NO WOT or top speed runs in 5th/6th gear? WHY?

[stone4779]

OK so Ive heard that you cannot do extended WOT runs in 5th/6th gear on these...WHY?

I mean whats the big deal? Why the hell shouldnt I go for a top speed run or WOT in 5th/6th gear with a forged motor, and a T56?

My LS1 Z28 would take all the beating I could throw at it, COUNTLESS 175+ MPH runs...so I know its probably not the T56...so that leaves either the drivetrain after the trans is the weak link, or it has something to do with the heat generated by the blower during an extended WOT top speed run..

Im guessing the last one has to be it....but can someone confirm this for me?

And what can be done to remedy this problem?

I just have difficulty believing that you cant do this in a T56 equipped car with a forged motor..

and whats with the "OH NO DONT SPRAY IN 5TH" ?

Why Why Why? lol oke:

 

[mustanginky]

its a couple things. your eaton is a heat sink, first through fourth will heat it up something crazy anyways, a long pull through 5th and 6th gears adds tons of heat to the air. this increases detonation. the second, load on the engine and the input shaft of the transmission. that is hard on an engine, forged or not. it takes alot more effort to pull through the top two gears than 1-4.

 

[Sniperdog]

hell, let her rip :thumbsup:

 

[02GTKB]

hell, let her rip :thumbsup:

:nono: :nonono:

 

[Sniperdog]

He has obviously heard from many that it is stupid to do so, hence the question. :bash: if he wants to try it like soo many before him and toast the motor, more power to him. :shrug:


not to mention you should read the first line of my sig as gospel :-D

 

[03mgtermi]

i wish people would f*$@ing READ...there has to be a thread or two every month started on this.....c'mon man :read:

 

[Black Talon]

 

[xXSnakeBiteXx]

First off SEARCH!!!!!!! but to answer you question its the tight piston to wall clearences these motors have+the heat from the eaton=expanding pistons and then boom

 

[fiveoh2go]

OP you've been a member here for more than 5 years, you should know the answer to the question you posed. If not, SEARCH FOR IT.

 

[rotor_powerd]

Piston to wall clearance is extremely tight on these motors.

Heat = expansion. WOT in OD gears for long periods of time = unbelievable amounts of heat.


You do the math.

 

[snakezilla]

you will go BOOOOOM!!!

 

[racebronco2]

OK so Ive heard that you cannot do extended WOT runs in 5th/6th gear on these...WHY?

I mean whats the big deal? Why the hell shouldnt I go for a top speed run or WOT in 5th/6th gear with a forged motor, and a T56?

My LS1 Z28 would take all the beating I could throw at it, COUNTLESS 175+ MPH runs...so I know its probably not the T56...so that leaves either the drivetrain after the trans is the weak link, or it has something to do with the heat generated by the blower during an extended WOT top speed run..

And what can be done to remedy this problem?

I just have difficulty believing that you cant do this in a T56 equipped car with a forged motor..

and whats with the "OH NO DONT SPRAY IN 5TH" ?

Why Why Why? lol oke:

Cooling a 450-550rwhp engine is alot different then cooling an ls1 with 350-400rwhp. Our piston to wall clearance is .001, with forged pistons it's .003-.0035. It's the heat created by the engine at those higher rpms and high speeds. The reason they call it a heaton is because it absorbs the heat generated from the engine causing the ait 2's to go sky high.

I have done many high speed runs at several track in 4 and 5th gears. The highest being 163 in the mile. I have manley forged pistons with .003 piston to wall clearance. the best cooling mod i have done is the mod that makes our hoods real heat extractor hoods. I have run in 107* weather with speeds as high as 142mph with no problems. Engine temps were about 230* and ait 2's were about 160* at the highest temps.

 

[Mystic03]

try it and let us know what happens

 

[stone4779]

To the ones that actually took the time to answer the question: THANKS!

There are a couple reasons I just posted a new thread. First its a b1tch to search for something like that...what do you search for? "no 6th gear"?, "top speed"?, I mean comon I would have gotten a billion threads asking "Whats the top speed of this?" "Whats the top speed of that?"....its different when you wanna know what belt to get for a 2.76 pulley...search for "2.76" youll find everything you wanna know about your pulley...but its not that simple with my question...kindof hard to figure what KEY words I should search for, seeing as how all the key words in my question are far to common to narrow it down to less that so I figured I would start a discussion. The MAIN thing I was looking to find out is this:

"And what can be done to remedy this problem?"

The heat from the blower I pretty much figured that...but I didnt know the PTW clearance was a factor.. Thank you for that new tidbit...

Soooo apart from swapping to a twin screw or turbo you're pretty much restricted 1-4 WOT runs huh? Well that kindof sucks but I guess not a real issue as its my daily driver...but when I had my Z28 I used to take it out for a 175+ run quite often and it was great...wish it wasnt such a big deal but I guess eventually the eaton is coming off anyways so my next question is this:

If you remove the eaton, and go twin screw, or turbo(big fat intercooler of course) IS this still a problem? Would the pistons heat and expand enough to do damage with a more efficient power adder? Side note: Would a 50 shot of nitrous keep it cool enough lol? I have had the NOS plate kit for like 4 months just havent put it on yet...

 

[stone4779]

try it and let us know what happens

I WILL. After its actually ready to take it. :-D

 

[stone4779]

Cooling a 450-550rwhp engine is alot different then cooling an ls1 with 350-400rwhp. Our piston to wall clearance is .001, with forged pistons it's .003-.0035. It's the heat created by the engine at those higher rpms and high speeds. The reason they call it a heaton is because it absorbs the heat generated from the engine causing the ait 2's to go sky high.

I have done many high speed runs at several track in 4 and 5th gears. The highest being 163 in the mile. I have manley forged pistons with .003 piston to wall clearance. the best cooling mod i have done is the mod that makes our hoods real heat extractor hoods. I have run in 107* weather with speeds as high as 142mph with no problems. Engine temps were about 230* and ait 2's were about 160* at the highest temps.

Cool cool good info. Wow .001! Thats freakin rediculous. Glad to hear you are out there having fun in it like we're supposed to I thought when I got this car I wouldnt have to really open up the long block but if I do decide I want to do some high speed laps at WOT I am going to have to for insurance. Its actually not that expensive for some good forged pistons its just a PITA to install...and if I pull the motor I already know theres gotta be something else Ill want to do while Im at it and it will never end lol...

SO I guess that was the answer I was looking for. So its agreed, increase the PTW clearance, and if possible, get rid of the eaton, and you are good to go (engine wise)?

I already have the 26 spline, I figured I would wait for something to give before having the tranny built, same for the rear end...

Guys the reason I asked is I do like to challenge the norm...someone told me "Awwee you cant even haul ass in 5th cuz you'll blow your motor.."...so I'm like "The hell I will....I'll make it so it WONT".

Oh, n RaceBronco: My Z consistently put down 525+ ;-) Those motors are pretty darn stout... I beat the ever-lovin crap out of it and I never had a problem with it. You just gotta showem some love I cant even tell you how many passes I put on that car. between me n my friends, must be at LEAST 1000..easy.

 

[stone4779]

He has obviously heard from many that it is stupid to do so, hence the question. :bash: if he wants to try it like soo many before him and toast the motor, more power to him. :shrug:


not to mention you should read the first line of my sig as gospel :-D

What was your sig? there isnt anything there now?? :shrug:

 

[Sniperdog]

What was your sig? there isnt anything there now?? :shrug:

"The above post may or may not contain copious amounts of SARCASM"

 

[JB]

I still can't believe how many people buy these cars without doing their homework
I don't buy ANYTHING without researching it first

 

[Jimmysidecarr]

175 plus should be reserved for the Texas Mile in Goliad, Tx

When forged pistons are installed at close to cast piston wall clearance they can and often do grow out and contact the walls, sometimes ripping ring lands right out.

Carlos(racebroncoII) did his right, he switched to a lighter Teksid aluminum block and adjusted his piston to wall to run Manley slugs.

He runs in Cali and instructs at open track events, he is a classic example of using these cars to their full potential.

I'm pretty sure he's not doing 150+ pulls on the street.

Some Terminated Terminator pistons, some documented as top end pull victims. It would seem that ring end gap may be a tad tight as well since some of these seem to have the rings pulled out of position.