I took the car to sisters bf today, the numbers are less than what I was expecting. Im not sure why the video is so dark.
Dynojet, 78% humidity, 80.31 degrees, 29.65 in-HG.
Run 1 made 308.3hp and 318.4 6tq
run 2 made 309.6hp ans 314.31 tq

Slp intake, EM LT's, random tech cats, and 3" slp cat-back. Tire spin in first run due to antifreeze on the ground (from an import haha)

 

Not bad numbers...what were you expecting? You have relatively light mods. The headers and exhaust will give only slight gains on a stock motor, but change your cam and and get a tune...you will see some of results those mods can do.

 

I was expecting a little more. So I guess this equates to 385 crank (20% loss).

 

Your number seem a little low, but could be due to 2 things. First, it looks like your numbers are not SAE corrected. At 80 degrees, I would expect your correction factor to be 1.02 (315.7) or 1.03 (318.8). Second, you need a tune to take advantage of your mods. With the exact same set up as yours (EM LTs and RT cats) and a tune and electric water pump my car made 327rwhp on a dynojet. Your numbers are not far off the mark. Get it tuned...!

 

with 90kmi a k&n drop in and an slp catback i put 298hp/303tq. i freaking hate how loud the slp is without cats. OMG its loud.

 

Yes most report SAE corrections, but on my last dyno test the STD correction factor was larger than the SAE correction.....

Yes you really need a tune to maximize the benefits of your mods....but 309 rwhp on on a near stock car is really sweet!!!

 

People charge too much around here for tunes. $500 or $600, maybe a mail order tune, but im sure they are not nearly as good.

 

Actually the SAE correction which is the correction factor most use when comparing chassis dyno results will give you lower numbers....about 4% less I believe. Whoever ran the dyno left the correction factor to standard (STD) to likely show you a better (higher) number.

I stumbled on this thread and quickly opened it curious about the numbers and figured I would better clarify the correction factor situation while I was here.

-Tony

 

Depending on your local emissions testing, I would seriously consider a cam change for your next mod.
Hotcam will work with your LT4 valvesprings, probably get you another 30 HP (with a tune). The engine will make good power to 6,500 RPM.
Go a step or two beyond the Hotcam (with new valvesprings), add a 52mm TB (and a tune), and you could gain up to 60 HP.

Once you get a cam that matches your heads and headers better, the next limiting factor will be the ignition/Opti (due to the additional power at higher RPMs). The simple solution is a MSD box and bigger/hotter coil. This adds some stress to the Opti, so just be prepared.

 

why do people always say the stock opti isnt good at increased power levels or higher rpms? theres a guy around my way named joe overton that has a built LTx trans am and regularly spins the motor over 7500rpms. car runs 9s as well... all on the stock GM opti. it was featured in GMHTP a few years back

 

I regularly spun mine past 7,000 RPM, in my daily driver. Didn't have the money for a LTCC.
It can be done with all combos, NA or FI.
The Opti does not partcularly like this treatment, though. The Opti rides on a very small axis, with a very short shaft, compared to the relatively large diameter of the rotor, and just a single bearing/support point. While a long shaft conventional distributor has much better support for high speed centrifigal forces. Also the compact design of the Opti makes it suseptable to electrical/firing issues because of the high energy levels that pass through it.
Also, not so much at higher power levels, but at higher RPMs, the small GM 'half' coil is firing quickly, with very little time to recharge/power soak between firings.
In stock form, the Opti system is a little more powerful than a HEI. However, like many things, was not designed to see much more than 6,000 RPM (3,000 cam RPM). Some will last over 100k miles, others will die for no good reason.
I'm not saying that every LTx should go out and get a Dynaspark or convert to LTCC/LS1 coils. Just saying when looking for more power/more RPM...
Be prepared.

Sorry to get off subject. I am not looking to start an Opti thread.

 

It looks like you have a very nice motor there. The mods are not huge power adders and your HP and TQ curves look good! 385 at crank for the stock motor is decent. A cam, more fuel and a good tune will more than likely get you the numbers that your expecting.

Noland

 

20% loss for an M6???? A4 with sloppy stall maybe! I believe your numbers equate to 309 on a dynojet which is not bad for your mods. Some dynos/dyno operators operate friendly dynos.

As for the opti it the 2nd gen (vented style) optis are pretty robust and mine has survived stints above 6800 without problems.


Mike

 

It looks like they used 1.04 as a correction factor..

 

Not to turn this thread into an opti discussion, but I had a rotor explode on a 6500 rpm shift @ TWS. I no longer have a rotor in my opti.

YMMV.