Disappointing dyno results
TECH Enthusiast
Joined: Apr 2009
Posts: 723
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trans is a 4L80E - same transmission/ convertor that was in it on the 1st 844hp pass along with the same 22" diameter rims. I initially thought the transmission was slipping but if it was the numbers would get worse with each pull if that were the case - or one would think??
Injectors are Injector Dynamics ID1300 (I spoke to tech at Injector Dynamics- gave all the information on the motor, turbos, setup, etc..)
Fuel pressure is at 45psi ( I think??) I forgot to ask the tuner - however I would expect him to check that. The tuner Im using is a noted tuner in my area and is familiar with high horsepower (1000+) forced induction setups.
Injectors are Injector Dynamics ID1300 (I spoke to tech at Injector Dynamics- gave all the information on the motor, turbos, setup, etc..)
Fuel pressure is at 45psi ( I think??) I forgot to ask the tuner - however I would expect him to check that. The tuner Im using is a noted tuner in my area and is familiar with high horsepower (1000+) forced induction setups.
When the motor let go maybe it could have done some internal damage that may cause drag?
Joined: Jul 2005
Posts: 350
Likes: 2
From: Mountain Home, ID on My way to Korea!
650 hp with 8* timing.....fix your detonation issues, turn that sucker up to 14* and I bet you'll see some better numbers. I didn't see what the compression ratio was. If its high there might be your problem with the detonation?
Looking back at the build thread, it looks like it has 823 heads on it. If so those heads don't take as much timing as cathedral ports. There was a thread on here the other day of a stock LS3 w/ 15#'s of boost and only 13* timing on E-85. The car was running mid 5's. Here's the link: https://ls1tech.com/forums/forced-in...-1-8-mile.html
The easiest thing to try after checking out the plugs would be to put some race gas in it. If your close to or at detonation you wont have any power.
Last edited by handyandy496; Jan 12, 2016 at 08:28 AM.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
Thank you everyone for your input. On the list of things we were going to try was draining the pump gas 92-93 octane out and throw some higher octane in and see what kind of results that brings.
In the past with the old setup I've personally seen 16 psi boost on the gauge driving the car - that was before all the re- fab work was done.
Forgot to mention the cyl. Heads are cnc'd L92/LS3 by west coast racing cylinder heads.
In the past with the old setup I've personally seen 16 psi boost on the gauge driving the car - that was before all the re- fab work was done.
Forgot to mention the cyl. Heads are cnc'd L92/LS3 by west coast racing cylinder heads.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
Was able to speak to the engine builder this morning and after answering questions/discussion he seems to think its overpower the torque convertor. Yes he did seem to think the timing was low however he did say that he's experienced issue on high horsepower drag car that over power transmissions/ clutches that causes tuning issues. He brought up a point that it's a big heavy car, low numeric gear, strapped down putting a load on the motor/drivetrain. Unlike the street where it's just blowing the tires off. And if the cars making more power than before it could easily overpower the fins in the convertor. You wouldn't see it on trans slippage. He suggested getting a purpose built convertor that will handle more power then have the car retuned.
I don't know what was done to the transmission/ type of convertor that's in it as it came to me by another shop and that was already done. It's possible that before the motor wasn't making quite enough power to "overpower" or "blow thru" the convertor before but since straighting out somethings like I did the cars making more power - thus overpowering the convertor like several of you had mentioned. Or it's possible that the convertor could have weakened from before when it was still driving around and with the new build - making more power - induced overpowering it??
I'll have to get with the customer and let him know what was suggested and go from there. I'll keep y'all posted. Once again thanks to everyone's thoughts & suggestions.
I don't know what was done to the transmission/ type of convertor that's in it as it came to me by another shop and that was already done. It's possible that before the motor wasn't making quite enough power to "overpower" or "blow thru" the convertor before but since straighting out somethings like I did the cars making more power - thus overpowering the convertor like several of you had mentioned. Or it's possible that the convertor could have weakened from before when it was still driving around and with the new build - making more power - induced overpowering it??
I'll have to get with the customer and let him know what was suggested and go from there. I'll keep y'all posted. Once again thanks to everyone's thoughts & suggestions.
10 Second Club
Joined: Jul 2011
Posts: 176
Likes: 1
From: Seattle
I definitely think you are on to something there especially when you say that fuel consumption was where you expected but power was down.
The part I don't understand is where you say you wouldn't see it in trans slippage. The slippage can absolutely be calculated if you have a log from the run with the proper data. When you calculate converter slippage there are pretty much only two places it can be slipping in the converter or the trans. I am well versed in this as I have been fighting converter issues for over a year.
The part I don't understand is where you say you wouldn't see it in trans slippage. The slippage can absolutely be calculated if you have a log from the run with the proper data. When you calculate converter slippage there are pretty much only two places it can be slipping in the converter or the trans. I am well versed in this as I have been fighting converter issues for over a year.
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TECH Fanatic
Joined: Jun 2013
Posts: 1,163
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From: Avon, Ohio
He brought up a point that it's a big heavy car, low numeric gear, strapped down putting a load on the motor/drivetrain. Unlike the street where it's just blowing the tires off. And if the cars making more power than before it could easily overpower the fins in the convertor. You wouldn't see it on trans slippage. .
Now the trans can indeed have an issue and absorb more power by way of increased mechanical action or friction which is typically something on its way of failure.
Is he suggesting the trans is just "absorbing" 350-400chp?
You would see that translated to absurd transmission temps-but that much would cause catastrophic failure pretty quickly IMO. Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
I definitely think you are on to something there especially when you say that fuel consumption was where you expected but power was down.
The part I don't understand is where you say you wouldn't see it in trans slippage. The slippage can absolutely be calculated if you have a log from the run with the proper data. When you calculate converter slippage there are pretty much only two places it can be slipping in the converter or the trans. I am well versed in this as I have been fighting converter issues for over a year.
The part I don't understand is where you say you wouldn't see it in trans slippage. The slippage can absolutely be calculated if you have a log from the run with the proper data. When you calculate converter slippage there are pretty much only two places it can be slipping in the converter or the trans. I am well versed in this as I have been fighting converter issues for over a year.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
Exactly!! That's what I questioned?? If the trans was slipping that much I would expect to feel/hear it as well as the numbers would progressively get worse the more the trans heats up & slips.. I'll get some graphs and post when I can.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
Let me ask this question to everybody - with the components / combination of this motor (cubic inch, size of turbos, amount of boost 16psi, transmission,etc..) am I over expecting - unrealistic at the amount of power it should make?
I'm just baffled at how it had such a wrong fuel system / design of the headers/ piping /components before and it turned 800whp and everything that was done to correct these things - it has 200hp less...
I'm just baffled at how it had such a wrong fuel system / design of the headers/ piping /components before and it turned 800whp and everything that was done to correct these things - it has 200hp less...
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
Here's the calculations my tuner gave me on the fuel & air consumption:
Inj. pw =13.0ms @5800 =20.7ms
125lb/hr. 62% X 8 = 620lb/hr.
10.3lb/m X 14.08 X .78L = 113lb/m airflow
Inj. pw =13.0ms @5800 =20.7ms
125lb/hr. 62% X 8 = 620lb/hr.
10.3lb/m X 14.08 X .78L = 113lb/m airflow
The fuel pressure must be dropping. I dont see an air/fuel curve but if you had one, with 1000hp of fuel and only 650hp to the wheels, it sounds like the engine would be too rich to run. or the injectors are smaller than you realize.
On the other hand, if it really is using 1000 horsepower of fuel, then A: you left a brake on, or B: something is absorbing enough power to explode shortly and will reveal itself (such as a brake-like device). when power just "disappears" you usually get a -> temp rise in whatever object absorbed it. i.e. the trans fluid would boil out if you push 300x10^x kw of power through it, etc...
lots of other great suggestions, like the boost leak test, do a compression test, basic engine diagnostics still applies. A boost leak would impede power; just like an exhaust restriction, or poor compression, etc... but none of these things should make an engine use almost double the fuel. That appearance is fuel pressure or injector size related.
On the other hand, if it really is using 1000 horsepower of fuel, then A: you left a brake on, or B: something is absorbing enough power to explode shortly and will reveal itself (such as a brake-like device). when power just "disappears" you usually get a -> temp rise in whatever object absorbed it. i.e. the trans fluid would boil out if you push 300x10^x kw of power through it, etc...
lots of other great suggestions, like the boost leak test, do a compression test, basic engine diagnostics still applies. A boost leak would impede power; just like an exhaust restriction, or poor compression, etc... but none of these things should make an engine use almost double the fuel. That appearance is fuel pressure or injector size related.
Last edited by kingtal0n; Jan 12, 2016 at 06:25 PM.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
The fuel pressure must be dropping. I dont see an air/fuel curve but if you had one, with 1000hp of fuel and only 650hp to the wheels, it sounds like the engine would be too rich to run. or the injectors are smaller than you realize.
On the other hand, if it really is using 1000 horsepower of fuel, then A: you left a brake on, or B: something is absorbing enough power to explode shortly and will reveal itself (such as a brake-like device). when power just "disappears" you usually get a -> temp rise in whatever object absorbed it. i.e. the trans fluid would boil out if you push 300x10^x kw of power through it, etc...
lots of other great suggestions, like the boost leak test, do a compression test, basic engine diagnostics still applies, look for exhaust restrictions, check the cam timing, put a dial on the valve
On the other hand, if it really is using 1000 horsepower of fuel, then A: you left a brake on, or B: something is absorbing enough power to explode shortly and will reveal itself (such as a brake-like device). when power just "disappears" you usually get a -> temp rise in whatever object absorbed it. i.e. the trans fluid would boil out if you push 300x10^x kw of power through it, etc...
lots of other great suggestions, like the boost leak test, do a compression test, basic engine diagnostics still applies, look for exhaust restrictions, check the cam timing, put a dial on the valve
Injectors are Injector Dynamics ID1300. I spoke to tech at ID at length about the engine combination, turbo size, fuel delivery, etc.. Before those size injectors were purchased to make sure I had more than adequate size along with the fuel delivery was plumbed for more than the HP requirements this motor will make. One thing I do is over engineer & build it for more than what it needs so I don't have to worry about breaking stuff. Fuel system is plumbed to support 2000HP.
Thread Starter
Staging Lane
Joined: Sep 2012
Posts: 79
Likes: 0
From: Saint Petersburg, FL
We did have the air inlet pipe coming from the inner cooler to the throttle body pop off from the bump silicone coupler during the last couple of pulls at 14psi. I'm currently correcting the pipe and tuner does plan on pressure testing the system afterwards. I agree with yours and a lot of others suggestions that to lose that much power or have it absorbed it would show. The fact that we're not finding something obvious is what's so frustrating and what lead to this thread being asked.