How much boost the block can withstand
08-12-2002, 04:45 AM
#16
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Interesting points- I would like to hear more about this Spearco water injection kit and intercooler stuff RADman 
Also, are you getting back to UT this semester? I may e-mail you in a minute...
Anyway, Rob Langley, a FL 951 owner, who had a Garrity Repta built 3.0L 951 engine- he chronicles his trials on his website, calling the car the big yellow bus- anyway, he was only running ~15psi and blew many a headgasket, although I'm not sure why- the point I'm getting at is, he has a friend who runs a 951 at 22psi (I believe- it WAS ABOVE 20psi) and had done so for several YEARS w/no probs! There was much discussion about this stuff on their web board- I'd have to find it if anyone's interested- and the high boost guy was always right there w/him, if not ahead of him- VERY depressing, considering the time, $, and effort involved in the 3.0L, and the fact that he was ALWAYS having probs- went through at least 4 headgaskets... Anyway, just chiming in to say that I'm aware of one that is definately above the 20psi mark, and, it performed flawalessly for at least 2yrs...
I was hoping to run somewhere b/t 15 & 18 at the most- mine being a street car...
Also, are you getting back to UT this semester? I may e-mail you in a minute... Anyway, Rob Langley, a FL 951 owner, who had a Garrity Repta built 3.0L 951 engine- he chronicles his trials on his website, calling the car the big yellow bus- anyway, he was only running ~15psi and blew many a headgasket, although I'm not sure why- the point I'm getting at is, he has a friend who runs a 951 at 22psi (I believe- it WAS ABOVE 20psi) and had done so for several YEARS w/no probs! There was much discussion about this stuff on their web board- I'd have to find it if anyone's interested- and the high boost guy was always right there w/him, if not ahead of him- VERY depressing, considering the time, $, and effort involved in the 3.0L, and the fact that he was ALWAYS having probs- went through at least 4 headgaskets... Anyway, just chiming in to say that I'm aware of one that is definately above the 20psi mark, and, it performed flawalessly for at least 2yrs...
I was hoping to run somewhere b/t 15 & 18 at the most- mine being a street car...
08-12-2002, 06:59 AM
#17
Race Director
One thing I'd like to point out is the difference between blanket qualitative, black & white, all-or-nothing, yes/no statements vs. quantitative analysis with shades-of-grey variations. With that in mind, we can make an easier determination of performance options using numbers.
"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.
Perry's right on about that one. A K26/6 CAN be made (more like forced) to crank out 18psi with an aftermarket wastegate and boost-controller. But the outlet temperature will be over 350 degrees-F. A more efficient turbo will keep that air to a more reasonable 250 degrees-F.
"One option I was thinking of doing is completely eliminating the intercooler by substituting it with a water injection intercooler system."
"But I believe I am better off staying witht the intercooler and using water injection."
Again, sounds simple in black & white terms, but the numbers don't support it. The stock intercooler will drop air-temps about 120-150 degrees-F initially. After about 10-20 seconds worth of full-throttle runs, heat-soak will limit this temp-drop to 100 degrees. Water-injection on the other hand, will only drop temperatures about 50-75 degrees. It is best used as a supplement, but not a replacement for intercooling.
"But on the other hand, you will take out a HUGE restriction on the intake by eliminating the intercooler."
Do you know what the restriction numbers are? At stock boost-levels, the intercooler drops less than a single PSI. At 15psi, it's roughly a 1.25psi drop and 18psi, about 1.4psi. The temperature reduction alone more than makes up for the drop in boost.
"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."
Depends upon how much you inject and how much of a temperature-drop you're aiming for. Water is actually a very dense and heavy molecule compared to air or gas. Thus it's latent heat-of-vaporiation of 543kcal/mole is an immense amount and cools the surround air nicely. However, if you take that cooler air and try to cool some aluminium, then use that aluminium to cool yet another air charge, you're losing most of its effect. Given the same volume of vaporized water, you can cool the intake-charge 15-20x more by injecting it into the intake-charge than by spraying it onto the intercooler.
"...or if you can find a company that makes a water to air intercooler..."
Now we're talking. Bob Norwood has always been the air-to-water intercooler king! His turbo Ferrari set-ups have always used air-to-water intercooler for 250 degree-F temperature drops. That's more than our air-to-air intercooler plus water-injection COMBINED!. That's like taking the outlet of our turbos and chilling it down to FREEZING temperatures. This allowed him to build a twin-turbo Testarossa that got over 1000bhp using 91-octane pump gas! <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
"By the way, what size are our injectors?? Are they like 550cc??? "
Check out these injector flow-reports: <a href="http://boards.rennlist.com/upload/InjectorReport-txhe951.jpg" target="_blank">Tom's</a> and <a href="http://InjectorReport-TonyGarcia.jpg" target="_blank">Tony's</a>. See this thread on how to standardize them to 3-bar @ 100% static-flow: <a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=001996" target="_blank">WTK- Injector requirements for 400rwhp</a>. In summary, the stock 951 injectors flow 362cc/min @ 3-bar (34.5lb/hr) and 302cc/min (28.7lb/hr) @ the stock 2.5-bar fuel-pressure. They really are a bigger limitation than most people think; but most people don't have the data from an injector duty-cycle meter to allow them to make a quantitative assessment. I maxed my injectors out at 12psi, as did Rage2, and Russ Murphy, etc. (just about anyone with higher-flow mods).
"Rob Langley, a FL 951 owner, who had a Garrity Repta built 3.0L 951 engine- he chronicles his trials on his website, calling the car the big yellow bus- anyway, he was only running ~15psi and blew many a headgasket,"
"VERY depressing, considering the time, $, and effort involved in the 3.0L, and the fact that he was ALWAYS having probs- went through at least 4 headgaskets..."
I've diccussed this with both Rob & Garrity and the problems have nothing to do with the boost-level that he was running. But rather due to the sealing methods he was using to assemble the head.
"he has a friend who runs a 951 at 22psi (I believe- it WAS ABOVE 20psi) and had done so for several YEARS w/no probs! "
That's right! The problem with blown headgaskets has nothing to do with boost-pressure. It's due to the intense heat generated by knock/detonation that burns through the headgasket, rather than blowing it apart. In which case, a wide firering headgasket doesn't really help that much because it has the same 0.1mm thick layer of steel facing the combustion chambers (the firering is holllow). I've known tuners who've blown several wide firering headgaskets just weeks apart. It's all about having fine control over air-fuel ratios across all load- and RPM-levels.
A really durable headgasket that doesn't have the strict installation requirements of a copper headgasket would be the metal/fibre sandwich type that HKS & Huntley sells. Those can stand up to a lot more abuse than the hollow compression-ring type our cars use. BUT it does NOT preclude proper tuning of air-fuel ratios, without which, you'll be frying valves and melting holes in pistons instead of blowing an expendable headgasket.
<img src="graemlins/wave.gif" border="0" alt="[byebye]" />
"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.
Perry's right on about that one. A K26/6 CAN be made (more like forced) to crank out 18psi with an aftermarket wastegate and boost-controller. But the outlet temperature will be over 350 degrees-F. A more efficient turbo will keep that air to a more reasonable 250 degrees-F.
"One option I was thinking of doing is completely eliminating the intercooler by substituting it with a water injection intercooler system."
"But I believe I am better off staying witht the intercooler and using water injection."
Again, sounds simple in black & white terms, but the numbers don't support it. The stock intercooler will drop air-temps about 120-150 degrees-F initially. After about 10-20 seconds worth of full-throttle runs, heat-soak will limit this temp-drop to 100 degrees. Water-injection on the other hand, will only drop temperatures about 50-75 degrees. It is best used as a supplement, but not a replacement for intercooling.
"But on the other hand, you will take out a HUGE restriction on the intake by eliminating the intercooler."
Do you know what the restriction numbers are? At stock boost-levels, the intercooler drops less than a single PSI. At 15psi, it's roughly a 1.25psi drop and 18psi, about 1.4psi. The temperature reduction alone more than makes up for the drop in boost.
"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."
Depends upon how much you inject and how much of a temperature-drop you're aiming for. Water is actually a very dense and heavy molecule compared to air or gas. Thus it's latent heat-of-vaporiation of 543kcal/mole is an immense amount and cools the surround air nicely. However, if you take that cooler air and try to cool some aluminium, then use that aluminium to cool yet another air charge, you're losing most of its effect. Given the same volume of vaporized water, you can cool the intake-charge 15-20x more by injecting it into the intake-charge than by spraying it onto the intercooler.
"...or if you can find a company that makes a water to air intercooler..."
Now we're talking. Bob Norwood has always been the air-to-water intercooler king! His turbo Ferrari set-ups have always used air-to-water intercooler for 250 degree-F temperature drops. That's more than our air-to-air intercooler plus water-injection COMBINED!. That's like taking the outlet of our turbos and chilling it down to FREEZING temperatures. This allowed him to build a twin-turbo Testarossa that got over 1000bhp using 91-octane pump gas! <img src="graemlins/jumper.gif" border="0" alt="[jumper]" />
"By the way, what size are our injectors?? Are they like 550cc??? "
Check out these injector flow-reports: <a href="http://boards.rennlist.com/upload/InjectorReport-txhe951.jpg" target="_blank">Tom's</a> and <a href="http://InjectorReport-TonyGarcia.jpg" target="_blank">Tony's</a>. See this thread on how to standardize them to 3-bar @ 100% static-flow: <a href="http://forums.rennlist.com/forums/ultimatebb.php?ubb=get_topic&f=18&t=001996" target="_blank">WTK- Injector requirements for 400rwhp</a>. In summary, the stock 951 injectors flow 362cc/min @ 3-bar (34.5lb/hr) and 302cc/min (28.7lb/hr) @ the stock 2.5-bar fuel-pressure. They really are a bigger limitation than most people think; but most people don't have the data from an injector duty-cycle meter to allow them to make a quantitative assessment. I maxed my injectors out at 12psi, as did Rage2, and Russ Murphy, etc. (just about anyone with higher-flow mods).
"Rob Langley, a FL 951 owner, who had a Garrity Repta built 3.0L 951 engine- he chronicles his trials on his website, calling the car the big yellow bus- anyway, he was only running ~15psi and blew many a headgasket,"
"VERY depressing, considering the time, $, and effort involved in the 3.0L, and the fact that he was ALWAYS having probs- went through at least 4 headgaskets..."
I've diccussed this with both Rob & Garrity and the problems have nothing to do with the boost-level that he was running. But rather due to the sealing methods he was using to assemble the head.
"he has a friend who runs a 951 at 22psi (I believe- it WAS ABOVE 20psi) and had done so for several YEARS w/no probs! "
That's right! The problem with blown headgaskets has nothing to do with boost-pressure. It's due to the intense heat generated by knock/detonation that burns through the headgasket, rather than blowing it apart. In which case, a wide firering headgasket doesn't really help that much because it has the same 0.1mm thick layer of steel facing the combustion chambers (the firering is holllow). I've known tuners who've blown several wide firering headgaskets just weeks apart. It's all about having fine control over air-fuel ratios across all load- and RPM-levels.
A really durable headgasket that doesn't have the strict installation requirements of a copper headgasket would be the metal/fibre sandwich type that HKS & Huntley sells. Those can stand up to a lot more abuse than the hollow compression-ring type our cars use. BUT it does NOT preclude proper tuning of air-fuel ratios, without which, you'll be frying valves and melting holes in pistons instead of blowing an expendable headgasket.
<img src="graemlins/wave.gif" border="0" alt="[byebye]" />
08-13-2002, 12:08 AM
#18
Burning Brakes
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I ran 24psi on my old 951 block. Hit 371 at teh tires, and would have ran more, but I think the boost controller (an electronic one) was limited.
I ran that 24 on the street, everyday, never blew a head gasket. The trick is simple, if you call it a trick. Keep the fuel coming, and coming strong.
Boost pressure will not destroy your motor, poor tuning, and detonation will, its like droping sticks of dynomite into the pistons and exploding them at random.
I would suggest building your motor with a goal in mind, or if your a bolt on guy, keep the bigger is better crap out of your project. A properly balanced motr, with the right sized turbo, and mods will be much more fun to drive than a motor built to hit its max at 6K rpm.
Peopel have a knack for putting the biggest they can find on the motor. Big cams, big injectors, big throttles, big valves, huge turbos and biger intercoolers etc etc etc...if your strapping these on at random, and your running a bone stock 951 block, you will not be as happy with your driver as you would if you would have kept it a little a on the moderate side.
Again, I've been there, done that.... a few times :-)
Take Care!
I ran that 24 on the street, everyday, never blew a head gasket. The trick is simple, if you call it a trick. Keep the fuel coming, and coming strong.
Boost pressure will not destroy your motor, poor tuning, and detonation will, its like droping sticks of dynomite into the pistons and exploding them at random.
I would suggest building your motor with a goal in mind, or if your a bolt on guy, keep the bigger is better crap out of your project. A properly balanced motr, with the right sized turbo, and mods will be much more fun to drive than a motor built to hit its max at 6K rpm.
Peopel have a knack for putting the biggest they can find on the motor. Big cams, big injectors, big throttles, big valves, huge turbos and biger intercoolers etc etc etc...if your strapping these on at random, and your running a bone stock 951 block, you will not be as happy with your driver as you would if you would have kept it a little a on the moderate side.
Again, I've been there, done that.... a few times :-)
Take Care!
08-13-2002, 02:17 AM
#19
Burning Brakes
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i know fuel is a must...i'll be running the 951 injectors with the fuel pump and a AFPR....im just wondering if that will be enough...
i was seriously thinking bout a j&s safegaurd.....anyone have one? do you think its worth it?
space
i was seriously thinking bout a j&s safegaurd.....anyone have one? do you think its worth it?
space
