I was wondering if any problums
I have a stand alone and i will use race gas on hi boost runs at the track. so why have 9/1 compresion im my opinion.
just want to here what some people have done and have to say.

 

I'm going to run 9.8:1 compression on my motor.

 

I hate to quote myself, but:

 

so yes with higher compresion this will alow you to acive higher hp. but with the right gas.
my question is how much boost or hp should i say will be safe with 10.5 to one copresion with a fully built golden eagle block and 93 octain.

 

That's not what I was trying to say, I was saying that with EQUAL dynamic compression, you make MORE power with a little higher boost than with raised static compression!

Static compression is just a useless number for "bragging rights". Dynamic compression is what really happens in your motor... running lower compression + more boost is effectively the same thing as raised static compression, except you get to add fuel when you add boost...

 

So a lower CR with higher boost is better that a higher CR with lower boost? Iv read on here many times from many different people that a hight CR is better so you can acheive higher HP levels with lower boost.

 

ok i undersand that buy the limits of hp in a 9/1 compresion motor are not as good as a 10.5/1 right. so if i can boost 20psi on a 10.5/1 on racegas at the track that would make sence to have 10.5/1. why not if you have a standalone and all the fule requirements.

 

i think dustin is saying that if the total compression is the same in both instances then this will be true: the engine with lower compression pistons (engine x) will make more power because there will be more boost. This is because there will be more fuel added to compensate for added boost.

if you add stock compression(A) and compression created by boost(B) then it will be the same with both motors. except engine x will now have more air and more fuel because more boost.

hope i got it

 

here's my take on the situation..
if it is a track only car that will never see below 5,000 rpm and 20psi... then sure.. go with a lower compression. but if you're like most of us and your car is 99% street driven, i would run around stock compression (10.0 with vtec/9.0 with ls.) the car will be alot more fun to drive... besides.. you can't run much more than 12 psi on pump gas anyway.

 

i don't know how this factors in in each situation, but more boost also equals more heat...but who knows how all these factors will even out in the end?

i'm sticking with JE 10:1, eagle rods, GE sleeves, and water injection to help cool things down even further.

 

To reiterate:

If it's used mostly for the street keep it 10:1, and if it's more so for the 1/4 use high test octane, and lower it to 9:1. But, in both cases get the timing and A/F as near perfect as possible.

 

lower compresson=turbo lag but great hight end (best for track)
hight compresson=less lag better bottom end (best for street)

i am going low compression so i can run the cheap gas, and i will just live with the street turbo lag!!

 

ok tell me where i must have gone wrong.
engine X fully built motor with 9/1
engine y fully built motor with 10.5/1
If i use at least 100 octain all the time. -why not its only a extra 6bucks a gill.
all you so is mix 7gal of 93 with 3gal of 114.
i am useing a standalone to contoll big injectors and fule.
i plain on driveing on the street and have better hp at the track
why not get 10.5/1

all tuned up even at the track Engine Y will have higher hp levels.
yes you can get more hp out of 9/1 compresion becase you can boost it more.
but why not boost the 10.5/1 just as much as the 9/1 and get even better hp.
yes you will have to run good gas all the time and have a standalone and fule.

 

if it's a race only engine, i would say ok.. but it's not gonna last very long running 20+ psi at 10.5:1. i built my engine with 10.0:1 compression and plan on running no more than 18psi at the track...which will happen maybe once a year.

 

well if u look at almost every professional race motor, they are running high compression w/ a huge amount of boost, but the motors are only built to last 1 season.. so after u get to the point where u r running max boost + huge turbo + u cant do much else but raise compression..

If u r building a street motor, and are going to be running 100 octane, u r still limited by dynamic compression.. You can only have so much dynamic compression on 100 octane.. so u need to figure out which set up, high compression w/ low boost vs. low compression w/ high boost will make more power at the same dynamic compression..

to answer ur question about 10.5:1 on 93 octane, I would say u can run 8-10psi of boost max and thats with perfect tuning.. then more on 100 octane, and even more on C16..

keep in mind lower compression w/ more boost will always make more power then highcompression with low boost, u just have decide if u want your power on pump gas, or on race gas only..




[Modified by DIRep972, 10:47 PM 4/12/2002]

 

can some onene explain what exactly dynamic compresion is.

It seems as if everyone has conficting answers. some say it is better to have higher compresion on a streetcar and some say only high comp on a race motor.

would you not have much better torque and low end power-band.
and i dont see how on a stand alone and a fully decked out golden eagle block can only handle 8psi. I would hope a little more than that.
Maby after i learn more about dynamic compresion i will get it more.
Please if you are baseing your answers on what you have herd but have not aculay had or have seen results of highcompresion turbo motors please do not confuse the situation worse.
thanks for all info.

 

don't reinvent the wheel, top turbo setups run 9:1 or less. You can only get so far running high compression on a given octane. There is far more to be gainer by running lower compression and higher boost.

 

ok i see on 91 octain how you might get more hp with boost and low -comp
just how high of a octain gas would you need to run lets say 20psi on 10.5comp. for track use.

 

you would have to run C16, leaded 116octane most likely..

I can't quite explain dynamic compression, but ill give u an example that might help.. A motor running 9:1 and 15psi will have app. 15:1 dynamic compression, that is considered the limit for 93 octane.. take that same motor and run 18psi, now u have higher dynamic compression so u will need more octane and so on and so on as u go up in boost and compresion..

 

how hard would it be on your motor and other parts to run c16 leaded.
the latemodal guys run turbo-blue wich is also a high octain gas like 114 or so. I do not have a cat on my car, it is just a 3inch all the way.

 

It kills O2 sensors.

 

i personally would never consider a compression higher than 9.5:1 on any honda motor. if you take a hard look at whats out there, not many people do it successfully. the ones that do run high compression usually only get a few race weekends out of them at best. never a whole season. no one with a 10.5:1 compression turbo race motor makes it last any longer than that. for the street guy(who realistically has to consider his/her limits on tuning and keeping it tuned) a 9:1 compression is best. its safer. period. if you wanna improve your 2500rpm-5000rpm range, go with a 84mm block. that will give you some added torque and get that turbo spooling.

seriously people, go with what works. you don't have to try and reinvent the wheel when trying to make good power. i see people on h/t all the time saying they want to try this and that......serious research and develpoment is pretty much out of all of our leagues here. that takes me back to.......go with what works.

a 84mm bore, 9:0 comp, t/4, stand alone motor will haul *** faster than any other street car on h/t......just ask littlebluecrx.

 

It doesn't matter what you have in that block if its detonating. People don't put sleeves in their blocks so they can drive and race while its knocking.

 

ok well lets say i can only run 8-10psi. on pumpgas.
The block has a 85mm bore. My car has all the other little mod you can get to achive all posable hp.
so wouldnt i get at least 300whp just on 10psi.
that would be ok for the street.
what is the highest octain you can get in a unleaded gas

 

I want to know were all the poeple went that were claiming 20psi and 10:1 on pump gas? and if you did not run that combo you were a dumbass?