Jaguar XJS progress.

frenchyd said:

The stock EFI has essentially a 5 inch intake. While 6   inch &half SU's  have a 9 inch intake. 
 SNIP

Wouldn't πr^2 be needed in your calculation? Sure, 6x1.5=9, but that's too linear.

In reply to keithedwards :

You are probably right. My back up formula was 1798cc x3 = 5.3 liters. Which is the same as the V12. 
Since I have your attention, Check my formula and math. 
    E85 requires 20% more fuel than straight gasoline.  The Jets are .090   So 1.20x.090 = .108 

     Is my math correct?   
    I'm thinking I'll use my .106 drill (#36 ) and then buy a .108 ream to get to the 20%. 

In reply to frenchyd :

Do you by chance know the Dowd brothers?  I think you are a bit younger than them.  Two of my mentors with respect to auto racing. 

frenchyd said:

In reply to keithedwards :

You are probably right. My back up formula was 1798cc x3 = 5.3 liters. Which is the same as the V12. 
Since I have your attention, Check my formula and math. 
    E85 requires 20% more fuel than straight gasoline.  The Jets are .090   So 1.20x.090 = .108 

     Is my math correct?   
    I'm thinking I'll use my .106 drill (#36 ) and then buy a .108 ream to get to the 20%. 

Since you asked, 1798cc x3 is closer to 5.4 liters. Your other math is correct, but again, increasing your flow by drilling out the jet is not linear. Flow volume should change with the square of the change in radius.

My disclaimer: I have dealt with changing needles in SU carburetors for a race car, but that was about 35 years ago. I still have a small selection of SU needles. Also, I have zero experience calculating jetting changes for E85.

In reply to keithedwards :

Please help me then. If I want to increase the flow by 20% what size do I ream my .090 jets to?  
 I've also modified stock needles to work better. For  example I used to richen needles slightly by using 1000 grit emery paper to refuse an area at that RPM.  It's easy to richen but you have to replace the needles to lean a particular area. 
   Same with the jet the needles go into.  Easy to enlarge but you can't make them smaller. 
Yes you are right. 5394 ( MGBx3 ) is bigger than 5343 (V12) 

The area of a circle is calculated as PI*r^2.  So the area of a .090 jet is 3.14*.045^2=0.00636.

1.2*0.00636=0.00763.  

So if you want an area of 0.00763=PI*r^2, or (0.00763/PI)^.5=r, or r=0.049.

Edit, a 20% increase in area does not necessarily result in a 20% increase in flow, but it'll get you close for challenge purposes.

In reply to Dead_Sled :

So, r=.049x2= .098 

 Alcohol has an much wider tolerance from too rich to too lean than gasoline and  since E85 is 85% alcohol, A number 39  (.099) ream or drill  should be good to go.  
    I fully understand that this is a starting point.  Once up and running I'll  go to a chassis dyno to see how close I am and tune accordingly. 
    I'm sure I don't have enough needles  for all 6 carbs. But of the over 50 I have  hopefully at least 3 will be some version of the AAU.  
     On the off chance they  make  the .100 jet  for  the HIF4  carb the solution is simple. Six of those and Bob's your uncle. 
     Then all that is left to do is get my trusty air density meter and go to the drag strip on a test and tune day.   Wait while the air density changes and see how many flats I need to adjust for based on the air density and I'm good to go. 

In reply to Dead_Sled :

We all know that Stoich for gasoline is 14.7-1  air to fuel
max rich is 12.5 

max lean is 13.23

   E85 is more complex. Stoich is 9.75-1 

Max rich  is 6.975

Max lean is 8.4687 

 if it's actually 15% gas and 85% alcohol. 
 Since it can be anywhere from 53% to 85% and still sold as E85 pump fuel  is a  crap shoot. 
 

The good news. Holley carbs of all people has a tester they sell for $22.00 to determine alcohol content.  
ps;  apparently in Brazil you can buy 100% ethanol at the pumps.  I'm not sure how they do that. Since100% ethanol is 200 proof alcohol. 
   Unless they sell booze a lot cheaper than gasoline. 

In reply to frenchyd :

well if you want to prevent people drinking it that's easy just spike it with something (very much like NO2 sold here for racecars - DON'T breath it expecting an experience like you would get at the dentist). 

But I think it's pretty hard to store a real 100% ethanol. It probably just means "above e85" or something like that. 

In reply to Robbie (Forum Supporter) :

Since I don't plan on visiting Brazil I guess it will remain a Mystery. 

In reply to Robbie (Forum Supporter) : ( not this car) 

JaguarV12 turned a 7.79 169 mph in the 1/4 !!!!! ( on nitrous) 
 Only the 3rd pass by the driver. 
Follow up with a 7.80/ 169. 
July Eurodragster news 

Engine was in a previously raced 23T 

frenchyd said:

Took a detour. Found a box truck, might work as a race car hauler, covered with graffiti plenty cheap. .20' box with-a lift gate. Needs some work. Won't be horribly expensive. 

issue #1  how much can a lift gate pick up? Enough to pick up a 3000 pound race car?  

   Issue #2  where can you keep a big box truck cheaply?  

   

A trailer is a much cheaper way to go since you already have a truck.

Would the car fit in the box truck ? How would you get it in/out? Strap it down? You're not 25 anymore.  No the lift gate probably couldn't lift the car (safely) with the additional leverage of extensions you'd need to make.

Slow progress over last couple of months, but that has worked out best for everyone's schedule. Time to resume work on the rollcage. 

Dead_Sled said:

The area of a circle is calculated as PI*r^2.  So the area of a .090 jet is 3.14*.045^2=0.00636.

1.2*0.00636=0.00763.  

So if you want an area of 0.00763=PI*r^2, or (0.00763/PI)^.5=r, or r=0.049.

Edit, a 20% increase in area does not necessarily result in a 20% increase in flow, but it'll get you close for challenge purposes.

I'm taking a step back. Instead of using 6 1 &1/2 SU's I'm going to four 2 inch SU's.  It's about flow. The carb manifold and both Fuel injection manifolds group the ports into 4 groups of 3. If I try to use 6 SU's  the middle two cylinders wind up with a long curvy track whereas the two carbs on the ends have short direct paths.   
  The problem is now I'm working with  .125 jets and need to calculate a 20% increase in flow.  But I'm also trying to figure out what needles will work best with the short 2&3/4 stroke. It sure won't be the ones off the XKE with their 4.17 stroke. 
 I'm looking at the Rover 2000TC.  Because it has the fuel bowl at the 30 degree angle I need 

In reply to frenchyd :

Another Jaguar XJS V12  To be raced. Lor  just picked up a 1989 for $500. 

Progress update. 
   Rollcage cut and bent.  Fits in nicely. Forward laterals cut and bent they too  fit nicely.  Plates to land on cut fit and bent.  
      Pictures to follow this evening.  
 Please don't laugh at masking tape holding everything in place. While we could have tack welded some stuff in place. We still need to fish mouth ends. 
I'm chicken, I always sneak up to the correct length rather than measure and cut.  Jeff is content to work with me on that basis. 

frenchyd said:

ps;  apparently in Brazil you can buy 100% ethanol at the pumps.  I'm not sure how they do that. Since100% ethanol is 200 proof alcohol. 
   Unless they sell booze a lot cheaper than gasoline. 

Brazil's biggest cash crop is sugarcane- don't remember the details, but in the late 80s they nationalized their production and processing into fuel for their alcohol-driven VW engines because they were one of the last to stop production of the Beetle. I think it was a way they were fighting poverty? Either way, They can get away with it because their climate is almost entirely tropical so the extreme richening an alcohol engine needs aren't as extreme for those 1-barrel carbs.

You'll need to start racking before you fishmouth or your mouths might be guppy. (Gappy)

What's the plan to weld the tops of the main hoop??

glad to see this thing chugging along. 

The main hoop looks awfully far forward in that pic.

All three of us fit and sit in the same seat in the same location. Carefully tried and measured.  Jeff carefully checked, checked and checked again that we conformed to regulations. 

jfryjfry said:

You'll need to start racking before you fishmouth or your mouths might be guppy. (Gappy)

What's the plan to weld the tops of the main hoop??

glad to see this thing chugging along. 

I probably should have shown the neat holes we drilled in the rocker panels. That allows us to drop the legs down about 5-6" to allow welding on top of the cage.  Then raised up and the required plates slid in place, welded to the rocker panels.  After that the legs welded to the plates. 
 It's about access to getting complete welds even though the bars  are  right against the roof. 
    Left to my own devices, I believe I would be further along.  But I'm trying very hard to make  it a team exercise without being too demanding.  It's really a pleasure working together and I want everyone  to feel they are fully involved and at whatever time their  schedules allow.  

In reply to GIRTHQUAKE :

 We took a major step  sideways this week. Earlier I contacted John  who had built the fender flairs for Group 44 ( and worked with the race team) and arranged to buy a set from him.  
        So rather than my best guess as to what Group 44's fender flairs looked like I'll have exact copies.  I'll drive to Virginia during the Christmas vacation.  

Low rider. 
   Actual we just lowered the cage so Jeff could put his beautiful welds on the top of the cage.   Just a bunch of stacked dimes