04 cobra shortblock with 97 b heads stock, d1sc new numbers.

[encasedmetal]

I was talking about the valve guides.. I know on my old motor not having enough timing put more wear and tear on my guides, atleast that's what my builder said..

I think that's the longest you've ever taken to respond before. lol
I have no idea why timing would effect valve guide wear at all though. guide wear has more to do with the seals, and the valves themselves. For example on the LS7, all of their problems were due to less than optimally designed sodium filled valves, and led to premature guide wear. If what you're saying is true though, I'd love to learn about it. Just doesn't seem that the rate at which a spark plug fires has anything to do with valve guide wear.

 

[98 Saleen Cobra]

I think that's the longest you've ever taken to respond before. lol
I have no idea why timing would effect valve guide wear at all though. guide wear has more to do with the seals, and the valves themselves. For example on the LS&7 and all of their problems were due to less than optimally designed sodium filled valves, and led to premature guide wear. If what you're saying is true though, I'd love to learn about it. Just doesn't seem that the rate at which a spark plug fires has anything to do with valve guide wear.

LOL I've been without a computer for 3 days.. and then while I was at work yesterday we had a huge storm come through and the Carnival Triumph broke all mooring lines and was floating freely in the river destroying shit lol!!

Yea nvm.. I think I'm wrong on that.. :/ That information that was given to me was bad info.

 

[uberstang1]

Bas should be in tomorrow, the car is being tune by Dave guy at dgr performance,formally sgs automotive, he doesnt seem concerned by the high boost as the cars taking it well. The d1s isnt being overspun either i checked with procharger withthe pulley setup and 7k rpms and they said its under the max impeller speed. Ill have to find out whatte timing advance is at hoping to hear back friday or eary next week. I know someone with a stock longblock terminator pushing 23psi on pumpgas with a KB and its been holding for years

 

[97snakebite]

Any updates

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[uberstang1]

Still waiting on final numbers, boost a spark is on and I asked Dave if he thought it was pushing it on pump gas and said the tune isn't even aggressive and is more than fine on 93

 

[97snakebite]

Still waiting on final numbers, boost a spark is on and I asked Dave if he thought it was pushing it on pump gas and said the tune isn't even aggressive and is more than fine on 93

good deal man.. keep us updated... your experience will be good info for people with prochargers on here. i know its helping me choose my setup

 

[Helomech74]

pretty sure they're 53cc but pulling that out of thin air this morning. He's below 8.5:1 though for sure. Boost is not the limiting factor as far as a motor goes. it's the timing. Shit- you can make 1000hp to the crank on a factory 5.3 LS motor with a turbo and low timing. Seen it, and it lasted for 3 nights at the local drag way. No, that's not dependability but I think most people are starting to realize that compression and boost are not the enemies we used to think them to be. 99.9% of all tuners will start all tunes with no timing in it, then add timing in 2 degree increments until it knocks- then back it off 2-3 degrees and leave it. I don't think I know of anyone that tunes with the boost in mind- it is what it is and dictates how the motor will act in relation to everything else- heat, valve float, timing, etc.

Doing the math for compression on that motor assuming stock bore/stroke, it's at around 8.42:1. If it's a .020 over bore then it's right at 8.5:1. Stock B heads are 52cc (at least every set I've CC'd has been on average).

 

[uberstang1]

Hoping to hear the final numbers by the end of monday, after that its on to a trans im torn between going with a built standard or going with a pa performance c4 with a forward mvb and transbrake. Kind of a hard decision for me there

 

[paulsauto]

I've got weapon x coils on my modular fox 4 valve and made 888 on corn no spark probs

 

[paulsauto]

At 23 psi

 

[yfz162]

I have a 96 cobra with stock heads milled .010, .020 over Manley 18cc dished pistons, block decked, and stock stroke. Not sure where my compression falls, but i'm pulling 18-19 psi from a T-trim with meth and sprayed a 75 shot from a wet kit with zero blow out issues. I'm running stock coils, tr6 plugs gapped at .025, and Taylor plug wires. My final timing on that combo is at 16* on pump 93. Hope you get it sorted out, but those are pretty good numbers for 6K imo.

 

[uberstang1]

The final numbers ended up being 603rwhp and 522rwhp at 6,000 RPMS, I will post the dyno sheet asap. For some reason the car will not rev past 6k rpms, can't figure our the plug blowout as all readings for everything are good and the only other possibility was some head lift but the plugs were pulled several times and showed no evidence of coolant being introduced into the combustion chambers. Dave guy said judging by the power curve if the car made it to 6800 it would be in the ballpark of 670rwhp as the torque was still continuing to climb at 6k rpms.

 

[97snakebite]

I'm having the same issue and we want to say Valve float maybe?

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[procharged 99]

How much boost was you seeing at 6k

 

[uberstang1]

20-21psi

 

[itSSlow98]

My guess is valve float. Boost gives valvesrpings hell especially if they arent designed for that type of application.

 

[uberstang1]

Would valve float cause plug blowout necessarily?

 

[encasedmetal]

Would valve float cause plug blowout necessarily?

you can usually tell if it's valve float if it falls on it's face powerwise prematurely. what valve springs are you using OP? if they're stock they ain't gonna hold that psi.

 

[97snakebite]

Would valve float look like this? Sorry not trying to thread jack

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[encasedmetal]

Would valve float look like this? Sorry not trying to thread jack

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not to my eyes. you can calculate when you should upgrade your valve springs and what you will need to be successful. If anyone needs valve float to be explained I can do that as well. here we go.
Stock 4v intake valves are 37mm with a 7mm stem. 37mm is 1.457". The area of the back of the valve is 1.666 square inches. A 7mm valve stem has 0.060 sq inches of area. Subtracting the valve stem area from the valve area leaves 1.606 sq inches of valve that sees manifold boost pressure. If you were to run say 20 psi- that means you have 1.606 * 20 psi or 32 lbs of seat pressure you have lost while under boost.

OEM valve springs only have 60 lbs of seat pressure, so 20 psi of boost only leaves you with 28lbs of pressure holding the intake valve shut when it is on its seat and the engine is at WOT. this obviously is not adequate as you want to retain a much higher margin of safety. you want to remain as close to the oem 60 lb of seat pressure as you can if not more with higher boost applications.