Got off the phone yesterday with Paul at Razors Edge and was going to order a 4lb pulley and get my chip done and I was asking him how much boost was safe for these trucks. He stated that he has changed his mind from 13-14 down to 10-11. He has THREE broken Harleys in his shop right now, all pushing 13-14lbs, all with broken rods and no signs of detonation. He and one of his SVT buddies feel like its because of the weight of our trucks, which is why the Lightning can get away with more boost. He states that the failure is usually happening on a downshifting situation rather than running through the gears such as a dragstip run. He says he will be discouraging any more than 10-11lbs unless the bottom end has been built. Very interesting. Since I have already visited the planet of BOOM, I'm going to keep my 10.5lbs of boost and chip it and call it a day.

 

I had planned on going to 11.5lbs of boost on my 01 HD, maybe I should rethink it now. You 02 guys have better rods than the 01's and 00's.

 

Definately something to consider. However, someone must have forgotten to tell the motors in Cobras' and Slingshots' trucks this, as they have been running 15lbs for quite some time. I think the key may be information and discipline--beware of too many hard downshifts.

 

and i believe stankyhd from the other site is pushing about 15 lbs of boost, and maybe a couple others with no trouble...yet

 

Hopefully I don't get "hammered" for bringing this up, but since I own both types of chips, I look at it as being completely unbiased.

What we know so far:
2 trucks from RPM Outlet have blown--Diablo chip.
3 trucks from REM have blown--Diablo chip.
Trucks from JLP that have blown (that we know of)-0--Diablo chip
Trucks from JDM that have blown (that we know of)-0--Superchip

Like I said, I have both chips, so I'm not insinuating anything! I would say that RPM has the worst reputation on the board. REM on the other hand, has gained the respect of the L community, and that in itself is a major accomplishment.

Johnny or Jim, Please chime in as we would love to hear your thoughts on tunning. Since there are twice as many HD's being made than Lightnings, I'm sure your customer base will broaden, and this will surely become a question for many owners.

 

outnumbered I agree, but you can't compare the 4.6 cobras to the 5.4s. You'll be hard pressed to find many cobra guys running more than 11lbs on stock bottom ends for very long---they just won't last and that has been well documented on the boards for a while (the reason I only run 11lbs in my snake). Slingshot has been lucky but he does have an excellent tune from JLP, plus he may just have a freak of a bottom end......who knows. Paul did say he had one truck pushing stock boost with a chip that had rod failure in a downshift situation???????? I like your tally of blown motors and programmers, make you think. On the other site the is another blown motor from a guy in Slidell, LA but he won't reveal mods.......smart. He was denied warranty secondary to evidence of a chip.

 

Drop-top,

When I was referring to "Cobra", I did not mean the Mustang, I meant CobraSVT that has the HD running in the 12's. 15lbs of boost, and many trips down the track, and he is still going strong.

 

(old run before he was in the 12's)




and the video of his 12.7 run

long version with a few runs
http://svt.kicks-***.net/videos/Brandons5runsatATCO.wmv

short verson of just the one run
http://www.tek-nics.com/videos/atcoharleytruckbest.wmv

 

How much boost is safe?

Depends how you define "Safe".

 

sorry outnumbered. Doesn't cobrasvt have a built bottom end from JLP?

 

nope, well, at least not yet, that's all i can say for now

here's a quote of his list of mods back from when he ran that 12.7

he's done a few more mods since then, not sure if he wants me to post them or not, so i won't, but he didn't have a built bottom end on his 12.7 runs and all those

 

Josh is right, he has the stock bottom end. However, given that he is in close proximity to JL, I would suspect that Manley rods, and an Autorotor are being installed as we speak!!

I also know that Johnny's wifes truck is pushing 15lbs; he must not be too worried about the boost.

 

What exactly is a 'hard downshift '??? I dunno... I do know that tune is everything! . My chip is out right now and on it's way back to JLP for a re-burn to fatten up the street tune. Throw the two RPM trucks out--those are most likely due to a really crappy tune... electrodes burned off are a pretty good tip off .
JLP has probably done more of the Diablo's than everyone else put together! So far no probs--that makes me feel pretty good.
Tomcat--I wish I knew the answer to your question, certainly 10.5 is safer than 13... 8 is probably safer than 10.5. I will keep running my 12.5-13.5 lbs (depends on air density... ) I figure I can get away with a bigger pulley than you sea level guys. Less air density equals less boost... if I did live in a lower altitude, would probably stick with a 6 lb lower.
I think the other big thing is how you drive the truck... you hammer it all the time--eventually BOOM! Funny thing is I actually drive this truck easier about 90% of the time than I did the last 4 trucks I owned (2 Z-71 Chebbies and 2 4x4 Fords)... it's like I know it's BAD--don't have to dog all the time it to feel like it. Weird, I know.
And one more thing--if you add boost... GET A WIDE BAND O2 MONITORED DYNO RUN!!! Cheap insurance... And BTW--I saw a banner ad on corral.net advertising new '02 L longblocks for $2900 today... Beats $6000+ from the dealer, warranty or not (like the warranty is worth anything if you have mods .

 

just for the record, i did not say anything

 

You didn't have to Josh. He already has everything in JL's catalog on his truck, and he is trying to get into the 11's. The next step would have to be 20+lbs of boost!! Go Cobra Go!!!