LS7 on the Dyno

[builder]

Got lucky! The LS7 is a beautiful powerplant, but the ECU and harness just doesn't exist for the it yet, except for one...and that was originally designed for boats. So, it doesn't have the granular control of a sophisticated system.

However, there's a company called BigStuff3 that makes an aftermarket electronic fuel injection system which is very popular with the LSx crowd. The owner (John) is credited with starting two previous successful ventures; "DFI" (now Accel DFI) and "F.A.S.T." (Fuel Air Spark Tech). BigStuff is his third such EFI company.

Another company, Wheel-2-Wheel Powertrain, has close connection to the Special Vehicles Division of General Motors. It's 47,000 square feet of powertrain toys. Check their website for more info.

My LS7 is in Michigan and is being hooked up to one of the four dynos at W2W. John, from BS3, will install and tune the new ECU and harness.

I know...I know... I should have them change the cam, or drop in some forged, low-comp pistons and/or throw a blower/turbo on there. But, not this time. There are some minor mods, but not power-related. I am sure the GTR will be absurd with stock LS7 power.

So, I should have a dyno sheet before too long. Of course, I will put it up. Oh...baby!

>> Edited by builder on Friday 13th January 16:08

[builder]

Thanks All,

Really looking forward to it! Will keep you posted...

-- Scott

[builder]

peterpsg said:

If you're intent on keeping it fairly stock, are you going to try and keep it compatable with emissions spec or ...? I'm sure if there was a drop in, emissions compatable, LS7 setup, it'd be a popular alternative to AS, and the like.

That's an interesting point. Regarding emissions testing in the USA, in particular in California, a test includes passing a visual inspection to verify the the "manufacturer's emissions equipment" is intact. That visual equipment inspection extends to headers, oyxgen sensors, cats, intake (Of course, in CA, they have special provisions for "Home Build" cars.)

Also, all vehicles 1996 and newer are required to use an OBD-II computer. Inspections on OBD-II cars (my experience only) don't test the gasses at the tail-pipe. They just plug diagnostic equipment into the OBD-II port and read the information while running the engine. So, it may be a challenge to get (even the best, cleanest-burning engine) through without fail. I imagine the "manuracturer" has some major hoops to jump through, with the EPA (environmental protection agency), to have their emissions system approved.

There are three options available to me in Nevada:

1) License the GTR in a region that has no testing. Luckily, I have a home for rent in such an area. So, that is an easy first option. However, if I sell that home, the challenge remains.

2) License the GTR with an old engine that requires no testing. Then, file a form indicating that an engine swap was performed. This may also be a good option, as there would be no subsequent testing required.

3) Take an old vehicle, weld some of the components to the GTR (i.e. a piced of chassis with the serial numbers), and register as that vehicle. I was thinking VW.

[builder]

G Man said:

I was looking at this engine today at the Autosports show very impressive, I read on the internet that Jay Leno was given one for a hot rod and that Chevy found a hot cam for him and found 600 bhp easily Have aftermarket cams become available yet ?

Wheel-2-Wheel helped with that car. You may be aware of the C5-R block which was the parent to the LS7. Jay's (rear-wheel-drive) Toronado engine is apparently a step between the C5-R and the LS7 while along the development path.

Yes, there are a couple of companies testing and selling new grinds. There are also three GM Hot Cams available...the biggest was dyno'd and made 600 BHP.

The issue for the guys with a Z06 is programming. Nobody has a product offering (yet) to modify the programming in the new PCM. Same is true for an LS2 made after 9/1/05, as it uses the same hardware. So, an aftermarket PCM is the only way to go right now.

[builder]

Adding to the above... The stock programming (and PCM, which I have here in a box with no programming in it) also requires the presence of another computer; the body control module. So, to use the stock PCM to run the engine stand-alone the BCM has to be programmed out of the PCM along with the anti-theft stuff. And, the stock throttle body is electronic (fly-by-wire), which requires the use of electronics on the loud peddle. So, I am switching to a mechanical TB as well.

[builder]

Yes, someone told me the Delphi MEFI-4B is "bank", but I think it can do both. Mine will be sequential.

[builder]

Boosted Ls1 said:

builder said: Yes, someone told me the Delphi MEFI-4B is "bank", but I think it can do both. Mine will be sequential. Afaik it's bank/batch but maybe it's evolved It could be ok to fire the stock injectors twice and save buying bigger if it's mappable. How mappable do you think these will be or will they be plug and play? Will you have MAF? Boosted.

I think the "M" in MEFI stands for Multiport, thus the batch/bank mode. But, I don't have any direct-use experience with them. The general comments have indicated that the MEFI might not deliver as smooth an idle, the same economy, or offer the drivability of other LSx-specific systems (or the stock PCM). But, at WOT, there's no difference. You might ask Jeff Schwartz about the MEFI. I know there are some guys successfully running the LS7 with it.

The BS3 system is MAF-less. It does use MAP, though, and wide-band oxygen sensors. Here's a link to the Gen3 (older) manual.

[builder]

Boosted Ls1 said:

Will you have MAF?

Turns out the system can be run in either Speed Density mode (MAP-based) or in Alpha-N (TPS-based). Don't ask what Alpha-N is. Maybe someone can tell me!

The BigStuff3 ECU and harness installation was successful tonight. I don't have the dyno sheet yet, but she made 548 HP @ 6100 and 529 ft/lbs from 4.7 to 4.9k. If my notes are correct, she made 400 ft/lbs at 3k! All standard-corrected numbers. WooooHoooo!

[builder]

d3vine said:

What is the rev-line on a LS7?

7k in the Vette, but 7200 really. I am gearing for 7000 and about 212 mph.

[builder]

Haven't seen the dyno sheet yet, but here are the results. And she was making 400 ft/lbs at 2500!!! All stock. Manifold spun 180 degrees with a mechanical T/B and dyno headers.

rpm----tq---hp
3000--455--260
3500--467--311
4000--504--383
4500--526--451
5000--529--503
5500--512--537
6000--480--548
6100--472--548
6200--463--547
6300--454--544
6400--445--543

[builder]

Regarding the fitment of the LS7, I don't anticipate too many issues. The LS7 is an evolution in performance, but still in the LSx family. It's the same form-factor as previous LSx engines, so, essentially, fitment has already been done with an LS1 or LS6 (aside from the dry-sump).

The accessory brackets are the same as the C5/C6 Corvette, so that shouldn’t be very challenging. Low mounts are available for right-side A/C and left-side ALT.

The exhaust flange is the same as the LS2, but I haven't really thought about a design yet. I might make a few sets when I do mine, if anyone is interested. They should be very affordable...by comparison.

The ECU and harness is available from a company called BigStuff3 (BS3), which is a sequential, speed density (no MAF) or Alpha-N system. For the near term, it can only be purchased from Wheel-2-Wheel Powertrain, as they have helped in the development and have an exclusive for a short stint. The BS3 system is highly regarded by folks with forced induction.

Other companies are working on cracking and reprogramming the stock PCM. I have the stock PCM as well. Nothing available yet, but four or five companies have said they are into the box and learning it's language. That I know of, only one of these companies is working on a "stand-alone" setup using the stock PCM.

Regarding boost, it probably wouldn't be a good idea to push the stock, cast pistons. The OEM is already building a forged set and they are available in the aftermarket now.

Engine mods for the GTR: The intake manifold has been spun 180 degrees. This was not too hard. The oil pressure sender was removed, the boss cut down, bored and tapped for a 3/8 plug. An engine plug was removed and he sender was put in it's place...a direct fit. A crank vent in the valley cover was rerouted using a 10" piece of AL tube. An aluminum fitting was designed to replace the stock oil hoses with -12AN braided lines. A C5 Vette oil take-off was fit for -12 lines to an oil cooler. I will drop a thermostat in with that.

The BS3 system is designed to use a mechanical throttle body. The stock LS7 unit is "fly-by-wire", which means the peddle requires electronics. A mechanical T/B was fit to the intake and brackets were designed for the cables. A 1.6" spacer was required between the T/B and manifold. The T/B was also mounted up-side-down because the blade opens opposite to the stock unit...which changes flow dynamics.

All said, no show stoppers yet!
-- Scott

[builder]

There is no doubt the GTR is a real racecar. However, it's also a street-legal car that I plan on driving A LOT. My goal is to have a dependable, wicked-fast street car that can cruise 1,000 miles on pump gas without having to carry too many spare parts. It's also been my experience that the more tweaking, the shorter the lifespan.

And, the GTR is relatively expensive. I have enough $$,$$$ in the budget to build it right, but not enough to build it twice! This build is deviating from a "stock" config by virtue of the engine and a host of electronics, but I am not using exotic or ultra-high-performance parts. This isn't a build for "maximum effort".

"Dependable" is important, as is longevity. My guess is, with huge HP and torque, the clutch/trans/diff won't last as long and I don't want to rebuild them every other year. The LS7, as it ships from GM, can probably go 70k - 100k miles without a rebuild. That's one of the real benefits of a factory lump, aside from the initial warranty.

When it’s rebuild time, I will likely go for forged, low-comp pistons and probably a centrifugal supercharger and 6-8 psi. This should boost the 548 hp to 700, or more.

Who knows? Maybe by then, there will be another engine available that will fit the GTR (maybe a hybrid) and I will put the LS7 in my Impala. I know for a fact that the LS9 is in testing. Don’t ask as I am sworn to secrecy.

-- Scott

[builder]

chuntington101 said:

ECU, well im not sure. any ideas?????

Hey Chris,

See BS3 above.

-- Scott

[builder]

G Man said:

Scott Did you consider a Motec system, I was thinking that as the LS7 is a fly by wire throttle and a Motec M800 can do FBW it should fit into an Ultima. With 12 degree heads IIRC is the engine taller than a SBC

Yes, but the BS3 system, engine wiring harness, dyno tuning, turning the intake, oil fittings, and throttle body spacer were free for letting them use my engine. I will have to buy a cable T/B, make the bracket for the cables, and I paid shipping one way. That's a hard deal to pass up. Officially, the BS3 doesn't perform traction control. But, I may not need to purchase anything extra for that function. I really like the missed-shift protection of the Racelogic.

Not sure of the exact height on the LS7. My engine should be back home in about a week. I am going to start moving into the new shop and unpacking the crate today. (I can't believe it!) One of the first things on the to-do list is to test-fit the engine and give the dimensions to my trans builder so he can make the correct length bell housing. I can pull some height measurements, too.

BTW, today starts the pilot production of the LS9, which is an LS7 with a supercharger. Those engines are for the '08 Z06 "Blue Devil". That engine may be a little taller still, but what a beast! Hope to see some power numbers next week...

[builder]

jellison said:

The ECU on the vettes LS range is the NUT - Mega Millions invested in it by chevy - highly tuneable - After market ECU a total waste of time (IMHO).

Agreed, to a point. However, nobody has broken the code in the stock PCM yet. Someone will...and soon. But, until it's cracked and the programming software written, there is no other viable stand-alone solution except Delphi MEFI-4B which doesn't deliver granular programability.

In fact, it's yet to be determined that the stock PCM can run the LS7 in a stand-alone configuration. There are so many hooks to other inputs, there may be challenges trying to strip the extra information out.

[builder]

Good stuff, Mack. I wasn't sure how Alpha-N worked. That clears it up a bit. Thanks!

-- Scott

[builder]

ezakimak said:

Builder, If you don’t mind me asking. What was the octane rating of the fuel that was used when the engine was on the engine dyno.

91 ... the cheap stuff. I told them it would have to be 91 because that's all we get in Reno; California gas. Other parts of the country, they serve 93 and 94.

[builder]

jellison said:

I think Wortech have been tweeking the new LS2 ECU in the new C6 - presume same ecu?

Might be. But, a any LS2 car made after 1 Sept, 05, uses the same PCM as the LS7 cars...the new, and improved PCM. Previous versions of LS2Edit will not work.

[builder]

Some folks here are changing out the crank reluctor and cam gear.

The new breed of LSx has a 58-tooth (60-2) reluctor and the old LSx has a 24-tooth. Guys are taking the engines completely appart and mounting new crank reluctors and cam gears just so they can use an LS1 PCM. That's a fair chunk of work, but maybe worth it to keep the old PCM in the car.

This method will also work for stand-alone installs. But, it just won't be THAT long before someone cracks the new PCM and can offer something good. My guess is 30-60 days.

[builder]

ezakimak said:

Would you care to speculate what the output of the engine would be on a different fuel.

As GMan said, with hardware changes, you can pull a lot of power out of the LS7. Unfortunaltey, our "Department of Transportation", our "gas guzzler tax", and our insurance providers are going to make it more challenging for car companies to offer engines/vehicles that have really big HP and really high top speeds.

For example, I think the top speed for the new Z06 Corvette is quoted at 198 mph. How hard do you think it would have been to change a cam lobe and make enough power to pick up 2 mph?

Regarding higher octane, my logic might be way off, but... An octane boost, by itself, isn't going to effect performance. The way I understand it, increased octane has a lower combustion temperature at pressure, so the engine doesn't melt when you run higher compression components. Higher compression...bigger bang...more power.

Can't really change the compression with a computer in an LS7 (yet). But, as ezakimak said, one can change the timing and cause the spark to ignite the fuel when it is compressed more...closer to Top Dead Center. Doing so would cause a hotter burn and the higher octane would counter the temp (no pinging).

After the blather, how much HP would it gain from a timing change and higher obtane? My guess would be 7-8%.

Here's a pic of the LS7 on the dyno with the spun intake. More later...