ThE sPaCeCoWbOy

how much boost can the 944 block hold up to....

i think the stock boost on a turbo is 12 psi...but i believe i remember some people running as high as 18

thanks,
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CPTdooberhead

Hey, I ran mine at 22PSI for 2 whole weeks! but...then the heagasket blew. (MBC broke on me and wouldn't lemme turn it down)

mideastmafia

I had to read the topic about 10 times to finally figure out it said "can the BLOCK withstand" rather than "can the CLOCK withstand"

its too early. im going back to bed

SHAUN

mrmunky

[quote]Originally posted by ElonDooberhead:
<strong>Hey, I ran mine at 22PSI for 2 whole weeks! but...then the heagasket blew. (MBC broke on me and wouldn't lemme turn it down)</strong><hr></blockquote>

hehe must've been a hell of a ride for about 2 weeks there, eh?

Perry 951

The block itself can withstand 25psi or more of boost. Boost is not usually the problem when it comes to engine failures, but lack of fuel or incorrect timing. There are a mess of other things like charge air temp, octane, ignition current and amperage (or lack there of) that will cause problems.

I ran 18-20 psi for the entire month before the fire. I had the correct amount of fuel and timing to go along with the extra air. That is the most important when running high boost levels. Again, as far as the block itself, it can take a lot of stress, more than would be needed.

BTW... 25psi or more is silly. By then, the air is heated so much that you kill the motors efficiency.

Later

ThE sPaCeCoWbOy

yeah...i agree 25 psi is silly especially for a road car but it still sounds and looks cool.....especially if you have a license plate that says "25 psi"

i think im going 18 and if i find a block that doesnt need sleeved, i want to make sure that the block can withstand that...

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Huntley Racing

I have run 25 PSI on track cars consistently with good results. I have made 30 PSI on stock blocks without blowing them up for short periods of time. Our 'Zebra' motor is made to run 35 psi consistently in endurance racing. Boost is not the inherent evil but detonation. Avoid detonation and most everything else will be OK.

mideastmafia

[quote]Originally posted by Huntley Racing:
<strong>I have made 30 PSI on stock blocks without blowing them up for short periods of time. Our 'Zebra' motor is made to run 35 psi consistently in endurance racing.</strong><hr></blockquote>



SHAUN

mideastmafia

a

CPTdooberhead

ok, my gauge actually read 25PSI, but I figured it was off, and was only dong 22PSI...and yes...it was a HELL of a ride! haha, that thing hauled ***. It would be nice to be able to keep that kind of boost constant, but I was nervous everytime i drove the car. I drove it all the way to Ga and back (from NC) before it blew 30 miles from home (I got lucky, could have ended up in the mts. of Ga or something worse). I wasnt driving it over 80mph either at the time it blew...oh well. I dont suggest this!

RAD951

Interesting thread,
I was going to ask the same question but slightly differently.


Whats the maximum boost I can go with autothority stage 2 chips, 2.5 bar fuel reg,stock injectors?? Can I run 18 psi without changing fuel injectors??

The reason why I am asking is because I am planning on purchasing a spearco water injection kit. The kit should let me run more boost but the problem is, will I go lean if I run 18 psi or maybe 20 psi??

I plan on using an alchohol/water mixture.

Perry 951

You can run about 17 before getting lean.

You should get an adjustible FPR. Your injectors will be fine, and the chips have a decent fuel curve with the stock turbo.

Once you do that, you can crank it up to 18-20psi, but the charge air will be hot. The stock K26/6 is not that efficient up high. With your head work, you might notice a greater drop in pressure since you can flow very well. I would bet it drops to 15 psi at 6000.

You may want to think about a bigger turbo, instead of the water injection. This will flow the air you need for the headwork and exhaust, and keep the air temps cooler at 18psi. With the above mentioned AFR, you could lay down some serious power. Much more than water injection and a stock K26/6.

I know this because I had the same setup before the fire. I ran a K26/8 cheater it at 20psi, falling to 17psi at 6000. I tried it with no MAF, and put down 255 at the wheels, 287 with the MAF. Sill got 24mpg highway.

<img src="graemlins/drink.gif" border="0" alt="[cherrsagai]" />

Danno

"Whats the maximum boost I can go with autothority stage 2 chips, 2.5 bar fuel reg,stock injectors?? Can I run 18 psi without changing fuel injectors??"

I wouldn't even run those chips past 15psi since they get so lean up top. Increasing fuel-pressure to 3.0-bar would help the top-end, but it would completely kill your mid-range and partial-throttle response (not to mention increase turbo-lag).

At a minimum, I would get custom chips. Do a dyno-run with air-fuel-ratio curve. Re-burn the chips with modifications to get flat air-fuel ratio at full-throttle/full-boost. About 15psi WILL be the limit of the stock injectors if you've got a free-flowing intake/exhaust, boost-controller and/or wastegate.

With a water-injection kit, you'll get even more air flowing through the system and at 18psi, you'll definitely need larger injectors.

A lot of people will push the limit and get decent HP numbers and think it's OK. But they don't have an injector duty-cycle meter and don't realize they're driving their injectors to 100%, which is not good for them or the DME. And they don't have dyno charts to see that they're getting dangerously lean in the high-RPMs. A simple upgrade to larger injectors will alleviate all these problems and give you potential for future upgrade into the 400-425rwhp arena.

RAD951

I what I will have to do is run the water injection with boost level no more than 15 psi. And when I buy bigger injectors, I can run 18 psi with the water injection.

I wish I could buy a bigger turbo and such but that is going to cost me at least $1000. Or I could go for the Guru MAP kit but thats another $1000.

One option I was thinking of doing is completely eliminating the intercooler by substituting it with a water injection intercooler system. But its a little risky because if the system fails, then the engine will induce some serious detonation. But on the other hand, you will take out a HUGE restriction on the intake by eliminating the intercooler. But I believe I am better off staying witht the intercooler and using water injection.

By the way, what size are our injectors?? Are they like 550cc???

ThE sPaCeCoWbOy

one thing i dont like with the water injection systems is that it takes up air space....maybe if you have it spray on your intercooler, it may cool the air down enough to run more boost without taking up air space....or if you can find a company that makes a water to air intercooler...

personally i think with a tec 3 or tec 2 system you should beable to up the boost with no problems.....it does come with larger injectors, new map sensor, allows you to do alot of cool little things with a labtop....all the graphs, and charts.... <img src="graemlins/yltype.gif" border="0" alt="[typing]" /> <img src="graemlins/bigok.gif" border="0" alt="[thumbsup]" /> .....oh boy....overload....i'll stop....