Power increase from removing stock air box?
04-10-2012, 04:14 PM
#33
I have seen some people who use a divide to block off some hot air from engine bay. At least it is blocking off the hottest part and is sealed by the hood. How effective would this actually be. I have been actually thinking about doing this, just waiting to have car running first.
04-10-2012, 04:19 PM
#34
I have seen some people who use a divide to block off some hot air from engine bay. At least it is blocking off the hottest part and is sealed by the hood. How effective would this actually be. I have been actually thinking about doing this, just waiting to have car running first.
04-11-2012, 01:48 AM
#36
Three Wheelin'
I think I found the ETG source, waiting for a reply from Germany..
04-11-2012, 08:07 AM
#37
Three Wheelin'
I found their website too (entered ETG porsche into google) then used google translate, and there is no online shop front to buy the snorkel from these guys, and the ebay auction link is for an ended auction 
so I have sent them an email, to see if I can buy one directly, as I really want to go this route rather than cone filter.
peace
Cyberpunky
so I have sent them an email, to see if I can buy one directly, as I really want to go this route rather than cone filter.peace
Cyberpunky
04-11-2012, 08:24 AM
#38
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I found their website too (entered ETG porsche into google) then used google translate, and there is no online shop front to buy the snorkel from these guys, and the ebay auction link is for an ended auction so I have sent them an email, to see if I can buy one directly, as I really want to go this route rather than cone filter.
peace
Cyberpunky
so I have sent them an email, to see if I can buy one directly, as I really want to go this route rather than cone filter.peace
Cyberpunky
homepage try this one etggissen@aol.com
04-11-2012, 09:41 AM
#40
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The AFM and air box will become a restriction when using a mid to large size turbo; the restriction is more pronounced as the boost increases.
On a car running a MAF in stealth mode, where the MAF sits in place of the AFM but keeps the factory air box in place (using a new air filter). Running around 14psi boost, when we replaced the air box with a cone filter, we saw a gain of approx 7-10rwhp with no other changes. The power curve changed across the range... Engine power was in the 290-300rwhp.
The test shows that the air box is a restriction at that particular engine/turbo/boost/flow. I attributed the cause of the restriction to be the opening between air box & MAF. The snorkel may be a restriction, but no separate test was performed to verify.
The above test is no ideal, as the MAF was getting hot air from behind the fans, however the engine lid was open so the heat effect may have been reduced.
Based on this test and results from guys running large turbos, I would conclude that the stock air box causes a restriction. Of course, the AFM has the same opening size at the factory air box and we can conclude it will also cause a restriction at higher flow numbers.
Another issue with the restrictive air box would be the pressure drop in front of the turbo which would also cause serious issues.
On a car running a MAF in stealth mode, where the MAF sits in place of the AFM but keeps the factory air box in place (using a new air filter). Running around 14psi boost, when we replaced the air box with a cone filter, we saw a gain of approx 7-10rwhp with no other changes. The power curve changed across the range... Engine power was in the 290-300rwhp.
The test shows that the air box is a restriction at that particular engine/turbo/boost/flow. I attributed the cause of the restriction to be the opening between air box & MAF. The snorkel may be a restriction, but no separate test was performed to verify.
The above test is no ideal, as the MAF was getting hot air from behind the fans, however the engine lid was open so the heat effect may have been reduced.
Based on this test and results from guys running large turbos, I would conclude that the stock air box causes a restriction. Of course, the AFM has the same opening size at the factory air box and we can conclude it will also cause a restriction at higher flow numbers.
Another issue with the restrictive air box would be the pressure drop in front of the turbo which would also cause serious issues.
04-11-2012, 11:56 AM
#41
Rennlist Member
04-11-2012, 12:14 PM
#42
The AFM and air box will become a restriction when using a mid to large size turbo; the restriction is more pronounced as the boost increases.
On a car running a MAF in stealth mode, where the MAF sits in place of the AFM but keeps the factory air box in place (using a new air filter). Running around 14psi boost, when we replaced the air box with a cone filter, we saw a gain of approx 7-10rwhp with no other changes. The power curve changed across the range... Engine power was in the 290-300rwhp.
The test shows that the air box is a restriction at that particular engine/turbo/boost/flow. I attributed the cause of the restriction to be the opening between air box & MAF. The snorkel may be a restriction, but no separate test was performed to verify.
The above test is no ideal, as the MAF was getting hot air from behind the fans, however the engine lid was open so the heat effect may have been reduced.
Based on this test and results from guys running large turbos, I would conclude that the stock air box causes a restriction. Of course, the AFM has the same opening size at the factory air box and we can conclude it will also cause a restriction at higher flow numbers.
Another issue with the restrictive air box would be the pressure drop in front of the turbo which would also cause serious issues.
On a car running a MAF in stealth mode, where the MAF sits in place of the AFM but keeps the factory air box in place (using a new air filter). Running around 14psi boost, when we replaced the air box with a cone filter, we saw a gain of approx 7-10rwhp with no other changes. The power curve changed across the range... Engine power was in the 290-300rwhp.
The test shows that the air box is a restriction at that particular engine/turbo/boost/flow. I attributed the cause of the restriction to be the opening between air box & MAF. The snorkel may be a restriction, but no separate test was performed to verify.
The above test is no ideal, as the MAF was getting hot air from behind the fans, however the engine lid was open so the heat effect may have been reduced.
Based on this test and results from guys running large turbos, I would conclude that the stock air box causes a restriction. Of course, the AFM has the same opening size at the factory air box and we can conclude it will also cause a restriction at higher flow numbers.
Another issue with the restrictive air box would be the pressure drop in front of the turbo which would also cause serious issues.
04-11-2012, 12:43 PM
#43
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If i or anyone else who has some decent Fab skills, we could fab up a higher flowing stock appearing airbox to fit in the original location that works with a 3" MAF made out of aluminium painted in some type of heat resistant black paint. I can see a lot of ways to improve on the design.
The problem being, cost and time to built would cost north of $500 from materials and fab time. where a 3" tube with an elbo + an air filter would cost ~$100 and most likely flow a lot more air.
The problem being, cost and time to built would cost north of $500 from materials and fab time. where a 3" tube with an elbo + an air filter would cost ~$100 and most likely flow a lot more air.
04-11-2012, 12:46 PM
#44
Three Wheelin'
Thanks for the info John. That's actually not too bad of a loss, and since I opened up the restriction that you think is the worst, with a bigger snorkel the loss should be even less. I'll just turn up the boost a litle to make up for it 
BTW Cyberpunky, I asked one of my relatives to e-mail ETG in German in case they don't speak English (assuming it's the right ETG.) If you get a reply before I do, lets try to do a group buy.
BTW Cyberpunky, I asked one of my relatives to e-mail ETG in German in case they don't speak English (assuming it's the right ETG.) If you get a reply before I do, lets try to do a group buy.
04-11-2012, 07:34 PM
#45
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From the factory the 944 Turbo was very restrictive with the AFM and the exhaust. The reason being is that in development the 944 turbo was faster than the 930 turbo and Porsche couldn't let that happen so they detuned the car significantly. In 1986 they easily could have had a 280-300hp 944 from the factory.
I have a pdf article from a while back of someone test driving a prototype 951 before it got detuned. From his test drives on the autobahn and runs with a Ferrari 512, which the 951 crushed, he said it felt waaaayyyyy more than the eventual 250hp.