95 Cobra R Vapor Lock

[bolt-on]

Having witnessed Lew Groth's R loose power in the heat at Gingerman last June and Brian Groth's 95 R loose power on a hot and humid day at Road America I have been curious about the cause. Both attributed it to vapor lock. I always thought that was a condition that could occur on carbureted engines, but had never heard of it on fuel injected engines. Regardless, it is a condition that race teams campaigning 95 R's would not tolerate. What did the race teams do to cure this problem?

Or is it just that Minnesota Cobra's can't tolerate the heat?:D

Larry

[kevin]

i beleive both lew and brian have figured out the problem. however, both are out of town (so to speak) but may be able to answer you next week

[Dave Schotz]

I would like to know about this also... I think my car may have done this once or twice... where it kinda 'bucks' under Full Throttle? When you have done repeated runs... run after run?

I am really interested in finding out what we can do to prevent this!

I just built my car for ESP in Solo 2 for next year... Here are some pics of the motor... and my most recent Dyno Graph (Yesterday)...

http://www.sccaforums.com/3rd Dyno.JPG

http://www.sccaforums.com/EngComplete1.jpg

http://www.sccaforums.com/EngComplete2.jpg

http://www.sccaforums.com/EngComplete3.jpg

I look forward to hearing about the Vapor Lock issue... I would love to see any of your 351 Engine Picks as well!

Anyone know how to get rid of the Check Engine light, once you have removed the EGR?

Thanks!

Dave

[cobrabitn]

Vapor lock occurs when the gas gets so hot in the fuel lines and it turns to vapor. What causes this is excessive heat in and around the lines. Most Vapor lock situations are solved by either rerouting the fuel line away from the engine (heat source) or by doing an old 60's trick of taking a piece of rubber hose and wrapping the fuel line with it so it acts as an insulator. I know, I use this on my 428 CJ in my 1969 Mach 1 and vapor lock is a thing of the past. Hope that helps out??? ;)

[Dave Schotz]

Thanks... that helps... so if I wrap the entire fuel lines from tank to motor (where exposed) with Rubber Hose... it would help?

I also would like to know what Lew, and Brian Groth's solutions were.

Thanks!

Dave

[cobrabitn]

You only need to wrap the line that is too close to the heat source and not the entire line from the tank to the engine. Just the lines closest to the engine. ;)

[Cobra-R]

Originally posted by Dave Schotz
Thanks... that helps... so if I wrap the entire fuel lines from tank to motor (where exposed) with Rubber Hose... it would help?

I also would like to know what Lew, and Brian Groth's solutions were.

Thanks!

Dave

Unfortunately we have not figured out where the real problem lies yet. Dad has wrapped his fuel lines along with adding a larger capacity fuel pump, just like Dean had done to my car before I bought it.
Dean, Kevin, and I were down at Hallet in June when Dean still had my 95, and in those relativly hot conditions didn't give dean any problems, but when I got the car I had trouble at MAM once and as you know at Road America. The problem only has reared it's ugly head twards the end of a day when the car has been run for many sessions.
The only thing I changed on the car from when Dean had it was back off some timing and switched to using 92 or 93 octane pump gas. I am planning on switching back the 100+ octane race gas when temps start getting in the 80-85 degree + days next year to see (as I suspect it will) cure the problem.
I belive the Vapor point of the fuel is the issue and apprently the 95R is pushing that limit. Of course all racers would never use pump gas, thus not have the prblem?????

Brian

[bolt-on]

Brian,

I forgot to mention when I started this thread that I REALLY enjoyed my ride in #23 despite the fuel problems near the end of the session. Thank you.

A 95 R is an awesome ride:thumbsup:

Larry

[johnbasf]

Try "Poor mans nitrous" I will tell you what it is if you want. LOL

[NJ2000R]

I experienced momentary power loss, fuel starvation, or vapor lock in my '00R coming hard off the last turn at Pocono when it was in the mid 80's, but not at Gingerman in similar conditions. I did notice that at Pocono, it occurred only during my last session, and I was down around 1/4 tank or slightly below 1/4, so there was possibly a wrinkle in the bladder, some other type of fuel starvation, or vapor lock while pulling a hard right hander onto the main straight....the rest of the way around the track it was fine....and has been fine since then....strange....

OK John, I'll bite: whats poor man's nitrous? :D

[johnbasf]

Take some kind of can and fill it with ice, coil up the fuel line and run it through the can. A buddy at work told me about it. :thumbsup:

[NJ2000R]

Originally posted by johnbasf
Take some kind of can and fill it with ice, coil up the fuel line and run it through the can. A buddy at work told me about it. :thumbsup: :thumbsup: :rotf: :rotf: :rotf: :rotf:

[johnbasf]

Hey, it really does work!!! :thumbsup: :thumbsup:

[Cobra R Man]

Originally posted by bolt-on
Having witnessed Lew Groth's R loose power in the heat at Gingerman last June and Brian Groth's 95 R loose power on a hot and humid day at Road America I have been curious about the cause. Both attributed it to vapor lock. I always thought that was a condition that could occur on carbureted engines, but had never heard of it on fuel injected engines. Regardless, it is a condition that race teams campaigning 95 R's would not tolerate. What did the race teams do to cure this problem?

Or is it just that Minnesota Cobra's can't tolerate the heat?:D

Larry

I had the same thing happen to me on hot days of open track. I was baffled, until I read an article in MMFF (Sept. '00) where Greg Biffle tested all of the "R"s. During testing, they discovered the smooth intake hose before the throttle body became soft and suctioned closed. They mentioned that "it was like stuffing a towel in the intake tract" (pg.57).

[Cobra-R]

Just an update. The car gave problems when we were at MAM a couple weeks ago, I came in and added 12 gallons of 100 oct race gas and the car ran fine the rest of the day. When you have this problem you will only notice a drop in power at maybe 5500 rpm and above, the longer you drive the car the lower the rpm the problem occurs at. On hot days, remove your gas cap, at mam it took a good minute for all the pressure to relieve with the cap completely off.
I have been to lazy to do it, but I plan to pull the charcoal canister (in the front right fender, right?) and make sure that isn't full of fuel adding to the problems.


Cobra R Man,
Did they mention how they fixed the intake hose?


Brian

[NJ2000R]

This past weekend I had a momentary lag when coming out of a hard right hander....actually a very tight 180....it lagged like it was starved for fuel....and my tank was completely full, 94 octane sunoco....I had a similar problem last year, also coming out of a right hander....but I was at 1/4 tank then....hmmmmm....any other '00R owners experience this???

[Cobra-R]

Ken,
Check your vent tube coming out of the fuel cell (on top right side, probly will have to drop the cell down to check) and make sure it isn't kinked. I believe the setup is the same between the 95 and 00, dad found his kinked.
If I remeber right, Dean found a problem inside the fuel cell on my (when he used to own it) when he was replacing the fuel pump with a 255 gpm unit. If he see's this, maybe he can enlighten us on what it was.

Brian

[Cobra R Man]

Originally posted by Cobra-R
Just an update. The car gave problems when we were at MAM a couple weeks ago, I came in and added 12 gallons of 100 oct race gas and the car ran fine the rest of the day. When you have this problem you will only notice a drop in power at maybe 5500 rpm and above, the longer you drive the car the lower the rpm the problem occurs at. On hot days, remove your gas cap, at mam it took a good minute for all the pressure to relieve with the cap completely off.
I have been to lazy to do it, but I plan to pull the charcoal canister (in the front right fender, right?) and make sure that isn't full of fuel adding to the problems.


Cobra R Man,
Did they mention how they fixed the intake hose?


Brian

They did not elaborate on how to fix, but I inquired at SVT, and they suggested a cold air kit.

[Cobra-R]

Ok, thanks! I do have a cold air kit, so maybe I am good in this respect. :thumbsup: