Preliminary dyno results for my SLC's engine

J

John Ross

Just heard from Brian Thomson that he broke in my engine and then did a dyno pull. He had promised the motor would make more power than a factory LS7, and it did.

Preliminary results are 735 HP @6900 and 657 TQ @4500. This was with factory Corvette LS7 exhaust manifolds, which is what I intend to use.

I've got a big, stupid grin on my face right now...

JR
 
J

John Ross

Stage7 said:
Nice #'s. Engine dyno? What are the general specs of the build?
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Yes, those are flywheel numbers, of course. I don't think you could get 700 RWHP on 91 octane without Forced Induction or nitrous.

General specs are 442 inch displacement, with (I think) a slight overbore and a stroke increase to 4.1". Intake is the Harrop ITB setup. CNC ported LS7 heads with unknown (to me) cam specs but it idles at 600 RPM, I'm told. I think the CR is 11.2:1.

If I sound woefully ignorant about exact details, it's not lack of interest, I just didn't want to micromanage the engine build of a guy that does engine development work for GM. I told Brian I wanted a strong street motor that would live on pump gas, and to build it the way he would for himself.

JR
 
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S

Ricardo Montalvo

John Ross said:
Yes, those are flywheel numbers, of course. I don't think you could get 700 RWHP on 91 octane without Forced Induction or nitrous.

General specs are 442 inch displacement, with (I think) a slight overbore and a stroke increase to 4.1". Intake is the Harrop ITB setup. CNC ported LS7 heads with unknown (to me) cam specs but it idles at 600 RPM, I'm told. I think the CR is 11.2:1.

If I sound woefully ignorant about exact details, it's not lack of interest, I just didn't want to micromanage the engine build of a guy that does engine development work for GM. I told Brian I wanted a strong street motor that would live on pump gas, and to build it the way he would for himself.

JR
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Nice. I figured it was an ITB when I saw the torque #'s. I'm surprised it peaked at 6900rpm with those cubes and an itb. It sounds like a stout setup. I have no doubt it idles at 600rpm, you have to love itbs!

Here is a pic and video of a similar build I did with a Harrop a few years ago:

DSC_0127.jpg


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S

Ricardo Montalvo

Are you planning to run it DBW, or DBC? What ecm, and who will do the chassis/street/strip tuning?

You have the right gearing for it. If you were running any of the Porsche boxes without an expensive regear, it would be like driving a jack rabbit with all of the low end torque and instant throttle response of an ITB.

BTW, those filters in the picture kill hp. Do not use. There are better solutions that don't hurt hp.
 
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J

John Ross

Stage7 said:
Are you planning to run it DBW, or DBC? What ecm, and who will do the chassis/street/strip tuning?
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It's DBW. I'll have to ask Brian about the ECM. I think it's a redone GM unit but I'm not sure. Tuning? The car's not built yet! I'll be exploring my options later...

JR
 
R

Roger

John Ross said:
Preliminary results are 735 HP @6900 and 657 TQ @4500. This was with factory Corvette LS7 exhaust manifolds, which is what I intend to use.

I've got a big, stupid grin on my face right now...JR
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Enjoy, and be careful - that a lot of power for a light / any car.
 
J

John Ross

shark said:
BTW: that's going to be a lot of power in a 2.5K lbs. car. RaceLogic TC control??
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That's my plan. Don't know that I can hit 2500 lbs empty, given the Ricardo, non-plastic intake, glass windshield, and lifts on both ends. Then again, minimal interior, no paint, and no stereo nonsense help in the other direction. Maybe helium in the tires...

JR
 
J

John Ross

Stage7 said:
You have the right gearing for it. If you were running any of the Porsche boxes without an expensive regear, it would be like driving a jack rabbit with all of the low end torque and instant throttle response of an ITB.
Click to expand...

That was my conclusion, too. I had originally planned to use a Griffin Sequential, but continued delays there scared me off. I looked into the 07-09 Porsche GT2 box with the 3.15 1st gear and a R&P swap to 3.00 final drive, but that was $19,000 all-up. Fran took pity on me...

JR
 
J

John Ross

BTW some of you have asked me privately about my "vision" for this SLC build. That's a fair question, and one that I have thought about long and hard.

After much deliberation, I decided I wanted to see just how much overall street and road course performance could be built in a home garage with a naturally aspirated, pump gas engine for approximately the cost of a ZR1 Corvette. My goal is to exceed the results that can be had from any factory-built car that costs one million dollars or less. (I don't know what a Venom GT costs out-the-door but let's just say that's not really a "factory" car...)

I considered forced induction, but decided the whole issue of boost levels would muddy the waters. Let's see how much we can accomplish the old fashioned way...

A comfortable seat and driving position, and air conditioning, are all the creature comforts I need. I LIKE the nothing-extra interior look of race cars and aerobatic aircraft. And a stereo in a car like this is like having Oprah on the TV when you're in bed with a porn actress...

Note to Fran: We need to talk first, but I'm probably going to be your first customer using the Bosch ABS system.

JR
 
T

Stefan Tuineag

John Ross said:
That was my conclusion, too. I had originally planned to use a Griffin Sequential, but continued delays there scared me off. I looked into the 07-09 Porsche GT2 box with the 3.15 1st gear and a R&P swap to 3.00 final drive, but that was $19,000 all-up. Fran took pity on me...

JR
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What is the story with Griffin, i believe they take orders! Is anyone using it? What is the lead time?
 
J

John Ross

Tuineag said:
What is the story with Griffin, i believe they take orders! Is anyone using it? What is the lead time?
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They have not yet delivered a transaxle to anyone, to the best of my knowledge. I was supposed to get one of their first three sequential boxes, which were supposedly the first boxes of any type they were going to make. That was last June. No contact from them since August. I don't want to use the word vaporware, but I couldn't wait indefinitely.

Maybe next year we'll all be singing a different tune.

JR
 
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