John..

Heads were shaved and o-ringed, it was something around 9.2:1. He told me the blower was efficient, but I suspect it was a hot day. I think his car had a Powerdyne?

You will have good control with that DTA....I would watch the ignition advance and keep it around 20 degrees max advance on full tilt. I'm assuming the DTA has ignition modules. If you can shut the injectors down low enough on the low end, you might be able to get by without the use of a rising rate regulator and just tune the whole fuel curve with one fuel pressure setting (1:1 rising rate adjustable regulator). Go to a larger MAF sensor and use it to tune. Don't know, maybe the DTA can do speed density (MAP) as well?

The 944t guys run about 20 degrees advance full boil but that is a 2 valve head....you may be able to go higher. Tune it with some margin of safety for yourself.

I've decided on 20 degrees max advance at full boost, I was running 25 degrees before. The extra 5 degrees was granted with the use of an air dremmel tool on the pressure retard stop. Glad I have a distributor...makes life very easy. Problem is one adjustment changes the whole curve, not just the part I want to change. Nothing is optimal unless it comes factory anyway so we live with the changes we make.

Good luck on the deck plate....that sounds like a lot of work...I have seen those welded in place. A CAD drawing of that would be easy.

BC

....The DTA will run sequential injection (39lb injectors running at 60-70% duty and sequential ignition(CNP - Coil Near Plug), . While I am planning on having a wide band 02 in conjunction with MAP and TPS inputs, there are trims for tempature (air) and coolant involved as well. With the sequential, I may take the plunge and do eight exhaust gas temp sensors when I supercharge, as that will let me trim each cylinder individually. And it will look cool with 8 tiny temp gauages next to the boost, oil temp, trans temp, fuel pressure, carge cooler water temp and head temp sensors. Maybe I could do without the head temp with those exhaust gas temps. I would probably put a "link" brand knock sensor there as well. IT is calibrated to the car its installed in and would be extra insurance.


The deck plate doesn't have to be hard - Honda guys buy them in aftermarket stores, and slip them in in there back yards. I would have the deck plates made (aluminum I suppose) and shouldered onto the block and THEN the boring and nikasil (or other).

John.

Be careful with MAP.....I hear it is hard to tune properly for a street car. Great for the track though. If the DTA is already seup for it I'm sure it can work. A lot of the new systems use MAP or MAF. I looked at the Link Electrosystems, but it could not work with L-Jet. Split Second was the only company willing to work it out. I assume it is the first on a 928, but I'm not sure?

Sounds like you'll have $1,000 in instrumentation in there.

How about running those pipes down in front of the car, mount a massive air to air unit, then feed back in under the plenum?

I like the idea of a water to air unit, but at full boil steady state they just become like an air to air unit, because you have to drop the heat at a remote location anyway. Would have good heat storage capacity for the occassional full tilt and they are obviously used when you have limited space, which is an understatement on a 928.

I'm still amazed at how much is crammed in my engine bay, yet hos stock the top side still looks.

BC

Limited space is very important as a consideration. The water to air efficiency is higher for the space it takes up. I can put ice in the tank when I go to the track for someextra detonation-insurance.

There really is no room for a simple air to air on the S4 with all the other stuff I want. I think the air to water idea is great - its just not used in production because of the end-user issues with plumbing, etc.

GM uses map on thier production vehicles. With some trim from other inputs, I think I will have a fully streetable package, with full tuning capability.

Warren928

Here is an intersesting question, just a theory question. i own a specialized sign shop and we have machining equipment here i could use to make this piece for just the cost of my time and material.

Suppose a person was to make a sandwich plate made of .030"(or suitable thickness) aluminum, then sandwich two head gaskets between them, therefore eliminating gasket flex, could this reduce the compression issue enough? Has anyone tried this?

How much does an extra gasket change compression?
how thick would the machined aluminum sandwich plate need to be for a 9.0 or 8.5 to 1 CR?

I would imagine .090" or .125" thick aluminum would be ideal because its thick enough to be strong under high stress.

I could make it out of 3000, 5000 or 6000 series easily, whats more compatible? their all aircraft alloy grade aluminum from my memory.

If we raised the deck .125 inches or more which gaskets would need to also be thickened or custom made?

Old & New

Errr, I think you had better look around. The supercharged Ford Lightning truck used one. (How long ago???)

GoRideSno

I'll add 2003 Mustang Cobra and Ford GT40 to the air to liquid intercooled from factory list. I have read about others too. It seems to me the plumbing is less complicated, since you use much smaller tubing/hoses.

I got this idea from Brendan and will be working on it soon. I am thinking of removing the spare tire and replacing it with a ~3 gallon tank of some sort for the intercooler. Something with a big enough lid so I could open it and drop a few bags of ice in it. The resivoir is more important than the radiator used with the intercooler. It supplies the cooling water to the intercooler and the radiator does it's job after the charge air has heated the water.

Andy K

BC

I did not know aboutr the ford Lightening. I would much rather have a production car with an air to water then anything else. Its great for changing, and the tempature-mass idea appeals.

The spare tire area, as I mentioned, is a great place, as it can then be plumbed down and under the car to the actual intercooler, and then the radiator could be anywhere. Cool stuff. It may make the battery difficult to get to though... :O)

John..

I agree, the radiator is less important than the mass of water in storage.....until you get to a steady state, then the radiator becomes very important. At that point the air to water unit becomes a complicated air to air unit....i.e. heat the water then transfer heat back to the ambient air through the use of the remote radiator.

The ice is a cool concept but not of much use except for a drag race or short bursts. Some really super efficient intercoolers have been made for offshore boat racing, where the water is in fact the ambient source where the heat is dumped. You can get hyper efficient numbers....over 100%

If anybody can invent an intercooling system for an automobile that can provide sustained ultra high efficiencies they will be an instant millioniare.

BC

Well, as a side update, its looking like 9:1 pistons by JE and they will be a bit bigger then stock. I have to decide if I am going to follow the bore plate idea to fruition or not, as that will dictate when I get the engine work (bore, plate) and what the over bore will be. If I do not do a plate, I will just go to 101 or 101.5. But if I can get a nice plate secured to the top of those towers, then I will do 103. That, and some port matching, no maf, early 32V cams, and headers will help me not miss that one compression point until I mUrph it.

Lagavulin

I found out that one of the intake cams require a different sized journal, so you can add that to your machining bill.

Warren928

With all the cost of machining and such, do you have numbers on what custom machining setups like the ones described would cost and who are reputable 928 custom machiners?

It sounds like a ton of money but i may be wrong.

Plus calculate in for if the machinists screw up, which does happen and your buying spare engine parts too.

For most people, it would be a wiser investment to buy a 911 turbo if they had the money for all the cost associated to that machining.

how well did mark hutchison make out with the 968 variocam setup he has on his 5.0 shark? I guess all this machining is not for the weak of heart.

BC

The only machining I would be doing (or having done) is to rebalance the rotating assembly after adding different pistons, and also to make the early 32v cams work. Thats it really.

John..

Sleeves, Nikasil, Plated pistons, coated pistons, or what combo of the three?

With the JE route....go through EBS out in Nevada. Ask for Don Weaver. It will save you a few hundred over going straight to JE. Also, you might want to stay with a stock Porsche size so you can use a stock Porsche ring pack....might save headaches on future rebuilds. The guy you want working on your pistons at JE is Jerry...he does most of the Porsche work. I have to say, the machining on my pistons was absulutely flawless in every aspect. The only thing I hated was their retaining clips....Porsche style, but like wrestling a snake to install. It took 4 hours for me to check ring end gaps, ring the pistons and install on the rods. My fingers looked like hamburger when it was all said and done. The guys at EBS don't recommend using JE's spiral locks, not sure why?

Make sure you get the 2618 pistons (they have another alloy available). You will need more piston to wall clearance, especially on higher boost. My engine runs 0.002 to 0.0025" piston to wall with a 95 mm bore. If there is one thing you want perfect, that it is. The last 0.0005 was because of turbocharging...JE recommended a minimum of 0.002 for the set...Millennium wanted a bit more clearance on the block, so I agreed.

You are approacing this project in the best possible way....now we just need to talk you into hanging some Garretts on the exhaust side and all will be perfect!

BC

John...John....John. Supercharging is just too easy, and there is just too much power to be had reliably, and with less plumbing. I'll murph this thing with the first ~9k I can get my hands on, and I will never look back. Well, except to see pretty much everything else on the road.

I have an "inside" guy with JE, so I will be getting my pistons, pins, and rings through JE this way. Kind of like your EBS people, but different. Being in SoCal, and within 45minutes to JE helps.

A Graham Bell suggests that JE says .003 for clearence on boosted applications. Not as much as some forged pistons, but JE suggests it. Looks like I will get the pistons made first and then send them when I get the engine done. Becuase the rings will come from JE, I will go to 101 or 102 just for that little extra bore.

A Graham Bell says something about pin keepers in his book, but I forgot what it was. He suggests one set over another.

Sleeves will be done when this block is used up, or blows up. I have a mechanic here that I gave my 81 auto engine to so he can "imagine" and "experiment" with his siamese and new tower ideas. All we need is money.

The deck plate idea is still not dead - its just looking like a alot of work and time and money I could spend on enjoying the car instead.