i took my lt4 to the chassis dyno for the first time tonight.
i have had a mail order tune from a well known programmer for a while and i wanted to see where it was and if it could be improved upon.
my baseline was 312.5 hp and 318.9 tq.
i was experiencing some detonation at 5700 and 6300 rpm.after some tuning i was rewarded with 316.3hp and 329.1 tq with no detonation.
at first glance it doesent appear to be a substantial gain.however,i maintained both hp and tq advantages from 2500rpm until 5800rpm.
it is evident i am having some spark issues with not being able to light the mixture completely from 5500 up.i have new plugs(ngk) and wires(msd)that are less than a year old.opti has 30k on it.i will inspect plugs and replace but i think the opti is probably to blame.until it worsens it will stay put.
just for kicks we made one last run with the somewhat dirty k&n removed to see if it was a restriction.it made 1.3 hp more with no air filter.i would say it is working well.
since my last trip to the track and prior to the dyno runs i removed my dyno max super turbo mufflers and replaced them with what appear to be borla's but the have no identifying marks on them.they are of a straight thru design and are much louder.the car seemed more responsive after the muffler change and even more so with the tune.it no longer feels soft down low and will break the tires loose from a 20mph roll.something it would'nt do before.
many thanks to jeff at carolina auto masters in durham nc.he is a super nice guy and just as eager to tune my car as the blown c5 approaching 1000 rwhp in the bay next to mine.
for reference here is my specs:
99k mile lt4
sw long tubes
no cats
x-pipe
borla muffs
descreened maf
enlarged polymer maff housing
cut lid w/k&n
ngk plugs
msd wires
cam dyno tune
sorry for the novel.time to go back to the track

 

[QUOTE] many thanks to jeff at carolina auto masters in durham nc.he is a super nice guy and just as eager to tune my car as the blown c5 approaching 1000 rwhp in the bay next to mine. [QUOTE]

absolutely love to hear about people like that. Glad you had a great experience

perhaps the coil may be the culprit ? Also when I first bought my car even with just 40k on it the springs were weak. Replacing them with new ones made a world of a difference in upper rpm smoothness.

 

perhaps the coil may be the culprit ? Also when I first bought my car even with just 40k on it the springs were weak. Replacing them with new ones made a world of a difference in upper rpm smoothness.[/QUOTE]

we did discuss the valve spring possibility.he seemed to think it was spark related.as far as the coil goes,i don't know.i have heard people say they tried the msd unit and had problems and switched back to stock.
while i'm here does anyone have any firsthand experience with the new msd,accell,or summit brand optispark distributors?

 

I'm going through plug wires around once a year it seems, working on that issue again right now. Can't find anything wrong with the ones I had, but it's running better after swapping some out last night. I wouldn't think it's the opti. When my opti went bad, it would barely idle much less run down the street.

There's really an endless list of potential causes of missing on these cars.

Congrats on the numbers!

 

[QUOTE=DieL][QUOTE] many thanks to jeff at carolina auto masters in durham nc.he is a super nice guy and just as eager to tune my car as the blown c5 approaching 1000 rwhp in the bay next to mine. Isn't he the "Milkman"?

 

Those are excellent numbers, some of the highest (documented) that I've seen for a stock LT4. (and I will believe you, even without the chart... )

EDIT: Oops! I just reread your post, with the mods listed. Hmmmm...not as good as I had thought; only 5hp up on my dead stock LT4.
(that is, if you can compare different dynos/weather/etc. directly, which you can't...) Thanks for sharing and keep working!

Larry
code5coupe

 

[QUOTE=F1Fan][QUOTE=DieL]yep thats him. www.milkman@lugnutz.com

 

311 RWHP on a dead stock LT4?????

I don't think so......not if you mean dead stock as in NOTHING altered..

Most LT4's that are in the typical 290-300rwhp range actually have some mods such as cat-back sytems, cut filter lids, tuning mods, etc.

No flame intended, but I suspect your car is not "bone stock" per my definition....not at 311rwhp(if that is what you were saying?)

I do agree that at 316 he is a little low considering his mods

 

George,

Congrats on the numbers . You made about 11 more rwhp and 25 rwtq than I did on the same dyno, which is probably in those good ol' headers. Even approaching 100K, yours is still cranking it out. Sounds like in your may have some 12's in your future. I'll bet your torque curve was flat as hell. You could set a drink on mine.

Jeff is a great guy and knows GM performance very well.

I'm planning on heading to Fayetteville this Sunday. Let me know if you can make it.

Chris