Jarren_b

Well Disappointment hit me square in the face today.
I learned the difference between a load dyno and inertia dyno the hard way

This first graph is my dyno (load) from about a year ago
Smaller cam 227/234 .612/576 4 degrees overlap, stock ls1 intake and tb, ziptie mod instead of a CAI and unmodded factory mufflers



This graph is from today at premeir (inertia)
232/234 .626/.626 11 degrees overlap, bbk intake mani and TB, modded factory muffler, CAI


I wasnt hoping for much because I knew the correction used on my first dyno should be about 5% higher than normal.

That being said I was thinking id be in the 390 or so range. But no. It definitely sucks spending tons of time and effort to end up with what looks like less power on paper. a lot less. I wasnt expecting to lose 30whp.
I talked to heath quite a bit about it and it is running 27 degrees timing instead of 29 now, I didnt ask him why but I trust him. We also agreed that you can have the biggest cam in the world but it doesnt mean a damn thing on stock heads so that might be next years project, Wish It would have been in the cards now since I had it all ripped apart

All that said, I know dyno's are just a tuning tool so im not going to worry about the number too much
The car runs great, pulls hard and definitely feels faster

Wish I could prove my gains but all ive got is a thumbs up from the Butt dyno
Ill bring up the rear with the slowest c5 on the board lol


Do my numbers seem low?
mods in sig

1989GTA

What make of dyno was the first dyno?

poltergeist 02

iTrader: (65)

What heads?

Jarren_b

Stock LS1 Heads.

First dyno was a superflo I believe.
This one was a dynojet.

Jarren_b

I know my stock heads are killing me, but could my stock mufflers be choking me out?

scotty2000ss

iTrader: (2)

I'd really want to know why the timing was brought down that much.

Are you happy with how the car drives? Wait to see what it traps.

conan

iTrader: (5)

Another Utah LS owner... I live up in Parkcity

Heath tuned my car as well, don't think he would steer you wrong. 2 things come to mind for your #'s

1. Salt lake is at 4,500ft Elevation, My car with full boltons and a 224 cam was a dog in this elevation compared to the 700ft when I lived in Pittsburgh. So thats not helping.

2. Your stock mufflers and Ls1 intake are killing that cam / combo. Cams need to breathe, open her up and you'll see a big change.

vettenuts

iTrader: (4)

First thing I would do is swap in an LS6 intake.

PS: You're not alone, many have had dyno disappointments.

Tuskyz28

Dynos don't really tell everything. Only way to really know what you have is take the car to track and see how it performs. Don't be upset bro.

perfect.ta

Bbk tends always to through hot air. Go for an ls6

SoFla01SSLookinstok

The HP & TQ seem to drop off a bit early in the second graph.

HCI2000SS

iTrader: (2)

Change the stock mufflers for sure. Before you get to discouraged by any of this see what it traps at the track. Last year on one particular dynojet (and with a really bad tune) I made 395 rwhp n/a but trapped 118 mph while hitting the rev limiter on the 1/2 shift and was fast enough to run with my buddy's ported/pullied 03 Cobra that made 500 rwhp on the same exact dyno

scotty2000ss

iTrader: (2)

What size are the headers and throttle body? Are you using the stock cats?

poltergeist 02

iTrader: (65)

The LS6 and BBK intake make almost the same power. I have seen back to back dyno testing on this.

427zm

iTrader: (9)

Not at that power level if you're running Z06 titanium Catback.

poltergeist 02

iTrader: (65)

Here is a good read for anyone interested. https://ls1tech.com/forums/generatio...vs-fast92.html

Jarren_b

Ok just as clarification for everyone.

My car is not a z06 so I dont have a TI catback.

I have the stock catback from 1997 haha

I have stock 339k heads (806 equivalent)

BBK intake flows barely better than an ls6 so I wont be changing

I have a 80mm bbk tb

My longtubes are 1 3/4

And I have a borla Xpipe as well


Im hoping I see a decent gain with an axleback because I dont really want to pull heads off this year. not only that, if you look at a cut-away from a stock muffler to z06 mufflers, they are hardly different. Im just going to go straight pipe I think. I know there has to be more power in my combo, I have a decent sized cam

Jarren_b

Its not a z06 unfortunately

scotty2000ss

iTrader: (2)

Keep us posted! I'd expect to pick up another 5 with a different exhaust set up like you mentioned.

SoFla01SSLookinstok

On the dynojet graph it makes peak tq right at 5k rpm. It immediately starts to fall. Also the hp peaks at around 5800 & starts to fall not much after 6k. I would think, with 11 degrees of overlap, it should pull strong past 6500.

Still a nice C5.