5.5psi on 91pump yes or no.

[sarki]

Ok guys im tired of getting mixed opinions about this. I know theirs someone out there that has the definitive answers for this question.

Can you run a 5.5psi pulley on the v6 Solara at 10.5 compression and still use 91 pump??

The reason im posting this is because 5 out of 10 people say NO and the other 5 people say Yes. Ive called several dyno shops including Church's and its the same thing. I know Evos and STI's have lots of boost and i dont see them disintegrating. So I know someone MUST have experience or a chart that can give me and others planning the same setup a REAL answer.

BTW my mods so far

S/C at 5.5psi
Jims fuel mod
Supra 330cc injectors
Gm knock sensor (Relocated)
Apex-i Safc II
Walbro 190

Thanks
Sarki

[Dawgz]

U should be fine with a good tune.


11.8:1 when in open loop.

[akora12]

A good tune is critical. 93 octane is more forgiving in higher boost situations, but I realize that's not available in all parts of the country.

[sarki]

I think so to but some people tell me that its not possible. Church's dyno shop went as far as telling me i need a Split Second or Greddy E-manage to make it work. Other dyno shops said its not necessary at all.

[trentmeyer23]

They just want money out of you, think about it

[Midias]

Get it tuned on 91 then you should be good to go on 93 and 91

[1gSE]

meth injection....

[Mole]

91 is fine.

besides, we dont get anything higher at normal pumps...

i know of a 76 that sells 100 oct pump over in old town area...

but thats overkill and expensive.

[jetbtkng]

sarki if you run 5.5 psi on 91 you will break somthing, bobs been through that already, 10.5 to 1 compression is alot for a boosted engine, i havent blown a knox sensor in my black lara yet and there the stock ones, because i use 94.2 octane when i was a 6psi, and track ran the >>I'm a douche<< out of it, now at 7psi still havent blown one yet, ive blown an engine up, and i know there weak points................

[trd4life]

a 5.5 pulley is gonna spike to over 6psi on the top end on a nice cool night.

You have a few options that will work.

1) Xylene (117octane) or toluene (114 octane). Around $18 a gallon. These are concentrated octane boosters that can be bought at home depot or any paint supply store. Add 2 galons of this stuff mixed with 6 oz. of marvel mystery oil into a full tank of gas you get franks 94.2 formula he uses in his solara. Problem solved.


2) Meth injection system. Around $300-$400. Sprays a mixture of methanol and distilled water into your throttle body when boost kicks in. Increases octane and cool things down substantially. Problem solved. In terms of cost and horsepower gains, this would be the best option.



3) Split second FTC , emanage, or MSD DIS-4. Aftermarket timing controllers that will give Church's the ability to pull timing on your car. You could run 5.5 on 91 octane with one these controllers, but would probably not make as much horsepower as option 1 and 2.




A few members here have got away with a 5.5 psi pulley , 91 octane, and tuned with and SAFC, but thats pretty uncommon and who knows if these people are driving their cars hard like me frank and bob, and yes you too sarki drive our cars

[sarki]

Replying to frank and Gabe. The Guy at the Dyno shop down the street who BTW does all the Turbo drifters tuning said guys have 10+ psi of boost on stock motors with no problem. Why am I going to have an issue with 5.5? I'm going to try out my luck with this. Who here has a chart that shows how much compression you get with each Psi of boost?

[jetbtkng]

ya but there not at 10.5-1 compression, more like 9-9.5-1. the pistons in our motors are >>I'm a douche<<, and really werent designed to be boosted, but it looks like you made up your mind, im only giving you my opinion & expierience of what these engines can handle, as ive blown one up already at 6psi on pump gas with safc, fuel mods............

[trd4life]

Sarki, If you had 93 octane in california you would probably be ok with 5.5psi. The 91 cali piss gas, combined with the weak piston'd 1mz-fe motor, combined with 10.5:1 comrpession= broken ring lands. Its happened to dozens of people on here including myself.

[crispone]

Replying to frank and Gabe. The Guy at the Dyno shop down the street who BTW does all the Turbo drifters tuning said guys have 10+ psi of boost on stock motors with no problem. Why am I going to have an issue with 5.5? I'm going to try out my luck with this. Who here has a chart that shows how much compression you get with each Psi of boost?

Don't be fooled by "oversimplification" of a much more complex dynamic. Speaking of DYNAMIC... you have to consider DYNAMIC COMPRESSION (look around on this) and realize, it's NOT about absolute BOOST pressure @ a given compression alone... and realize further, that compression is NOT an absolute that is linear either.

There are FAR too many variables at work to say X psi @ Y compression = Z octane. That's OVERSIMPLIFICATION of the dynamics of flow, boost, and compression. Just to further stimulate your mind... think about this, You aren't always seeking MORE BOOST in the interest of gain. I.E.: If you FLOW much more efficiently, through a larger turbo, freer flowing head, larger cam lobes with tuned profiles, you are potentially netting FAR GREATER HP at any given PSI of boost, even to the point where at a LOWER PSI on a given motor with certain OTHER mods (such as cams, a/r, trim and overall flow) you are gaining MORE HP than a higher boost level with a "lesser" efficient setup.

Case in point, my supra is now running a 61mm trim spool after several smaller hybrids through a fully flowed and ported head with BIG cams... and I generate SUBSTANTIALLY more HP at LESS PSI boost than ever before, but I am ALSO needing HIGHER octane or additives to slow the burn due to my increased DYNAMIC COMPRESSION.


Keep in mind, BOOST is also a byproduct of RESISTANCE to flow. If you FLOW much better, less boost can be generating more HP. The key is FLOW and how effectively you can harness the most out of each cycle of the engine... or "dynamically compress" the charge.


On the original question... let me just ask this as a counter-question... why WOULD you want to run 91 if you have the choice? Who could POSSIBLY take all the factors at play into account in YOUR specific application and make this judgment? Fuel LOSES it's octane number AS IT SITS in the tanks at the station... so the average ratings on the pump are BASED on measurements taken, but won't necessarily reflect actuality.

Run the best you BELIEVE you can get, then learn to recognize the SIGNS of knock, detonation and such... then mitigate your boost (whatever the number) until it stops, or by SLOWING your rate of burn in the combustion chamber with fuel additives, etc... which achieve the same effect as using higher octane fuels.

Personally, I CARRY a quality octane booster (Lucas, BLENZALL, Xylene, etc...) AND have full control of boost levels to ADDRESS the octane limits of what I can find... JUST IN CASE I have to run 91 or even 90 octane in a pinch... but I NEVER deliberately compromise on my octane, EVEN in my "regular" cars...

...that's like licking honey from a sharp blade. If you want to savor the sweets, better make sure they won't "cut" you back...


Just my $0.02.




-crisp

[JavaJoe_2]

I'm guessing here but probably over 50% of the guys running 5.5 or higher on these boards are running fine.
I'm at 8 (10 by spring) but I have meth injection with a E-Manage on Paladins old ride.
Prior I was running my Camry at 5.5 with all the fuel mods and had no issue. I did so for over a year or more. So, all I can say is run a richer tune and you should have no problem.
And, yes I was running the stock knock sensors on my Camry.
But if you want full potential......throw more money at it!!
Speed costs Money!!