question about psi and hp
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From: orlando, florida
I got a Freind with the QMP kit, His cooler is the same size as the TTI one but with sheetmetal end tanks and there both made by spearco if i remember correctly. Also this is the same cooler used on TTI`s 800hp mustang kits. If your boosting 10psi your flowing the same amount of air wether your using a 60-1 or T76, yes the 76 might be a little more efficent but my IAT`s are only 100-105 at the end of the 1/4 so the intercooler is working. Can a bigger turbo flow more air into the engine at the same boost level as a smaller one? I`m not a engineer so i have no idea.
Last edited by MYTURBOT/A; Jan 25, 2004 at 03:44 PM.
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From: Austin, TX
Originally Posted by MYTURBOT/A
I got a Freind with the QMP kit, His cooler is the same size as the TTI one but with sheetmetal end tanks and there both made by spearco if i remember correctly. Also this is the same cooler used on TTI`s 800hp mustang kits. If your boosting 10psi your flowing the same amount of air wether your using a 60-1 or T76, yes the 76 might be a little more efficent but my IAT`s are only 100-105 at the end of the 1/4 so the intercooler is working. Can a bigger turbo flow more air into the engine at the same boost level as a smaller one? I`m not a engineer so i have know idea.
Hell yes, you are forgetting about backpressure. I think I remember reading that you want to keep back pressure in the exahust lower than 2x boost. the A/R ratio has a major impact on this.
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From: orlando, florida
Originally Posted by QuickSilver2002
Can a bigger turbo flow more air into the engine at the same boost level as a smaller one?
Hell yes, you are forgetting about backpressure. I think I remember reading that you want to keep back pressure in the exahust lower than 2x boost. the A/R ratio has a major impact on this.
Hell yes, you are forgetting about backpressure. I think I remember reading that you want to keep back pressure in the exahust lower than 2x boost. the A/R ratio has a major impact on this.
On The Tree
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From: Charlestown, Indiana
Our IC is the same size as the TT IC, but completely different. Ours flows over twice what the TT IC flows, with a higher efficiency and less pressure drop. The IC included with the TT kit is made by Spearco and was originally designed to be used with the Honda 4cyl Turbo kits. "It was never meant to support more then 450fwhp", as told to me by Johnny **** of Spearco personally.
Our standard custom Spearco IC was designed to support 900-1000fwhp.
Lastly, FWIW, I'm actually using the smaller T76 housing on the Formula. It has the 4" inlet, but smaller 2 1/2" outlet. The "larger" T76 comes with a 4" inlet and a 3" outlet. Both will fit on the car with our kit, but according to John Craig of Limit Engineering, there is basically no difference in power.
I has the smaller T76 in stock, so that's what we used.
Our standard custom Spearco IC was designed to support 900-1000fwhp.
Lastly, FWIW, I'm actually using the smaller T76 housing on the Formula. It has the 4" inlet, but smaller 2 1/2" outlet. The "larger" T76 comes with a 4" inlet and a 3" outlet. Both will fit on the car with our kit, but according to John Craig of Limit Engineering, there is basically no difference in power.
I has the smaller T76 in stock, so that's what we used.
Launching!
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So, if Rob's kit is as great as he claims, if you took a TTi kit, used the same intercooler as the QMP kit, you'd pick up a huge amount of power, right? So, knowing that the QMP kit is a TTi kit with a larger header primary and crossover, somehow QMP is picking up over 50% more power than the same TTi kit on the same psi? Hmmmmm.....
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Verdad Gallardo TECH Resident
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From: orlando, florida
Originally Posted by sbrown99TA
So, if Rob's kit is as great as he claims, if you took a TTi kit, used the same intercooler as the QMP kit, you'd pick up a huge amount of power, right? So, knowing that the QMP kit is a TTi kit with a larger header primary and crossover, somehow QMP is picking up over 50% more power than the same TTi kit on the same psi? Hmmmmm.....
My IAT (with the turbotech kit) were a good 80 degrees over ambient at the end of the quarter....maybe more..I'll have to search for my old post to see. That ain't none too good boys 
Notice Harlan said EFFICIENT setup gets 30hp/psi....I got about 23-25 hp/psi on my turbotech kit but that was with a very bad mail order tune. Once I got to the intercooler/turbo limitations, i saw the hp/psi numbers drop. Don't forget that the alky/methanol is helping Rob a lot. If he ran just gas you'd see those numbers drop to something more believable. i for one believe him.....he is right...dyno run is only 4 seconds. Rob hasn't said that his car will run 9s.....run 140mph in the quarter.....I think he is just showing what a stock motor can take for a short burst and what his kit can provide you on a forged bottom end and a good fuel system.
Notice Harlan said EFFICIENT setup gets 30hp/psi....I got about 23-25 hp/psi on my turbotech kit but that was with a very bad mail order tune. Once I got to the intercooler/turbo limitations, i saw the hp/psi numbers drop. Don't forget that the alky/methanol is helping Rob a lot. If he ran just gas you'd see those numbers drop to something more believable. i for one believe him.....he is right...dyno run is only 4 seconds. Rob hasn't said that his car will run 9s.....run 140mph in the quarter.....I think he is just showing what a stock motor can take for a short burst and what his kit can provide you on a forged bottom end and a good fuel system. 
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From: orlando, florida
[QUOTE=cablebandit]My IAT (with the turbotech kit) were a good 80 degrees over ambient at the end of the quarter....maybe more..
Damn how much boost were you running to get that much of a increase? I`ve never seen my IATs go above 120 at the track, even on a 90deg day. even in stop and go traffic I don`t recall it ever going above 125* in the summer here in florida. I ran the car last weekend it was on a 70* day my temps were only 102* at the end of the run. Maybe it`s because i`m only running 8psi. I also have the front license plate area cut out so i get some flow through the intercooler.
Damn how much boost were you running to get that much of a increase? I`ve never seen my IATs go above 120 at the track, even on a 90deg day. even in stop and go traffic I don`t recall it ever going above 125* in the summer here in florida. I ran the car last weekend it was on a 70* day my temps were only 102* at the end of the run. Maybe it`s because i`m only running 8psi. I also have the front license plate area cut out so i get some flow through the intercooler.
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From: College Station, Tx
Originally Posted by QuickSilver2002
Can a bigger turbo flow more air into the engine at the same boost level as a smaller one?
Hell yes, you are forgetting about backpressure. I think I remember reading that you want to keep back pressure in the exahust lower than 2x boost. the A/R ratio has a major impact on this.
Hell yes, you are forgetting about backpressure. I think I remember reading that you want to keep back pressure in the exahust lower than 2x boost. the A/R ratio has a major impact on this.
Now sure, the thumper would have less backpressure, but you wouldn't see this manifested really in the manifold pressure; rather, the car would have less pumping losses, and could alter the cam timing to take advantage of the reduced backpressure (or to compensate for increased backpressure).
On a given engine configuration at a given boost & temp level you are getting the same amount of air in there, regarldess of the source.
Now a smaller turbo should make boost sooner/have less lag than a larger one - as to which would be more effecient, you would have to look at the map. A smaller turbo in it's effeciency range could very easily be better than a to-large turbo out of it's range (on the low side).
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From: Austin, TX
Originally Posted by ChrisB
If the pressure (manifold psi) AND the manifold temps are the same, then you have the exact same massflow going into the cylinder, whether it's coming from a T-72 or Thumper.
Now sure, the thumper would have less backpressure, but you wouldn't see this manifested really in the manifold pressure; rather, the car would have less pumping losses, and could alter the cam timing to take advantage of the reduced backpressure (or to compensate for increased backpressure).
On a given engine configuration at a given boost & temp level you are getting the same amount of air in there, regarldess of the source.
Now a smaller turbo should make boost sooner/have less lag than a larger one - as to which would be more effecient, you would have to look at the map. A smaller turbo in it's effeciency range could very easily be better than a to-large turbo out of it's range (on the low side).
Now sure, the thumper would have less backpressure, but you wouldn't see this manifested really in the manifold pressure; rather, the car would have less pumping losses, and could alter the cam timing to take advantage of the reduced backpressure (or to compensate for increased backpressure).
On a given engine configuration at a given boost & temp level you are getting the same amount of air in there, regarldess of the source.
Now a smaller turbo should make boost sooner/have less lag than a larger one - as to which would be more effecient, you would have to look at the map. A smaller turbo in it's effeciency range could very easily be better than a to-large turbo out of it's range (on the low side).
It seems like the same thing with a NA car that has a better header for scavenging. CFM goes up, but manifold pressure stays the same.
What am I missing here? I’ve always thought the intake and exhaust stroke were tightly related and that there was much more than pumping loss to think about with the exhaust design.
That (my high IAT) was on around 11psi if i remember correctly. FWIW I got 40 more rwhp thru a cutout insead of full exhaust and that is on the same psi. Now IF I remember correctly..I THINK TTi is supposed to be using a little better intercooler as of late...might explain your IAT. I didn't cut out any of the front end either. Please don't underestimate the benefits of the alky/methanol. It cools...it fuels...it's cheap. I dunno if Rob has any pulls minus the alky kit. If so, that might get you some numbers to compare with what others have pulled on gas/racegas.
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From: College Station, Tx
Originally Posted by QuickSilver2002
Hey, I'm no turbo expert by any means, but I do know that PSI will drop and CFM will increase on a blown motor when you take out simple restrictions in the exhaust (I've seen this happen). So why would this not be the same on a turbo car? PSI obviously stays the same because of the waste gates, but it seems like the CFM would increase with less back pressure and more efficent use of the exahust gasses to spin the compressor.
It seems like the same thing with a NA car that has a better header for scavenging. CFM goes up, but manifold pressure stays the same.
What am I missing here? I’ve always thought the intake and exhaust stroke were tightly related and that there was much more than pumping loss to think about with the exhaust design.
It seems like the same thing with a NA car that has a better header for scavenging. CFM goes up, but manifold pressure stays the same.
What am I missing here? I’ve always thought the intake and exhaust stroke were tightly related and that there was much more than pumping loss to think about with the exhaust design.
That said, I think it's still a matter of degree - I don't think it will be a large difference (more than 20-30hp max) unless we are talking extreme changes though (going from 3:1 to 1:1 backpressure) - but nevertheless, a good point, thanks!
