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Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Mon Jul 19, 2010 6:44 am Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Gary,

  

 In reference to Arjay's email copied  below.

  

 I've discussed the testing you mentioned to me  some time ago with several people. That is your temperature testing of the  air in the induction where you found no heating from the cylinders at cruise  speeds. 

  

 I just wanted to confirm that I remembered  your results correctly. That is you found no increase in the air temp from the  cowling entrance to the induction entrance at the rear of the baffles. That is  correct right?

  

 I would wager that the NACA used in LoPresti  design actually yields a lower manifold pressure than the stock  induction and not any cooler temps. It is well known and recorded in the NACA  literature that a NACA scoop is a very poor design for use where RAM is desired  such as in an induction where it was shown that up to 30% pressure loss  occures.

  

 I own both a LoPresti nose bowl and a Jaguar  Cowl. I purchased the LoPresti years ago  when it was the only option. I also owned another Tiger with the  LoPresti.

 I did a lot of researching other owners of the  LoPresti and found that all but one found no speed increase. Most said that the  engine temps were lower and more even. One person Stu Morse, who is a racer,  who, although he did not have just before and just after numbers, thought the  LoPresti added 2 or 3 kts and helped in cooling both CHT's and oil temps. Glen  Hadley who's Tiger I owned did have before and after flight tests and said  he found no speed increase but also said cooling was improved.

  

 Just to be clear, there really is no common  ground between the LoPresti nose bowl and the Jaguar cowling. They are 2  completely different things and the LoPresti in no way comes even close to the  benefits of the Jaguar. One of the things I like about the Jaguar is that it  retains the stock induction location. I had already proven that this is good for  3/4 - 1" of manifoild pressure increase over the stock AG5B  location.

  

 From all the flight testing I have done over  the years I have learned that it is quite difficult to  repeat flights with the same conditions. It is also difficult to  quantify 2 or 3 kts difference in speeds due to mods.

  

 I think I will utilize my EI engine scanner  and place probes at the entrance of the cowl and at teh entrance of the  induction just to confirm what  Ithought you had told me about these temps.  I'll report back with the results.

  

 Your Fellow Grumman Enthhusiast,

 Ned

  

  

  

 ---

teamgrumman(at)YAHOO.COM
Guest

Posted: Mon Jul 19, 2010 9:13 am Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Ned, 

When I measured temps at the inlet to the airbox on the back of the #3, I found the temps to be within a degree of ambient.  I found no excessive heating of the air.  Certainly not 20 degrees.  Unless the plane is sitting still with the engine running.

As for the NACA flush inlet, a couple of things.  First, any energy in the air is totally lost when it slams into that wall at the end of the inlet, makes an abrupt 90 degree turn and goes straight up and then through 3 or 4 feet of rough SCAT tubing, building a boundary layer the entire time, and then into the airbox.  Second, the goal is to bleed off any excess air coming into the engine that isn't being used to cool the engine.  Which brings up  CHTs.

You'll always see higher CHTs on #1 than the others during climb.  That was done intentionally.  The inlets are not symmetric, left to right.  Subtle, but different.

Your CHTs will not be that good with a richer mixture unless you can use the early carb.  Yours has different jetting to compensate for the dual airboxes on the AG.  

As for airspeeds, I see 2 to 3 knots variation depending on how it's trimmed.

Like you, I have never talked to anyone who has seen an increase in speed with the LoPresti nose-bowl.  The improved CHT #3 temps is due to the ramp on the right inlet.  

The best location for the inlet hasn't been tried yet.  Stay tuned.

Gary



From: 923te <923te(at)att.net>

To: teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 7:45:53 AM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance



          Gary,

  

 In reference to Arjay's email copied  below.

  

 I've discussed the testing you mentioned to me  some time ago with several people. That is your temperature testing of the  air in the induction where you found no heating from the cylinders at cruise  speeds. 

  

 I just wanted to confirm that I remembered  your results correctly. That is you found no increase in the air temp from the  cowling entrance to the induction entrance at the rear of the baffles. That is  correct right?

  

 I would wager that the NACA used in LoPresti  design actually yields a lower manifold pressure than the stock  induction and not any cooler temps. It is well known and recorded in the NACA  literature that a NACA scoop is a very poor design for use where RAM is desired  such as in an induction where it was shown that up to 30% pressure loss  occures.

  

 I own both a LoPresti nose bowl and a Jaguar  Cowl. I purchased the LoPresti years ago  when it was the only option. I also owned another Tiger with the  LoPresti.

 I did a lot of researching other owners of the  LoPresti and found that all but one found no speed increase. Most said that the  engine temps were lower and more even. One person Stu Morse, who is a racer,  who, although he did not have just before and just after numbers, thought the  LoPresti added 2 or 3 kts and helped in cooling both CHT's and oil temps. Glen  Hadley who's Tiger I owned did have before and after flight tests and said  he found no speed increase but also said cooling was improved.

  

 Just to be clear, there really is no common  ground between the LoPresti nose bowl and the Jaguar cowling. They are 2  completely different things and the LoPresti in no way comes even close to the  benefits of the Jaguar. One of the things I like about the Jaguar is that it  retains the stock induction location. I had already proven that this is good for  3/4 - 1" of manifoild pressure increase over the stock AG5B  location.

  

 From all the flight testing I have done over  the years I have learned that it is quite difficult to  repeat flights with the same conditions. It is also difficult to  quantify 2 or 3 kts difference in speeds due to mods.

  

 I think I will utilize my EI engine scanner  and place probes at the entrance of the cowl and at teh entrance of the  induction just to confirm what  Ithought you had told me about these temps.  I'll report back with the results.

  

 Your Fellow Grumman Enthhusiast,

 Ned

  

  

  

 ---

n2_narcosis(at)YAHOO.COM
Guest

Posted: Mon Jul 19, 2010 3:46 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Again, being new to this list and tiger ownership I have a couple of questions.  Is the Jaguar cowl the cowl that Gary at AUCountry working on?  I can only assume it is STCd by now.  if not, what is the Jaguar cowl, and will it fit on stock 76 Tiger.

  

 Thanks

 Brock



--- On Mon, 7/19/10, 923te <923te(at)att.net> wrote:



 [quote]

From: 923te <923te(at)att.net>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: teamgrumman-list(at)matronics.com

Date: Monday, July 19, 2010, 9:45 AM



    Gary,

  

 In reference to Arjay's email copied below.

  

 I've discussed the testing you mentioned to me some time ago with several people. That is your temperature testing of the air in the induction where you found no heating from the cylinders at cruise speeds. 

  

 I just wanted to confirm that I remembered your results correctly. That is you found no increase in the air temp from the cowling entrance to the induction entrance at the rear of the baffles. That is correct right?

  

 I would wager that the NACA used in LoPresti design actually yields a lower manifold pressure than the stock induction and not any cooler temps. It is well known and recorded in the NACA literature that a NACA scoop is a very poor design for use where RAM is desired such as in an induction where it was shown that up to 30% pressure loss occures.

  

 I own both a LoPresti nose bowl and a Jaguar Cowl. I purchased the LoPresti years ago when it was the only option. I also owned another Tiger with the LoPresti.

 I did a lot of researching other owners of the LoPresti and found that all but one found no speed increase. Most said that the engine temps were lower and more even. One person Stu Morse, who is a racer, who, although he did not have just before and just after numbers, thought the LoPresti added 2 or 3 kts and helped in cooling both CHT's and oil temps. Glen Hadley who's Tiger I owned did have before and after flight tests and said he found no speed increase but also said cooling was improved.

  

 Just to be clear, there really is no common ground between the LoPresti nose bowl and the Jaguar cowling. They are 2 completely different things and the LoPresti in no way comes even close to the benefits of the Jaguar. One of the things I like about the Jaguar is that it retains the stock induction location. I had already proven that this is good for 3/4 - 1" of manifoild pressure increase over the stock AG5B location.

  

 From all the flight testing I have done over the years I have learned that it is quite difficult to repeat flights with the same conditions. It is also difficult to quantify 2 or 3 kts difference in speeds due to mods.

  

 I think I will utilize my EI engine scanner and place probes at the entrance of the cowl and at teh entrance of the induction just to confirm what  Ithought you had told me about these temps. I'll report back with the results.

  

 Your Fellow Grumman Enthhusiast,

 Ned

  

  

  

 ---

flyv35b(at)minetfiber.com
Guest

Posted: Mon Jul 19, 2010 4:35 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

It's finished, is STC'd and will fit on a 76  Tiger.  Gary has the data but I haven't seen it published.  It is  a definite improvement in both cooling and speed.

  

 Cliff

 [quote]   ---

ArjayS(at)AOL.COM
Guest

Posted: Mon Jul 19, 2010 5:07 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Hi Brock

 The Jaguar cowl is indeed what Gary at AU Country is working on. It's a very nice looking cowl. He's been at it for ten years now. There are no final performance figures or prices yet but I think he selling the first units for about eight thousand. (You would need to check with him). I do not believe it's certified yet but he's got to be very close. I think Cliff may have one of his first units. They are both nice guys.

 

 As far as convincing Cliff of anything, I kinda don't think that's possible for me. I'm retired from Apple computer, I was one of the original Mac designers. I mention this because for some reason folks take the Mac vs. PC as almost a religious issue. (Which makes as much sense to me as defending your purchase of a GE toaster instead of a Sears.) It looks like many folks in aviation take the same stance about their "beliefs". I have four engineering degrees generally because I'm a nerd but mostly because I'm curious. I have a little bit of both knowledge and experience when it comes fluid dynamics and thermodynamics but I do try to keep an open mind. However, when you meet someone who comes to the table with a set belief, then the only thing you can do is be polite.

 

 Or look at it this way. Maybe, I'm completely full of beans. So instead of listening to me, let me send you to lots of LoPresti customers who have our products and feel they work equal or better than advertised. Probably the most famous is Greg Amy and his gorgeous Tiger. He says he gets in the low 140+ knots and loves the look and cooling.

 http://www.gatm.com/flying/feedback.html

 

 OR maybe a 100% money back guarentee is enough. Dunno...

 Either way it takes the look of the Tiger out of the late 1950's and that alone is a good thing.

 

 Just my 2 cents!

 Thanks!

 Rj Siegel CEO/LoPresti Aviation Engineering  [quote][b]

teamgrumman(at)YAHOO.COM
Guest

Posted: Mon Jul 19, 2010 5:12 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

It isn't published because then I'd have to do a whole bunch of performance testing to verify the improvements.  Then, I'd have to change the POH.  Then, I'd have to do a supplement.  Then . . . . 

I just did the cowling for cooling reasons.  

At 1000 MSL, if I push my plane, I can true out at 158 to 160 knots.  It will comfortably go at 150 knots all day.  



From: flyv35b <flyv35b(at)minetfiber.com>

To: teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 5:26:26 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance



        It's finished, is STC'd and will fit on a 76  Tiger.  Gary has the data but I haven't seen it published.  It is  a definite improvement in both cooling and speed.

  

 Cliff

 [quote]   ---

ArjayS(at)AOL.COM
Guest

Posted: Mon Jul 19, 2010 5:23 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

COOL! As far as publishing the results, I agree, it's a GIGANTIC pain and it never ends.

 Rj

 

 

  	  Quote: 	
		  It isn't published because then I'd have to do a whole bunch of performance testing to verify the improvements.  Then, I'd have to change the POH.  Then, I'd have to do a supplement.  Then . . . . 

 

 I just did the cowling for cooling reasons.  

 

 At 1000 MSL, if I push my plane, I can true out at 158 to 160 knots.  It will comfortably go at 150 knots all day.

 

 	


 

   [quote][b]

teamgrumman(at)YAHOO.COM
Guest

Posted: Mon Jul 19, 2010 5:23 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

pic



From: flyv35b <flyv35b(at)minetfiber.com>

To: teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 5:26:26 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance



        It's finished, is STC'd and will fit on a 76  Tiger.  Gary has the data but I haven't seen it published.  It is  a definite improvement in both cooling and speed.

  

 Cliff

 [quote]   ---

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teamgrumman(at)YAHOO.COM
Guest

Posted: Mon Jul 19, 2010 5:40 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

The Jaguar cowling was approved a year ago.  There are 4 out there flying, including mine.  Average speed increase is 5-6 knots.

As for the $1000/knot myth, that was posted here a while back by someone other than myself, that was in pre-1970 dollars (before inflation).  In today's money, it's about $2000/knot.

From: "ArjayS(at)aol.com" <ArjayS(at)aol.com>

To: teamgrumman(at)YAHOO.COM; teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 6:15:26 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

 COOL! As far as publishing the results, I agree, it's a GIGANTIC pain and it never ends.

 Rj

  	  Quote: 	
		  It isn't published because then I'd have to do a whole bunch of performance testing to verify the improvements.  Then, I'd have to change the POH.  Then, I'd have to do a supplement.  Then . . . . 

 I just did the cowling for cooling reasons.  

 At 1000 MSL, if I push my plane, I can true out at 158 to 160 knots.  It will comfortably go at 150 knots all day.

         [quote][b]

n2_narcosis(at)YAHOO.COM
Guest

Posted: Tue Jul 20, 2010 1:32 am Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Gary and/or Ned and whomever is flying the Jag cowl, how much did your CHTs drop during climb and cruise?  I am seriously considering the jag cowl as my old stock cowl is cracking.  The plane is getting its annual(my first, ouch) and Fletch squawked it so at some point I either need to fix or replace and I really like the look of the Jag cowl.

  

 Thanks Brock

      



--- On Mon, 7/19/10, Gary Vogt <teamgrumman(at)YAHOO.COM> wrote:



  	  Quote: 	
		  

From: Gary Vogt <teamgrumman(at)YAHOO.COM>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: ArjayS(at)aol.com, "Teamgrumman List" <teamgrumman-list(at)matronics.com>

Date: Monday, July 19, 2010, 8:39 PM



     The Jaguar cowling was approved a year ago.  There are 4 out there flying, including mine.  Average speed increase is 5-6 knots.

 



 As for the $1000/knot myth, that was posted here a while back by someone other than myself, that was in pre-1970 dollars (before inflation).  In today's money, it's about $2000/knot.

 

   From: "ArjayS(at)aol.com" <ArjayS(at)aol.com>

To: teamgrumman(at)YAHOO.COM; teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 6:15:26 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance



COOL! As far as publishing the results, I agree, it's a GIGANTIC pain and it never ends.

Rj

  	  Quote: 	
		  It isn't published because then I'd have to do a whole bunch of performance testing to verify the improvements.  Then, I'd have to change the POH.  Then, I'd have to do a supplement.  Then . . . . 



I just did the cowling for cooling reasons.  



At 1000 MSL, if I push my plane, I can true out at 158 to 160 knots.  It will comfortably go at 150 knots all day.



	




 

 	  Quote: 	
		  



st" rel=nofollow target=_blank>http://www.matronics.com/Navigator?TeamGrumman-List

et=_blank>http://forums.matronics.com

llow target=_blank>http://www.matronics.com/contribution



	


	


         [quote][b]

flyv35b(at)minetfiber.com
Guest

Posted: Tue Jul 20, 2010 6:37 am Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Per Rj:

  

  "I do not believe it's certified yet  but he's got to be very close. I think Cliff may have one of his first units.  They are both nice guys."

  

 It is certified.  No, I don't have one  of Gary's cowls.  In fact I don't have a plane that it would fit on.   I have an O-320 powered AA-1C and a V35B Bonanza I fly when I want to go  somewhere distant.

 

"As far as convincing Cliff of anything, I kinda don't think that's  possible for me. I'm retired from Apple computer, I was one of the original Mac  designers. I mention this because for some reason folks take the Mac vs. PC as  almost a religious issue. (Which makes as much sense to me as defending your  purchase of a GE toaster instead of a Sears.) It looks like many folks in  aviation take the same stance about their "beliefs". I have four engineering  degrees generally because I'm a nerd but mostly because I'm curious. I have a  little bit of both knowledge and experience when it comes fluid dynamics and  thermodynamics but I do try to keep an open mind. However, when you meet someone  who comes to the table with a set belief, then the only thing you can do is be  polite."

  

 Actually, It's not that difficult to  convince me as I have a pretty open mind I think.  It just takes facts and  actual test data or side by side comparisons.  I suppose that my  engineering background and 45 years experience in GA require that it pass the  smell test as well.  I started out asking a couple of pertinent questions,  which really never were answered, just comments about come down here and we'll  show you the proof or at least wine and dine you.  And as far as asking  people who have purchased your products (nose bowl) I have learned that those  kinds of testimonials are not necessarily totally unbiased.  After all it's  kind of hard to admit you spent thousands of dollars on a product  doesn't do what it claimed.  The best analysis comes from someone who  doesn't have a dog in the fight and truly is totally unbiased.  And  independent analysis such as Aviation Consumer does holds more water so to  speak.

  

 BTW, what does Apple vs. PC computers  have to do with this conversation?

  

 Cliff   A&P/IA

  

  

  

 

 

 [quote]   ---

teamgrumman(at)YAHOO.COM
Guest

Posted: Tue Jul 20, 2010 10:53 am Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

I don't think that either I nor Ned are the right ones to ask.  We usually firewall the throttle and leave it there.  On a JPI, I can easily push 470 degrees in a 1000-1500 fpm climb from 2500 feet to 4000 feet turning 2500 rpm.  Straight and level at 2500 feet, leaned to max power, and WAY over redline, I can do the same.  

Jeff and Martin, on-the-other-hand, the other two owners, are typical flyers.  Both (with JPIs) show 360 to 380 in cruise and rarely go over 420 in a climb.  #1 CHT will peak first in a climb; it's designed that way.  In cruise, it's very close to the rest.  

From: Brock Windsor <n2_narcosis(at)YAHOO.COM>

To: teamgrumman-list(at)matronics.com

Sent: Tue, July 20, 2010 2:31:56 AM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

 Gary and/or Ned and whomever is flying the Jag cowl, how much did your CHTs drop during climb and cruise?  I am seriously considering the jag cowl as my old stock cowl is cracking.  The plane is getting its annual(my first, ouch) and Fletch squawked it so at some point I either need to fix or replace and I really like the look of the Jag cowl.

 Thanks Brock

--- On Mon, 7/19/10, Gary Vogt <teamgrumman(at)YAHOO.COM> wrote:

  	  Quote: 	

From: Gary Vogt <teamgrumman(at)YAHOO.COM>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: ArjayS(at)aol.com, "Teamgrumman List" <teamgrumman-list(at)matronics.com>

Date: Monday, July 19, 2010, 8:39 PM

     The Jaguar cowling was approved a year ago.  There are 4 out there flying, including mine.  Average speed increase is 5-6 knots.

 As for the $1000/knot myth, that was posted here a while back by someone other than myself, that was in pre-1970 dollars (before inflation).  In today's money, it's about $2000/knot.

   From: "ArjayS(at)aol.com" <ArjayS(at)aol.com>

To: teamgrumman(at)YAHOO.COM; teamgrumman-list(at)matronics.com

Sent: Mon, July 19, 2010 6:15:26 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

COOL! As far as publishing the results, I agree, it's a GIGANTIC pain and it never ends.

Rj

  	  Quote: 	
		  It isn't published because then I'd have to do a whole bunch of performance testing to verify the improvements.  Then, I'd have to change the POH.  Then, I'd have to do a supplement.  Then . . . . 

I just did the cowling for cooling reasons.  

At 1000 MSL, if I push my plane, I can true out at 158 to 160 knots.  It will comfortably go at 150 knots all day.

 	  Quote: 	

st" rel=nofollow target=_blank>http://www.matronics.com/Navigator?TeamGrumman-Listet=_blank>http://forums.matronics.com

llow target=_blank>http://www.matronics.com/contribution

    	  Quote: 	

               [quote][b]

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue Jul 20, 2010 12:09 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Hi Brock,

  

 I'm still flight testing the Jag cowl but I am  getting some data points that I think are reliable.

 As far as cooling performance of the Jag cowl  I am finding a gain of 25 to 30degF in cooling of the CHTs. I run LASAR which is  known to cause CHT's to run 30 -35 degF higher than stock.  I always run  WOT with an MT constant speed prop and always lean to best power and turn the  RPM for best speed. Last year while racing I typically saw CHT's in the 380  range.  Recently, while flight testing the Jag cowl I have been seeing  CHT's in mid 350's. This for a DA of 4500'. 

  

 On my flight home from California in April  after installing the Jag cowl I had rather higher than normal CHT temps. I found  that the under cylinder baffle safety ties (normally springs) were broken  and I believe this was why I saw the higher than usual temps.  This  info for those that have followed my emails concerning the Jag  cowl.

  

 For climb I really cannot give you a good data  point from my flights for comparison as I usually use mixture to keep CHT's  below 400 in climb.

  

 Know that Gary uses JPI and I use EI and Gary  has determined that JPI reads 70degF higher than EI. So when Gary says his CHT  is 470 that is the same as my CHT reading 400....

  

 I'm still working and flight testing to  determine what speed gains the Jag may have given my plane. I do think there is  a speed gain and will give those numbers when I have good repeatable flight  test data to share.

  

 If you have a stock cowl there are a number of  things that can be done to increase cooling. But the Jaguar cowl is really an  excellent way to upgrade a Tiger. It looks really good and I think you will find  both cooling and speed benefits in addition to bringing the look of the plane  into the 21st century.

  

 The LoPresti is NOT a cowl. It is a nose bowl  and not a cowl. If you need a new cowl the LoPresti won't replace your old cowl.  

  

 Another thing to keep in mind is that with the  Jaguar cowl you get ALL NEW baffles and baffle seals. And Gary did an excellent  job designing these new baffles so that they seal very well. Most old  Tigers are in need of this.

  

 Here are some links to pictures of a completed  Jaguar Cowl installation:

 http://web.mac.com/jkeesaman/N1976T/N1976T_Returns_Home.html

  

 http://web.mac.com/jkeesaman/N1976T/Cowling_Spy_Photos%21.html

  

  

 Your Fellow Grumman Enthusiast,

 Ned

  

  

 ---

n2_narcosis(at)YAHOO.COM
Guest

Posted: Tue Jul 20, 2010 5:32 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

Wow, I am in trouble.  My plane has a single EI CHT probe on number three and was seeing CHTs in the 440s on climb. That would be 510 on the JPI!!! The plane is still at Fletch's.  I might have him do some cowl mods until I can get a new cowl.

 

Brock



--- On Tue, 7/20/10, 923te <923te(at)att.net> wrote:

From: 923te <923te(at)att.net>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: teamgrumman-list(at)matronics.com

Date: Tuesday, July 20, 2010, 3:11 PM



Hi Brock,

 

I'm still flight testing the Jag cowl but I am getting some data points that I think are reliable.

As far as cooling performance of the Jag cowl I am finding a gain of 25 to 30degF in cooling of the CHTs. I run LASAR which is known to cause CHT's to run 30 -35 degF higher than stock.  I always run WOT with an MT constant speed prop and always lean to best power and turn the RPM for best speed. Last year while racing I typically saw CHT's in the 380 range.  Recently, while flight testing the Jag cowl I have been seeing CHT's in mid 350's. This for a DA of 4500'. 

 

On my flight home from California in April after installing the Jag cowl I had rather higher than normal CHT temps. I found that the under cylinder baffle safety ties (normally springs) were broken and I believe this was why I saw the higher than usual temps.  This info for those that have followed my emails concerning the Jag cowl.

 

For climb I really cannot give you a good data point from my flights for comparison as I usually use mixture to keep CHT's below 400 in climb.

 

Know that Gary uses JPI and I use EI and Gary has determined that JPI reads 70degF higher than EI. So when Gary says his CHT is 470 that is the same as my CHT reading 400....

 

I'm still working and flight testing to determine what speed gains the Jag may have given my plane. I do think there is a speed gain and will give those numbers when I have good repeatable flight test data to share.

 

If you have a stock cowl there are a number of things that can be done to increase cooling. But the Jaguar cowl is really an excellent way to upgrade a Tiger. It looks really good and I think you will find both cooling and speed benefits in addition to bringing the look of the plane into the 21st century.

 

The LoPresti is NOT a cowl. It is a nose bowl and not a cowl. If you need a new cowl the LoPresti won't replace your old cowl. 

 

Another thing to keep in mind is that with the Jaguar cowl you get ALL NEW baffles and baffle seals. And Gary did an excellent job designing these new baffles so that they seal very well. Most old Tigers are in need of this

Discover

Joined: 26 Feb 2007
Posts: 429

Posted: Tue Jul 20, 2010 5:47 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

The bottom line of the JPI EI 70 deg spread as it was discussed a few years ago was that Lycoming probes were like the EI probes so that the EI temps or the JPI minus 70 temps are what should be used when comparing to Lycoming limits

As far as you being in trouble I would agree that 440 is too high although it is within Lycoming limits

There are several things that should be looked at on your cooling system and perhaps your mixture in the carb



Sent from my iPhone it gin 



On Jul 20, 2010, at 8:31 PM, Brock Windsor <n2_narcosis(at)YAHOO.COM (n2_narcosis(at)YAHOO.COM)> wrote:



[quote]Wow, I am in trouble.  My plane has a single EI CHT probe on number three and was seeing CHTs in the 440s on climb. That would be 510 on the JPI!!! The plane is still at Fletch's.  I might have him do some cowl mods until I can get a new cowl.

  

 Brock



--- On Tue, 7/20/10, 923te <923te(at)att.net (923te(at)att.net)> wrote:



 [quote]

From: 923te <923te(at)att.net (923te(at)att.net)>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: [url=mailto:teamgrumman-list(at)matronics.com]teamgrumman-list(at)matronics.com (teamgrumman-list(at)matronics.com)[/url]

Date: Tuesday, July 20, 2010, 3:11 PM



  Hi Brock,

  

 I'm still flight testing the Jag cowl but I am getting some data points that I think are reliable.

 As far as cooling performance of the Jag cowl I am finding a gain of 25 to 30degF in cooling of the CHTs. I run LASAR which is known to cause CHT's to run 30 -35 degF higher than stock.  I always run WOT with an MT constant speed prop and always lean to best power and turn the RPM for best speed. Last year while racing I typically saw CHT's in the 380 range.  Recently, while flight testing the Jag cowl I have been seeing CHT's in mid 350's. This for a DA of 4500'. 

  

 On my flight home from California in April after installing the Jag cowl I had rather higher than normal CHT temps. I found that the under cylinder baffle safety ties (normally springs) were broken and I believe this was why I saw the higher than usual temps.  This info for those that have followed my emails concerning the Jag cowl.

  

 For climb I really cannot give you a good data point from my flights for comparison as I usually use mixture to keep CHT's below 400 in climb.

  

 Know that Gary uses JPI and I use EI and Gary has determined that JPI reads 70degF higher than EI. So when Gary says his CHT is 470 that is the same as my CHT reading 400....

  

 I'm still working and flight testing to determine what speed gains the Jag may have given my plane. I do think there is a speed gain and will give those numbers when I have good repeatable flight test data to share.

  

 If you have a stock cowl there are a number of things that can be done to increase cooling. But the Jaguar cowl is really an excellent way to upgrade a Tiger. It looks really good and I think you will find both cooling and speed benefits in addition to bringing the look of the plane into the 21st century.

  

 The LoPresti is NOT a cowl. It is a nose bowl and not a cowl. If you need a new cowl the LoPresti won't replace your old cowl. 

  

 Another thing to keep in mind is that with the Jaguar cowl you get ALL NEW baffles and baffle seals. And Gary did an excellent job designing these new baffles so that they seal very well. Most old Tigers are in need of this.

  

 Here are some links to pictures of a completed Jaguar Cowl installation:

 http://web.mac.com/jkeesaman/N1976T/N1976T_Returns_Home.html

  

 http://web.mac.com/jkeesaman/N1976T/Cowling_Spy_Photos%21.html

  

  

 Your Fellow Grumman Enthusiast,

 Ned

  

  

 ---

teamgrumman(at)YAHOO.COM
Guest

Posted: Tue Jul 20, 2010 8:47 pm Post subject: TeamGrumman-List:LoPresti Nose Bowl Performance

First, before you panic, what kind of probe are you using?  Under the spark plug?  What shape are the baffles in?  Send pictures.  A single probe is really quite useless.  It could be wrong.

From: Brock Windsor <n2_narcosis(at)YAHOO.COM>

To: teamgrumman-list(at)matronics.com

Sent: Tue, July 20, 2010 6:31:54 PM

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl  Performance

 Wow, I am in trouble.  My plane has a single EI CHT probe on number three and was seeing CHTs in the 440s on climb. That would be 510 on the JPI!!! The plane is still at Fletch's.  I might have him do some cowl mods until I can get a new cowl.

 Brock

--- On Tue, 7/20/10, 923te <923te(at)att.net> wrote:

 [quote]

From: 923te <923te(at)att.net>

Subject: Re: TeamGrumman-List:LoPresti Nose Bowl Performance

To: teamgrumman-list(at)matronics.com

Date: Tuesday, July 20, 2010, 3:11 PM

  Hi Brock,

 I'm still flight testing the Jag cowl but I am getting some data points that I think are reliable.

 As far as cooling performance of the Jag cowl I am finding a gain of 25 to 30degF in cooling of the CHTs. I run LASAR which is known to cause CHT's to run 30 -35 degF higher than stock.  I always run WOT with an MT constant speed prop and always lean to best power and turn the RPM for best speed. Last year while racing I typically saw CHT's in the 380 range.  Recently, while flight testing the Jag cowl I have been seeing CHT's in mid 350's. This for a DA of 4500'. 

 On my flight home from California in April after installing the Jag cowl I had rather higher than normal CHT temps. I found that the under cylinder baffle safety ties (normally springs) were broken and I believe this was why I saw the higher than usual temps.  This info for those that have followed my emails concerning the Jag cowl.

 For climb I really cannot give you a good data point from my flights for comparison as I usually use mixture to keep CHT's below 400 in climb.

 Know that Gary uses JPI and I use EI and Gary has determined that JPI reads 70degF higher than EI. So when Gary says his CHT is 470 that is the same as my CHT reading 400....

 I'm still working and flight testing to determine what speed gains the Jag may have given my plane. I do think there is a speed gain and will give those numbers when I have good repeatable flight test data to share.

 If you have a stock cowl there are a number of things that can be done to increase cooling. But the Jaguar cowl is really an excellent way to upgrade a Tiger. It looks really good and I think you will find both cooling and speed benefits in addition to bringing the look of the plane into the 21st century.

 The LoPresti is NOT a cowl. It is a nose bowl and not a cowl. If you need a new cowl the LoPresti won't replace your old cowl. 

 Another thing to keep in mind is that with the Jaguar cowl you get ALL NEW baffles and baffle seals. And Gary did an excellent job designing these new baffles so that they seal very well. Most old Tigers are in need of this.

 Here are some links to pictures of a completed Jaguar Cowl installation:

 http://web.mac.com/jkeesaman/N1976T/N1976T_Returns_Home.html

 http://web.mac.com/jkeesaman/N1976T/Cowling_Spy_Photos%21.html

 Your Fellow Grumman Enthusiast,

 Ned

 ---

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