Greddy Turbo Installed - Details Inside!!!!
#876
Originally Posted by dmp
I still don't buy 100hp from 7psi on a 1.3L. I probably can't argue 'why', but that's where I stand. IMO, mid 200s at the wheels is the most one can expect.
fwiw, on my last car - 2.5L Mazda V6, my car went from ~160whp to ~250 whp on 8psi - similar sized turbo as the GReddy RX8 kit uses, IIRC.
Side note: Quoting 'crank' HP is a bad habbit, imo...it's impossible to measure, and in reality, doesn't mean squat.
:D
lol :D
fwiw, on my last car - 2.5L Mazda V6, my car went from ~160whp to ~250 whp on 8psi - similar sized turbo as the GReddy RX8 kit uses, IIRC.
Side note: Quoting 'crank' HP is a bad habbit, imo...it's impossible to measure, and in reality, doesn't mean squat.
:D
lol :D
#882
RX8 and a Truk....
Originally Posted by twospoons_
By using the same algorithm I came to 55.4% increase in power using 8 psi. So, 248.64 hps on the mazda v6.. Guess there isn’t that much magic to this after all.
yeah - 248hp at the wheels - A side note, I had 17hp MORE in 4th gear, than in 3rd, during most dyno pulls.
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
Remember....the V6 had a 1.2L more displacement.
![Wink](https://www.rx8club.com/images/smilies/wink.gif)
Still, I'd rather be pessimistic - if you expect the worst, you won't be dissapointed.
#883
Registered
iTrader: (5)
Now I will tell you again why you can't tell hp gain from pressure.
Go to the first few pages of the axial flow thread or search for the plots produced by Turbine_pwr.
Here he shows you the mass flow for different efficencys.
I'll give you a simple equation to show what gets into the engine, it's called: density ratio. As opposed to pressure ratio which is what you guys are using.
P2/P1 = Pr
Pr x T1/T2 = density ratio or the actual amount of additional mass entering the engine.
Temps are in degree R, or absolut F. Or ambiant plus 460.
Given a Pr of 1.5 which is roughly 7.5psi. Then given an efficency of 65% we can calculate the temp rise.
Pr to the power of .283-1 gives the y factor
So 1.5 ^.283-1=.1215
this times the tempR at std cond=520F
=63 F at 100 % eff.
divide by eff so 63/.65=97 temp rise
so 520 + 97=617 therefore 520/617=.84
.84x1.5=1.26
so if you want to use your 14.7 std times 1.26 you now have18.6
or 18.6-14.7=3.88psi worth of air.
So you really are getting 3.88 if it were a perfect world that is what you would need to produce to get the same results.
So use your 3.88 times whatever power you had to start with and you will be closer.
The question is how much does the ren produce? And what is the real eff of the turbo. As that is a big part of the equation.
If It is what I said and you were getting say 170 WHP mult it by 1.388=235 WHP
Lets see how close that number is. I'm betting a bit less because i think the eff is less due to heat transfer from the turbine side. Which is never figured into the compressor maps.
Next I'll tell you why you might get more then the math says you will. But I have to go to work so save it for later. Or you can go back and study the math provided at the start of my thread.
Go to the first few pages of the axial flow thread or search for the plots produced by Turbine_pwr.
Here he shows you the mass flow for different efficencys.
I'll give you a simple equation to show what gets into the engine, it's called: density ratio. As opposed to pressure ratio which is what you guys are using.
P2/P1 = Pr
Pr x T1/T2 = density ratio or the actual amount of additional mass entering the engine.
Temps are in degree R, or absolut F. Or ambiant plus 460.
Given a Pr of 1.5 which is roughly 7.5psi. Then given an efficency of 65% we can calculate the temp rise.
Pr to the power of .283-1 gives the y factor
So 1.5 ^.283-1=.1215
this times the tempR at std cond=520F
=63 F at 100 % eff.
divide by eff so 63/.65=97 temp rise
so 520 + 97=617 therefore 520/617=.84
.84x1.5=1.26
so if you want to use your 14.7 std times 1.26 you now have18.6
or 18.6-14.7=3.88psi worth of air.
So you really are getting 3.88 if it were a perfect world that is what you would need to produce to get the same results.
So use your 3.88 times whatever power you had to start with and you will be closer.
The question is how much does the ren produce? And what is the real eff of the turbo. As that is a big part of the equation.
If It is what I said and you were getting say 170 WHP mult it by 1.388=235 WHP
Lets see how close that number is. I'm betting a bit less because i think the eff is less due to heat transfer from the turbine side. Which is never figured into the compressor maps.
Next I'll tell you why you might get more then the math says you will. But I have to go to work so save it for later. Or you can go back and study the math provided at the start of my thread.
Last edited by Richard Paul; 01-21-2005 at 03:10 PM.
#885
RX8 and a Truk....
Originally Posted by Richard Paul
Now I will tell you again why you can't tell hp gain from pressure.
Go to the first few pages or search for the plots produced by Turbine_pwr.
Here he shows you the mass flow for different efficencys.
I'll give you a simple equation to show what gets into the engine, it's called: density ratio. As opposed to pressure ratio which is what you guys are using.
P2/P1 = Pr
Pr x T1/T2 = density ratio or the actual amount of additional mass entering the engine.
Temps are in degree R, or absolut F. Or ambiant plus 460.
Given a Pr of 1.5 which is roughly 7.5psi. Then given an efficency of 65% we can calculate the temp rise.
Pr to the power of .283-1 gives the y factor
So 1.5 ^.283-1=.1215
this times the tempR at std cond=520F
=63 F at 100 % eff.
devide by eff so 63/.65=97 temp rise
so 520 + 97=617 therefore 520/617=.84
.84x1.5=1.26
so if you want to use your 14.7 std times 1.26 you now have18.6
or 18.6-14.7=3.88psi worth of air.
So you really are getting 3.88 if it were a perfect world that is what you would need to produce to get the same results.
So use your 3.88 times whatever power you had to start with and you will be closer.
The question is how much does the ren produce?
Next I'll tell you why you might get more then the math says you will. But I have to go to work so save it for later. Or you can go back and study the math provided at the start of my thread.
Go to the first few pages or search for the plots produced by Turbine_pwr.
Here he shows you the mass flow for different efficencys.
I'll give you a simple equation to show what gets into the engine, it's called: density ratio. As opposed to pressure ratio which is what you guys are using.
P2/P1 = Pr
Pr x T1/T2 = density ratio or the actual amount of additional mass entering the engine.
Temps are in degree R, or absolut F. Or ambiant plus 460.
Given a Pr of 1.5 which is roughly 7.5psi. Then given an efficency of 65% we can calculate the temp rise.
Pr to the power of .283-1 gives the y factor
So 1.5 ^.283-1=.1215
this times the tempR at std cond=520F
=63 F at 100 % eff.
devide by eff so 63/.65=97 temp rise
so 520 + 97=617 therefore 520/617=.84
.84x1.5=1.26
so if you want to use your 14.7 std times 1.26 you now have18.6
or 18.6-14.7=3.88psi worth of air.
So you really are getting 3.88 if it were a perfect world that is what you would need to produce to get the same results.
So use your 3.88 times whatever power you had to start with and you will be closer.
The question is how much does the ren produce?
Next I'll tell you why you might get more then the math says you will. But I have to go to work so save it for later. Or you can go back and study the math provided at the start of my thread.
I have learned there are three types of HP.
1st is the "Planned HP" where ppl make predictions, based on experience
2nd is the "Mathematical HP" where ppl like you write up equasions to PROVE their predictions
3rd is "The HP the car actually makes" where people sit around and scratch their heads because their experience, their math all seemed in order, but the result was different.
#887
1st 13 sec Mazda MP3
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Originally Posted by bureau13
Hmmm, so unless you're planning on upping the boost by quite a bit over the stock GReddy settings (and incuring the greater risk to your motor by doing so) the complaints about the GReddy turbo in the kit being a bit on the small side are probably irrelevant.
jds
jds
Exactly. A friend of mine (Dreamwarrior) was telling me that people were complaining about the turbo that came with the Greddy kit was too small. I told him it was probably unfounded, and unless you were running BIG boost, there was no reason to have a big turbo.
On top of that, a modern "smaller" turbo can still be efficient until relatively high boost levels.
You really have to look at compressor maps to make any judgement calls.
#888
Registered
Originally Posted by dmp
yeah - that is all great and stuff, but it means nothing to me.
I have learned there are three types of HP.
1st is the "Planned HP" where ppl make predictions, based on experience
2nd is the "Mathematical HP" where ppl like you write up equasions to PROVE their predictions
3rd is "The HP the car actually makes" where people sit around and scratch their heads because their experience, their math all seemed in order, but the result was different.
I have learned there are three types of HP.
1st is the "Planned HP" where ppl make predictions, based on experience
2nd is the "Mathematical HP" where ppl like you write up equasions to PROVE their predictions
3rd is "The HP the car actually makes" where people sit around and scratch their heads because their experience, their math all seemed in order, but the result was different.
Planned horsepower output is the goal that is hopefully to be attained.
Mathematical horsepower is in fact what is determined by years and years of equations based on actual testing in order to determine what would on paper appear to be the best route to take in order to reach said planned output.
The hp the car actually makes is only finalized after testing. It is in fact true that a design on paper can vary from the real thing. This is usually a fine tuning issue but on occassion can mean going back to the drawing board. If this is the case then it would seem that there was an incorrect equation used in the math part so in reality the math is not flawed but the variables used in the original equation were. When done properly, the math can and does exactly prove the outcome. Now you know how products are designed, tested, retested, finalized and put into production.
They can't get a good product to the market with pure speculation that it "should" be this much power based on how much another car or engine had at the same psi level. That's irrelevant. That means nothing. The only thing of relevance is that exact product combination and not another one that is merely a resemblance.
#891
Registered
Originally Posted by Kooldino
Exactly. A friend of mine (Dreamwarrior) was telling me that people were complaining about the turbo that came with the Greddy kit was too small. I told him it was probably unfounded, and unless you were running BIG boost, there was no reason to have a big turbo.
On top of that, a modern "smaller" turbo can still be efficient until relatively high boost levels.
You really have to look at compressor maps to make any judgement calls.
On top of that, a modern "smaller" turbo can still be efficient until relatively high boost levels.
You really have to look at compressor maps to make any judgement calls.
#892
Riot Controller
Join Date: Jan 2004
Location: Orlando, FL
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Originally Posted by smrx8
question why does his turbo make his exhaust pop so much i hate to be driving that thing farting up a storm everywere i go.
#893
RX8 and a Truk....
Originally Posted by rotarygod
Too bad none of that explains ANY direct correlation between pressure and power output nor does it explain how a rotaries theoretical power output can be figured based on what happened on a Mazda 6. If those are the only "3 types of hp" your own reasoning of power output would seem to be unjustified.
.
.
Here's my point; I think you are over-engineering the issues:
With a similiar sized turbo, (as on the GReddy) my 2.5L engine made 90 hp more than before boost, at 8psi. Most people are predicting about 235-250hp for the GReddy turbo system on an RX8 at close to the same boost. I contend, similiar sized turbos, similar boost, a lower displacement engine will make LESS power.
#894
8 the HARD way.
Join Date: Feb 2003
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Originally Posted by epitrochoid
the map runs very rich to keep the egt's within reason, and all that unburnt fuel is ignited in the hot exhaust system. the car is basically backfiring, but the cat and mufflers arrest most of the flames. ours cars do it stock too.
#896
Everyone please stop and read this article, then please continue this thread:
http://www.rx7.com/techarticles_displacement.html
Using the RP displacement calculation the 13b is equates to roughly a 2.6L 4-cylinder 4-cycle engine. This is a pretty logical assessment from a knowledgable source.
Carry on with the bench racing now...
http://www.rx7.com/techarticles_displacement.html
Using the RP displacement calculation the 13b is equates to roughly a 2.6L 4-cylinder 4-cycle engine. This is a pretty logical assessment from a knowledgable source.
Carry on with the bench racing now...
#897
Originally Posted by dmp
I still don't buy 100hp from 7psi on a 1.3L. I probably can't argue 'why', but that's where I stand. IMO, mid 200s at the wheels is the most one can expect.
Besides the rotary engine has no air restricting valves and larger intake ports so it might even pump more air than a comparable 2.6l piston engine (higher volumetric efficiency). Also the intake cycle lasts longer 270 degrees compared to 180 degrees on a piston engine.
#898
RX8 and a Truk....
Originally Posted by globi
Why do you compare it with a 1.3l piston engine? A 1.3l 4 stroke piston engine displaces 0.65l per revolution and NOT 1.3l per revolution.
Besides the rotary engine has no air restricting valves and larger intake ports so it might even pump more air than a comparable 2.6l piston engine (higher volumetric efficiency). Also the intake cycle lasts longer 270 degrees compared to 180 degrees on a piston engine.
Besides the rotary engine has no air restricting valves and larger intake ports so it might even pump more air than a comparable 2.6l piston engine (higher volumetric efficiency). Also the intake cycle lasts longer 270 degrees compared to 180 degrees on a piston engine.
#899
RX8 and a Truk....
Originally Posted by 1975yellowBSPz
Everyone please stop and read this article, then please continue this thread:
http://www.rx7.com/techarticles_displacement.html
Using the RP displacement calculation the 13b is equates to roughly a 2.6L 4-cylinder 4-cycle engine. This is a pretty logical assessment from a knowledgable source.
Carry on with the bench racing now...
http://www.rx7.com/techarticles_displacement.html
Using the RP displacement calculation the 13b is equates to roughly a 2.6L 4-cylinder 4-cycle engine. This is a pretty logical assessment from a knowledgable source.
Carry on with the bench racing now...
EXCELLENT info...thanks - I'll read that
![Smilie](https://www.rx8club.com/images/smilies/smile.gif)
#900
Originally Posted by dmp
I still don't buy 100hp from 7psi on a 1.3L. I probably can't argue 'why', but that's where I stand. IMO, mid 200s at the wheels is the most one can expect.
fwiw, on my last car - 2.5L Mazda V6, my car went from ~160whp to ~250 whp on 8psi - similar sized turbo as the GReddy RX8 kit uses, IIRC.
Side note: Quoting 'crank' HP is a bad habbit, imo...it's impossible to measure, and in reality, doesn't mean squat.
:D
lol :D
fwiw, on my last car - 2.5L Mazda V6, my car went from ~160whp to ~250 whp on 8psi - similar sized turbo as the GReddy RX8 kit uses, IIRC.
Side note: Quoting 'crank' HP is a bad habbit, imo...it's impossible to measure, and in reality, doesn't mean squat.
:D
lol :D