Interesting observation

[turbov6joe]

As some of you might recall, I had to freshen my motor this winter due to a weaping headgasket and wiped #1 (intake) and #5 (exhaust) cam lobes that both appeared at the end of the 2003 race season. I'm not 100% certain that the leaking HG caused the cam lobes to round, but I'm suspect that it had A LOT to do with it as they both reared their ugly heads about the same time....co-ink-e-dink to anyone else??? Yesterday I had the first opportunity to take the TTA our for a cruise since last fall, so I figured I'd put some miles on the new bearings and headgaskets before I take it to the track for the first time this comming Sunday. I put ~25 miles on the motor before I laid into it. The WG bleeder was closed and the WG rod was backed out a few turns, so I assumed that I should be sitting at ~17 psi....boy was I mistaken! I rolled into the fast pedal and WHAM...I was sitting at 25 psi before I could blink twice!! Now here is where my interesting observation comes in. Other than going back to the OE cam/lifters, I changed NOTHING else from last year. Because I assumed that I would only be running ~17 psi, I backed the alky pump speed down from "max" to #6 where I would usually run it at 17 psi. What's crazy to me is that at 25 psi, and a pump speed of #6, I had only .5º of KR, a low O2 of .799mv, and an EGT of only 1516º all the way up to 140 mph. Typically at 25 psi the alky would have to be maxed out and I would still see LOW single digit KR numbers and EGT's in the mid to upper 1600º. I can't imagine that going from a 212-212 cam to the stocker would have that much to do with this. I know that the 212 cam allowed more air in, but that much more to make this much of a change??? What do you all think?

 

[Scott231]

Hey Joe,

The 25psi occurence prolly came about due to two factors. 1) the wastegate puck/assembly isn't moving as freely as it should (wicked winter in SE KC?) and 2) the smaller cam allows for quicker spool up.

The cooler EGT and minimal knock are a result of you using the tune for a 212/212 cam with a smaller cam. As such, the motor is running a good bit richer. With a smaller amount of air being burned, the EGT will not be so great - all other things being equal.

Hey - 25 psi ain't so bad huh?!

 

[1badTTA]

Did it feel like 25psi as compared to 17psi??? How does the car run overall? Does everything else feel good about it?

Just trying to make sure you don't have a problem with the cam being out of time or something else that could have happened with a cam change.

 

[RobR]

Maybe overlap with the old cam and you were blowing boost out? Stock cam, less so more boost. Does that make sense?

Just something off the wall...

 

[TT/Ameasap]

Another off the wall occurence could be the alky cleaning effect w/ no carbon deposites ect. Razor would know more on that though. I have just seen it once where it took a few 1/4 mile runs and the KR was back w/o alky.

 

[Razor]

799 is way fat to make any decent power. If you were talking 730's for O2's, then that would be a totally different issue.

My car resently underwent the opposite, It got heads and cam, I was running 27-29 PSI and I backed the WG rod 6 full turns. Well on saturday nite, it was blowing 24 PSI. So much for boost reduction.

Air temps, alky, who knows if the old cam wasnt letting the motor breathe correctly. Lots of variables..

Congrats, aint it great to be back on the road again

Julio

 

[turbov6joe]

The car was running like a top....140 mph was there so fast it kind of blew my mind for a moment! I've become pretty anal as I grow older/wiser when wrenching on anything, I'm 100% certain that the cam was timed perfectly....hell, the car felt every bit as powerful as my ass dyno could remember of the 2003 season. The only problem was I have the OE rear tires on the car right now....can you say TRACTION LIMITED After giving it more thought I agree with you all that the smaller cam is prolly the main reason why things were the way they were, but still never expected the cam swap to make such a significant change as far as fueling is concerned. Something else I failed to mention is that I'm using one of Eric Marshalls new speed based timing chips which may have changed some things also??? I gotta tell ya, I've had some good chip burners over the years (yes you Scott), but Eric has really come up with some neat stuff these days! Right now he's working on a variable timing/fueling chip for the 50's that I'll be trying out once he's done. That guy has dug so far into the chip algorithems (sp) that's he's all but lost me in chip technobabble these days.

Yea Scott, 25 psi on 92 Amoco isn't so bad.... I can honestly say that my car pulls so much harder on pump/alky versus race gas, I may never go back to 114. With the cost of race gas getting so damned expensive, and the fact I have a connection for filtered commercial grade denatured at ~$2/gallon, it's almost cost prohibitive to run the race stuff....not to mention wasting O2 sensors every so many passes. I think my pop might even try alky this year. Speaking of my pop's car, he should have a 6 point in his ride by BG. I found a local chassis shop out by my place that quoted me a super price for the TTA, so the GN should be pretty close.

 

[Razor]

Hey Joe I got one of them you'll be trying soon U-know-whats from U-know-who that will be making its debute this weekend.



Alky is the the way.. I had a customer email me last nite, he ran 11.61 at 121 with a 1.88 60 foot, on a GN with stock heads..

 

[turbov6joe]

SWEET!

 

[RobR]

Eric is the man! I'm playing with one of his WOT fueling chips. Interesting to say the least