Regular or Premuim as the debate continues?

The 1UZFE EGR Delete Kit is available for sale here.
J

jibbby

New Member
Now, I know that this has been talked about before, but in the last year I have been putting regular gasoline in my SC400 and I can't tell a damn difference..Now regular gasoline in California is 87 Octane where as in many other states and countries regular gasoline is 85 octane...

Does it really matter? The Engine doesn't knock, knock sensors are good and aren't effected...I don't see the big deal....Does anyone agree? You save on average $4 with every fill up...

Any opinions on this?
 
your gonna torch those spark plugs man.....
i know on the vh45de - q45... if you run regular for about 1000mi.. you will need plugs..

on the 1uz, it is better than 1000mi, but not great, and the plugs are more expensive
 
Please explain?

I run cooler running plugs with my nitrous application...Still, I have never heard of slightly lower octane fuel roasting plugs on the 1uz-fe's.... I would like to learn more about this..

The difference between Premium and regular fuel is 4 octane points...91 to 87 here in Cali...
 
I always thought the higher the octane fuel the hotter the burn...Just like Nitrous Oxide which will burn out regular plugs...

How is this then possible with the Q45's? It doesn't make sense... Lower octane fuel should burn at a lower temp creating less power...
 
your right about the combustion temps, and i do not know about Cali, i am in TX and have only seen what happens here in the summer..
we in TX have the same octane ratings
from what i understand of it the issue is that with a lower octane fuel it is not as "pure" (lack of better term) as the higher octane. this couple with slightly higher combustion temps can leave particles on the plug, and on the chamber.
the plugs are what is in question here so. with the impurites left on the plug, it causes the plug to heat up (hold heat) more than intended, causing it not fire properly ....eventually, causing the plug to fail pre maturely due to excessive heat.

IE- the Q45 (vh45de) runs the timing more advanced than the 1uz, causing this issue to be compounded, and for the plug to run even hotter with the impurites on the insulator and diode.

all this info is based on higher intake temps (in texas its hot) less dense air (higher above sea level) and the engines in question running bone stock configs..
 
That makes a little more sense to me... Thanks..

Hey pres6 - A little off topic but I have always wanted to ask someone that had knowledge about the Q45 (VH45DE) and 1uz-fe motors as to which motor they preferred more and for what reasons?...I could never find anyone with that kind of hands on experience...It appears you may be just the guy for that... Can I kindly ask you for your opinions on both motors and what differences you can tell good and bad? I am very fond of that Q45 motor myself but have never owned one.... I live and breathe the 1uz-fe motors though...


I must ask this now while I have the chance even though this thread is a gasoline thread.. Hope no body minds....
 
well, i can tell you that i prefer the 1uz for sever reasons, most of which have to do with part availability, believe it or not parts are easy to find for the 1uz compared to the vh series motors. and the bottom end of the 1uz is much stronger than the vh45, that being said...

in stock form i would go with the vh45, or even the vh41, for the power, tourque and the sound (putting it in the floor in a 90-92 q45, it sounds amazing) and for a 5000lb car the torque moves it really quick.. not to many luxuray cars can launch like that... the issue with the vh series and older nissan in gener is the transmission.... its a POS!!! if you beat on a q45..you WILL blow the tranny, and a rebuild will cost 2grand.. all of the older q's i have seen have or have had tranny issues (catastrophic internal failure) the J30 was the same way..

now on the 1uz, the tranny appears to be very strong (duh- its a toyota) until you get up to 400+rwhp, at that point it is anyones guess what will happen..

the vh has a larger TB and intake runners, they are shorter though.. and this lets in more air, makes more low end torque/ and more of the Valve sound comes back out too...(thats why it sounds soooooo pretty)

and if i remember right..the vh45 is an iron block?? could be wrong...not sure..

all in all.. i am a brand guy... so if i ever build a badass 240/ datsun 510, or j30... i will go with a vh45..
if its a yota... i am sticking with the 1uz..
JCC
 
Pres. interesting info...Thanks for your input..

Just to let you and others know, you maybe mistaken about the 1uz-fe mated stock transmissions...I have blown two 92 SC400's trannies already. However, I didn't have a cooler on either of them as I was running nitrous 5 or 6 seconds at a time, so I didn't think the heat build up would be an issue.. In any event I am not so very confident a used early year Lexus transmission with a cooler can hold 400whp for a long period time... However, the replacement cost of that used tranny can be as low as $500 at the yards or on Ebay unlike the Q45's..... I know because I recently looked..

Some may disagree with my above statement, but I can only speak from my personal experiences and reads.. However, at the time I wasted the two trannies I was running anywhere from a 100-150 shot of nitrous combined with all the outside the engine mod's on my 92 stock internal 1uz-fe motor showing 115,000 miles on it.. The first tranny snapped and gave up the ghost in second gear under a nitrous run..The second tranny was built but slipped probably from too much heat as I continuously road the nos and I believe it heated up.. In my opinion it is the torque numbers more people should be concerned about rather then trying to rate these trannies by whp numbers... Just my opinion... Push over 400 torque while pushing well under 400whp like my 92 SC400 and the stock Lexus V8 tranny may just snap on ya... 92-94 SC400 transmissions are identical in every way..95 the electrical changes but not the body of the transmission...That is what I know for fact..


This thread is going in every direction, but since it is the General Discussion Section where anything goes...I believe this to be OK, I could be wrong though but I do believe this is good info.
 
i think we are safe on the moderation, this is a discussion, with what i believe to be good information for community.
that said, i may be mistaken on the tranny strength, i have heard so many things from different people in the last 4-5 yrs since i started researching the 1u for a swap into a supra i still have in storage for all of 5yrs.....as i type this my 4 yr old son is telling me alot of amazing things (he is why the car has no made no progress in those 5 yrs, never thought i could be so happy about it).
regardless of that, i have no doubt that many transmission will break well below the 400 mark, and god knows i have broken way more than my share of car parts for odd, even unbelievable reasons.. atleast the cost of the R154 conversion, and the part availability here in the US is finally getting within reach of the poor man..
and for that i am thankful..

i have to ask about your nos...
how well or not well did the motor hold the 100 and a50 shots? over how many miles did you spray it?
 
Octane rating is basically the resistance to detenation. The higher the octane, the more you can compress the mixture without detenation or pre-ignition. However 87 octane is a little more volatile and will be a good candidate for low compression because they do not need to compress the mixture as much because due to heat and pressure the lesser octane fuel. Also the higher the octane of fuel, the better your car will be with cold start applications, which is why on E85, it is so volatile that in very cold weather it sometimes can not provide a rich enough mixture for those cold minnesota starts, which is why GM and all other E85 fuel vehicles state that if your vehicle will not start on a cold morning, add normal gasoline. An easy way to look at percentage of octane is the number stated whether it be 87, 89, or 92, the remaining number in the equation is cetane, a fluid that DOES NOT LIKE HEAT AND COMPRESION, hense why Diesel is rated in Cetane, and does not use spark plugs...
 
i have to ask about your nos...
how well or not well did the motor hold the 100 and a50 shots? over how many miles did you spray it?[/quote]

Pres6, just to let you know if you haven't read this already in many recent threads on this forum here it is again.....The 92-94 1uz-fe motors are proven to be the cheapest and stoutest out of the bunch but deliver the least amount of power at stock form.......However, they were built with the strongest rods..I've read about one holding a solid 500whp on the stock internals... They really are still unproven as most people get nervous and turn to forgies prematurely... Probably the best motors to get if you want to boost it without messing with the internals... Perfect for the smaller budgets..

For me I ran 100hp Nitrous shot ( a bit lean too) for two years constantly then graduated to the full 150 shot for almost another two years...That's when things started to break on my SC400..Trannies and other drive train stuff... As far as the motor itself is concerned it is as solid as rock and continues to carry on pur... I have never been concerned about the motor and I have literally beat on it daily for the last 4 years... I have a heavy foot...

Now my car dyno'd at 210whp N/A so with the nitrous I may have gotten in between the 300-350whp mark at times.. It's the torque numbers that were impressive and destructive...

Hope that helps..
 
stilltippin said:
Octane rating is basically the resistance to detenation. The higher the octane, the more you can compress the mixture without detenation or pre-ignition. However 87 octane is a little more volatile and will be a good candidate for low compression because they do not need to compress the mixture as much because due to heat and pressure the lesser octane fuel. Also the higher the octane of fuel, the better your car will be with cold start applications, which is why on E85, it is so volatile that in very cold weather it sometimes can not provide a rich enough mixture for those cold minnesota starts, which is why GM and all other E85 fuel vehicles state that if your vehicle will not start on a cold morning, add normal gasoline. An easy way to look at percentage of octane is the number stated whether it be 87, 89, or 92, the remaining number in the equation is cetane, a fluid that DOES NOT LIKE HEAT AND COMPRESION, hense why Diesel is rated in Cetane, and does not use spark plugs...
Click to expand...


That's a good explaination on Octane and what it does... So in colder climates higher octane fuel is the best choice to avoid pre-det.. Once the engines are warm it really doesn't make a difference is my guess...
 
If you do not run the recommended octane you are risking damage PERIOD. It is not a sales advantage for a car to require premium fuel it is an engineering reality.

A "knock" sensor listens for detonation and if heard retards timing to reduce cylinder pressure and surpress said detonation. They only work properly IF there is detonation to surpress. Detonation is BAD... PERIOD... mild can be tolerated but it cycle stresses parts and is cumulative.

Reduced timing creates other problems and is to be avoided. It is far less damaging than detonation but is not something you want.

If you run nitrous or turbo/supercharger you DEFINITELY want the highest possible octane. If you do not understand why you REALLY need to spend time with google or yahoo and learn WHY. If you do not want to take that time you should either NOT run a power adder or you should get ready for some level of engine failure.
 
WOW, thanks John...Now that is an explanation.. I did know about the knock sensor and how that applies to bad gas to these motors...

How about using 89 octane (as the middle ground)?... What octane level is it considered bad to run thru these UZ motors?

I do go back and forth at time between premium and regular but never realised it made a difference...I did think it was overkill... John I will take your word for it....
 
Wow, I hate to be the new guy here and revive this thread to correct some of the mistakes but I feel it my duty to do so. Most of what has been posted above is wrong or opposite.

Lower octane burns more easily and hotter, makes more power and is cleaner. Only an engine that will knock/ping/detonate on 87 needs to run more octane. The cooler the environment, the lower the octane needs to be, especially for cold start.

E85 is "alcohol", has terrible thermal efficiency, more has to be burned to create the same amount of power. It is very clean and knock resistant.

I've been trying to find what the compression is for the 1UZFE, anybody know? I would assume it is a good design that doesn't need higher octane to compensate for flaws.
 
Interesting numbers on the octane, I thought we had low octane fuel but our regular unleaded is 91 octane. I cringe at that going in my UZ anyway, I used to use at least Premium @95 octane, or ideally the top shelf 98 octane fuels.

Now I run gas @ about 105 octane :D
 
My comments pertain to American Pump Gas. Consider Race gas completely different. Do you know how similar you gas there is to our gas here? In the US, as the octane goes up the efficiency of the gas goes down.
 
As advertised here, generally the higher the octane rating and quality of the fuel, the more miles per gallon you can get out of each fill.

Most 'normal' common 6 cylinder sedans that would generaly get say 600km out of 91 octane unleaded will see close to 650km out of a tank of 95 octane 'Premium Unleaded.'
 
i tried ngk platinum and bosch copper spark plugs in my 1uz.

what i found was if i was using 96 or 98 octane fuel the platinum plugs were igniting the fuel better than the copper plugs (blacker deposits). if i was using 91 octane fuel the copper plugs were igniting the fuel better than the platinum plugs (blacker deposits). So i decided that the standard toyota denso plugs that came with the car were best for my needs. ATM

The fuel consumption was the same give or take 10kms city, but highway was improved by about 30 to 50kms out of a tank using 98
 
I have been using 89 octane in my stock 95 LS400 for probably 10 years, and there has been absolutely no problems
 
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