube - Reliant vs Supra at dragstrip
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point taken.. I used to own a shelby turbo back in 85.. bought it new.. I remember winding that little 2.2 engine up to get it going ! problem with that things was the trans.. I blew two of them up in short of 20K miles. Still it was a fun ride.. later I traded it for a mustang 5.0 which was faster and had a bullet proof drive train.

As stated I dont race so what do I know... :toothy10:

for fun though I should get a utube of my 474 on a procharger smoking the tires off idle starting from second gear.
Unfortunatley I'll have to wait til spring now, I have her all taken apart for the winter projects.
 
Dave_n_68383S said:
Prochargers are a serious hoot on a bb.. the instant on torque is a near sexual experience.. I can see the advantage to the slight turbo lag getting off the line for a turbo though.. I dont drag race but it would seem an advantage. Beyond that the procharger has a very predictible power curve all be it exponetial especially after 4K rpm.. but in the interest of harmony.. I sure dont have it all figured out yet..
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I hear ya Dave, I dont know it all either. I will say that when a Procharged car comes on boost it sounds incredible! It makes the hair stand up on the back of my neck!
 
turbodart68 said:
I hear ya Dave, I dont know it all either. I will say that when a Procharged car comes on boost it sounds incredible! It makes the hair stand up on the back of my neck!
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They do sound cool.....[ame="http://www.youtube.com/watch?v=zagXF6692lQ&feature=related"]YouTube - 1000hp Duster[/ame]
 
The only replacement for displacement is dollars. Barring dollars, displacement is king.
 
sr71mopar said:
The only replacement for displacement is dollars.
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Don't agree.

Some turbo kits can be done very cheap and forced induction butt.

The most expensive part of the Reliant was turbocharger which in a lot of cases would be cheaper than what people would spend for a forged slugs alone with a V8.

I was deep into the 12's with bone stock parts and running 11's with a mild turbo upgrade.

Not bad for 153 cubic inches.
 
The best replacement for displacement IS knowledge of internal combustion engines....and experience with how they react to being Forced Inducted.

Experience is the hardest ingredient to acquire.

Trial and Error will lead you to the promiseland.

One day the information that you will have collected throughout your experiences will just "click" and the angels will sing and you will have to become a Volumetric Effificiency formulatic wizard to calculate the airflow vs volume vs pressure deviants to the inth degree.

Accomplishing this will only cost:

1 long block
2 crankshafts
2 sets of rods
2 fully built, ported and polished cylinder heads
3 blown head gaskets
2 FOD injested turbochargers
2 lo-quality air filters
4 fuel system upgrades
2 or maybe 3 transmissions
4 sets of tires

It sure is worth it though!!!! :-D
 
turbo boost is sexy.ive had nitrous cars and ridden in superchaged cars and nothing compares to the feel and sound of a turbo.the only thing close is the sound high compression big block.......just remember though its not turbo lag its foreplay
 
I'm really interested in this thread. I am wondering if for any given mod, engine for engine, wouldn't you be better starting off with a bigger displacement?
Just asking with my haven't had coffee adled brain.
 
Revhendo said:
I'm really interested in this thread. I am wondering if for any given mod, engine for engine, wouldn't you be better starting off with a bigger displacement?
Just asking with my haven't had coffee adled brain.
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I asked one of the local shops that does turbo work the very same question. His answer was basically at 15psi a forced induction motor will perform like it's size has doubled, all things being equal. He said in the case of a car with a cramped engine compartment this is not necessarily true. If the headers are a compromised design, if the turbo was to far from the collector, mentioned something about using timed exhaust pulses (read that in a boost book also). He claimed all of this comes into play. One of the things he mentioned was an exhaust system. He claims one of the things you want to stay away from is a chambered muffler, as this creates resistance. He also mentioned that while a big hp turbo car needs a larger exhaust, going gigantic does not necessarily help. Again, these are all his claims, take them for what they are worth....the company is http://www.wrenchrat.com/
 
If I remember correctly, isn't it the exhaust heat that spins the turbo? I would think that some backpressure would be of benefit. Or is it just that once the exhaust is thru the turbo you want to get it out as fast as possible?
 
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