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Discussion Starter #1
Static compression on the NA motor is around 9.5:1. With the turbo motor at 6.5lbs of boost it is 12.4:1. With the 550 injectors and the lexus AFM you can handle 25% more air, raising the boost to 8.125 and giving a static compression ratio of 13.2:1. This isnt even pushing it yet, as we all know. Add boost of stock value to the NA motor, we get a comp ratio of 13.7, barely above that of the Lexus AFM'd Turbo motor. And now you're pulling about the same power out of the NA motor as the Turbo motor at 25% higher psi.

Give me some feedback on this, no thread bashing please... I already know that past stock boost you need more serious tuning and that the NA electronics wont handle it. But for about 500 bucks you can slap on a turbo and go without serious problems, and be in the 250whp range very easily. And with the 7m's being very similar NA vs. Turbo, the stock internals will hold up.

You can always upgrade electronics to the Turbo later to go past the 250whp mark, and if you do the parts bought wont be wasted. I think this is a good start for people wanting to learn about turbos, not just slap parts together based on the reccomendation of someone that has slapped the same parts together. Thats not what a being a Tuner is about.... So... Read, learn, and finally do.. and if you fuck it up, do it differantly. :p
 

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maybe this would be better in the mkiii genral, not some much technical but kinda is.
 

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Dr. Jeff Lange
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What kind of feedback do you want?

You just seem to be stating a bunch of facts and not really asking a question...

Stock compression on the N/A is 9.2:1, Turbo is 8.4:1, just so you know. :)
 

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for real! 8:4:1??? thats damn good right? isnt like 8:5:1 the best?
 

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Can't wait for Spring!
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Jeff Lange said:
What kind of feedback do you want?

You just seem to be stating a bunch of facts and not really asking a question...
ya


................................
 

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Discussion Starter #6
Do i need to state a question? The point of this thread was to hopefully get a differant perspective on this approach to turboing the NA, instead of putting in a turbo motor. Maybe argue a point that I 'stated.' Maybe someone has prior experiance turbocharging a previously NA motor... I dont know. Anything but, "ya ......................................... what he said"
 

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i was going to do this to my car a few months ago, but ran into 2 problems that make it more than just a slap on turbo. I did not have an adequate (sp?) size oil drain and i wasnt sure how to change the maf from the n/a to turbo. i have since done a complete swap to turbo motor with all fresh gaskets and arp bolts so i have no more problems. IM still just curious about it. thanks!
 

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7m > 2jz > 1jz
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i am sorry but this just might be me, i have an 88 n/a myself at the moment and i have considered doing a bolt turbo kit mainly from the stock turbo motor.
But i have read around some and more talked to people that have experience with doing this and its just not worth it.
esspecially a person like me when all said and done i want to be at 600rwhp and you cant complete that with the n/a block, at least no one yet has done it.
so why waste the time and money, do it right the first time. :dunno:
-sean
 

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Discussion Starter #9
ALPINSUPRA said:
i am sorry but this just might be me, i have an 88 n/a myself at the moment and i have considered doing a bolt turbo kit mainly from the stock turbo motor.
But i have read around some and more talked to people that have experience with doing this and its just not worth it.
esspecially a person like me when all said and done i want to be at 600rwhp and you cant complete that with the n/a block, at least no one yet has done it.
so why waste the time and money, do it right the first time. :dunno:
-sean

You cant run 600 WHP on stock turbo internals... And none of this would be a waste of time, just a learning experiance. The exh mani, DP, turbo and fuel system upgrades are all pieces needed to do the full swap anyways...
 

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Discussion Starter #10
supradupra500 said:
i wasnt sure how to change the maf from the n/a to turbo.
You dont have to change the MAF out, actually you cant without going to the gte computer.
 

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thescamp said:
You cant run 600 WHP on stock turbo internals... And none of this would be a waste of time, just a learning experiance. The exh mani, DP, turbo and fuel system upgrades are all pieces needed to do the full swap anyways...
I'm not trying to contradict you, i plan myself to be in that range with stock internals. ive seen 500+ easy on stock internals.. aljordan (supraforums handle) had a 7m rod shot peened and tested.. and it did 800+ HP at 8,500 RPM before it failed. i think 600 HP is very do-able on stock internals. I mean, if i am wrong about something.. tell my by all means.. i myself am still learning im just putting in my 2cents.. good luck to everyone!
 

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thescamp said:
You cant run 600 WHP on stock turbo internals...

My good friend sean just made 557rwhp on STOCK INTERNALS! and he is going higher.

... and the reason i posted " ya..................." is cause i wanted to just say "ya" but there is a dumb post charector min. now.

AND IF YOU WOULD JUST SEARCH! there are plenty of threads in SF detailing the Pros/cons of the NA-T swap and all its variations including the 1/2na-t version. I followed the footsteps of the people before me that paved the way for the conversion I dubbed the "1/2na-t."

as i said, a simple search, will yeild tons of threads, all explaining how to do it, the benifits and risks, why its better than a full conversion. ect. ect.

yes, you can remove the AFM ( the load sensor that the 7mge uses for ecu input and fuel trim) without using the gte ecu or electronics. There are aftermarket converters, piggybacks, and the like that will translate a MAP sensor for your AFM.

and there is more to it than just adding simple compression ratio's. I did the math a while back and i cannot remember exactly right now, but the compression ratio difference between the NA engine and the T engine has a static gap of .8 that gap increases exponentially as more boost is added. The NA compression is 9.2:1.

The SINGLE problem with the 1/2na-t is tunability. the added compression, distributor ignition, TCCS, and GE ecu play havoc when trying to tune. direct ignition is FAR superior to distributor ig, because the direct is computer controled and HIGHLY accurate. the added compression gives nice beefy torque and gets that turbo spinning earlier, but, it gets the cylinders hotter, compresses the gasses tighter, and makes the is harder for the engine and ECU to resist detonation. The GE ecu has NO FUEL CUT, which is awesome because turbo guys are plauged by this. A 1/2na-t can see infinate boost and never have computer induced fuel cut. The problem with the GE ecu is its programmed to run an NA engine. And when RPMS start raising, it starts doing crazy things with the ignition timing, if it advances too much... uh oh.. you've pre-ignition. The TCCS, Toyota Computer Controlled System that stores long and short fuel trim values for the learned ECU memory also has a tendancy to store lean maps that cause lean mixtures.

Fortunately, there is an answer to all of these inherit problems with the 1/2na-t. Its a direction i will soon be taking, its called the SMT-6 by perfect power. the closest thing you can get to standalone while having a piggyback. It will control ignition, fuel, boost, and additional injectors, as well as remove that god-awful AFM and replace it with a MAP sensor. all for a price cheaper than an SAFC2 brand new.

before you ask any more questions... read here....

1/2na-t FAQ


Other Threads/sites related to the 1/2na-t

She Lives by Jong
1/2 na-t guys by 87supra
Na-t by Porn-adkt
Tons of Turbo Trivia by Jong
1/2na-t Page
The "1/2na-t Conversion by Jong
Tips for Removing the engine... by Jong
The 1/2na-t in one week by Jong
I think I've got a BIG problem... by Jong
na/t oil line route by Tihgae
SS oil lines and coolant by Jong

JT87NA also has a whole slew of other threads regarding conversion questions and his own conversion. he has an equal amount of information on SF

anything else?
 

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*I see you*
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Why the hell is it called 1/2 na-t???? That's silly to me. I'd call it TNA(T&A) ..hahahahahah Seriously though. I shake my head every time I see 1/2 na-t. Oh well. I don't have to say it, so whatever. Right!?!? Right.
 

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Discussion Starter #16
That SMT6 by perfect power is awesome, just the kind of information i was looking for. ;)

And I've already read all of those articles, those were more on how to bolt pieces together, not thoery, which is more of what I was looking for.

That SMT6 would be good for the turbo guys too... Nice alternative to standalone at 425 bucks when it also gets rid of the AFM...
 

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7m > 2jz > 1jz
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i know this, you can make 600whp on the stock internals, but its wiser to go better internals such as je.
it is however very pointless to me, but yet a learing experience for many to do this.
i just dont really see the point in turboing a n/a motor when we already have a turbo motor to pump up.
eh its just me
keep us posted.
-sean
 

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ALPINSUPRA said:
i know this, you can make 600whp on the stock internals, but its wiser to go better internals such as je.
it is however very pointless to me, but yet a learing experience for many to do this.
i just dont really see the point in turboing a n/a motor when we already have a turbo motor to pump up.
eh its just me
keep us posted.
-sean
Well, if you have an n/a car and not enough money/time to do a comlete swap and you're not looking for big numbers, just more power... id say its the way to go.. but i think the biggest reason that a lot of people do the 1/2 n/a-t is $$ and time.. Those are my thoughts. good luck everyone!
 

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Discussion Starter #19
I would say that the 1/2 NA-t is good up to the 300whp mark, after that, you should start upgrading internals anyway, at which point i'd drop the compression with the JE pistons, and do a turbo upgrade and start cranking boost. You dont have to be 600whp all at once. The fun is building it, not impressing people with dyno numbers.
 
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has anyone tried running high compression pistons in a GTE? Did it work out? I realize that this would limit peak power production, I was wondering along the lines of lag and off boost torque.
 
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