Simple question, at what horsepower or boost range should one look into running "race" gas.

I've had an 84mm built LS block for about 3 months now, i've begun tuning and turning up the boost. However i'm taking it in baby steps. IE 8psi - 10 - 12. Before I start getting to deep into the boost, i'd just like to know what I should stop at before I need to start running "race gas". I also considred some method of water/alcohol injection as an alternate method to increasing the octane rating.

I'd honestlt rather run some type of injection system, as opposed to have the expense of constantly running race gas. So anyone who has experience with water injection systems on their boosted Honda is encouraged to post.

Thanx guys

~Steven


[Modified by Speed PHreak, 12:26 AM 2/5/2003]

 

it depends on what compression you are running.It wont depend on how many pounds of boost you run or what hp figure either.

 

Sorry, should have included that in the original post.

I'm running 8.8:1 C/R, looking to boost in the 16~20psi range. This is out of a t3/t04e (.63a/r - 54 trim). I'm shooting for the 350~400whp range, so I guess about 450 crank HP.

I appologize for the "noobness" of this post, I just haven't ever worried about it before now since it wasn't an issue.


[Modified by Speed PHreak, 12:48 AM 2/5/2003]

 

with proper mgmt you should be able to boost 16-20 psi with the 8.8 compression on pump gas. I would still mix it for 20 psi but 16 psi on pump should be no problem.

 

I am actually curious about this too. I know alot of people just run C16 and dont worry about anything else for race gas. but then some people run 100 unleaded.

pump gas is easy, 9:1 compression, good sized turbo, 300whp/15psi is usually the general conservative limit.

but, what about w/ 100 unleaded?

C16 pretty much seems like it will cover u for all u can give it, i don't think there are many limitations on how far u can push it on C16 at least on a street car.

motormatrix- do u run leaded race gas daily?


[Modified by DIRep, 9:55 PM 2/4/2003]

 

i run pump if i'm just driving to my shop or to somewhere i'm not going to race. For race nights I'm always on c16. I have a 19psi wastegate spring so if i plan to step on it i have to be on c16. the car was tuned though to 17psi and almost 400hp on pump when I had the 10lb spring.dont forget not only is the compression a factor but also how aggressive you set the timing.


[Modified by MotorMatrix.com, 1:04 AM 2/5/2003]

 

yeh, there is a point where u just can't pull out anymore timing, and u have to have higher octane.

basically i am just wondering how much more power 100 is good for over 93. or how much boost it allows u to run. I know alot of the supra guys run 17-18 on pump, and 23-24 on 100, then 30 on C16.

 

supra is a bad example. they make 800+ on pump.

 

what pump are they getting there gas from? i need to go there!

actually, there are a few places u can get 100unleaded at the pump. it has a nice checkered flag next to the usual yellow 93, 89, 87 tags were used too. if i ran that could i tell people im running pump? hehe

 

Sweet. I've got a wideband in car to keep track of A/F ratios so........i'll just have to be conservative with my timing. I've only got an 7psi wastegate spring, but it creeps to 10~11 with the boost controller turned off(damn DRAG exhaust manifold). Currently i've got a XS manual boost controller, with it set to 12psi.

As soon as the parts get here I'm going to run a 2-stage. cockpit switchable, boost controller. It works off a 12v 3-way(1 in, 2 outs) pneumatic soleniod. With the flip of a switch I can divert the WG 2 ways. I'll have 1 way set go route straight to the WG for low boost, and the other routed through the current XS boost controller. That'll give me the option of running lower boost 7~10psi, then if I need it -- the 16~20psi. Think i'll lable to toggle switch i'm using, NORMAL -> 7-10psi and GO BABY GO -> 16-20psi




[Modified by Speed PHreak, 9:56 AM 2/5/2003]

 

Hows it going Steve? Good to see you still messing around with your car. How is it running with the bigger injectors? Is the Zdyne giving you a decent idle? I am working on building a Evac pump like my brothers got on his supercharged Stang(660whp). It keeps the motors together longer and vents out crankcase pressure under load (which is a major plus). If we can incorporate a simillar system in our Honda motors our longevity would be amazing. Thus giving you the latitude in running higher boost on pump gas and not detonating as easy. Its worked wonders in the Mustang world. They run them off their pullies so I am trying to find a way to use our pullies the same way, because I don't have power steering any more. I will let you guys know how it works when its done.

 

personally, at 14 deg timing and about 9.0-1 CR i run race gas if i plan on going anywhere above 1bar. i have alws been told that 1bar is the limit for pump gas no matter what tho!

 

Well my stock O2 took a ****, so now it idles like absolute ***. My stock O2 is way back near where the cat would be, and since it's 1-wire that's not close enough for it to stay heated. I yanked a 4-wire off of a friends old engine, we'll see how that does.

This Evac pump sounds like a kick-*** idea... tell us more

 

Ethanol baby!

 

This Evac pump sounds like a kick-*** idea... tell us more


Our pcv valve works on vaccum when we are idling, but once we start boosting our pcv valve isn't doing sqwat. The k&n breather on the valve cover isn't doing much for you either except smelling up the inside of your ride when it starts getting oil soaked. This Evac pump vents crank case pressure under load. Saving your piston rings and blow by that occurs after occasional boosting. It does what it says. Evacuate crank case pressure. You may notice when you really stand on your ride, that your dip stick pops upout of its seal. Thats because of all that crank case pressure thats there when boosting. That same pressure is what wears out piston rings and jacks up your bottom end. Its not the answer to all boosting problems, but it sure saves the life of your motor if tuned right obviously.

 

This is where a J&S comes in handy Either that or if you know your pinging/detonating time to put race gas/pull timing out.

 

That's a really good idea....do you just vent it always to the atmosphere then, or back into the IM? I suppose just atmosphere until you are due for an air test, then just back into the intake.
How much vaccum should be created to evac the crank case? This could probably be done either by an electrical pump, or by a mechanical pump (off one of the accessories). Hmmm, this has got me thinking, can you give me any more details? I will definately look further into this.