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Andy Hollis
Andy Hollis
5/15/24 1:14 p.m.

Our biggest question mark going into this event was whether the new head gasket would hold for the duration.  
 

With the overbore of the K25, there is much less gasket material to seal between the cylinder and the surrounding water jacket than with a stock bore K24.  Further, our head had a little divot in it right near where the previous leak occurred.  
 

We were super careful about surface prep and also added an extra 5 ft-lbs on the head studs (ARP).  That did the trick as we used no water all week.

Well...actually we had a minor overflow issue when we got caught in that 5 mile backup when the interstate was shut down.  
 

Evidence of "wet burp"...

 

Andy Hollis
Andy Hollis
5/15/24 1:15 p.m.

Digging further, here's our four spark plugs which all have excellent coloring.

 

Andy Hollis
Andy Hollis
5/15/24 1:18 p.m.

And finally...compression test.  
 

Unhook injectors, pull coils and plugs, depress throttle fully and crank.  

Results were very even:

189, 189, 193, 192, 189

Note: I always bracket my tests.  Cylinder #1 gets done at both ends to verify nothing changed (e.g. weak battery)

For reference, the last time I tested this engine these were the results:

186, 184, 187, 188, 186

Andy Hollis
Andy Hollis
5/15/24 1:32 p.m.

Our engine oil consumption was also as expected...just a little over a quart over 3500 miles and 40-ish track laps.

While we didn't track it carefully, our fuel mileage was better than planned, often exceeding the 24 mpg was saw in testing.  Some of this was due to lower ethanol content.  In fact, the lesson learned was that the engine was happy running way less ethanol and mileage improved greatly.  There appears to be a sweet spot around E50 where the octane is sufficient for the engine, latent heat effects are still significant, yet mileage is quite good. 

The flex fuel system worked perfectly...both the sensor and the Hondata KPro V4.   We'd check the content and fuel trims once we fired back up after refueling, using the bluetooth connected phone app.  Great sense of security having this info.


Heres the sensor plumbed into the fuel return line:

Andy Hollis
Andy Hollis
5/15/24 1:35 p.m.

And here's the bluetooth phone app...


madmrak351
madmrak351 HalfDork
5/20/24 9:50 a.m.

Congratulations on a great performance. I found the post race evaluation quite interesting. Thanks!

Andy Hollis
Andy Hollis
5/25/24 5:48 p.m.

More follow-up...

Fixed the one still-leaking bleeder  by reverting to the older brass design (I have a stack of old worn-out calipers...yeah, pack rat).  
 

Drained the fluid level in the caliper below the bleeder threads, cleaned and dried them.  Then used Permatex 59214 High Temp Thread Sealant on the bleeder and muscled it on.  Dried overnight, bled and took it to the track.  
 

Result?  Bone-dry.  Huzzah!

 

 

Andy Hollis
Andy Hollis
5/25/24 5:55 p.m.

Speaking of going to the track, we hadn't run our home track with both the new aero and the big motor...until now.  New personal best (1:18.9) by a ton.  300hp vs 225 was worth well over a second despite 90-degree ambients..
 

Here's a comparo...

 

Scott Skillman
Scott Skillman New Reader
5/29/24 2:39 p.m.

In reply to Andy Hollis :

I had the same issue with the leaking adapter and went back to stock brakes. Did you use a thread sealer? That is what Wilwood recommended, but I was not sure what could handle the heat.

Andy Hollis
Andy Hollis
5/29/24 3:45 p.m.
Scott Skillman said:

In reply to Andy Hollis :

I had the same issue with the leaking adapter and went back to stock brakes. Did you use a thread sealer? That is what Wilwood recommended, but I was not sure what could handle the heat.

From my post just above...

" Then used Permatex 59214 High Temp Thread Sealant on the bleeder and muscled it on.  "

wink

If you look at the data sheet for that sealant, it specifically mentions brake caliper fittings.  I've been using it for years.

Spoke with our guy at Wilwood and it turns out they only used those bleeders for a short time.  New updated ones are on the way. 

He also suggested subbing a plug in for the bottom bleeders to avoid random damage from rocks, etc.  These calipers can be run on either side of the car, so each has four bleeders.  Once installed, the bottom ones no longer serve a purpose.

Pete. (l33t FS)
Pete. (l33t FS) MegaDork
5/29/24 6:59 p.m.

I am 99% sure that one can buy brass 1/8NPT bleeder screw "repair kits" at almost any auto parts store.  They are for fixing calipers that have trashed bleeder screw threads.

Stampie
Stampie MegaDork
5/29/24 7:03 p.m.

In reply to Andy Hollis :

I think it was a recent Roadkill Garage where they bleed the upper and lower bleeder.  I was wondering why they had two bleeders but that makes sense.

Tom Suddard
Tom Suddard Publisher
5/29/24 8:51 p.m.

In reply to Stampie :

Yeah, it cuts down on part numbers to stock and spares to carry--every caliper is both a left and a right. They really bled the bottom one on TV...? Wow. 

pkingham (Forum Supporter)
pkingham (Forum Supporter) Reader
5/29/24 9:20 p.m.

Please tell me if I'm reading the plot wrong, but I'm seeing the benefit of extra power on the straights, but I'm not seeing a benefit to more aero under braking or in cornering.  Corner speeds are right about the same and braking is generally steeper on the slower lap.  Is the aero improvement just not that signficant?

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