The Evil Muffin said:-
don't remember much else from the post, but i do remember that little tidbit, maybe he'll see this post an expand on it
well... and the fact that X said he was gonna work on plans for a turbo header....
X said yes.
I can say that it's still ductile iron, its still fits the stock log, and it eliminates the service issues I've seen on most aftermarket installations. And if things go okay with my current commitments, you'll get to see it, then use it soon enough. Ductile and SGI is a speciality down these parts. I'm not knocking the sensational work Does10s, Import Killer, the66mustang and others have done, but I'm sceptical that any turbo header system would last six months of regular use if it was welded. The amount of head is simply huge, and the starter and alternator are under stress. Ford Australia's XR6 item is a benchmark. Investment casting with green sand isn't that expensive, and after seeing the the current bread of Supra RZ and X-Flow aftermarket items, I'd never want one for fear of it cracking.
As
addo and
Ecconline-64 and others know, I may be s-l-o-w, but you'll end up with the goods soon enough!
Let me be clear. I've not made an In-line six turbo, but I've done a 2.3 V6 Colonge, IHI turbo and LPG conversion at 6 pounds. 9.0:1 compression, electronic ignition, blow through via Endecots sieve reciever covering a CA 300 Impco carb. It was easy to do, but never worked well because it was done on a 120 000 mile Cortina. That doesn't make me any expert, so you can take it all with a grain of salt.
The issue with any 200 Turbo is this: Detonation! If you had a compression and fuel delivery distribution right, you could run a 6.5:1 compression, twin 2-bbl 350 Holley'd turbo 200 to 20 pounds on the street. The intercooling just adds effective boost and gains a little more power becasue its less likely to detonate.
That's enough for 370 hp at 4500 to 5000 rpm, perhaps 440 lb-ft at 3500 rpm. A TO3 Super 60 starts to look real small at that level.
The limiters to power are just fuel delivery, compression, and a means of richening the fuel circuit according to temperature and boost. Ignition advance is tailored to suit, should be less than 35 at low boosts, down to 25 to 28 at very high boosts.
The reason Jack dislikes the carb concept is that he's possibly never seen it work well on a volume production car in America. In England, the Esprit Turbo and Mini Metro Turbo ran the same size TO3, and both ran a carb set-up with considerable success. (Low boosts, but the Metro ran a 9.4:1 CR and 4 to 6 pounds of modulated boost)
Any engine is detonation limited. I have worked through the failure mechanisms at a theory level on every production carburettor turbo, and the exhast, fuel distribution, head gasket, and ignition woes feature again and again. Hot fuel soak, fuel running out at wide open throttle. Bensons turbo systems in Australia isolated it. Run any turbo lean, and you'll kill it.
Jack favours EFI with fuel and ignition control primarily because anyone who want's a 300 hp 200 cube turbo badly enough should be smart enough to save the headaches, and do it once and correctly. An EFI turbo won't put you crook if you follow the rules. SDS, Megasquirt, Delco, Haltech, Motech and Holley make these systems.
As for me, I've seen to many foolish people spend more money than I've ever seen on name electronic gear, yet have them behave like asthmatic horses at the drags. Give a person enough rope, and they'll hang themselves, no matter what the system. Turbo's do not suffer fools gladly.
My hit list is
a) Mustang Geezer style twin carbs.
b) Two Holley 2300 carbs with
stock power valves and an idle control circuit plumbed into the adjustajet set-up. These are the after market screw jet systems. How its done is so simple its scary. The IC stepper motor turns a special rack and pinion set-up, and this richens or leans the effective size of the main jet from 60 to 100 thou. This trims the fuel air ratio to below 14.7 to above 12:1 under load and boost if you use the stock EEC computer. There are early Fairmont and V8 Ford systems that run an fuel control valve. The key is getting the car to lean cruise off turbo, then richen up underload. It requires a wide angle O2 sensor for comfort, or you may be able to run the stock 45 buck Lambda sensor. There is no rocket science in it. It's 25 year old technology.
c) The Holley carb can handle 9 to 12 psi boost if boost referenced. If it is enclosed, it can take more than 20!. Brass or nitrophyl floats are a total waste on any turbo engine. Biff them, and use the David Vizard set-up.
The floats can be removed entirely, and a standpipe set up with a restriction jet plumbed up. Race tank foam is added, and a bleed off pipe is used to control the fuel level to equal that of the stock float in the carb. That's the stock half inch below level, with the site glass level maintained.
The delivery of gas into the carb can be done by a 7-psi mechanical pump at even 20 psi if you follow Dave Emanuel's set-up in his 1980's Holley carb book. Who needs Hobbs switches, dangerous systems that squirt raw fuel into the engine bay in an accident. Then a simple Holley blue electric fuel pump takes the excess fuel away via a fuel return line. A fuel cut-off switch can be used to stop fuel flow, but the delivery runs under only 7 psi boost when the boost referencing drops off. A simple propane fuel trick.
d) The rest is as per good turbo building practice. Ignition control can be any modern set-up. Boost retard isn't mandatory, but remember, best fuel economy is via very high advance under part throttle, and detonation under boost will kill a piston like a hot knife through butter. It's best that it run up to 35 degrees under no load at 3000 rpm, and then drop back to perhaps 25 degrees BTDC under boost.
When I've done mine, I'll publish the details. If you read every David Vizard and Dave Emanuel Holley book, and then scrutinize the Lotus Esprit Turbo and Metro Turbo systems, you'll understand the systems. Look also at the GM Regal and JetFire set-ups, and case study the early carb 2.3 Mustang flop. You've gotta understand why a modern EFI turbo works too. I'm against any electronic system that requires comprehensive mapping, because I've yet to anyone set one up properly unless they have a dyno and race the car in weekends.
My machinist who does my head, block and manifold adapters used to run a rear wheel drive Escort race car with a Link computer and the non-turbo 300ZX V6. The computer was 1500 NZ dollars. With twin TO3's, he got 285 rear wheel hp. He followed the set-up instructions, and safeguarded a 16 psi turbo installation on a 9:1 compression engine. After selling it, the new owner is up to 350 rwhp just via dyno tuning.
Since most of the work is dyno tuning, I don't think its worth it paying for EFI. An engine that detonates on a dyno and its caught, it is
good. You can then fix it in an instant by locking advance, dialing in the right air/fuel ratio, and then deal with peak boost via a waste gate or other means. It's more likely a car will over heat on a dyno, so its simply the best way to gain a huge factor of safety. I'd rather spend 1500 bucks on a dyno tune, than 1500 on any computer system.
dEANO
