Shawn MacAnanny

iTrader: (12)

I took my car to get it dyno tuned today. It had a mail order tune from HPE which was working pretty well. On the dyno the A/F was perfect, but the injectors were just about maxed out as far as duty cycle. Anyway i am very dissappointed with my numbers.

I managed a best of 410rwhp and a best of 380rwtq SAE. Now i have some pretty heavy modifications so i was wondering why it was so low.

I have a 2001 Corvette Z06. It has:

ET Performance CNC'd LS6 heads 2.055 valves, 309CFM @ .650 lift (intake), not milled
HPE S cam, 238/242 .608/.612 115LSA
Kooks 1 7/8" headers, 3" x pipe
chamered 3" mufflers
borla straight pipes
vararam
LS6 intake
new plug wires
new plugs
160 thermostat
spec 3 clutch
billet steel flywheel
dte brace


Car was tuned on the dyno with 30 degrees of timing advance.

Any ideas guys? I am trying to download a viewer for the dyno files. I post the graph as soon as it's finished.

pdd

iTrader: (3)

did you have the heads independently flow tested? are the heads milled?

v8maro

iTrader: (4)

That sucks man, I was expecting to see some shitty mods in your thread, those are all nice quality products. I dont know much about that cam tho. I would definitly get the car re-tuned, mailorders just aren't good IMHO. As for the injectors you may want to upgrade them. Oh I just so happen to have a set of 42lb'ers sitting here, PM me if you want them, $315
-Steve

Sigforty

Just because heads have good flow numbers does not mean they will make power. I was having a conversation with Allan Futral about that. He told me the head work is not all about numbers and that the heads need to be matched to the cam. It is not so much about peak hp as much as area under the curve.

Shawn MacAnanny

iTrader: (12)

I got a set of 42lbers sitting at the tuners for $300. The heads are CNCed by ET Performance so i assume they are all the same. The heads are not milled.

Also here is my dyno graph. There are like 3 or 4 of them there. I just put them all together to give you a better idea of the powerband. The real test was run in power/speed.

GTO_Scott

iTrader: (3)

You have the 1 7/8 headers, that big camshaft, and ported heads - maybe you should be upgrading to a FAST 90 intake and 90mm TB of your choice.

What numbers were you getting before the person started tuning (baseline run when you got there with the mail order tune)?

SideStep

Slowhawk

iTrader: (12)

Could be a tuning/compression problem. With that Cam I like to see 11-1 compression which really pulls the #'s up.

Shawn MacAnanny

iTrader: (12)

The compression is whatever a stock LS6 is which is 10.5:1. The base tune to the dyno tune was exactly the same. He actually pulled some timing and such before he started tuning and gradually added it to see if it helped any. We started out with like 403rwhp with 26 degrees of timing advance.

SideStep

Do you have any idea what your DCR is? What are the other specs for your cam? LSA? Advance??? I am thinking with a cam of that size (and overlap) that your DCR is low (really low) and more compression will help... A higher DCR would help, maybe 8.4-8.5ish. Below is a chart that may show your current DCR, given the examples.


Just for comparsion, if your cam had XE-R lobe profiles (I know these may not be the exact HPE used lobe)... assuming a static of 10.5ish

LSA/Adv.......DCR......Overlap @.006/.050
112+2..........7.78.....65/16
112+4..........7.93.....65/16
114+2..........7.64.....61/12
114+4..........7.78.....61/12

PREDATOR-Z

Looking at your graph, I can see the AFR steadily dipping from ~ 4300 rpm, so it makes me suspect fuel related issues which combined with 30* timing register some KR.
To make sure why don't you slap a Fuel pressure guage and monitor on the dyno.
Also what was your injector cycle at WOT?

Shawn MacAnanny

iTrader: (12)

Not sure of the injector cycle, i'll ask. The cam is on a 115lsa. Could that be the reason for such low power? so i should retard timing? I believe they were watching for knock and kept advancing the timing until it stopped making power and wasnt knocking.

Ragtop 99

iTrader: (7)

Did you try running a little leaner up top? Looks like you are around 12:1 above 6000 rpm.

Chuck@

iTrader: (1)

The a/f goes a little fat (looks like 12:1) on the top end, so we could lean it out a little bit, and that could be worth around 5-10 hp. But I'd say your biggest restriction is going to be the intake and possibly those mufflers. Put a 90mm Fast on there with a ported LS2 tb, and maybe a set of cut outs, to see what she does. I think you've got the potential for a really nice setup, just gotta round it off with a few finishing touches to get you where you want to be.

There's nothing in my tune that should make your car fatten up almost a complete point of fuel at the top end. The only thing that would be causing that is the actual VE of your motor going down. It's something I see all the time with LS6 intakes on setups like this. I almost guarantee you'll pick up great numbers with the 90/90 setup and a free'd up exhaust.

Nice car btw.

Chuck

SideStep

If COT is still enabled it would richen the mix, but it would show up sooner in the rpm range???

410/380 is low, LS6 intake or not. Your HP numbers are low for the mods listed. I do not know how you feel about throwing more money at this without getting what you already have working to its optimum. There is also the "LS1" factor. Your engine just may be a low dynoing engine and you will always be saddled with low numbers, compared to the mods used.... it has happened to several on this forum....

Shawn MacAnanny

iTrader: (12)

Yeah i am definately not buying a fast 90/90. That would be rediculous to spend another $1500 on a car that should be 40rwhp higher. I am not wasting anymore money on this car until it gets fixed. I may end up selling it becuase it's frustrating me. How much do you think i could get for it? Lol. Has 56k on it, less than 2k on mods.

So are these typical numbers for your cam Chuck? If i switched over to the Trex like i had orgionally wanted, would i see a 50rwhp gain? BTW Chuck you tuned this car for Fran Schatz of Clayton, Delaware (My mechanic). I believe be said he even called you after the dyno run and asked you why thse numbers were so low, you said thats normal without a 90/90 so is it because of your cam?

ArKay99

iTrader: (1)

I had COT enabled at one point in tuning my C5. It started in around 6000rpm and sent me from 13:1 to 11.5:1 in about 25rpm's. I see tthe fuel ratio dipping way rich from around 4krpm's up. Ideal afr for optimum hp/tq is 13:1, the red dashed line in the graph. He's nowhere near that at peak hp/tq points. If it is leaned out to 13:1 across the board as Predator pointed out I'm sure he will pick up at least ~10hp more. I suspect cr is a factor also. As Side Step pointed out a big cam needs high SCR to achieve good DCR. Also the heads flowed 309cfm @ .650" lift, but what are the real numbers and how were they flowed? Also, the cam was spec'd @ .608"/.612". What are the flow numbers at that lift?. Was that number a peak lot number or the number from those heads. Also, from my experience a FAST 90/90 setup should give him another 15-20rwhp. As we all know this stuff adds up. One last thing, a billet steel flywheel will suck up some inertia so there is few more ponies hanging out in the flywheel.

ChucksZ06

iTrader: (9)

I would make sure that your pcm is not taking a lot of timing out because of noisier engine. I would pull the timing back to 26 degrees and turn off all the kr and see what happens. I hate having the timing being pulled out when tuning as you never know where your at.

Shawn MacAnanny

iTrader: (12)

Here are the flow numbers for my heads. They are CNC'd so they should all be the same.

http://www.etheads.com/flowsheets/GM....055_STG.2.htm

SideStep

Shawn,

The TRex would make more TQ based on the tighter LSA/ICL, but needs to be spun higher and is a nasty beast on idle (or to get to idle), also it does not like cats, I am not sure if you are using them.

To be honest with you, your current mods look more like a big cubic inch package compared to a 346 system. You can get away with wider LSAs and big runner volumes on bigger displacement motors. Strokers and big inch engines inherently have more TQ down low and you can bias your mods to help it breath up high in the rpm range and not hurt the bottom end. Unfortunately, this does not work on small displacement engines that need port velocity, high DCR, and good quench to build low-end power.

I know you don't want to hear this but it would probably ROCK!!! on a 382/402/408...