Forcefed86

iTrader: (4)

Not true… An engine with a higher VE will come closer to doubling the HP per Bar. It’s more efficient at making power per atmosphere.

That’s a pretty big assumption, as we do not have compressor maps or testing done by On3 that proves their billet 66 wheel flows more than their cast 76mm wheel. I really doubt it would. 10mm is huge size advantage. Since we are just talking power and not response time, the bigger turbo will be more efficient. Just not more than 100%.

Regardless of being “maxed out” the OP's engine can’t do what the dyno numbers claim. He claimed his dyno sheet was an accurate representation of the engines true power, it’s not.

The 5.3 example uses twin 76’s as well? Whether he needs the IC or not, a proper A2W setup like that will lower the IAT’s much more than his A2A IC would. The A2W will make more power per pound of boost is the point…

slowride

iTrader: (3)

I'm just not seeing how the VE of the two matters as the turbos system is whats doing the work and the engine is just an air pump at this point. The higher VE engine makes more NA and more at 2 bar sure, but what makes the lower VE engine not comparable, but on a lower scale? So you think taking a stock 5.7 vs a heads/cam 5.7 and using the same exact turbo system on both that the ratio of power to boost will be different between the two? I'm just not seeing it, but I'm all ears to see some write up on it.

Comparing the turbos would be closer to comparing a ported s cover PTE CEA 6766 T4.81 vs a standard s cover (76 is to large for a ported s) Turbonetics TC76 .81 except a even smaller exhaust side(65mm). What do you is his engines true power NA would have been that night uncorrected? It only needs to be ~365 or better to be close.

Forcefed86

iTrader: (4)

Yup. The more you make NA the more you'll make per pound of boost. (assuming the turbos can keep up)

mkvamso

iTrader: (2)

Not to mention that the tune will be drastically different
That engine might make 325 na
Take away timing for the increased cylinder pressure and fatten it up and it won't make that
At 1 atmosphere it will make x amount of power
At 2 atmosphere, under perfect conditions, it will make 2x power

There's no mystery to it, it's just not possible to make more than that, regardless how big the turbos are or how light the drivetrain is

The car makes a bunch of power and seems to run well, but its not a physics bending marvel

slowride

iTrader: (3)

Sorry that engine on a dynojet will be making way more than 325. It's not bending any laws it's just making more power NA than you think. It might be around that power in the conditions that he raced it in but not 2 months ago on a cold night. It's not like we correct for the track most times. Say it only made 650-675 that day are you really saying it couldn't make 730 on a cool spring/winter day. Do you guys not see a 5 mph swing fro hot to cool days at this power level? It's possible.

mkvamso

iTrader: (2)

You think a bone stock ls1 is going to make that much power?
We had a dyno day less than a week ago
Plenty of ls cars on it, The highest powered stock one there made 331


It doesn't make 370 hp at the flywheel, let alone the tires, regardless of the temperature change.
It would need to be making right around that to make the claimed numbers, and it simply isn't possible

slowride

iTrader: (3)

Well the numbers you are going by from that dyno day would have probably been corrected right(if you know both that's perfect). What was the DA like that day? Did the car have an exhaust, cats, long tubes, intake pipe, etc. Friends c5 did 330 also untuned so that part seems right but with tuning it will pick up 10+ To compare the NA vs turbo setup you need to use both uncorrected numbers. With really good DA the correction factor would have to take power away on a NA setup.(one thing I don't get about the op's numbers going up with correction). **** guys in the northeast on mineshaft days can see a 40+ hp correction on crazy low DA days with NA cars. This is why cars go faster at the track on cool spring/fall days vs summer. Stock ls1s with dyno headers and tuning will make ~390 on a machine shops engine dyno just a FYI.

Inertia dynos will show quite a bit of gain with lighter parts. I've seen 5 hp on lighter wheels and tires, 10+ on a super light clutch. Etc. I've seen others claim more than 365 whp on a full bolt on ls1 on this site and while it seems high for a sae corrected number it is very possible on a good day uncorrected.

Let's look at that hotrod test engine for a second. That 4.8 deal made 453 with all the bolt on parts heads cam intake, longtube headers etc. The turbo setup made 900+ at 2 bar and doubled its power right? What would that engine have made using the same junk shorty headers the turbo setup used, 430-440? **** that would make the example over 100% increase so explain that one.

I don't think anyone is going to change anyone else's mind on this so waiting for results is all that's left. Not many people set there best et or mph on the first day out so making judgement on just that seems a little shortsighted. I'm just as interested in knowing what's going on here and in no way have I made up my mind. It's just not as easy to dismiss as some you you make it out to be. Too much going on.

coltboostin

Again guys, the car made 850 UNCORRECTED. And NA car spinning the roller at the same speed would have made 850 UNCORRECTED. The thought process that a turbo car will magically make a different number spinning the roller at the same rate of acceleration is beyond ridiculous. The dyno has no idea who, or what was sponning it! The temp that day was 50 deg, humidity 7%, so the SAE correction only bumped it to 852. I will post those here
https://ls1tech.com/forums/forced-in...hp-record.html
And will not discuss this any further in this build thread.

This is about as good as it gets. Car makes a pull NA. Same day, same dyno, then proceeded to make a ton of jam.

But somehow, this does not count either.

https://www.youtube.com/watch?v=JBVMaufrwjI


Guys, if you want to continue to argue about uncorrected dyno numbers, please do it here.

https://ls1tech.com/forums/forced-in...hp-record.html

I will be glad to entertain this discussion further there, but I will not reply to one more post about it in this build thread.

Thanks.

coltboostin

Got a spare 45 minutes to troubleshoot the tach issue




The Summit Tach works well, and is much "faster" that the current VDO tach. I did not get a chance to let the car come to temp (when the current tach dies) but all signs definitely point to a Bunk Tach. I will take for a spin over the weekend to find out.


I will say now that I am in the market, I am really digging those speedhut gauges. Hate the price, but love the look and functionality. Anyone have reliability issued with them? Also like the GPS speedo to 200mph, as mine does not work either.

rotary1307cc

iTrader: (5)

Can't beatv the speedhut gauges. Very cheap for what you get. I have the 200mph GPS speedo, works excellent

Only thing missing from it is a pulse output

coltboostin

That would be nice- to log and somehow integrate it into a boost or traction control system.

May be an easy thing to add and they just don't know there is a demand. Would be worth a call to them.....

rotary1307cc

iTrader: (5)

I sent them a message couple weeks ago. Said they sent it down to engineering

coltboostin

That's great to hear! Keep us updated.

The Alchemist

iTrader: (19)

If you guys would like to argue or discuss dyno differences, please do so in his other thread.

https://ls1tech.com/forums/forced-in...on-thread.html

Coltboostin PM'd me asking me to clean up this thread with the dyno arguments.

Thanks guys.

coltboostin

Thanks Alchemist.




On the short list of things to sort after I establish that the tach is fixed is additional fuel, and a better rear brace for the stock diff. They are exceptionally weak and the front pinion brace seems to help. Funny, and I seem to break it fairly regularly

I'd like to also build real intakes so I am not sucking hot engine bay heat, and figure out why my windows no longer work. The car's wiring is pretty hacked up, so any time I have to dive into it I cringe a bit about what I will find.


The short list of "mandatory" mods before my next track visit-

-100% working Tach
-Intakes
-A real catch can. Sealed system with vacuum pulling from the intakes
-A beefy pinion brace, or old school snubber

I'd also like to complete the season

-a 3rd pump, or swap for duel 340's so I can run big boost in 4th and 5th without going 12.0+ AFRs
-Valve springs. We think the car floats near redline now, and bumping the redline to 6800 should keep the car well enough in boost going to 5th. I don't think this will be possible with stock, and likely tired valve springs
-engine diaper!
-Love to find some 29+ tall tires to borrow for a pass or 2

If I can get more pump in the car, a bit more RPM, and a diaper on the engine, i will try to make some passes with the high boost setting near 20psi. Should back half pretty hard.


I don't see any way a rear end swap will happen until winter. After the season, I will asses the condition of the motor/drivetrain and figure out what the next move is. I have a big cam that was garbage picked from a local shop, and a 6.0 short block on a stand. I'd like to put the standard SBE mods on that one (ARP's, LS9 gaskes..ect) and really turn it up. We will see what this year brings...

coltboostin

So, I rigged up the random Summit tach I found in my box-o-stuff, and it works perfectly. I am not sure how, but my VDO tach is toast. Eventually I will replace it with something that fits nicely in the cluster. For now, its 100% better than nothing

(Dont mind the mess, I had everything apart checking wiring for the gauges)



Taking it out for some test hits and see how it does on the 4th to 5th shift if I actually take it to redline in 4th, now that I wont be guessing and know where redline is LOL

Project GatTagO

iTrader: (7)

I wouldn't lean too hard on 5th. The OD gears are not made to handle the power you're making (or not making). Fourth gear is by far the strongest since the power is applied straight from the input shaft to the main shaft.

Andrew

Tjabo

THAT was funny!

coltboostin

Until I swap rear ends, I have no choice. Trust me, I dont want to go into 5th, and I know I am losing ET and MPH from it.

Project GatTagO

iTrader: (7)

So don't! Why risk grenading a perfectly good T56? Because you want to buy a rear end AND a trans rebuild?

Andrew