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98ka24det
05-15-2006, 11:18 AM
This is for mainly the ka-t guys out there whether your stock block or built block. I was curious to know how far you were pushing 93 octane pump gas pressure wise...

I have heard as much as 19 on stock block and as high as 21 on built blocks from other forums. Trying to see what others out there are doing...

And would also help if you noted what size turbo your are running cause that makes a big deal..

Thanks

jdm_s14_zenki
05-15-2006, 05:10 PM
15psi with 92 octane no pinging or detonation. ive seen 18psi on 91..so..

BigVinnie
05-15-2006, 09:02 PM
Depends on the turbo that you are running. Different A/R trim will give a different heat discharge, some actually running cooler than others and some compressing air much more effeciently. depends more on your setup and the tune that you are using. Injection flow rate is also vitally important.
Guys out here in Cali have ran 18PSI on pump 91gas. Thats also because fuel out here is also under rated and is mixed with a 5% ethanol mix.

98ka24det
05-15-2006, 09:34 PM
Depends on the turbo that you are running. Different A/R trim will give a different heat discharge, some actually running cooler than others and some compressing air much more effeciently. depends more on your setup and the tune that you are using. Injection flow rate is also vitally important.
Guys out here in Cali have ran 18PSI on pump 91gas. Thats also because fuel out here is also under rated and is mixed with a 5% ethanol mix.

If it helps any i have a T3 turbine with stage 3 ex wheel and .48 housing with a T04B H3 compressor..

A buddy of mine had this same turbo and he maxed it out at 25 psi.. It just wouldnt go past it. But he was able to run 93 octane up to 21 psi b4 he blew the nissan headgasket on that turbo... HE then upgraded to a .63 housing and still blew the HG at 21 psi on pump... BUt this was on a built motor with oem hg... He kept blowing hg's like it was nothing. But pistons never got damaged

BigVinnie
05-16-2006, 05:33 PM
I still can't answer that for you.
Besides giving me the info on your turbo you still haven't told me what your engine management is, what your MAPS are set at, blow off valve, intercooler, and even the compression of your engine, besides using the correct injection pulse width/injection flow rate. I would be an Oximoron to answer a question that is truely a trick question, unless you have DETAILED information. Not one boosted FI engine ever runs the same.

98ka24det
05-16-2006, 06:33 PM
you still haven't told me what your engine management is, what your MAPS are set at, blow off valve, intercooler, and even the compression of your engine, besides using the correct injection pulse width/injection flow rate.

What does the bov have anything to do with running pump gas at high pressure levels..??

secondly i never asked for a direct answer. I simply asked what people out there are taking pump gas to.. And at the same time i asked what size turbo they were using and if they were on stock block or built block..

I know there is no DEFINITE answer cause ALL setups are different and there are SO many variables to take into consideration.

Threeyearitch
05-16-2006, 07:00 PM
I know how advanced or... erm... retarted your ignition is plays a big role in avoiding detonation. And I don't have to tell you that "psi" is a real general term when talking about turbo set-ups (aka: 15psi on a t25 is NOT the same as 15psi on a t3/t4). The flow rating of the turbo, measured in cubic feet per minute (cfm), is a much better indicator for this type of stuff.

That being said......

On totally stock blocks, It depends on how reliable you want your set-up :) Guys run 20 psi, but it usually doesn't last, and there are guys that have been running 7 for forever and a day.
If you do decide to go w/ a built block, the lower the compression the pistons, the more tolerate they will be of pump gas.

Hope I helped :)

98ka24det
05-16-2006, 07:16 PM
If you do decide to go w/ a built block, the lower the compression the pistons, the more tolerate they will be of pump gas.

Hope I helped :)

I do have a built block by the way..

This whole thing with running pump gas with high boost started one day when i noticed that a few buddies of mine that own srt-4's and evo's all run like 20-25 psi on pump gas with their stock turbo's and stock internals..
Granted their motor's are built for turbo abuse ( like the sr20 ) but their turbo's are smaller than mine which gives me the 1st advantage over them.

Secondly i have better internals than their factory internals. The ONLY advantage they may have over me is that they are probably running 8.5 compression vs my 9.0 compression.

They run fmi from the factory and i have a fmi. So they really only have 1 good thing over me which is the lower compression.

They seem to run 20-25 psi ALL the time on those small turbo's and seem to hold up just fine.

Here i am with a slightly larger turbo, stronger internals, with slightly less compression and yet i am told by MANY not to pass 12-13 psi on pump gas..... That sh*t aint right...!!

That is why i was asking for all the ka-t guys to let me know how far they are pushing pump gas... and if they are on stock or built block and what size turbo....

BigVinnie
05-16-2006, 07:43 PM
What does the bov have anything to do with running pump gas at high pressure levels..??


Obviously you need to read more indepth on what a BOV does besides prevent turbo surging and shorter life span.
If you are not using the correct BOV to your boost pressure you just get leaking, which only makes the turbo to continually spin faster also creating hotter less dense air.
Here is an example that is quoted part a.) of this link that I am leaving you with.



The turbo will eventually spin fast enough to overcome the leak and get the boost pressure up. At this point the turbo is running way outside its efficiency curve and is doing little else than pushing very hot air and working hard to do it. Hot air knocks, detonates, and contains less air mass than the same pressure/volume of air at a cooler temp (remember your physics PV=nRT) and you'll be pissed that your car is slower than a Honda Insight
http://www.jumptronix.com/2g_go_faster/Stages/details/BlowOffValve.htm

g6civcx
05-16-2006, 08:13 PM
It depends on how much risk you're willing to take. Generally speaking, an increase in boost yields higher power, but also results in higher cylinder pressure. More pressure means more stress on your internal components.

For a daily, people do not want to have problems so they are more risk averse. For race, the motor is rebuilt after every race so you can extract maximum performance without worrying about long-term reliability.

So in order to assess how much boost you can comfortably run, you need to decide how much risk you're willing to take. The acceptable level of risk is dictated by your level of mechanical aptitude, disposable income, leisure time, etc. This will be different for everyone.

I saw somebody on another forum put a dollar sign on his boost controller. He says that every time he turns the knob, he ends up spending more money to fix the motor :)

Generally speaking though, you can go as high as 21 or even 25 PSI on 93 octane pump gas. It really depends on your particular setup.

98ka24det
05-16-2006, 08:44 PM
Obviously you need to read more indepth on what a BOV does besides prevent turbo surging and shorter life span.If you are not using the correct BOV to your boost pressure you just get leaking, which only makes the turbo to continually spin faster also creating hotter less dense air.
Here is an example that is quoted part a.) of this link that I am leaving you with.

Generally speaking yes that is true and i knew this already.. but in my case, i dont have a stock cheap dsm or "knock off" type bov....
I have a greddy type S and type R and none of those will leak at ~22 psi...

pr240sx
05-17-2006, 07:55 AM
I am running 8psi with 87 octane on a fully stock engine.
Using JWT ECU trimmed with SAFC

Bone
05-17-2006, 09:12 AM
17psi on stock internals, Small t-3 hybrid, SAFC II, MSD BTM, 9x26x3 FMIC, 3" downpipe and 14" electric fans wired to run when the car is running plus stock clutch fan.

Heat plays a HUGE part in the octane game along with timing through the hotter part of the year I will sometimes mix some higher octane with the 93 to be safe when I am going to raise hell, Not really needed but my engine has clocked 40k with the Turbo setup and has a total of 180k on it so I am trying to keep the old girl alive a bit longer shes earned it ;) That and I think she has seen here replacement at the shop under the tarp :doh:

98ka24det
05-17-2006, 02:23 PM
I am running 8psi with 87 octane on a fully stock engine.
Using JWT ECU trimmed with SAFC

C'mon... serioulsy man..!!

U cant boost on 87 octane.....