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  #16  
Old May 28th 2005, 10:15
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Coincidence ? 911 Alternator Cap W/ FAT Cooling shroud

Wierd .... I just installed the factory 911 alternator cap with 2 diverters into the FAT shroud .... it fits with NO modifications and the back and top of the diverters hug the back of the shroud .... almost like the shroud was made to fit this like a glove.

Now for a road test/logging session to see if it amounts to anything positive.

Sandeep
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  #17  
Old May 28th 2005, 15:49
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Looks like that diverter does make a difference after all ... 30degF cooler on average for 3&4 and 15degF cooler for 1, but 2 stays the same on average :shrug:

I think that 3&4 are getting more air now and 1 is getting less (but might have been getting too much in the beginning and the shroud may not have been able to get rid of the air around #1

Out for some more testing and more diverters !

Sandeep
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  #18  
Old May 29th 2005, 06:21
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Quote:
Originally Posted by Sandeep
Wierd .... I just installed the factory 911 alternator cap with 2 diverters into the FAT shroud .... it fits with NO modifications and the back and top of the diverters hug the back of the shroud .... almost like the shroud was made to fit this like a glove.

Now for a road test/logging session to see if it amounts to anything positive.

Sandeep
Yes, the same with the BAS shroud: I thought about it as well and I think they probably made/modelled the shrouds of an original 911 shroud for the part thats directly behind the fan housing.

Interesting data!

Greets,
Walter
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  #19  
Old June 5th 2005, 11:29
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Wally,

I've made quite a few changes to the diverters on the alternator cap but I can't seem to get the temps on 3-4 to drop anymore, 3-4 are still about 40 degF higher than 1, and 2 is about 25 degF higher than 1.

I am going to try the T1 under cylinder tins now, but still wonder why #1 runs so cool with the T4 tins ... can't get it above 325 degF no matter how hard I try.

#1 has a nice airflow path from the alternator ring ... almost a direct shot of air to the head. Perhaps the diverters are directing the air to the cylinders and not the head on the 3-4 side

I will try the T1 tins first and then try your method of the horizontal plate over the cylinder bank as the airflow may be having a hard time getting past the first fin on the head towards the case. It is much taller than the last cylinder fin towoards the head and perhaps this is an airflow barrier.

More testing !

Sandeep
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  #20  
Old June 5th 2005, 15:30
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Quote:
Originally Posted by Sandeep
... as the airflow may be having a hard time getting past the first fin on the head towards the case. It is much taller than the last cylinder fin towoards the head and perhaps this is an airflow barrier.
Yeah, my thoughts also and with the scarsely finned (at the top anyway) 964 nikasils, that may be even more true.
The shroud should be a bit higher at the heads therefore imho, at least at the front cylinders (2 and 4) to have room for better air guidance and to direct the airfow 90 degrees there, so the air comes from the top down eventually...

My cylinder plates may work with nikasil cylinders, but you might get in trouble with steel cylinders because of the blocking of air flow essentially, so be carefull!
When you block off the cylinder air too much, you should see an increased oil temp very soon,...I think.

Take care,
Walter

BTW I have decided to have the heads 'done' after all and even increase cylinder capacity quite a bit (its never enough) while we're at it, so my testing has halted momentarily..
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  #21  
Old June 15th 2005, 10:50
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Update

An update ...

During this week of testing its been averaging mid 30C with humidity in Toronto so I'm happy with the results so far.

That SC diverter works wonders with this shroud along with T1 under-cylinder tins. I have modified the stock alternator cap diverters and added a 3rd diverter to the cap to direct the airflow more to #4. Initially I had too many diverters and the temps actually got worst the harder I drove it, but looked great when idling / light driving.

So I'm down to 3 diverters and here's the stats:

1. #1 and #2 run on average within 10F of each other.
2. #3 and #4 run on average within 13F of each other.
3. 1-2 bank runs on average 36F cooler than 3-4 bank.
4. 1-3 run on average 24F cooler than 2-4.
5. Hottest temp with current setup is 341F on #4 (Highway running, 5000 RPM in 4th - at this RPM I think there is too much air for the shroud to get rid of, but I rarely drive at 5000 rpm)

On my drive to work (20 mins with idling in traffic, 80kph top speed) highest temps for #1 are 289F, #2 301F, #3 312F and #4 319F

The interesting thing about this whole diverter setup is that all 3 diverters are on the 3-4 side of the alternator cap. 1-2 get a direct shot of air with no mods required.

If 1-2 run so cool (hottest temp for 1-2 with current setup average 323F) with no diverters/deflectors of any sort, I'm confident 3-4 can run just as cool.

Next step is to tweak the diverters a bit by placing tufts of yarn on the diverters and looking through the fan to see which way they blow. The stock diverters blew the air right to #3 cylinder and not the head.

After I get the air poining in the right direction, I will make the pulley mod Jake has recommended. I don't think I need to use Wally's horizontal tin mod as my shroud sits higher than his does, and it does not look like the airflow is being blocked by the first fin on the head towards the case.

Thats it for now !

Sandeep
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  #22  
Old June 16th 2005, 00:44
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Excellent work Sandeep. I would like to see how those mods held up in a higher load arrangement, what is your gearing??? Tire size"?

#1 is generally, no matter what is done the coolest cylinder- This holds true on all shrouds except the stock TI doghouse which robs its air for the oil cooler from just above #1 and heats it up 20 degrees in my testing.

#1 and #2 are on the same tangent as the fan so you have increased pressure and volume there, but normally the FAT shroud bakes #2 and freezes #1, but the smallest engine I have used for the testing was a 2270. I would be interested in seiing the plenum pressures associated with the shroud with these mods compared to what I saw here. Do you have an old Boost gauge laying around that will go to 15 PSI??

Your temps are pretty close together now and definately acceptable, as far as the deltas between the cylinders, but your stock engine is still running 25 degrees hotter than Zens 2316.... BUT it's DTM cooled.. LOL

I really like your work on the shroud, it makes me want to speed up my development and get to the 911 shroud faster, but it won't happen till 2007 at this rate.

Like I have said all along, the 911 shroud is not horrible, but off the shelf none of them have touched a DTM, and Sandeep is proving that as well as the fact that they can be made to work if you have the instrumentation and time to make the mods.
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  #23  
Old June 16th 2005, 08:35
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I love the fact that he is doing this work. If all goes well we will have a 911 system that's a bolt on. I don't mind cutting the back of my deck lid.
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  #24  
Old June 16th 2005, 10:11
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The system that I already have the molds for does not require any cutting of the decklid. Since the outside physical parts of the shroud have already been completed (Joe did this before he died as he was working on a 911 system that actually worked with even air distribution) I only need to take the time to test it the way that Sandeep has and right now I have other priorities that are more important like a heater box exhaust system and my Billet heads.

I don't know if we can ever get a 911 system that will beat a DTM, it is my goal to make them exactly the same but I do believe the DTM will win the challenge in the HP loss from the fan category due to the radial fan primarily. I have an idea for this that would release pressure within the upper plenums of the shroud at high RPM when pressure with the axial fan skyrockets and reduce the HP loss- You'll like it.

Sandeep is having an easier time doing his work than I had imagined. Sandeep you should send me that shroud for a heavy load test when you are all done toi see how the mods impact the cooling on a bigger engine on the dyno. I now have my logger in place and can measure the temps much faster and easier. That would be a fun comparison.
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  #25  
Old June 16th 2005, 10:18
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Quote:
Originally Posted by Massive Type IV
Excellent work Sandeep. I would like to see how those mods held up in a higher load arrangement, what is your gearing??? Tire size"?
I'm using stock 914 gearing and using a 265/35/18 ZR 18 rear tire on an 18"x10" wheel ... that sucker with tire weighs 52 lbs. I'm also using a 930 rear rotor (309mm x 28mm) so I'm thinking that adds some additional load when compared to a beetle 165/80/15 rear tire and drum brake setup .. not sure how much more though or if it is significant.

Quote:
Originally Posted by Massive Type IV
I would be interested in seiing the plenum pressures associated with the shroud with these mods compared to what I saw here. Do you have an old Boost gauge laying around that will go to 15 PSI??
No I don't but that is a good idea ... I will see what I can find at JJB 2005 on June 26th in the swap meet. How should I hook the hose up as I've never used a boost gauge ?

Quote:
Originally Posted by Massive Type IV
Your temps are pretty close together now and definately acceptable, as far as the deltas between the cylinders, but your stock engine is still running 25 degrees hotter than Zens 2316.... BUT it's DTM cooled.. LOL

Like I have said all along, the 911 shroud is not horrible, but off the shelf none of them have touched a DTM, and Sandeep is proving that as well as the fact that they can be made to work if you have the instrumentation and time to make the mods.
The DTM is the King of cooling, you've proven that already. I'll be taking my heads to Mark this winter for a refreshing and the jugs for a light hone ... I'll be looking for a RAT cam/lifters then as well ... maybe by then I can make up that 25F

Sandeep
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  #26  
Old June 16th 2005, 10:27
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Quote:
Originally Posted by Massive Type IV
Sandeep is having an easier time doing his work than I had imagined. Sandeep you should send me that shroud for a heavy load test when you are all done toi see how the mods impact the cooling on a bigger engine on the dyno. I now have my logger in place and can measure the temps much faster and easier. That would be a fun comparison.
I think the reason I am having an easier time is that I'm only working with 3 diverters .. 2 stock with modifications and 1 that I added, and not trying to engineer a whole system like you did. I can also visually see the results of air distribution by using yarn tufts and looking through the fan while it is running to see where they end up pointing.

I'll send it to you during the winter for testing when I am freshening up my motor.

Sandeep
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  #27  
Old June 16th 2005, 11:50
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I have a Race- Technology DL-1 logger with digital SPA instruments for quick reference.

The logger is set up for in car use and Dyno use by simply disconnecting the wire harnasses that are hard wired into the Bug, 914 and the dyno.

The logger even utilizes a GPS to track map the position of the car at the time the data was recorded, so I can literally watch the temps rise going up hills and etc all while measuring TQ and HP and even G forces...

I am having a real learning curve with this logger- It has so many features that its very confusing to get used to, but DAMN is it awesome (and expensive)
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  #28  
Old June 17th 2005, 14:58
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Sandeep,

Where did you order your 911 fan diverter from?

Thanks,

Randy
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  #29  
Old June 17th 2005, 15:19
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Lucky find on EBay

Sandeep
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  #30  
Old June 21st 2005, 10:19
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Another step forward

I had some spare time last night so I thought I would try Wally's horizontal tin mod on 3-4 bank only to see what a difference it would make.

I made a piece of tin 7" long by 4.5" wide and cut it in such a way that one 4.5" side runs parallel with C/L of #4 cylinder and the other 4.5" side runs parallel with #3. The attachment point to the case is the 2 - 6mm holes for factory tinware on top of the case under the shroud.

I then made a U shaped hole in the center of the tin to allow some air to get between #3 and #4, but the majority of the air would go over the cylinders and to the head.

Well ... this decreased the temps of #3 and #4 by about 15F :agree: So now the differance between 1-2 and 3-4 is 1-2 runs about 20F cooler on average than 3-4. I guess the cylinders DO catch the majority of the air flowing across them ... thanks Wally ! :agree:

I am not sure how this will affect oil temps (seemed fine on my testing run) or if this will create hot spots on 3-4 cylinders due to the decreased air to the cylinders.

I have about 40 logs now of different senarios ... 5MB each ... big files.

I think I may be at the end of these mods as the temps seem quite acceptable for the street. Next step is to go to the track ... no track days coming up till September though the spaces are all filled.

Sandeep
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