Went to Barona drag 1/8mi strip last night , was a cool night temperatures as low as 60 degrees
Car was pulling like a beast and had great traction
Most runs were under 8.3 , best was 8.25 at 88mph , best trap was 89mph
For comparison last year, same track with only a pulley mod, was running best of 8.5 at 84mph with 60ft of 1.9
Now compared to last year the temperature is around 10degrees cooler. I have added 2 gallons of race fuel to 7 gallons of 91. I also have done port and polish of a throttle body, opened up stock Intake more and am running an experimental tune from a friend of mine.

 

Port and polish throttle - Did you use Maxbore for this

Opened up stock intake - Are we taking about opening up the stock runners/ports on the plastic inlet manifold here ?


Also congrats on the time based on the 1/8 to 1/4 mile conversions thats a 12.9 pass !!!

 

Steve I was at 13.15 on 1/4mi with 107 trap In vegas few month back when I was only pushing 85mph 1/8 trap and with density altitude of 2800 corrected this is around 12.9 and 109mph trap
So thinking 4mph higher trap in 1/8 should equate to 12.5- 12.7 territory around 111-113mph optimistic but that trap speed increase is no joke. I did a port and polish myself. Opening up the intake consists of cutting out plastic grilles in front of the air filter, cutting out extra openings on the bottom of the intake boxes, replacing corrugated rubber connector with straight through silicone pieces. Tested before and after intake restriction with a manometer , results were initial restriction of 21inches per Intake side down to 17 inches , so around 8 inches total restriction reduction or .3 of 1 psi.

 

Interesting

Did you manage to get any pics of the modified air intake system

 

What style manometer did you use and how was it hooked up? I have a 0-10" magnehelic that I was going to tinker with but reference it to the Y above the throttle body so I could see inches of water column restriction (loss) out to the filters and snorkels. I also have a Miljoco absolute pressure gauge that reads 10" of mercury when open to atmosphere.

It's interesting that there was so much restriction between the Y and the filters and simple silicone couplings took care of some of it. I had considered opening the air filter boxes up to the side grills and add a balance tube to try and avoid the MAF bias difference CEL. I'd also considered doing a carbon fiber or aluminum intake tubing in true diameters vs crushed how the OEM stuff is. Just wasn't sure if the juice was worth the squeeze.

 

Yes I have them somewhere. Basically all of the plastic grill in front of the air filer removed and maybe around 2x8 inch cut out on the bottom of both airboxes.

I found the link to my post on this https://www.jaguarforums.com/forum/x...rboxes-165613/

 

The manometer I use is the electronic type, which is able to do recording to see what the max vacuum was. I plugged the unit in on the drivers side where the breather hose connects into the air intake. I dont think silicone couplers did much, maybe straightened the airflow a little, main improvement was cuting out air-box holes and maybe the grill in front of the filter. Makes sure that you use a heat gun after cutting the grill out to bend the filter box out on the side so it does not cave in.
Just fyi I have tried hooking up a slightly larger diameter 3" dryer hose on both sides and didn't see any improvement, so thinking the bottle neck is in the snorkel, maf, airboxes area.

 

Makes sense. Sounds like your's is an absolute manometer or it just references the input vs. the cabin pressure. It's probably just academic where it references. I wanted to see vs. the inlet to the throttle body since that 'should' isolate pressure differences to only the plumbing itself.

The same setup could be used to determine after cooler efficiency. On mine when I eventually get there I plan on cooking the oil and crud out and installing a catch can for the PCV circuit. That made a huge difference in my '93 Mustang with keeping the charge paths flowing well and clean.

I don't like how small and convoluted the snorkels are either. I can understand some relative high pressure air behind the grill at higher speeds compensating for the small tubing but the engine is definitely sucking through a straw at low speeds.

Some time I need to pull the nose back off to replace my dysfunctional horns and plan on modding the air boxes then. Probably open the fronts and foam seal them to the nose. I'll add a balance hose behind the grill and maybe a spring loaded flap to avoid water ingestion. I'd love to go generic cone filters down the line as well.

Fun times.

 

I dont think water ingestion should be an issue especially with the bottom plastic cover, unless your panning to be running over deep puddles.
I think what would be really nice, is to have a one way flap that would open inwards and open up the second path of air when there is vacuum or demand for it due to snorkel restrictions, but flaps would stay shut if there is positive pressure coming in from the snorkel.
What do you mean by a balance hose behind the grill?

 

From reading, if the MAF signals vary too much side to side it'll throw a CEL. Adding a balance tube (say 2" diameter reinforced hose) between the boxes should keep the relative pressures the same side to side. I'd expect when passing a semi or something similar that the pressure off the front could 'supercharge' that sides air box and trip the MAF, especially if it was high enough on one leg to reduce the flow on the opposite side.

A couple years ago I ran through a death puddle after a heavy T storm. It was a length of interstate during construction that had the middle lane ground off and higher pavement on each side. At the bottom of a dip it was 3-4" deep and 50 yards long. I hit it doing 65 mph and swore I was going to die. The car slowed to 30 mph and pushed a huge wave of water ahead of it. That was with my '93 Mustang and it sits a lot higher vs. the XKR.

Just some thoughts.