safe boost level on stock ct w/ fuel and engine mods

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89whitepkg

I hate rust !
Mar 7, 2006
121
0
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Lexington, KY
I'm in the middle of my rebuild and it looks like the one thing I'm going to have to wait to put in is a bigger turbo. So what kind of pressure can I run on my ct in the mean time?

Mods:
Je pistons
Eagle Rods
5 angle valve grind
fully machined, balance and blueprinted block and crank
MHG
Arp main studs, rod bolts, and head studs
FFIM, modifined stock
FMIC 31X12X4 with 3 inch hard pipes
Blitz dd blowoff valve
denso 550's
Safc Neo
Lexus afm
Fully 3inch exhaust w/o a cat
afpr w/ j tube bypass
walbro 225
Manual bost controler
Lc-1 wideband
remote oil filter and thermostat controlled oil cooler



My thinking was this......Spend the money on everything needed to safely run a bigger turbo rather that give in to temptation and just slap on a bigger turbo and not really have the fuel setup to support it. I know that huge inter cooler is going to cause so extra lag in the meantime, but I'm trying to think long term.

So, what is a safe amount of pressure to expect out of my stock ct (in great shape, no shaft play)?
 
bountykilla0118

bountykilla0118

In Pursuit of 500rwhp
Jul 16, 2005
1,088
0
36
40
Atlanta GA
starscream5000;979662 said:
About 12 psi, then it begins to get out of it's efficiency range and starts producing some hot air.
Click to expand...

I made 289rwhp at the 14psi mark on a old motor..... I drive at 14psi every day
 
GrimJack

GrimJack

Administrator
Dec 31, 1969
12,377
3
38
56
Richmond, BC, Canada
idriders.com
Put it on a dyno and listen for detonation with a set of electric ears. Turn the boost up until you start to get detonation, then turn it back down a bit.

I'd be willing to bet with that setup you get a fair bit of power.
 
D

Dan_Gyoba

Turbo Swapper
Aug 9, 2007
1,836
0
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Alberta
www.gyoba.com
Rennat;979818 said:
shouldnt he be able to do 13-15psi because of the IC, and the fact he has 3'' piping... seems like it would cool the hotter air.
Click to expand...
Yeah, he could go with more pressure, but it wouldn't make more POWER, because in the end, it wouldn't get more air into the cylinders.

Probably you could get a fair amount of power from that setup. Chances are that it won't be detonation that's the limiting factor on how much boost you can run, but the limitations of the CT26 to flow more.

As for the "lag" introduced by 3" piping... It's insignifigant.

Let's say, for argument's sake that you have 20' of 3" pipe. That's 240" in length (Nobody should have that much IC piping, this is just an example.)

Formula for a cylinder is pi * R * R * L or 1696.4 cubic inches for the entire length. That's about 0.98 cubic feet.

One cubic foot of air (at standard atmoshperic temperature and pressure) is 0.0807 lbs. Compressed to 16 psi, we'll call it double that.

Let's say that we're at relatively low RPM and want to move that air through our 1 cubic foot tunnel, so the turbo starts to spool and starts moving what, 18lbs/minute of air That 18 lbs is about 117 cubic feet. That means that in one second, the turbo has pushed about 1.9 cubic feet of air through that ridiculously long IC pipe (I mean really, you could have a front mount intercooler on an MR2 for that much pipe!)

So, even discounting the volume that the smaller piping would have, that means that at most you're waiting an extra 0.5 seconds of lag.

Now take into account the regular 2" pipe (About 1/2 the volume) and we're down to 0.25s Account for the fact that we're NOT going to pressurise the whole thing to 16 psi, and it reduces it further.

You'd have to go awful big before the IC piping had a serious effect on lag, I think.
 
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