chuntington101

Dont read it just look at the pictures!

just shows you what can be achieved with a little time.

ratt_finkel

So details are still coming together. But I have partnered with a local shop to help me prep the car for the race!

They are dead set on making the car reliable. Which is a great thing of course. So they want to build the motor. Which means we will be going for the original power goals.

850whp @ sea level should be around 800whp @ the start line which is roughly 9k feet. Will need a separate map for further up the hill where I will toggle to a higher boost setting in order to maintain that power level all the way to the 14k foot summit. Again, I'm guessing roughly 900whp at sea level.

Peak numbers are not the goal here. I need a drive able power curve, with smooth delivery and reliable power under the harshest conditions. And preferably with the least amount of lag.

So the question is: how do I get there.

Rkreigh

awesome project, it will be really tough getting traction with the c5 at those hp levels

I went ttix on my car and bought it done.

it currently does 800 at the tire but the ttix has room for more

getting a good tt with the right drivetrain will make an awesome hill climber

good luck!

ratt_finkel

Big aero and big tires will help with that. Plus most of the race is spent in 2nd-4th gears. Getting off the line isn't really an issue.

So I've been doing a lot of research. Looks like the aps kit should be able to get me to 850whp. Still undecided on race gas or e85. I guess I'll leave that up to the tuner. May play with cams or heads if I can't get the power I need with the current hard parts.

2bridges

I have a similar power and reliability requirement for a 49 ford coupe road race effort in the works.
Here is the approach I am going - fully forged and make the power without a ton of rpm.

ERL dry sleeve LS2 - 4.125 bore (darton sleeves are longer and support piston at BDC for stroker)
4" callies crank
callies ultra H rods
weisco pistons (final compression in the 9.7-10.0 range)
TFS 255 heads ( the 4.125 bore will accept LS3,LSA heads for a cheaper alternative)
holley Hi Ram

custom twin 6266 is probably the FI method that will be employed

ratt_finkel

Tear down starts today!

http://www.jbcorvette.com/paint-and-body-2-1

I think for simplicity. We are planning on: upgraded rods, pistons (uncertain on CR) E85. Push these APS turbos to the limit. And then find out where the weaknesses are. Still trying to find a tuner. Lots of options here in DFW. We are hoping to find someone who can travel with us and be available for track testing. Hard to do without writing big checks.

2bridges

One easy swap to consider is trans swap to the MM6 (NON Z06) instead of the M12 (Z06) box.

MM6 1-3 ratios are spaced much better for a high powered car than in the Z06 box.
MM6 M12

1st Gear Ratio 2.66 2.97:1
2nd Gear Ratio 1.78 2.07:1
3rd Gear Ratio 1.30 1.43:1
4th Gear Ratio 1:1 1:1
5th Gear Ratio .74 0.84:1
6th Gear Ratio .50 0.56:1 (or .57 source depending)

At your power level the tight 1-3 ratio is the last thing you can use.
This is one of the changes I am happiest with on my 640rwhp Z06 open road race car.

dougrodriguez

Reason I upgraded my aps turbos is everyone here say they are no good at more boost. So we shoved a new housing and bored it out to accept a 59mm Billet wheel. They also upgraded the bearings and whatnot inside. I didn't want a super laggy setup but wanted to touch 1000hp when I'm ready for it.

ratt_finkel

Stock ratios
On a 28" rear tire:
7000 fuel cut 57 82 119 170

On a 25.5" rear tire:
7000 fuel cut 52 75 109 155

I prefer the top gearing because it gives me a lot of flexibility to use 3rd. I'm expecting top speeds to be in the 130-140 range on the fastest sections.

We plan on doing lots of testing before the car ever sees the mountain. And gearing is something I am prepared to play with.

We are going to push these aps turbos to the max. I'll let you know how much of a weakness they really are

ratt_finkel

So it looks like we're going to go ahead and pull the motor now. The original plan was to work on getting suspension, aero, cooling, brakes and the general setup tested to an extent. And then work on adding the power later.

Since the car is already in pieces. It's easier to do it now.

So getting the engine built has just moved up on the priority list.

I had already planned on rods and pistons. Which pistons and what comp ratio should I be looking at? What rods and why?

What about the crank? The motor may make as much as 1000 chp. I don't plan on spinning it past 7k.

Also, a cam is on the list too. I've got pushrods in it already. What springs and retainers? What other hard parts am I forgetting?

2bridges

Don't understand your logic on this
we must be missing each other on this.

The Z06 box 1-3 all deeper (higher numerical) and closer than non Z06

MN6 (NON Z06) ratios
1st Gear Ratio 2.66
2nd Gear Ratio 1.78
3rd Gear Ratio 1.30
4th Gear Ratio 1:1
5th Gear Ratio .74
6th Gear Ratio .50

M12 Box (Z06)
1st Gear Ratio 2.97:1
2nd Gear Ratio 2.07:1
3rd Gear Ratio 1.43:1
4th Gear Ratio 1:1
5th Gear Ratio 0.84:1
6th Gear Ratio .0.56:1

assuming you use the 3:42 r&p

28" tall tire **NON Z06**
1st @ 7k = 64.10 mph
2nd @7K = 95.78mph
3rd @7k = 131.15mph

28" tall tire **Z06**
1st @ 7k = 57.41 mph
2nd @7K = 82.37mph
3rd @7k = 119.23mph

You will not hook 850rwhp in 1st,2nd on a road race tire with either trans.
Having 1,2,3 be shorter and tighter is of no benefit with this much HP, and seems to me a detriment forcing you into 4th at less than 120mph

ratt_finkel

Luckily I don't need to hook in 1st gear. 2nd gear somewhat. The slowest I'll be at about any point on pikes peak is 25mph. Even with the M12 gear box, I expect there will be some initial lag in 2nd gear (not a bad thing) but enough engine torque to get the car moving, planted, the wheel straightened out and just in time for the boost to kick in at roughly 50mph. I'll modulate if need be until 80 and 3rd gear should be good to go at that point.

Most of the time I'll be between 50-100mph. I want the flexibility to leave it in 3rd much of the time and stay in the meat of the power curve. With the occasional down shift to 2nd and occasional upshift to 4th if need be.

The actual road courses here in TX won't see anything less than 3rd gear.

We will have ample time to test before the event. So there may indeed be a gearing change along the way.

ratt_finkel

Engine has been pulled. Still trying to decide on what internals are going in. But it's going to be built no matter what.

2bridges

surprised there are no suggestions from others.
This is what I would do

keep the stock crank assuming it checks out (adding cubes will require even more air from what sounds like already near maxed tt setup)
Rods - ultra H callies, nice stout rods still semi-budget priced
Pistons - forged wiesco or diamond
compression - would target no less than 10:1 with race gas or E85

chuntington101

That seems like a very sensible solution. But it depends on how much budget you have! Yes a 4.125 inch bore block with a super light short stroke crank would be great. But if it's out of budget there is no point.

Def think higher comp., assuming 100% race fuel or e85, is a good idea. People forget that FI engines are just na engines that breath higher density air. Higher comp. ratio, assuming your not dept. limited, is always better. Water injection would also be on my list to keep temps in check at higher altitudes and reduce egts.

Might be worth looking at piston oil squirts also. Prolonged high rpm and boost isn't good for pistons.

slow ride

If this thing will live on e85 or race gas 24/7 I would def keep compression at 10.0:1 and probably even higher (up to 11.0:1 but the tuning window will get smaller) due to the limit of turbochargers. Any forged rods should take as much or more beating than the stock crank so the ultras are fine if not overkill. I like the piston squirter thought, but not sure if they have ever been installed into a gen 3 block or not.

ratt_finkel

Yeah, I was really hoping to get more feedback.
I've been told by one reliable source that the LS6 doesn't like to be bored much. And I wasn't planning on doing more than a hone anyway.

I've been doing research on pistons. And there are probably 10,000 choices lol! Hard to find real empirical data.


Indeed, coming from the 4cyl world where high boost and high compression are synonymous. I wasn't sure where the happy place was on the LS6. 10.0 is certainly not low. Would love 13

Again, in the import world. Oil squirters and all the other fancy stuff is common place. Well worth the small investment.

Is the stock cranbk really going to be happy being beat on at these power levels?

I understand completely that the higher the C/R, the lower the margin for error. I guess I may have to go conservative for now. 10 or 11:1.

Thanks guys!

chuntington101

Key thing is find an engine builder & tuner that knows what they are doing when it comes to road race engines! Let them design the engine to fit your requirements.

It's obviously not just about high comp ratio, you are going to want an engine that's efficient as an NA mill that the turbos can then add to. Broad power band is also a key factor.

You mentioned can choice, I'll drop you a pm of a guy on ls1tech that only gets good reports.

ratt_finkel

I FINALLY got a hold of the tuner here I wanted to speak to.
He recommended 9.5-10.1:1. Said the stock crank should be fine at those power levels. Going to be calling Brian Tooley to ask about cam selection. He also recommended 1300-1500cc injectors for E85. And Holly EFI for the standalone.

Torque Obsessed

This is really cool. Good luck!

I don't think I've seen anyone mention that there are some weaknesses worth doing preventive maintenance on for the LS6. Specifically valve springs and timing chain, if I recall. There are threads here with the right info; sorry I can't remember the specifics. I'd also suggest upgrading the oil pump while you're at it. I'm sure you're planning an oil cooler so I won't bother you with that. I've seen recommendations to add an extra quart of oil for track days, which might be useful here too.