BC

The are ductile iron, so the wear issue is still the pistons, which don't need to be coated, just as in your nicasil case. The issue, though, is the steels 250,000psi strength, compared to the original Alusil 30,000, or whatever lower number is, by many times.

hacker-pschorr

There is no need to plate a hardened steel cylinder. His motorcycle has over 100,000 miles with no issues with the steel cylinders and multiple other race engines with his cylinders. Todd is also an expert metallurgist at his day job - this is his speciality.

Not to mention Todd is not the biggest fan of any type of plating for multiple reasons. He would never coat an engine of his own.

Big Dave

OH. MY. GOD.

hacker-pschorr

I forgot to add, this motor:
https://rennlist.com/forums/928-forum/239222-110mm-bore-928-engine-project-plans-for-a-7-4-liter-in-the-works.html
has logged about 4,000 miles already in the red car shown on the lift in the initial post.

Herr-Kuhn

Remember Hacker...there is also heat transfer and piston to wall clearance. My guess if this engine is using JE 2618 pistons there will be at least 0.004" piston to wall. With the Nikasil on Al you can run down to 0.002"

hacker-pschorr

Hey guys, don't shoot the messenger here. It’s his opinion based on his experience building motors and who knows what kind of equipment with his day job. He literally spends 12+ hours 6 days a week working with metal – every kind. The place that does the Nikasil coatings is less than an hour away from here, he is very familure with it.

Any possible long term issues are a major factor to him. Gaining a few extra HP doing something that could possibly shorten the life of the motor is not an option to him. He has built race engines for people that were plated – he’s just not going to plate any of his own.

90 S-4

The pistons that are going in the 7 ltr are coated, moly skirts & ceramic tops

Barry Johnson

omg... I can't handle this... I'm WAY excited for all these developments! I wonder though why he spent all that time and money building this monster motor, and went with a centrifugal supercharger? TT would require more work, but at that level, its kind of moot :^).

For a little bit I thought, why would you bore everything out when you can get loads of power from 5 liters with proper tuning. Then I thought, well I suppose if you're going to lower compression, you'd get new pistons, then you could sleeve for strength, then you might as well make them gigantic... I like this guy!

But 7.4 liters? Thats 158ci over the stock 5l!!! This is awesome!

hacker-pschorr

This topic has been beat to death around here – I do not want this thread to become another boosted cat fight. I'm simply going to say he had his reasons to use a supercharger when he started this project 4 years ago. I'm pretty sure simplicity was his #1 reason. When he started this project, boosting a 928 was pure witchcraft. When he saw how perfect Tim Murphy’s kit was, how well it worked with a simple bolt on – that gave him a known good formula to start from.

Todd is a fan of anything that produces more hp, including turbo’s. He has a ton of experience with both systems, with 911 race cars to the motorcycle he built over 20 years ago with a Vortech supercharger. I’m sure some day he will play with turbo’s on a 928 – the exhaust you see on the car is 100% made by him. I’m sure he could probably have a set of turbo’s hung on the car and plumed with intercoolers in a day.

His first motor was a stock 5.0 with lowered compression via 951 pistons @ 22psi. That was a simple, awesome setup, wasn’t fast enough for him. He has spent a lot of time tearing down engines, playing with rod to stroke ratio to find just the right combination. Some are too peaky, other have too much low end etc…. I remember one day at Road America he was describing what he did not like about whatever motor was in his car that day. We headed back to Green Bay around 5:00PM – by midnight the motor was out, torn down & he was putting together the next formula. I’m not sure he will ever stop developing.

SwayBar

Simple: centrifugal superchargers work. And they work very well on a V8 which typically does not require the low-end help one gets from a positive displacement blower.

Under hard acceleration, my 5.0 Liter GT already spins it's wheels in first and second, why would one want more low-end than that? I certainly don't, and I can't imagine what a 7.0 Liter would be like, and I mean without the centrifugal bolted on.

With a V8 under max acceleration, it's all about beefing up mid and top-end power production, right where a centrifugal delivers.

Yes, they are more work, and on a V8, the added complexity and generated heat are deemed not worth the horsepower the turbo is able to deliver for a street car. It all depends upon the application.

On a 4 or 6 cylinder street-car, I would definitely want a positive displacement blower, or a turbo, because those engines need the added low-end. Has anyone driven a 951 off-boost? It's a painful experience...

On an all-out racecar with everything on the line, there's no doubt a turbo with an air/air intercooler is the way to go.

But on a street V8 such as an S4, I'll take the centrifugal as it's power delivery is absolutely perfect by minimizing wheelspin, and likewise maximizing all-important hook-up, thus accelerating as hard as un-humanly possible.

The icing on the V8-cake is the centrifugal's all-important SIMPLICITY.

But that's just my take on things.

GlenL

Hacker,

Any photos showing more how he's drilling the cranks? Like with a pencil sticking through it?

Does Todd drill those himself or farm it out?

Funny, I think I met this guy at RA a few weeks back. "Glen, this is Todd." Just didn't click. JLPs former espresso brown car?

Art_Z

i wonder if this car will be able to keep up with the SRT8? LOL!

hacker-pschorr

If you are talking about the crank in the picture, that is not a 928 factory crank. I think it's a Moldex Crankshaft. I'm not sure he has ever drillout out a 928 crankshaft for one of his cars. He created a pretty slick air / oil seperator on Jim Pages car many years ago, installed one on his & Tim Murphys car. Seams to be working great. I've talked to Todd about offering this setup to the public, he is not 100% done testing it yet. I'll be talking to him tomorrow, I'll see what he has done with the oiling issue on the stock crank, if anything. If any of his cranks were drilled out, I'm sure he would have done it himself. The silver disc with the hoses on the left side of the motor is part of the seperator system.

Might have been, not sure what weekend that was, NordStern? He usually shows up when one of us are running at the track.

Herr-Kuhn

Sway Bar...please explain how a CS minimizes wheelspin in its power delivery. It has no regard for engine load whatsoever. I'd challenge you that a turbo offers far, far better power delivery than a CS. If you size it for the application (V8 here) the turbo can be made to not deliver full tilt in 1st gear...you don't need it all there anyway. Then when the car is on full tilt and loads are high you get all your boost as soon as you call for it with your right foot. Many people have not grasped this concept and just assume to turbo gives too much mid range everywhere....the correct statement is the turbo offers great boost modulation through proper sizing for the application. That is because boost levels depend on load, not just RPM. It is the key advantage to the turbocharger. The CS boosts the same curve in all gears...too much when you don't need it (known as 1st gear) and not enough when you do (3rd on up). Then there is wear...a turbo will outlast all other forms of forced induction when applied properly. I have a turbocharged Audi with 260,000 on the clock. Show me any CS that has lasted that long. So your statements about simplicity are also misleading.

Clearly there are some fundamentals of forced induction that are simply not understood by people who post on this board.

Regardless this post is about internal engine work and this work is very impressive.

hacker-pschorr

Knock it off - myself and I'm sure 99% of the people here are sick of the turbo vs. blower ****.

Todd used a blower because he wanted to - plain and simple. It's his project, his car, his money and his time. I'm only sharing this since I feel most are interested in any development with the 928 world & Todd is a very open person about his projects.

If it were not for Tim, Todd, Carl, and Jim Page (and others, not trying to write an Oscar speech) - there would be 40+ 928's still running around with stock power who are now enjoying far more HP than that factory ever offered. Everyone I have had contact with is damn happy with their setup - they could care less about the "other" setups. What they have works very well, accomplishes what they wanted - a faster 928. It's that simple.