GurgenPB

iTrader: (2)

Well, 2 and 8L is gonna be totally different turbos, and different number of turbos.

For your 4.2L, if you truly must have 1500, then you are gonna have to stick with GT47 and have an ugly torque curve (unacceptable for a street car).

Here is free advise: If you can live with 1100 though, and want a NICE torque curve, then GT42 is the ticket, with the higher A/R housing (a must). I'd try the 1.15 A/R then 1.28 A/R, in that order, just because overall car balance matters much more to me than peak HP.

SoundPerformance

Im guessing that you would not like the GT55-91 on my 3.0 L supra then? It is fully in by 7200 RPM and we can spin it to 10K. The motor is never below 7500 going down the track.

The GT45Rs work very well also on the supras. The T4 Ex housing 1.01 A/R will make full boost by 5400 and put out well over 1000 RWHP. The larger A/Rs certainly free up some top end HP but you sacrafice a ton of bottom end.

IIQuickSilverII

iTrader: (13)

lol bahhh its just a joke..dont take personal...i tried to put enough smilies in the post to make it clear it was just a joke... i still you still didn't get it
ligthen up a bit =]

doug

iTrader: (5)

so is someone going to post the RPM or what?

GurgenPB

iTrader: (2)

GT45 is pretty close to GT42, but I'd rather do GT42 with higher AR than the GT45 with lower AR...you will get about hte same spoolup but make more power because of the higher compr eff.

Now, the 10000rpm is a different story. The mapping changes significantly with RPM, since it's a major flow determinant.

I was talking about 7000 rpm on a supra. 10,000 would indeed change things. Even so, the perfect turbo there would be the GT47-88 with 1.39 housing IMO. No questions about it in my mind.

GurgenPB

iTrader: (2)

Never tried to look at the emoticons... Good deal, no offense taken.

redlineryder

A gt42r would be a perfect match for this motor on the street, absolute terror.

Joeschmoe

Gurgen, you let your idle time get the best of your "knowledge". If you have never actually used a specific turbo that you speak about in any application then you sincerely have no grounds for an argument about turbo sizing, spool up characteristics, etc. Anyone that has applied said turbos to different applications comes to find that sometimes the plotted compressor maps are completely off, and a turbo thats charted to flow a maximum of 52lbs a min @ a certain PR might come to see 600+ WHP dyno charts. The compressor maps are made by a manufacturer that would rather see people prove them wrong, then have people be disappointed by their product line. Just because you read alot on line doesen't mean **** FYI try getting dirty instead of pounding away at a keyboard all day Just because you read a couple tutorials about how to figure out engine flow, and plot it on a map is novice IMO. I'm not trying to sound like a dick, but if you're trying to sound credible maybe you should know what you are talking about and have real-world experience in the subject matter before you reply.

GurgenPB

iTrader: (2)

Riiight... Look who's talking.

This is not about pounding away at a keyboard, you ****head. I didn't just read couple of tutorials... you know what forget it, why would i justify myself to an idiot like you. Nonspecific claims without making an effort to actually THINK about what i am saying is all you did here...that's I am sure will reflect positively on you!

My only motivation is to contribute to the comunity in a positive way. Everyone and anyone is going to disagree at some point. For everyone else, tutorials is what i read in the first 30minutes of my research, the latter dozens of hours were very much engineering level text ALWAYS backed up by practical examples of the said turbo sizing applications on different displacement, RPM range, VE, CE engines. Just in this last case with the Supra, the plotted curves predict almost exactly how close my estimations are...and they did so many times before this example.

Again, my only motivation for commenting is to contribute, that's all.

Joeschmoe

By saying you're going to get 1100WHP out of a GT42R is rediculous, maybe if you compound that with a 150 shot and use some crazy correction factor.. just maybe....

Instead of getting defensive why don't you prove me wrong

IIQuickSilverII

iTrader: (13)

+100

IIQuickSilverII

iTrader: (13)

well Joe is not just naming practical example, he has personally designed and worked on many applications of very high horsepower btw that you ahve never even touched.....just so you know...and its nice that you ar trying to contribute with all this science which i dont dissagreee...but u fail to agree that you are too quick to dismiss real practice, real data from peopel that have worked with this size turbos for years... and know what it truly takes to make a high whp application than putting it all jsut on paper....
Plus in this thread u came with a funny attitude tryng to put doubt into the work by Greg, ...if he hasnt put a plot out is probably because he might be workign in sorting the torque converter or what ever the issue is and plot a better dyno chart...

Joeschmoe

Well if you are as smart as you try to be, then the first thing anyone does in this line of work is throw compressor maps right out of the window, and by the way you can't calculate the VE of the engine just on a whim, since you brought it up, i'm very curious as to how you are calculating VE on paper . Considering the fact you need a MAF to pre determine the volume of air flowing through at a specific RPM, it's not as simple as well this is a 4.2l so this calculation says that it will flow this and that lol.

Show me how you figured a GT42R with any specific hotside will yield you close to the realm of 1100whp, I'm curious as to how you calculated that too.

All I'm saying gurgen is that your info isn't 100% correct not trying to be an ***, but it's easy to read compressor maps, and figure on paper you can make x amount of horsepower but there are too many real world variables that make it extremely inconsistent. If everytime you are plotting/informing off of a compressor map/formula it'd be ideal to say "In a perfect world" before anything you say

IIQuickSilverII

iTrader: (13)

ii think thats the point injected, Sp, joe and many have been trying to tell you Gurgen specially of your compressor map/formula. "In a perfect world"

Sam@GTM

iTrader: (7)

To Greg and crew, congratulations on your recent accomplishment no matter how you slice it, its a 1000rwhp car and is certainly is a great accomplishment. Keep up the good work

SAM

GT Motorsports

Sam@GTM

iTrader: (7)

I could agree with you that everything that is on paper does not apply in the real world all of the time. But to say to throw the compressor maps out the window, that is a complete ignorant statement.

For the record, we knew exactly how much power we were going to make on our 4.24L stroker at a given boost pressure and rpm based on turbo compressor maps.

Just out of curiosity why does Intense Motorsports post under "Joeschmoe"?

SAM

GT Motorsports

GurgenPB

iTrader: (2)

Wow....I really don't know where to begin...

Yes, that's definitely a good place to start in designing a turbocharging system, throw out the only objective piece of evidence you have, nice. That's good to know.

I wasn't born yesterday. I know exactly how to calculate VE. And yes, of course I used a MAF sensor, extracted the voltage to g/sec calibration from the stock ECU, including standard errors for each RPM and load range, then using the exact MAF information (converted to lbs/min from g/sec), and IAT ambient P (accurate), P drop across intake filter (all of which allowed me to find density), the MFR's only unknows is hence VE. This was done at 2000 through 7000rpm data points, the 8000rpm point was extrapolated. I did this on data from my friend's stock VQ35DE (N/A), as well as my VQ35DE (with GTM cams/no headwork).

That's how I figured out VE, not that I was eager to disclose it to you.

I don't think it's as big an assumption as you made about me not knowing the requirement of MAF for VE calculations, but in this case I will assume that you don't know how to do this, and I do not intend to help you do it.

I will say that, for the compressor side, you examine the BSFC's (brake-sepcific fuel consumptions) of the engine at different load sites (for the most part, it stays constant thoughout the different load sites), then use that value and approximate crank power production. The key is of course to use car-specific BSFC and not the generally quoted one of .5-.6. That will allow you to get a pretty close estimate of power production at higher MFRs (and to know the MFRs you MUST know the VE's and CE's).

The turbine side is much more complicated...and I am definitely not going to tell you how to do that. All I will say, is that the quoted MAX turbine flow efficiency is not sufficient for accurate estiamtion, and you need to know the turbine efficiencies for different turbine P/R's (even though Garrett only commonly refers to max effieciencfies in their simplified drawings).

OK...enough with the technical discussion...

Let me just say the following, foregoing any name calling that would otherwise be one's impulse to do. On the subject of "too many real world variables": yes, predictions don't ALWAYS hold up EXACTLY, and when they don't it's almost always because there were unknowns that one didn't think about accounting for, didn't know how, or it was impossible to do so (in very rare/specific cases). In MANY cases means "too many real world variables" is code for "I don't know WTF is happening" and sad to say that that appears to be the case here, just by going on what you posted above. I am sorry but that's the only reasonable conclusion I can arrive at.

After all, talk to a real engineer, not someone like me, but someone who does this for a living, and I will guarantee you anything that he will give you a reason for EVERY LITTLE THING TAKING PLACE in your engine. This is man-made science, and there is always an explanation. Just because you call them "variables", doesn't mean that they are really "variables". IMHO, it would pay dividents not to jump to conclusions next time about my or anyone else's comments without pondering it for a little while.

This is the problem with public internet forums, people believe what people like you tell them.

IIQuickSilverII

iTrader: (13)

he does? oh well, but doest it make any difference in the concept that compressor maps are a guide and not 100% the same all the time giving the many factors involved in building an engine and making power?
why is that have to do so much now with this thread anyways...

he's just been stating facts and apologized if it sounded harsh but it shouldn't be linked to a company on it's own personal time probably. You should tell you mods or admins that they are both paying sponsors, schmo hasn't been trying to start drama ...

Your "padawan" was the one who brought all this up as the reason for the 300whp drop anyways. And trying to criticize(quite sutil and indirectly btw) Injecteds accomplishment and then SP who has been working on supras and large turbos for years. Was there any GTM calling on the other side, why make this a shop vs shop thing... ? its jut about Gurgen and his posts

I dont doubt that you look at engineered compressor maps to design expectations in your very nice stroker kit(no sarcasm btw). Any engineer would..its fair... how ever even before you put it in your car, or on Alex, you knew what you could expect, but not what it would happen given the many factors. Id be a lil too arrogant to say that.. its a best guess situation. I dont doubt predicting ball park numbers...
Overall the whole thing is aobut...as posted in previous paragraph your padawan dissing injecteds accomplishment

looks like some one went crying to daddy and the "higher powers"

GurgenPB

iTrader: (2)

Wow.... definite bone head. I don;'t need anyone's help, i am sure it's evident from my post.

IIQuickSilverII

iTrader: (13)

then why did you got to touchy felling man... i mean i joked in previous page and you got all sensitive about it...a couple other things on this thread and next thing you know another sponsor, your own friend/tuner, comes here and tries to make this a vendor vs vendor thing when it was NOT THE CASE AT ALL!!!...
funny how he brought that up when nobody was doing that, and obviously somebody rather than him with access to the ip check did the police work on that for BS really....it was truly a reasonable convo vs convo thing and thats where it should have stayed.

no need for those "tactics"