Without knowing your CR I would say the blower is maxxed. Great numbers, must be a fun ride.

 

Why the big secret on the compression? I assume its much higher than what you typically see on a FI build, but it's not like it hasn't been done before.

 

Definitely. I called up Mcleod and spec'd out a specific pressure plate and clutch disc. Was relatively inexpensive, decent peddle feel, and holds upwards of 700 ft/lbs of torque. Not bad.

Yes the cx 4" intercooler. Mine is only a 12x31x3". Compression is mid 10s.

Compression is mid 10s. Nothing really secret about it I guess. I saw what all the ls2 and ls3 guys make with a Procharger on a stock block, and decided to keep my compression in the mid 10 range, which might be why my torque curve looks so damn pretty, at least to me it does.

FYI, here's what the graph looks like in STD correction:



765/706 has a nice ring to it.

 

Cool, thanks...nice numbers too!

 

I wonder if you could make it live in the 11:1 compression ratio range.

 

What clutch is it?

 

Looking really good with a lot of power!!

 

Clutch consists of a Mcleod pressure plate and disc, and a fidanza flywheel.

The pressure plate is a 12" with 2900# clamping force, and the disc is a 600 series disc. It seems to be holding, which is a good thing.

 

First thing I would check on it nosing over up top is whatever inlet hat/filter setup you have on the blower.... Before you try anything else, take that thing off and dyno it with just the open blower.... You will be quite surprised at what it will do..... You'll gain power and it will hold on much better...

For reference, here is my dyno chart. The lower HP pull is with the 4" air inlet with a 90* bend and a filter on it.... Notice it has a crappy boost curve and it drops power like a stone up top.



The only difference between those two pulls is one was thru the 4" inlet/filter and the other was with a velocity stack on the blower, no filter.

4" / 90* inlet with oval filter



V-stack


So if your air hat or air inlet assembly as restrictive as apparently my 4" inlet was, that would be the very first thing I would check.

I have since shortened my air inlet filter, cut most of the bend out of it and used a DP big mouth filter. I think I reduced the restriction by about half..based on what I see on the logs.


1)Look at your air filter setup and test without it.
2)Datalog without it and let us see the Kpa curve up top, then we can determine if the belt is slipping.

I'm pretty sure your problem is in the air filter setup... But with that being said, it still may not peak as high in the RPMs as you would think... I bet it will peak and hold on for a bit before it noses over... But it will still nose over eventually... Especially if youre still running an LS6 intake. (Which I am)...I believe that's one reason why the FI setups peak at 6500 or less and just hold on, then nose over... Rarely will they peak at 6800-7000 and hold on from there... Unless its under 700 hp or something.

 

Oh and on your HPT log screen shot, put the pointer over the peak power/rpms and save the screen shot there so the data pulls over to the legend on the left side. I can't tell **** by looking at your chart with no numbers on it... The data in your legend is obviously with the pointer somewhere before the pull started.


A D1sc will make a solid 800rwhp when maxed out so yours isn't quite maxed out yet.... 8" balancer and 3.4" pulley and spin it to 6800 or so will put it slightly past max impeller speed but that will get you the max power out of one. You'll probably see 18-19 psi on your combo with it maxed out... 93 oct/M15&M10 nozzle meth and 15* timing and you'll make 800 rwhp pretty easily...

 

What blower hat / filter are you running?
Also what gears do you have in the rear? I'm shooting for the same power level with a 6 speed street car, and I don't think I'm going any lower than the 3.42 ratio.

 

I hear what you're saying. Unfortunately, because of the location of the blower, the truck inlet hat is the best we have, and it's far from being the most efficient.

Here's the data... I forgot to move the cursor.

It's weird, I was getting this phantom knock at 4200-4600 at like 0.5-0.7, but you can see the afr is rich, and the timing is way conservative.


Gears are 3.73s and I have the truck inlet hat with a monster 10" filter on the end, or whatever the largest that Bob sells.

 

What is HP / TQ in CF SAE?

 

742/688.

 

Needs more exhaust duration IMHO. It would carry the power past 5500rpm you're losing right now.

Because torque peaks at such a high piston speed, you're moving a very high amount of exhaust volume at 5500rpm. This creates less effective time for the exhaust port to evacuate the cylinder. Combined with your headers and exhaust system, you can see where this is headed.

I would keep overlap roughly the same as it is now, but extend exhaust duration and widen the exhaust centerline.

Your numbers are very good though and I wouldn't be upset with them at all! Especially building the engine yourself!

 

Thanks... That new pic helps a bunch. Tune looks pretty good other then its pretty damn rich... You have 30-40 rwhp in air fuel tuning sitting there at around 6000.. As you notice, right when your afr takes a rich dip, is right around where the power starts nosing over. This could partially be due to the restriction of the air as well, as you can see the map (kpa) starts to flutter just a slight bit at that same spot...

All in all, Id say it looks pretty damn decent and very safe, but you definitely have more power in it just from tuning it a bit up top. And I hear ya on the air hat being the only option...Sometimes you have to make do with what you have... But before becoming too concerned about the high rpm power drop or even gaining more power, you have to pull that hat off and make a pull to see what youre REALLY making...

You have a very solid setup with what you have... Drive/race/enjoy it and when youre bored in 6 months, start tweaking...

Congrats on the build!

 

Yeah, looking at the curve, it's not like the it totally falls off, it's just not pulling up top like it 'feels' in butt dyno. I probably should have chosen a different cam when I was rebuilding the motor, but hindsight is 20/20 I guess.

I'm quite pleased with the results, but you always second guess yourself after a dyno. It's one of the reasons I never planned on dyno'ing it because it's a fun street car, so the power level really didn't matter to me, but the scientist in me now has data, and I scrutinize data to the n'th degree.

 

Good numbers man. It was about time you strapped her down! Lol

 

Have you ever read the thread called the Power of Timing? Adding a degree to see if power picks up would not be careless. Adding 5 would be, lol. Add a degree, power increases, if it stay the same then go back to where you were, its simple.

Alchemist, I think you are extremely extremely rich. 10.2 leaves a lot more power on the table. I understand the safe approach, but go up to at least 10.8-11.0 or so. I bet there is is 50 hp in a afr tweak and possible 1 degree of timing. Regardless, the power its making is damn fun and dynoing it only makes you want more, lol.

 

Congrats great results! What heads? Anything done to them?