ratt_finkel

Brought home an 02 Z06 with APS TT kit this weekend. This is being built for the Pikes Peak Hill climb. Mods are:

-APS Twin Turbo Kit with Twin Intercoolers
- McLeod Twin Disc Clutch w/ upgraded Master Cylinder.
- Upgraded Beehive Valve Springs
- Alcohol Injection Systems, methanol injection kit
- Hardened Push Rods
- Hurst Competition Short Shifter
- Twin in tank fuel pumps
- Borla ATAK exhaust
- Upgraded Injectors (unknown size)
- No Cats


There may be more but that's what I know. The car supposedly makes 615whp on a dynojet with 91 octane, though meth was not tuned into those figures. It's purely a supplement should the a/f ratio go south.

Reliability is key at Pikes Peak. Heating is an issue for almost everyone. I'm not planning on building the bottom end yet. Realistically on race gas or E85 what is the most power I can make without having to worry in the back of my mind? Ideally I need to make 800whp at altitude. I'm a newbie to boosted LS's. So please enlighten me.

Thank you,



Jeremy Foley

2bridges

sounds like fun to me!

In this case the additional air requirement is significant
Pikes Peak start is 4,720 ft , finish is 14,110 ft elevation

Absolute pressure = Boost + atmospheric pressure
Atmospheric pressure at sea level =14.7 psi
Atmospheric pressure at 14000ft elevation = 7.988 psi

you will effectively loose .48 psi Atmospheric pressure per 1000ft elevation
So you will have to make up the air loss in additional air from turbos

at sea level if you make 800whp @ 20PSI boost {14.7+20=34.7 absolute pressure}
at 14,000ft the turbos will effectively be moving 26.7psi worth of air to overcome the deficit and make the same 20psi absolute and make the same 800whp {7.988+26.712=34.7 absolute pressure}


If you truly are after reliability under hard use the stock bottom end at this power is the obvious shortcoming.

danieloneil01

I got nothing but if you do it, get a good camera setup and post it up.

chuntington101

Wrong platform for the event if you ask me. Something smaller and more "chuckable" would be better. Although the 996RSR did VERY well going up the hill.

Is this your first pass up the hill? If so dont bother with the turbos as you will have enough to worry about with keeping more important things like brakes, water, oil, gearbox and yourself cool than cooling hot air from the turbos. ESP as the Vette isn't known for its great cooling. Plus you want to get the car strong enough before you add power. Brakes are notorious for "stopping working" half way up there and with loads of power you could find yourself in trouble quickly.

4DRUSH

Words of wisdom right there

ratt_finkel

This will be my 3rd trip up the hill. 4th visit to the mountain.
I've been racing for 10 years. And this not my first corvette.

I chose the C5Z specifically for it's performance potential. The class I'm running has set the bar @ 9:46.xxx with 750whp and 2700lbs. Hyundai Genesis.

My aim is to go after that record. Though I'd be happy with anything under 10 minutes.

Chuckable or tossable is the last thing you want at pikes peak.

You guys have probably seen the video of the Evo driving off the side of pikes peak in 2012. That was me.

I'm really not hear to discuss the merits of the car selection. Just looking for some advice on making reliable power.

Thanks!

Jeremy Foley

slow ride

It will require some upgrades to the base kit to get the power you are asking about (elevation is a big part of that). Turbos on the kit are basically Mitsubishi 20g with custom exhaust housings. Get with DKT or Robert from Forced Performance for turbo upgrade options.

ratt_finkel

I'm planning on running E85 and or race gas. Approximately what kind of boost range are these turbos capable of? Are the intercoolers going to be a bottleneck of any kind?

Transmission is being pulled this week for a rebuild. And while the car is not going to be launched, I realize that big power does break things. Anything else in the drivetrain that I should be proactively upgrading?

Reliability is key here. Many people never make it to the top due to mechanical failures. Some fail during qualifying. So until I can build the motor. What is a safe power level that won't keep me from finishing?

2bridges

HOLY CRAP! Just watched the video. One hell of a spooky ride there


You are probably fairly close to the durability limit at the 600-650 whp level.

I have run dozens of standing mile and a few open road race events at 650rwhp on my procharged Z06 without issue. Turbo certainly has the potential to be harder on parts but if you can keep oil/water temps in check would expect similar durability.

2bridges

You may be better served in the roadrace forum https://www.corvetteforum.com/forums...roadracing-23/

Most on the folks here are more drag race focused
Several guys here make 800 on stock bottom, but as you know 1/4 mile and road race reliability are much different.

slow ride

The most power I have seen on the c5 aps kit is ~800whp or a little more and upgrading the inlets to the turbos is a must since they tend to collapse. As the others have said it might be a little much pushing the small turbos to that level, but at sea level I can see them doing it with good fuel, not at elevation though. I'd probably stay at the 600-700whp level also for a stock gen 3 engine, guys make more, but not under this type of racing condition.

ratt_finkel

Perfect. This is exactly they type of information I was looking for. I'll leave the rest of the setup questions to the road race guys

Really appreciate it

4DRUSH

Holly crap, same navigator sign up for this year?

ratt_finkel

They eliminated co-drivers the next season. Though supposedly due to other reason. I ran the 2013 event solo. My co-driver from the wreck competed this year (2014).

4DRUSH

Good stuff, glad everything worked out.

Far as safety, might want to replace the Corvette floor panels with metal

Rkreigh

Jeremey those turbos will take you to 800 rwhp on e85

make sure you use a very competent fuel system

I'd be tempted to run lower boost at the bottom and ramp it up as you go to maintain the hp at higher alt.

for sure you have experience, and the engine will make the power just fine. just make sure you keep it out of detonation which is hard to do going up hill under load.

make sure the car is tuned a bit conservative

the e85 is a very good idea, it's much more forgiving on the tune

make sure you use a very competent fuel system

I'm going to use FIC bosch 127 injectors and I would recommend a pair of 450 pumps wired on a hobbs switch one of them might have to be external, these pumps are big and can stress the wiring

the vette is pretty stable but I'd move the battery to the back for better traction and consider a fairly big wing on the back if your class allows for better traction

good luck! the other thing is to for sure consider modifying the APS inlets. they can pinch down the airflow I'd like to take the air from the gill panel of the car with a big square filter and a fabbed box to allow plenty of air to the turbo inlets that is pretty restrictive on the aps design where they pinch down the pipes

give that a try

slow ride

On DSM's back in the day guys would make low to mid 400's on those turbos in single configuration. Now keep in mind that was on a 2.0l and I'm not sure what the A/R or turbine wheel size is of the stock C5 APS turbos. I think the biggest drawback is the inlet system. You would be way better off routing the pipes like I did and reduce all those bends and cheap soft tubing that can collapse. Running E85 will help with engine cooling also so thats a plus on these cars.

Now those turbos MIGHT make 800 at the base of the hill, but I seriously doubt at the top. Thats like what 7000-1400 ft.

chuntington101

Sorry Jeremy, there was no offence intended. Just pointing out that the hill is VERY hard on cars and thus more isn't always the first thing on the list of things a car needs to have. As you are aware, even the big budget teams often struggle to get a car to the summit let a lone brake any records!

The problems with the APS kit is its not really a race designed system. It a pieced together kit for road cars. if you really want to do a turbo setup why not get some proper headers in the with the correct turbos for A) the power you want and B) the power band you need! Its seems a bit half arsed, esp as you are used to out and out race cars.... sure the APS kit mounts them nice and low to help with weight distribution and center of gravity, but thats about the only plus points! Turbos are small, cheap and not efficient, esp on a setup that will be spending most of its time in the upper RPM range.

Also i don't like the intercooling on the APS stuff if you are leaving the radiator up front. They block off far to much for the rad and you are stacking coolers, which in thin air and relatively low speeds isnt the best route to safe reliable power. Would be much better off seperating the cooling air routes and optimising them for each cooler. Water and oil cooling together and intercooling separate.

And this leads me on to the point of why the Vette isn't a great starting point for a Pikes Peak car. There simply isn't enough cooling on these cars. Look at any road race corvette and they struggle to keep 500bhp NA power plants cool in thick (ok hot) air. Then look at the Pikes peak stuff thats done well. They have scoops and ducts all over them to try and keep them cool. is there even sufficient room on the corvette to mount a rear mounted rad?

Why not go for something like a HOWE or other tube frame chassis and with a bodywork with a little more front area? That way you can at least get the cooling air required and in a strong and dependable (as well as fixable) chassis.

Also do you NEED to keep the V8? I know i will get shot on here for saying it but you could get your power goal from a turbo 4/6 pot V6 that might be easier and for a similar weight to the LS with turbos, even f using an iron block! The Vette engine bay is VERY tight and you will want lots of nice cold air flowing to stop things cooking plus give you loads of space for turbos and there accompanying stuff.

have a look at these build for some ideas. I personally LOVE the RWD tube frame car racer. its going to be coming in at 1250lbs and be running 350bhp but could be running ALOT more power! With optimised aerodynamics and more power it could make for a great hill climb car.

600 BHP RWD SEAT Ibiza tarmac rally car build by a guy that has worked for several OEMs and Rally teams:

http://www.pistonheads.com/gassing/t...za+-+rwd+turbo

RWD Space-Frame Silhouette Racer

http://www.pistonheads.com/gassing/t...acer&mid=36792

Mid engined twin turbo (1000++bhp) tube frame car

http://www.pistonheads.com/gassing/t...+Answer+is+%21

Once again i'm not trying to teach you anything.

momo20

I was right there when that evo went off the side that was insane glad your ok!

maybe its the same evo? here is the one I got pics of when I was there at the pikes peak hill climb

ratt_finkel

I'll have to check the rules. But I don't believe that is legal.

Thanks for the info. Didn't realize the turbos had any physical restrictions like that. Already on all the other points. Lessons learned from previous races

Yeah, a 20g was a mild upgrade for Evo's too. For reference, the Evo I ran with a 2.4 Stroker and 35R on E85 made 550/500 @ 7k feet. The race starts at 9k and goes to 14k. I have not had the car assessed by a tuner yet. But we plan on going over the whole system. What about the pipes can you tell me?

Not a problem. Indeed it is. A grueling race of both man and machine. And the mountain is never forgiving.

That is probably something I will do in the future. But for right now I will work on maximizing the efficiency of this system. I actually am going to work on both gear and power band tuning to stay in the 3k-5k RPM range. This is for a number of reasons. Minimize shifting, minimize wheel spin, keep the motor happy, keep heat down, etc.

Yes, cooling and intercooler upgrades are all on the list.

The cooling question remains to be seen. But I believe with proper engineering and testing we can keep it cool. Rear mounted radiators are not even on the list. They are a complete nightmare to engineer. And typically offer less cooling capacity. They are popular with rally type vehicles because frontal accidents and clogging are issues. I know this from talking with Global Rally Cross engineers directly.

It appears, despite your statement, that you DO want to discuss the merits of my decision. So here it is. I'm working on a limited budget. Within a fixed rule set. (Time Attack 1/Time Attack 2) If you can think of another car that I can build for 30k that will make 600-800whp. And where replacement parts and motors won't cost 1/3 to 1/2 of that. By all means, please point me in the direction of said vehicle.

I'd LOVE a TA/2 (trans am howe chassis) car. And my eventual goals are to run in that or World Challenge. I've had me eye on one that goes for 50k. Most cost about 70k to build. And again, those cars do not make the power to weight or meet the class rules for my goals at Pikes Peak.

Those plans are well down the road still. Unless someone here wants to buy me one

Technically I don't need a V8. But again, on a budget. A boosted LSx is my best option. Turbo 4's will not make the power reliably. Trust me. I did look at cars with inline and V-6's. But again, the cost for building and replacing motors is substantially higher.

Hell yeah! All those cars are bad ***! But none of them are legal for the Time Attack classes. I'm not going after the overall mountain record. Nor do I think my driving capabilities could get anywhere near that.

If I had an unlimited budget and ran in the unlimited class. No, I would not be building a C5Z.