HEADGASKET dissertation...
09-24-2002, 05:10 PM
#16
Danno "While I hadn't dyno-tested the car, I'm going to assume the my air-fuel ratio looked similar to Dan Worley's and Adrial's above."
Danno it appears that Dan Worley's A/F ratio is roughly 11.5 at 6.5K RPM. This doesn't appear to be lean (under 12). Granted the A/F is overly rich in the mid-range. So if your A/F ratio was similar to Dan's do you think one is in jeopardy of blowing a head gasket?
Danno it appears that Dan Worley's A/F ratio is roughly 11.5 at 6.5K RPM. This doesn't appear to be lean (under 12). Granted the A/F is overly rich in the mid-range. So if your A/F ratio was similar to Dan's do you think one is in jeopardy of blowing a head gasket?
09-24-2002, 07:14 PM
#18
Race Director
Thread Starter
"The first dyno sheet (Woorleys) doesn't look like it gets to a too lean condition. His stays under 13 all the way to 6500 rpm."
"Danno it appears that Dan Worley's A/F ratio is roughly 11.5 at 6.5K RPM."
Actually I was referring to the tendency for the mixture to get leaner in the upper RPMs. With fuel-pressure set to give a good mid-range mixture, it got progressively leaner and leaner as the RPMs rose. So by richening up the mixture across-the-board, you end up sacrificing A LOT of the mid-range power in order to keep the high-end mixture in check. This gives you a sluggish, soggy mid-range/partial-throttle response.
The goal is to have chips that provide you with a flat mixture across the board at the maximum power-producing mixture of 12.5:1 all the way to redline. Not only is this the safest, but the most powerful. If you look at 'end AFR' dark-blue curve from the EuroProducts chips above, you'll see that by cleaning up the mixture, we got a 20% boost in mid-range torque with a lot less turbo lag. In fact, by 2800rpm, we got more torque than the entire torque curve of the uncorrected chips.
On Dan Worley's car, if he was able to get a flat mixture of 12.5:1 across-the-board, he would've gotten 20% more torque & power for his goal of 300rwhp. This would be typical of K27 turbos @ 15psi if you can get a clean mixture. But, safety and durability should take precedence, so he sacrificed alot of power and mid-range torque in order to keep the high-RPM mixture from getting too lean.
"Danno it appears that Dan Worley's A/F ratio is roughly 11.5 at 6.5K RPM."
Actually I was referring to the tendency for the mixture to get leaner in the upper RPMs. With fuel-pressure set to give a good mid-range mixture, it got progressively leaner and leaner as the RPMs rose. So by richening up the mixture across-the-board, you end up sacrificing A LOT of the mid-range power in order to keep the high-end mixture in check. This gives you a sluggish, soggy mid-range/partial-throttle response.
The goal is to have chips that provide you with a flat mixture across the board at the maximum power-producing mixture of 12.5:1 all the way to redline. Not only is this the safest, but the most powerful. If you look at 'end AFR' dark-blue curve from the EuroProducts chips above, you'll see that by cleaning up the mixture, we got a 20% boost in mid-range torque with a lot less turbo lag. In fact, by 2800rpm, we got more torque than the entire torque curve of the uncorrected chips.
On Dan Worley's car, if he was able to get a flat mixture of 12.5:1 across-the-board, he would've gotten 20% more torque & power for his goal of 300rwhp. This would be typical of K27 turbos @ 15psi if you can get a clean mixture. But, safety and durability should take precedence, so he sacrificed alot of power and mid-range torque in order to keep the high-RPM mixture from getting too lean.
09-24-2002, 08:30 PM
#19
Nordschleife Master
How do your chips work with someone who already has a moded car? For instances I already have a HR Stage 3 MAF, ARC2, HR 3" testpipe, Greedy Boost controller low set @ 10psi, high set at 15psi, adjustable fuel pressure regulator, and HR chips (which I heard were autothority bootlegs). I notice the mid rpm bog if I gas it, so I guess my real question is if I purchased a set of chips from you can I return them if I don't see a difference with my setup?
09-25-2002, 12:04 AM
#21
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It must be tough for Danno to not brag/promote his products. But as the owner of APE stage II chips, I'd like to know if his chips will keep me from running too lean. For me, it would be worth the cost of new chips, for the peace of mind. Not all of us can/know how to rebuild our top end, bottom end or any other end for that matter. 
09-25-2002, 01:09 AM
#22
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Thanks for the time Danno - We all appreciate it.
Heh, I don't have anything else.. My car is a stock 'looker', I think I'll keep it that way for awhile.. 
More car than I need already anyway.
<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
Heh, I don't have anything else..
My car is a stock 'looker', I think I'll keep it that way for awhile.. More car than I need already anyway.<img src="graemlins/beerchug.gif" border="0" alt="[cheers]" />
09-25-2002, 03:54 AM
#23
Race Director
Thread Starter
Let's have a little discussion on how the DME converts a 0-5v signal coming from the stock air-flow meter (AFM) into an injector duty-cycle. First is a conversion table that generates a duty-cycle number based upon AFM input-voltage and RPM:
<img src="http://www.gururacing.net/ImagesMisc/Headgasket-VAFoutput.gif" alt=" - " />
Notice that given the identical voltage inputs, the duty-cycle will vary as a function of RPM as well.
The second part of the procedure then overlays a 3D correction map on top of that duty-cycle conversion. This is expressed as +/- percentages. Here are some sample correction maps used under partial-throttle conditions:
<img src="http://www.gururacing.net/ImagesMisc/FuelMap-PartialThrottle.gif" alt=" - " />
After these corrections are applied, further adjustments to the duty-cycle numbers are made based upon altitude, air-temperature and O2-sensor feedback. However, these final adjustments can only affect the final injector duty-cycle a certain percentage, so it's vitally important that the correction map correlates to your actual airflow conditions closely.
This leads us into the full-throttle fuel-map. Think of it as the single stripe on the far, far left of those 3D-maps above (on the left-hand wall). I've extracted that full-load stripe from several chips and compared them:
<img src="http://www.gururacing.net/ImagesMisc/Headgasket-WOTfuelCompare.GIF" alt=" - " />
As you can see, the two other aftermarket chips provide a significant fuel-enrichment correction in the mid-range only, and they dial out fuel in the higher-RPMs. We actually have three distinct chips to deal with air-flow conditions from a stock K26/6, a TurboS K26/8 and a K27/Garrett aftermarket turbo that can hold max-boost all the way to redline.
"How do your chips work with someone who already has a moded car? For instances I already have a HR Stage 3 MAF, ARC2, HR 3" testpipe, Greedy Boost controller"
Due to the difference in voltage-output vs. airflow of a MAF compared to a AFM, you would need a different initial VAF-to-Injector Duty-Cycle table for a MAF sensor. We're working on that for our MAF-5 kit. However, since you've already have the ARC2, you can manually make that correction. So our chips would work fine in that configuration. And you can return them if they don't solve your mid-range bog issue. This mid-range sogginess is actually a combination of too much mid-range fuel and igntion-timing.
"as the owner of APE stage II chips, I'd like to know if his chips will keep me from running too lean. "
Yup, as you can see from the comparison chart above, we've dialed out a lot of the mid-range richness and added it up top to combat the high-end lean tendencies.
"It must be tough for Danno to not brag/promote his products. "
Nah, why bother. I've had enough frustrations with getting my car tuned optimally and not getting much help from the 'tuners' in the market (who just wants to sell products). Blown things up a couple of times. That's why I've come up with solutions that were intially aimed at solving the particular problems that I've had. If it's not the fix for your particular problem, I'm going advise against it and point you in the right direction.
"Thanks for the time Danno - We all appreciate it."
You're most welcome! <img border="0" alt="[byebye]" title="" src="graemlins/wave.gif" /> <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" /> <img border="0" alt="[cherrsagai]" title="" src="graemlins/drink.gif" />
<img src="http://www.gururacing.net/ImagesMisc/Headgasket-VAFoutput.gif" alt=" - " />
Notice that given the identical voltage inputs, the duty-cycle will vary as a function of RPM as well.
The second part of the procedure then overlays a 3D correction map on top of that duty-cycle conversion. This is expressed as +/- percentages. Here are some sample correction maps used under partial-throttle conditions:
<img src="http://www.gururacing.net/ImagesMisc/FuelMap-PartialThrottle.gif" alt=" - " />
After these corrections are applied, further adjustments to the duty-cycle numbers are made based upon altitude, air-temperature and O2-sensor feedback. However, these final adjustments can only affect the final injector duty-cycle a certain percentage, so it's vitally important that the correction map correlates to your actual airflow conditions closely.
This leads us into the full-throttle fuel-map. Think of it as the single stripe on the far, far left of those 3D-maps above (on the left-hand wall). I've extracted that full-load stripe from several chips and compared them:
<img src="http://www.gururacing.net/ImagesMisc/Headgasket-WOTfuelCompare.GIF" alt=" - " />
As you can see, the two other aftermarket chips provide a significant fuel-enrichment correction in the mid-range only, and they dial out fuel in the higher-RPMs. We actually have three distinct chips to deal with air-flow conditions from a stock K26/6, a TurboS K26/8 and a K27/Garrett aftermarket turbo that can hold max-boost all the way to redline.
"How do your chips work with someone who already has a moded car? For instances I already have a HR Stage 3 MAF, ARC2, HR 3" testpipe, Greedy Boost controller"
Due to the difference in voltage-output vs. airflow of a MAF compared to a AFM, you would need a different initial VAF-to-Injector Duty-Cycle table for a MAF sensor. We're working on that for our MAF-5 kit. However, since you've already have the ARC2, you can manually make that correction. So our chips would work fine in that configuration. And you can return them if they don't solve your mid-range bog issue. This mid-range sogginess is actually a combination of too much mid-range fuel and igntion-timing.
"as the owner of APE stage II chips, I'd like to know if his chips will keep me from running too lean. "
Yup, as you can see from the comparison chart above, we've dialed out a lot of the mid-range richness and added it up top to combat the high-end lean tendencies.
"It must be tough for Danno to not brag/promote his products. "
Nah, why bother. I've had enough frustrations with getting my car tuned optimally and not getting much help from the 'tuners' in the market (who just wants to sell products). Blown things up a couple of times. That's why I've come up with solutions that were intially aimed at solving the particular problems that I've had. If it's not the fix for your particular problem, I'm going advise against it and point you in the right direction.
"Thanks for the time Danno - We all appreciate it."
You're most welcome! <img border="0" alt="[byebye]" title="" src="graemlins/wave.gif" /> <img border="0" alt="[bigbye]" title="" src="graemlins/xyxwave.gif" /> <img border="0" alt="[cherrsagai]" title="" src="graemlins/drink.gif" />
09-25-2002, 12:28 PM
#24
Nordschleife Master
Danno Private message me so we can work out the details of this transaction. I won't need the boost enahancer deal or the 3 bar regulator as I already have those departments covered. Just need the chips.
Dan
Dan
09-25-2002, 12:43 PM
#25
Rennlist Member
This is GREAT information! Thanks Danno!
One question: you mention the 3D correction maps that are applied after the initial duty cycle number is computed. What purpose do these maps serve and how are they chosen?
One question: you mention the 3D correction maps that are applied after the initial duty cycle number is computed. What purpose do these maps serve and how are they chosen?
09-25-2002, 07:28 PM
#27
Drive-by provocation guy
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Well, I just had my headgasket blow due to overheating problems, proving Danno's point that HEAT, not PRESSURE is the leading cause to blown headgaskets. I went with the wide fire ring just to be safe.
p.s. I have a stock BRAND NEW IN THE BAG head gasket for sale. email me with an offer toddk911@aol.com.
I also just placed my order for GURU's chips as we have heard on Rennlist time and time again...THE KEY TO ENGINE SAFETY AND PERFORMANCE IS A CLEAN AIR FUEL ratio.
Makes me very interested in setting up a water/alcahol injection system. I have read a few sites that home mechanics have built and installed themselves to tremendous gains and increased engine safety. They were reading 120-150 degree drops which made the engine run MUCH cooler and allowed for more boost and ignition advance. I think 3-4 more psi. i.e. much safer engine with 30-40 more hp to the wheels!!!
p.s. I have a stock BRAND NEW IN THE BAG head gasket for sale. email me with an offer toddk911@aol.com.
I also just placed my order for GURU's chips as we have heard on Rennlist time and time again...THE KEY TO ENGINE SAFETY AND PERFORMANCE IS A CLEAN AIR FUEL ratio.
Makes me very interested in setting up a water/alcahol injection system. I have read a few sites that home mechanics have built and installed themselves to tremendous gains and increased engine safety. They were reading 120-150 degree drops which made the engine run MUCH cooler and allowed for more boost and ignition advance. I think 3-4 more psi. i.e. much safer engine with 30-40 more hp to the wheels!!!
09-26-2002, 12:24 AM
#29
Burning Brakes
Thanks Danno for an informative discourse. I'm curious why a lot of smart 951 owners and well respected engine builders who are creating big horsepower have gone through the effort and expense of O-ringing if A/F ratios are the critical element for a good head seal. Is this undertaking a safety backup to lean conditions which may cause premature HG failure or is there more of a functional mechanical benefit provided by O-rings in engines running higher boost? Any builders following this thread? Also curious about opinions on head studs: stock lifespan, value of higher buck (e.g raceware, garrity, etc) studs. Thanks very much
09-26-2002, 01:45 AM
#30
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[quote]Originally posted by toddk911:
<strong>Makes me very interested in setting up a water/alcahol injection system. I have read a few sites that home mechanics have built and installed themselves to tremendous gains and increased engine safety. They were reading 120-150 degree drops which made the engine run MUCH cooler and allowed for more boost and ignition advance. I think 3-4 more psi. i.e. much safer engine with 30-40 more hp to the wheels!!! </strong><hr></blockquote>
Waterinjection itself won't gain any HP, in fact it will displace air and fuel in the cyl and make less HP. You will gain some anti-knock resistance, but you won't benefit if you don't need it.
A bigger intercooler should do much the samething. Some have gone so far as to mist the intercooler with CO2
<strong>Makes me very interested in setting up a water/alcahol injection system. I have read a few sites that home mechanics have built and installed themselves to tremendous gains and increased engine safety. They were reading 120-150 degree drops which made the engine run MUCH cooler and allowed for more boost and ignition advance. I think 3-4 more psi. i.e. much safer engine with 30-40 more hp to the wheels!!!
</strong><hr></blockquote>Waterinjection itself won't gain any HP, in fact it will displace air and fuel in the cyl and make less HP. You will gain some anti-knock resistance, but you won't benefit if you don't need it.
A bigger intercooler should do much the samething. Some have gone so far as to mist the intercooler with CO2