[g-machine]

stock motor gave out, heres what I have going, 70mm gt42 turbo, fmic, mopar rt heads that are freshly redone, 47lbs injectors, 2bar map, turbonetics wastegate and blow off valve, sct tuned by chris at pie. truck ran good but gave up after only 200 miles, it does have original abused bottom end and gave out at 12lbs.. I want to put back together and be able to safely run 10-12 lbs, Is it necessary to used forged internals or could I just run a good set of rings and make sure its tuned properly.. the bottom end on the truck has seen over 20 bottles of 100 shot nitrous so the fact it was weak does not surprise me. any insight from other turbo magnum owners would be very helpful, I have seen stock bottom end trucks on here running 15lbs and be fine and ive seen some at 10lbs blow, whats the deal.....

thanks in advance and my apologies for for my lack of grammar..

 

[g-machine]

Turbo guys.. what has worked for you? Meth injection? Im curious on what has worked for you....I have done a lot of research but everyone has an internet opinion.. I want first hand experience..

Thanks

 

[g-machine]

bueller, bueller, bueller, anyone?:huh:

 

[Bang4theBuck]

Methanol here. I am however using a supercharger, but boost is boost. You can get away with alot more with it. I use straight windshield washer fluid. Works great! I even made a pass or 2 thinking my wideband sensor was going bad (reading 14.3 wide open) but later finding out I was having a fuel pump issue. I popped the hood and the headers were glowing bright red after the second pass. I knew then that the wideband was right and I was dancing with the devil! Everything held fine and this is on stock head gaskets and bolts! No more than 22 degrees of timing and stay in the mid 11's on the wideband (with the meth) and things should hold up well. When u build the new motor make sure you use 1008 head gaskets and arp head studs and enjoy!

 

[g-machine]

Methanol here. I am however using a supercharger, but boost is boost. You can get away with alot more with it. I use straight windshield washer fluid. Works great! I even made a pass or 2 thinking my wideband sensor was going bad (reading 14.3 wide open) but later finding out I was having a fuel pump issue. I popped the hood and the headers were glowing bright red after the second pass. I knew then that the wideband was right and I was dancing with the devil! Everything held fine and this is on stock head gaskets and bolts! No more than 22 degrees of timing and stay in the mid 11's on the wideband (with the meth) and things should hold up well. When u build the new motor make sure you use 1008 head gaskets and arp head studs and enjoy!

thanks for your response, I was running arp head bolts but stock gaskets, I have had the motor apart now 2 times so maybe I should put studs in as im sure arp bolts might be stretched now...... I will ask chris at pie what my timing was, thanks again.

 

[RTchas]

Methanol here. I am however using a supercharger, but boost is boost. You can get away with alot more with it. I use straight windshield washer fluid. Works great! I even made a pass or 2 thinking my wideband sensor was going bad (reading 14.3 wide open) but later finding out I was having a fuel pump issue. I popped the hood and the headers were glowing bright red after the second pass. I knew then that the wideband was right and I was dancing with the devil! Everything held fine and this is on stock head gaskets and bolts! No more than 22 degrees of timing and stay in the mid 11's on the wideband (with the meth) and things should hold up well. When u build the new motor make sure you use 1008 head gaskets and arp head studs and enjoy!

You SS Bastard! When did you track that thing? And why didnt I get an invite? Oh and what didi it run?

To the OP I have a rear mount and run 10#'s at the track 5 on the street, I ran the stock bottom for several thousand miles/years and it was the heads that did mine in started to leak from cracks in valve chamber's.

Now I have a stock bottom with 1008's and ARP studs, I got a set of PIE heads and custom grind cam truck went 11.80's and has more Chris @ PIE will be going thru the tune again when I get it down to DE for some tweeks. The 11.80 was right off PIE dyno same day first pass:jester:

The stock crank is stout and depending on your HP goal's Forged is nice insurance but not needed IMO for a mild turbo set-up, comes down to what you wanna do with it ?

 

[kohake85]

On my 02 trans am methanol did awesome. It was pretty extreme though cranking out about 1200 ponies. I eventually added a 50 shot of nitrous just to help with intake temp under long hard pulls. Don't see why your stock bottom end shouldn't handle 12 psi intercooled. Methanol would def help. A good tune is 95% of the battle, and I agree with bang4thebuck on the gaskets and head bolts. Only thing I would possibly add would be better crank and rod cap bolts, but I don't think I is a big issue. Have yet to see a stock engine that can't handle 12 psi with proper tuning and intercooled. Any that have went that I have seen with that had a mechanical issue that caused it or were just tired. I think your def on the right track. Best of luck!

 

[g-machine]

Yeah at 200 miles I cracked stock heads and blew gaskets. I just wanna avoid doing this again this year lol... I just got the rt heads and was thinking if i got a cam also I could run a little less boost... I basically want to drive it again haha.

 

[g-machine]

On my 02 trans am methanol did awesome. It was pretty extreme though cranking out about 1200 ponies. I eventually added a 50 shot of nitrous just to help with intake temp under long hard pulls. Don't see why your stock bottom end shouldn't handle 12 psi intercooled. Methanol would def help. A good tune is 95% of the battle, and I agree with bang4thebuck on the gaskets and head bolts. Only thing I would possibly add would be better crank and rod cap bolts, but I don't think I is a big issue. Have yet to see a stock engine that can't handle 12 psi with proper tuning and intercooled. Any that have went that I have seen with that had a mechanical issue that caused it or were just tired. I think your def on the right track. Best of luck!

Im thinking motor was just tired. Wot air fuel was 11 to 11.8. And from what ive seen chris at pie seems to know what hes doing. Thanks

 

[77Aspen318]

Any '67-up 273/318/340 crank would work- they didn't have cast cranks until '68, and 340s didn't until '72. There's a different in the torque converter/crank junction on earlier than '66 motors, but the cranks do physically interchange from the 273s and "wide head" 318s.

 

[Bang4theBuck]

You SS Bastard! When did you track that thing? And why didnt I get an invite? Oh and what didi it run?

:nono: I don't like to admit to it but these were street passes (closed road of course) and not at the track where I would like to have been. I'm a drive shaft loop install and fire jacket away from being track legal and you will get an invite!

 

[TheOtherDodge]

What gave up on the bottem end? How much power were you making?

What rods and pistons?

I run a forged crank, billet mains, studs but only 11 lbs so far. Going to test 15 lbs this fall.

 

[g-machine]

What gave up on the bottem end? How much power were you making?

What rods and pistons?

I run a forged crank, billet mains, studs but only 11 lbs so far. Going to test 15 lbs this fall.

Stock.... just rings... I was running 13lbs when it damaged rings..

 

[Hahns5.2]

Stock bottom end should take around 15lbs. Stock headgaskets usually give up around 10PSI (as you've found). I boosted the stock motor at 100k miles for 37k miles at 8PSI with no problem, when I rebuilt it I opened up the ring gap and went with Felpro MLS headgaskets and ARPs and 10-11PSI hasn't been a problem for the 20k miles it's been together. Out of curiosity have you measured the existing ring gap on any undamaged rings? I went extra safe with .028". How many miles total on the motor?

 

[gdonovan]

Stock bottom end should take around 15lbs. Stock headgaskets usually give up around 10PSI (as you've found). I boosted the stock motor at 100k miles for 37k miles at 8PSI with no problem, when I rebuilt it I opened up the ring gap and went with Felpro MLS headgaskets and ARPs and 10-11PSI hasn't been a problem for the 20k miles it's been together. Out of curiosity have you measured the existing ring gap on any undamaged rings? I went extra safe with .028". How many miles total on the motor?

Good info.

I'm building a 5.2 with Indy heads with stock headgaskets and bolts for the moment with a KRC 210? Roller cam.

Going to be SC with a Novi 1200 unit, the only real question I had was about intercooling.. which even at fairly low boost levels is free lunch as far as I'm concerned but I have been considering alc injection instead.

Gary