I know what your post is but proper rods and pistons are forged. Who was doing that at home? Hah

 

Back in the 40s and 50s Hot Rod culture. I guess it was more Rat Rod hahaha.

 

I would think that at somewhere north of 1000hp, rod bearing load is 'substantial', but that is a serious feat of engineering, any which way you cut it.

Bravo.

 

To make a high rpm / high power street engine is one thing. To make a high rpm / high power race engine that can operate at or near the limit on a continuous basis is entirely another. The details that need to be addressed which hardly anyone (including myself) has never even thought of is quite mind boggling. The reason that all the engines (and gearboxes) that Chris has built for me have been utterly reliable under a tremendous amount of abuse is the attention to these "less than obvious" details. Obviously, with the Cervelli Gen 3 engine, we are doing something that has never really been done on the Mezger platform up to this point. We are targeting around 900whp with modestly low 500 wtq and around 0.7 bar (10psi boost).

 

Is the benefit there to preserve the new gearbox?

Doesn't the lower torque value hurt acceleration, and or, spooling at such low pressure?

I can only imagine some of the things (failures), and what the post failure analysis revealed.

 

HP, not torque, is what gives you acceleration. Spooling is not an issue when you are operating between 6-8.5K and there is no loss with the lightning fast shifts of a sequential. The idea is to develop the most HP with the least amount of boost. Less boost = less heat, lower IATs, less wear, etc, etc. The Holinger MXT is rated at 660 ft.lbs for a 24hr race.

 

Good thermal management approach - what do the temperature reductions translate to in real world numbers?

That BMW with the hollinger in it was shifting in such a quick manner that the only way I could tell it had shifted was by the change of engine tone, quicker than a pdk in my assessment.

 

An old flat head piston is pretty simple, yeah. Modern pistons, even if machined from bar stock, would be pretty darn complicated to machine on a manual lathe.

I can make bushings now at least, hah.

 

Very cool that the rods arrived! And I thought I was doing good being around 5 grams lighter than a Carillo. Are you going to try the v-band turbine housings on the new motor?

I'm not sure it is quantifiable? But easy answer would be reliability and consistency.

 

John ran the car at High Plains a few weeks ago and give me data where the Ambient Temp during the race was 102 degrees. During this session the Inlet Air Temp got as high as 170 degrees. From these two channels we can create a channel called Compressor Temp Rise which would be simply be Inlet Air Temp minus Ambient Temp. This channel value moves around during a lap, but eventually generates a lap average Compressor Temp Rise.

If we build and install the Gen 3 engine and then run it in similar conditions, hopefully the lap average Compressor Temp Rise will be smaller. The difference represents an increase in Manifold Air Density, which is roughly the same as increasing the boost pressure. There is a spiral in play here, where if you can use less boost pressure to meet your torque goal, the Inlet Air Temp is automatically lower, and the Manifold Air Density higher, which means you can then maybe run a little less boost yet and still meet your torque goal, which might lower the Inlet Air Temp again, and so on.

The goal devolves to using the least possible amount of compressor compression to meet your torque goal. This is always going to lower the exhaust pressure too, which is going to improve the torque also. This further devolves to getting the most torque out of the least fuel, by means of not using the fuel to do unnecessary compression or to push exhaust gas out of the cylinder. All of these efficiency improvements decrease the waste heat also, so the coolant temp and oil temps come down.

Real world numbers.... The engine will produce more power with lower Inlet Air Temp so the lap times will presumably be faster. There are many other variables, so I have not quantified this.

Chris

 

I intend to, but right now the shop is weak on exhaust fabrication resources. We don't have a reliable guy for TIG welding jobs at the moment.

Chris

 

I was just wondering if there were notable changes; for example, put a 10 row oil cooler on the Sti awhile back and the temps dropped about 15f across the board - probably a little more in the coming cold.

 

Many, many variables. That's interesting that less airflow in this scenario is actually cooler, whereas one would normally think that more airflow helps keeping things cooler by shedding more heat.

This is a very fascinating process to watch you guys figure out and optimize, never would I have thought I'd see a car running 900whp with a little over 1 bar boost.

 

Ultimately yes but like Chris mentioned the exhaust fab work is the bottle neck right now. I have a brand new spare set of the XR1000s so I may just initially use those with the existing 48mm 321 headers and as can devote the time elsewhere as there will still be a decent amount of integration and fabrication to get everything fitted. Swapping the turbos to a V-band configuration can always be time after the fact as time allows.

 

I think with the Gen 3 engine we will be able to hit that number with no more than 0.7 bar boost. It's amazing how much can be optimized on these motors.

Chris just recently did a 996RSR 3.8L engine which put down near 500whp at 9100rpm on the mainline dyno. That's close to 550whp on a Dynojet. Pretty impressive for an N/A motor.