roots blower alky ques.
- Thread starter kshef
- Start date
But temperatures change... your sig says your in GA - 40 deg is pretty cold down there... Just put them pre-blower. We've also done them where they shoot pre-blower and where the blower sits atop an intake-style IC.
Either way I think it will still help however: when the blower is on its compression stroke the heat buildup is much greater than 40 deg, or whatever the ambients are. Just because the ambients are "cold" doesn't meant that something inside an insulator (blower housing, intake, piping, etc...) are also that cold. With the alky injected pre-blower, it gets incorporated into the compression chambers created by the vanes. Here it can absorb heat as early as possible, increasing the efficiency of the system. This was even more pronounced when we had installed the IC, which in turn didnt have to "work" as hard to cool the air.
Ambient temps will indeed effect this, but i think overall its better to have them before the blower. Do what you want though, not that hard to try it out for yourself!
Either way I think it will still help however: when the blower is on its compression stroke the heat buildup is much greater than 40 deg, or whatever the ambients are. Just because the ambients are "cold" doesn't meant that something inside an insulator (blower housing, intake, piping, etc...) are also that cold. With the alky injected pre-blower, it gets incorporated into the compression chambers created by the vanes. Here it can absorb heat as early as possible, increasing the efficiency of the system. This was even more pronounced when we had installed the IC, which in turn didnt have to "work" as hard to cool the air.
Ambient temps will indeed effect this, but i think overall its better to have them before the blower. Do what you want though, not that hard to try it out for yourself!
rocket468 said:
none with compelling results :redface:
so when the air is compressed/heated inside the blower does the alky help cool outlet temps?
right now my car ET's pretty close with or without octane, but there is usually a 3-4mph pick up on high octane
Compressing air creates heat. Every PSI creates approx 12 degree's. 10 PSI=120 degree's. Spraying before the blower will add a little boost like 1 PSI, and also bring inlet temps to ambient or slightly below. Hence why I said temp wise no. So even if you bring inlet to zero degree's.. outlet is still 120.
This is why IC are placed after heat sources not before. While the benefit is there, once it gets cold outside.. do not spray anything with water content.
Your issues are tuning related.. period. You will be able and increase timing due to octane.. but this octane has to come from the alky. The alky is a fuel, and you must compensate accordingly. The L67 is a strange platform.. as its computer does not allow suffiecient tuning.. unlike other GM vehicles like the C5/GTO/4th gen/etc.. that do. On a mag C5 you will pickup 25 just by spraying into the blower.
The L67 community needs someone smart.. ie.. Eric Marshall/ Bob Bailey/etc.. that work on tuning the pcm's. Once this occurs.. you will see results. Until then spraying 50/50 will give not so compelling results.
This is why IC are placed after heat sources not before. While the benefit is there, once it gets cold outside.. do not spray anything with water content.
Your issues are tuning related.. period. You will be able and increase timing due to octane.. but this octane has to come from the alky. The alky is a fuel, and you must compensate accordingly. The L67 is a strange platform.. as its computer does not allow suffiecient tuning.. unlike other GM vehicles like the C5/GTO/4th gen/etc.. that do. On a mag C5 you will pickup 25 just by spraying into the blower.
The L67 community needs someone smart
.. ie.. Eric Marshall/ Bob Bailey/etc.. that work on tuning the pcm's. Once this occurs.. you will see results. Until then spraying 50/50 will give not so compelling results.The factor with heat with L67 is rpm of the blower it self. I am running a 2.6" pulley on mine. With all of my mods I am only getting 11 psi of boost. This size pulley on a stock l67 would produce I am guessing excess of 20 psi. But that will pop pistons. I know of stock l67 with 3.25 that can get over 15psi and run into 2 bar map problems.
Eaton 90 turn into heatpumps with anything any smaller than an 2.55 pulley zzp which is has there own in house supercharger dyno With 45 degree water and a simulated 13lbs of boost they determined how much each intercooler cooled. They found that the nices intercooler pulled 150 degree temperature drop from the charge. I can't rember what the outlet was aftewards and can't find it on the internet but i rember it being close to 40 deg over amb with use of an ic. outlet temps on these suckers easly reach high 200's low 300's
There are people who know there stuff in the 3800 field David Buckshaw is pretty good and is the one of the best to have your car tuned by. He has done the majority of the 10 sec and faster grand prixs.
Eaton 90 turn into heatpumps with anything any smaller than an 2.55 pulley zzp which is has there own in house supercharger dyno With 45 degree water and a simulated 13lbs of boost they determined how much each intercooler cooled. They found that the nices intercooler pulled 150 degree temperature drop from the charge. I can't rember what the outlet was aftewards and can't find it on the internet but i rember it being close to 40 deg over amb with use of an ic. outlet temps on these suckers easly reach high 200's low 300's
There are people who know there stuff in the 3800 field David Buckshaw is pretty good and is the one of the best to have your car tuned by. He has done the majority of the 10 sec and faster grand prixs.
I've got the L67 tuning figured out pretty well, but I also can't afford to blow up my transmission just yet to I keep it conservative.
While the PCM is hard to tune, its far from impossible. Most of the L67 guys like to bolt on and go, custom tunes were almost unheard of until about a year ago.
The PCM has a fuel trim system, skews a % of fuel in closed loop, nothing unusual. When you go into open loop (power enrichment), it 'locks in' the last know fuel trim, and 99% of the time it stays 'locked'.
So to tune for alky, you wait till the fuel trim locks in before you spray, so the PCM never actually sees the extra fuel. This is easy, because open loop will happen before you get into boost and start spraying. If it doesn't for some reason, you lower the TPS% to activate open loop.
From there, you pull fuel in the power enrichment tables and replace it with methanol. Its not automated like some of you guy's piggy backs, but you keep an eye on the A/F ratio and tweak it alot. Its not too difficult, really no different then trying to tune your A/F ratio from the PCM alone except you can adjust it on the fly with the progressive controller.
Spraying before the blower also increases the volumetric efficiency a good amount, which is a huge benefit with a roots blower, but if you spray too much there is noticeable bog. *I think* when you try to shove a bunch of liquid through the rotors, the drag/friction required to turn them increases exponentially, so parasitic loss goes way up. Imagine trying to use a roots blower as a water pump, not gonna happen. I think this is also one reason that L67's haven't had much success, people just didn't know what they were doing.
I am looking into using a small nozzle in front of the blower to get the increased efficiency and slight cooling, and then use one or two (depends if I think I can get even distribuiton to all cylinders) below the blower for the majority of cooling and octane.
While the PCM is hard to tune, its far from impossible. Most of the L67 guys like to bolt on and go, custom tunes were almost unheard of until about a year ago.
The PCM has a fuel trim system, skews a % of fuel in closed loop, nothing unusual. When you go into open loop (power enrichment), it 'locks in' the last know fuel trim, and 99% of the time it stays 'locked'.
So to tune for alky, you wait till the fuel trim locks in before you spray, so the PCM never actually sees the extra fuel. This is easy, because open loop will happen before you get into boost and start spraying. If it doesn't for some reason, you lower the TPS% to activate open loop.
From there, you pull fuel in the power enrichment tables and replace it with methanol. Its not automated like some of you guy's piggy backs, but you keep an eye on the A/F ratio and tweak it alot. Its not too difficult, really no different then trying to tune your A/F ratio from the PCM alone except you can adjust it on the fly with the progressive controller.
Spraying before the blower also increases the volumetric efficiency a good amount, which is a huge benefit with a roots blower, but if you spray too much there is noticeable bog. *I think* when you try to shove a bunch of liquid through the rotors, the drag/friction required to turn them increases exponentially, so parasitic loss goes way up. Imagine trying to use a roots blower as a water pump, not gonna happen. I think this is also one reason that L67's haven't had much success, people just didn't know what they were doing.
I am looking into using a small nozzle in front of the blower to get the increased efficiency and slight cooling, and then use one or two (depends if I think I can get even distribuiton to all cylinders) below the blower for the majority of cooling and octane.
