Power limits on the standard pistons

[Ray Hall]

I have the 5.0L V10 BUH engine fitted to a Ultima Evolution. The engine is stock except for the direct injectors are not used and port injectors fitted. The turbochargers are Garrett GTX3071R Gen II. The engine makes 803 HP at the wheels at 22 psi boost. Here is the dyno chart. I have damaged two pistons and bores from detonation. Not from the tune, incorrect fuel in the tank. I rev the engine to 7000 rpm. I am considering fitting iron selves to the bores and forged pistons. Is this necessary at this power level or just make sure the correct fuel is used.

Ray.

[welwynnick]

What an interesting car that must be. Rather than answering any questions, I just want to know more about what you've done. Tuner? ECU? Intercoolers? Manifolds? Gearbox? etc

Anyhow, there are usually two sorts of answers to this. Go ahead and add a bit more boost and then tell us all what happens - or - summarise what other people have done so far. The latter can be answered quite well with this thread:

viewtopic.php?f=47&t=131533

There are three particularly successful BUH tuners - MRC, THT and Madness. They have tuned several engines with hybrid turbos and stock internals to over 1000 bhp flywheel, and THT have tuned several cars that run 2 bar boost with water methanol injection, and they produce over 1400Nm / 1000 lb-ft flywheel. So I think that means you probably don't need to upgrade the internals.

Fitting iron sleeves seems like a funny thing to do with this engine as the bore spacing is so small, and the whole concept of the engine revolves around having a hypereutectic (silicon saturated) alloy block casting. That's the approach used in the R8 & Huracan, and they rev reliably to 8500 rpm - in fact they have the highest piston speed this side of a top fuel dragster - so the block must be doing something right

Nick

[IanH755]

Hi Ray,

Th BUH internals are pretty strong so while you can rebuild with forged if you wanted it isn't necessary for the power level you're currently running which is almost identical wheel HP to my car (802hp vs 803hp). I'd suggest anything north of 1100hp Flywheel is were you "need" to be forged with anything 1000-1100hp Flywheel advised but not essential and anything below 1000hp not needed.

One thing I would point out looking at your dyno chart is that Garret turbo's you're using seem quite laggy in comparison to the more recent ones designed specifically for the RS6/BUH like the TTE 1000 etc, which hit full boost around 1000rpm sooner than the GTX3071R does, make the same power/torque figures but do so with a more linear delivery.

[Ray Hall]

What an interesting car that must be. Rather than answering any questions, I just want to know more about what you've done. Tuner? ECU? Intercoolers? Manifolds? Gearbox? etc

Anyhow, there are usually two sorts of answers to this. Go ahead and add a bit more boost and then tell us all what happens - or - summarise what other people have done so far. The latter can be answered quite well with this thread:

viewtopic.php?f=47&t=131533


Fitting iron sleeves seems like a funny thing to do with this engine as the bore spacing is so small, and the whole concept of the engine revolves around having a hypereutectic (silicon saturated) alloy block casting. That's the approach used in the R8 & Huracan, and they rev reliably to 8500 rpm - in fact they have the highest piston speed this side of a top fuel dragster - so the block must be doing something right

Nick

The whole car build is here. http://www.turbofast.com.au/UltimaEvoCoupe.html
This is a walk around video of the car during the build https://youtu.be/pUqnkEjbTRs

The people making the forged pistons where not keen on the aluminum bore so recommended using iron sleeve. They will be thin.
I also feel this will give me a greater margin of error and not have to do this again.
Ray.

[Ray Hall]

Hi Ray,

Th BUH internals are pretty strong so while you can rebuild with forged if you wanted it isn't necessary for the power level you're currently running which is almost identical wheel HP to my car (802hp vs 803hp). I'd suggest anything north of 1100hp Flywheel is were you "need" to be forged with anything 1000-1100hp Flywheel advised but not essential and anything below 1000hp not needed.

One thing I would point out looking at your dyno chart is that Garret turbo's you're using seem quite laggy in comparison to the more recent ones designed specifically for the RS6/BUH like the TTE 1000 etc, which hit full boost around 1000rpm sooner than the GTX3071R does, make the same power/torque figures but do so with a more linear delivery.

Yes the turbochargers are a little big. They would be better with a smaller A/R turbine housings. I have had enough traction problems and do not need a big hit at lower rpm.
The ECU use is a Motec M150GPR . I tuned the engine on my dyno.
Ray.

[Ray Hall]

What an interesting car that must be. Rather than answering any questions, I just want to know more about what you've done. Tuner? ECU? Intercoolers? Manifolds? Gearbox? etc

The tuner was me, ECU is a Motec M150GPR, Large water to air intercooler. I designed and made the manifold. Gearbox is Porsche GETRAG 996 4WD transaxel 6 speed manual.
Ray.

[Pinkfoot]

Quality stuff Ray

[welwynnick]

What a car. That looks like a no-holds-barred attempt to make the fastest thing on four wheels.

The stock pistons are 10.5 cast Al-Si and the rods are cracked-forged, so custom forged pistons and rods offer obvious advantages, but I guess you need someone familiar with this engine.

I'm not aware of any off-the-shelf solutions, but there are three piston manufacturers for this engine who get close - FCP, JE and Wiseco, and would probably be a good starting point. Only minor customization would be needed to meet your application - pin diameter, compression height, etc.

The Al-Si block needs a few considerations - the pistons need iron-based anti-friction skirt coatings, and the compression rings need to be barrel-faced rather than any other profile in order to avoid damaging the exposed silicon particles. Other than that I don't think there are any other issues apart from increased bore clearance, and those three manufacturers have proven products in this application.

Does your ECU use knock detection?

Cheers, Nick

[Ray Hall]

Nick,
The ECU does have knock control I never set it up the car is a, Ultima Evolution it is a kit car based on a Group C le mans 24 hour car built for McLaren. Ultima Sports in the UK makes it. Normally it used a GM LS engine.
Special Piston Services In Melbourne Australia are making the piston. I will put a picture here when I get them.
Ray

[welwynnick]

I've been following the progress and achievements of Ultima for several years. They seem to make a mockery of other supercars. Interesting that you can fit a V10 AND a big charge cooler in front of it.

Regarding the pistons it sounds like you've made your mind up. What CR are you going for? Are you going iron liners as well? If you fit proper rods you'll be able to rev higher as well.

All the best, Nick

[Ray Hall]

Nick
I was going to get the pistons made with he same 10.5:1 compression ratio. I am looking for rods at the moment. Not much out there for the BUH engine.
Ray.

[welwynnick]

Hi Ray,

In that case FCP Engineering offer forged pistons and rods off the shelf. You need to buy them as a package because they go their own way with rod length and compression height.

However, since you're a turbo tuner, and you're trying to get more power, and you're going to fit forged pistons, I thought dropping the CR would be the logical thing? 10.5 is fine for 0.5 bar boost, but at 1.5 bar you must be pulling the timing?

I like the look of your charge cooler - RS6 owners are much more restricted. Could you share the details of your cooling system? Which pump do you use? How do you bleed the system? I went into this in some detail over the last few years (and still learning of course):

https://mbworld.org/forums/m275-v12-bi- ... pumps.html

Nick