EkFG

11.3:1 CR and Turbo Charged

okay after about a month and a half ive been contemplating about this set up.
I started my build as a NA semi stock rebuild motor.
Spec's"
B18c1
Rebuilt cylinder head and milled .008 with valve job
Block was bored and hone to 50mm
Type R pistons 50mm USDM spec
piston to wall clearance was 1-1.5 (thousands of an inch)
crank was polished and chamfered
Rings were gap at 1st at .016 second at .018 third at .015 for oil control
everything else was replace gaskets seals bearings etc...

I just picked up a turbo kit from my buddy practically FREE.
Consist of
T3/t4 hybird A/R 50 and 63 exhaust housing
ramhorn

Highest pump gas around here is 91 octane
now that i have the turbo its time to decide.
I figured my CR @ 11.3:1 and static CR with 5 psi at 14.9:1-15.3:1,
using the zealautowerks calculator. I wasn't too sure about it and contacted
JE and they said that sounds about right with there calculator.
I know tunning will be a issue , but im thinking that if i stay under 6 psi i might be okay on a decent tune. I know that with different gas and better tuning i could up my psi but
Im not looking for a whole lot.

Im sure a lot of racers are running high CR with boost at the track but they never want to disclose any info, lol i dont blame them.

any input would most deff be considered.

the way im looking at it and from what i have been reading :
low compresion and boost just leaves option for mistakes
verses high CR with boost.

tony413

just try it and see. i personally think you will be fine as long as you pay attention on the dyno. watch your timing and listen as well as read plugs inbetween runs. work in the turbos efficency range, you dont want to blow a ton of hot air.

MTVtec

Seems like a pretty high CR for 91 octane but like you said, low boost and a conservative tune will keep you safe.

EkFG

Im putting things together right now. I was just looking to see if anyone has experience with something like this.

TheShodan

iTrader: (14)

Check with TOny the Tiger. He had 11.5:1 on AEM. It is VERY risky, but it can be done.

EkFG

which AEM system was he using? I think he was running like 12 PSI thats a little too high compared to what im going to run which is 5 PSI

dohczccrx

why would you make this in twice in two different sections

EkFG

2 is better then one, lol plus this is the FI sections so maybe someone here might have good info as well.

HiProfile

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EkFG &raquo;</TD></TR><TR><TD CLASS="quote">Type R pistons 50mm USDM spec
piston to wall clearance was 1-1.5 (thousands of an inch)
</TD></TR></TABLE>

Those are the 2 biggest issues I see, at least due to the high CR. Cast pistons really don't like any detonation. You may also have issues due to the tight tolerances between your pistons and sleeves. Keep in mind most stock motors have a larger gap because they aren't boosted right from the sales floor, but with &gt;50k miles worth of wear.

TheShodan

iTrader: (14)

^^ very true. Even Tony's setup used forged components at the compression. I didn't look at the fact that these are cast components. With that in mind, I would definately keep this NA, or build from the beginning with lower compression components and good tuning.

Which AEM he used or what psi is irrelevant, it is the fact that it was tuned immaculately that is important.

EkFG

the clearance for the pistn to wall was what concerned me as well other then that the cast piston should be ok along as the tune is done correct.

...Well Im gonna go for it, because if i dont it will bother me
the motor is replaceable memories are not, lol


Will talk to some tuners see if they are up to it.

I will keep you guys updated.

thanks

tony413

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by EkFG &raquo;</TD></TR><TR><TD CLASS="quote">the clearance for the pistn to wall was what concerned me as well other then that the cast piston should be ok along as the tune is done correct.

...Well Im gonna go for it, because if i dont it will bother me
the motor is replaceable memories are not, lol
</TD></TR></TABLE>

now you talking post pics of the carnage if theres any

EkFG

[freak] it right might as well

MiraiZ

stock ITR pistons will not survive that setup without some REALLY good tuning

MiraiZ

Fuel and timing solution??

EkFG

im in the proses of asking my tuner what he feels comfortable with either AEM ems or Hondata s200 and MSD , also Type r pistons are able to handle it.

Tony the Tiger

With 91 octane, you are looking for trouble... There's too many potential variables can destroy the motor. With factory cast pistons, I consider this motor to have almost no margin of error and won't tolerate even the slightest mistakes. I consider dyno tuning be a potential cause as well just because no tuner can determine what timing is too safe or too aggressive until it begins to slightly ping because it's way behind in octane requirement. I think even that slightest ping will cause troubles. At this rate, if you are looking for power just for track events or weekends, plop in some 93+ octane fuel. For everyday driving, just pull out the wastegate spring or disconnect the charge piping.

EkFG

humm gonna try and look for higher octane around here because i would like to drive this car around.

you think 5 psi would really give me alot of trouble?

mar778c

iTrader: (1)

PTW clearance is too tight for boost.

vw1320

Not sure where Near You WI is but this might help:

http://e85vehicles.com/e85-wisconsin.htm

Not saying to turbo your motor but at least this is an answer to the octane issue.

rorik

figured my CR @ 11.3:1 and static CR with 5 psi at 14.9:1-15.3:1
You could feed 100psi into a chamber at ambient temp, compress that at 11.3:1, is that going to be hotter than 14.7 (1 atmosphere) x 11.3:1?
An hour reading about gas laws on wikipedia, and I'm nowhere.

e85.. just what I thought too.
That should work.


Modified by rorik at 6:52 AM 9/1/2008


Modified by rorik at 5:51 PM 9/1/2008

MiraiZ

I did 11:1CR for about 2 weeks before my engine blew. Cracked ringlands left a huge scratch on the cylinder walls. Fortunately it was easily honed away, but trust me, stock ITR pistons aren't going to cut it, not even at 5psi. You would have to totally baby your car and keep the revs down. I would hate to drive a car like that. Like Tony said, there is VERY little margin of error. I'm surprised that your tuner wants to even touch your car. Does he even know what CR your running?

93 octane is nothing. I was running 100 when mine blew. If you want to drive your car regularly, get some forged pistons AT LEAST. If you can't afford them, then wait until you can.


Modified by MiraiZ at 5:33 PM 9/1/2008

TheShodan

iTrader: (14)

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by MiraiZ &raquo;</TD></TR><TR><TD CLASS="quote">Fuel and timing solution??</TD></TR></TABLE>

Damn MiraiZ, haven't heard from you in YEARS. Hows it hanging in Yokohama?

blakkvtec

So if this was done with forged pistons(11.1-1) On E-85? Hows it gonna hold up then? Safer I'm guessing but how much, still any risk?

EkFG

all good feed back guys. AWESOME thanks..


I think what im going to do is just pack up the turbo and store it, and start building a
d series Z6 low comp like 8:0:1 maybe vitara pistons and h beam rods. I will just ride this GSR with 11.3:1 with 91 octane and beat the **** out of it. that way next summer I will drop in the D with boost ,. thanks again you guys never FAIL.

If you guys lived near by I'd invite you all to some GREAT WISCONSIN BEER.