It is probably a half-*** stupid question but I am going to be using a GT35R with all supporting mods, sheetmetal intake, 272/272, fuel pump, regulator, header, full exhaust, intake, front mount, fuel injectors, wideband, etc... I am trying to figure out how much boost I can run without seeing knock OR timing. I do not have any OBD-2 datalogger which is worth a crap. And obviously can't see knock. I will be using the Zeitronix for all my datalogging and tuning help. It can only see RPM, Boost, EGT, TPS, and Wideband 02.

With only that datalogging help, how can I be sure to be tuning the car safely for both pump and race? The only thing I can do right now is kinda guess the boost upon what most others are doing with the GT35R and tune it for wideband and be sure the EGT's are under control.

Any advise on what PSI for both Pump and Race Gas would be nice and also what should I be looking for as far as EGT's are concerned? I am thinking right around 19 on pump (93) octane and around 26-27 Race (C-16). This sound right? Also, what do you think a good boost number for 110 octane would be? 23-24?

 

boost levels are somewhat irrelevant as they are only a measurement of the air that ISN'T getting into the engine. A high flowing head will have lower boost levels but make more power since more air is getting into the engine. You cannot tune to an EGT. Anyone who claims to be able to tune with an egt has a very minimal grasp of what is going on inside the engine. A/Fs I typically tune to the low 11s, but my major concern here is your lack of management. WIthout a way to effectively control both fuel AND timing, your motor is probably not going to last too terribly long not to mention you will never get to those boost levels without hitting boost cut.

 

ok well thats not the answer I was looking for. Thanks for you input though. I have seen many a motors last many a years by JUST using an AFC for adjustments.. you will not make the MOST power and be able to run the highest boost without timing adjustments but it won't hurt the motor a bit. And yes, boost levels do matter and are not irrelevant. Otherwise why wouldnt we all set our boost at 30psi and whatever the motor wants to use it does

Sorry but that is a very interesting idea there. Take a canister and fill it to 100psi and the same sized one at 10psi. Which pushes more air into a small opening when a valve is opened? Nice idea though.

Anyone else care to help a bit? I know I can't get the tune to be perfect but a decent idea would help.

 

Oh.. BTW, call Road Race Engineering about tuning with an EGT.. your not really tuning with it but you are using it to give a good idea that your not meling anything or retarding the timing through knock enough to send flames through the exhaust. I guess they "have a very minimal grasp of what is going on inside the engine."

 

Also, I have boost cut feature eliminated.

 

What are you tuning with?

 

I'm not sure how accurate it is, but I spliced the User 1 input on my Zeitronix into the knock sensor wire so I can somewhat log knock. It's not the best way to do it, but it does give a bit of an idea of knock voltage.

-Paul

 

Your misunderstanding MayhemSi... He is right, but you turned it into an apples and oranges bash... You CAN run the set up you mentioned on an AFC, but why would you want to? It would be like trying to track an F50 on Kumho 712's tires... you could, but why? What he pointed out that was dangerous, and you are missing, is that you can't properly tune what you can't properly monitor. How would you know the effects of your changes, if you can't see your air fuel ratio? It's not like tuning your set up is like tuning Dad's carberated pick up truck by monitoring the plugs. You're saying that you won't be able to moitor air/fuel or knock... not good!

 

He said he'd be logging A/F (wideband O2) and EGT.

 

I missed some of that... as others have missed some of it also...

 

Trina, I have a pretty good article on plug reading that will help you. Audible knock is going to be hard to hear over your dump tube and exhaust, so this is pretty much your only option without any sort of datalogging capability. It's on my shop pc, so shoot me a reminder e-mail.

 

plug reading is nice, too... lol... when the tip is gone, you've run too much timing... hahaahaha

 

My advice would be first to run 19-20 psi on pump and 24-25 or race to make things last on the stock block. Next spend an extra 500 bucks and buy Alky injection for safety then run 22lbs on pump with the AFC and you will be a happy person. I have seen this done on the stock long block and they car runs very , very well.

 

2 thoughts... 1 helpful and 1 not...

1. What about that knock link deal that you sit on yer dash?

2. After spending so much money, why not spend just a little more for ems?

 

you missed the most important part of all supporting mods... engine management.

octant numbers should be the relatively the same and wtih these margins should always be more than close enough as far as running boost:

pump gas will always be around 19-22psi, i'd say anyone runnin more should be running 94 octane or pump gas with addatives (such as toluene)

i won't mention the various types between 100-110

110 will always net you somewhere from 26-32psi depending on how efficient your big turbo is and how much knock supressing stuff you are running (ie big intercooler that actually works etc.) i realize the margin i give is big but that's the truth of the matter... on a 3071 you prolly can't push much past 29-30 cuz things just get too hot and dangerous. but on a gt35r you can get more than 30psi... i know several people doin' it.

116 will get you to the sky... 35+ psi depending on your setup... i don't think discussing the ceiling of c16 is that relevant.

my plug earlier about engine management was because i didn't read the rest of the posts. you can run this on safc... adn it could be safe... you won't have anywehre near the exact fuel you should be running and your safety margin will be eating up most of your hp... but it can work... it won't be dangerous... the stock ecu will save yer *** if things get hot and heavy. but the benefits TO an ems are too many to name. the various amount of timing that you can tune, the idle control functions (you won't be able to fix cam lope with the afc, although you'd be able to save yer *** from stalling embarassingly you'd be blacking out your bumper doing so) the exact fuel trims that you can tune with an ems are simply the best, outstanding, you can't beat it with anything else unless it's another stand alone. so if you want exact efficient power without a whole lotta beating around the bush... you gotta do the ems thing.