Turbo Owners

Sorry Dave just noticed this post. Kind of srange I didnt see it when it was fresh. I would love have a tech talk with other turbo owners. I havent had much time with mine but have driven it enough to have a first impression.

Blaine

Dave, I don't think Pat Micals monitors this BB but he built a twin turbo. Quite a setup from what I understand.

Not sure we need anything formal, but it would be neat to compare notes and compile a list of turbo cars with how each turbo system is done. I have a feeling that almost every turbo system is unique. Many older systems dont work well and those people could benefit from some others experience. I know my car runs very well even thought I have had some trouble with the efi system. I have been turbocharged since 1990. I only owned the car 3 years when I added turbos. Beating every Mustang and Camaro in town with a 4V carb engine was just not enough. It took me three engines to learn what it takes to make it last.

Jeff Kimball in Washington State has a twin turbo car though I dont think he is on the BB. Ken Green down CA is also building a twin turbo setup and I have been keeping in touch with him via email.

I dont have much reliability testing on my car though I feel it is built sufficiently to last. I did 3 years of research bufore buying the car and another 2 before I actually built the turbo system. The only think I would possibly think about changing is getting a turbine housing with a smaller AR to get them to come on just a little sooner. Right now I dont see anything from the turbos until 3500 RPM but once there it goes like a raped ape. It would be nice to have a bit more gradual of a torque curve for driveability.

Where is your boost threshold Dave? Do you find it pretty reasonable for street driving?

Blaine

My car is very easy to drive. I also want to go down in A/R. I get boost starting at 2000 and have full boost at 3000 (10 psi). I want full boost by 2500 or even 2000 rpm. Just dont want to get to restrictive. Currently I dont have wastegates. I just use a home made blow off valve to regulate boost. This winter I am adding intercoolers and Wastegates along with the new turbo housings and a custom intake. It is time to play with my car again.

In town driving is really good. I have a progressive throttle linkage I rigged up to make it less sensative. I can drive it like any NA car. Then if I stomp it the boost ramps up and it pulls like a train. The boost comes on slow enough I dont really have traction problems, yet. We will see when it is modified. On the track it runs well. If you keep it above 4000 rpm then you have almost instant boost like a blower car.

My setup is a 375 cid with a Hydraulic Crower Cleveland Turbo cam (older grind). I have a wild custom roller but got tired of changing the bronze gear. The turbos are Turbonetics with 0.96 O trim turbiines and H trim compressors. My headers are a mini header style.

Bart Lowrey in Southern California has a twin turbo Pantera, but I don't think he is a regular on this list?

Dave,
Sounds like you have quite a jump in HP coming soon. It seems like we are opposite for boost control as I run wastegates but no blow off valves. I hope to get one mounted this year. I would like to rig up a progressive throttle system but it is pretty low on the priorities. The car is manageable now but gets a little hairy as the boost comes on fast. I have a solid roller Comp Cam 248 intake 252 exhaust at .050 with 113 lobe sep. It seems to start building power at around 4000. I am running distributorless ignition as well but use a dry sump system so the gear on the cam does abolutely nothing. Eventually I want to change my system to a sequential setup but that wont hardly load the cam gear at all.

Blaine

Blaine, the progress throttle is very easy to make. It can be done in one of two ways. The first way is how I did it. You use a right angle linkage. The cable pulls a near flat lever. The cable side pulls just like a carb, across center. The other side of the lever has a solid rod to the throttle body. But it does not connect at the correct angle. It starts almost flat instead of the typical 45 degrees. Then as you press the throttle it progresses up to about 100 degrees. This way as you press the throttle it actuates the carb very little and when it is opened up it moves faster. Makes off idle much easier. The other way is to use a loose cable and wrap a milled ecentric attatched to the throttle body. This is the way it was done on the GM Tuned port cars. You can change the rate of the ecentric to change your progression rate. It is easy to do by just drilling a hole in a pulley off center and mount it to the throttle body.

Your cam sounds pretty big for the street. Is it a turbo cam or a standard grind? This might be part of your problem with the sudden boost. I smaller cam with less duration might help. It also shows a longer exhaust than intake which is a blower cam. Turbo cams have a longer intake and close the exhaust quickly. This prevents the turbo back pressure from blowing back in the intake valve when it opens. This also makes for earlier boost. My cam only has about 15 degrees of overlap. I suspect you have about 80 deg. If you want a custom grind roller cam, I have one I had made by crower I am not using. I am not sure where the cam card is but it is like 246 intake and 238 exhaust at 050 and only 268 or so at 005. Overlap is like 30 deg. It has a very agressive lift and lifts to over .600. It was custom speced by Danny Crower simiar to one of their salt flat cars. When I ran it it worked very well, but I didnt like the idea of changing the brass dizzie gear. For you this is not a problem. You are welcome to try it if you like.

Dont spend your money on Sequential injection. It does very little for a performance car. The semi-sequential is just fine. Sequential is used for low throttle emissions not WOT power. Trust me on this one. When you get up to 6000 rpm, the injectors are open about 90% of the time anyway so you are injecting on the intake, compression, power and exhaust stroke.

quote:

Dont spend your money on Sequential injection. It does very little for a performance car. The semi-sequential is just fine.

Dave, what is the difference between the two?

Thanks.

The eccentric cam throttle setup sounds very easy. I might tackle this one in the future.

I expected the camshaft to be a bit big for street driving as I requested one for race use. I plan to race the car and dont mind dealing with less driveability around town. The cam was a turbo cam albeit a big one. The overlap is 54 degrees so its not as bad as you might think.

The only reason I would be interested in sequential injection is the ability to trim fuel to each cylinder. Im not sure I have optimum air distribution in my motor so it would be nice to be able to trim it out. Electromotive makes a cam sensor that bolts directly into the distributor slot and it runs about 150 bucks. Seems like a reasonable price for the setup.

I would also like to get an 8 channel ego guage. There is one online called a stratomaster tc-2 for 250 with another 250 in thermocouples. It is an aviation guage with with an LCD screen that is completely configureable and displays all 8 cylinders at the same time. Its a bit pricey but far cheaper than any equivalent ones I have seen. There is no better way to catch problems before they cause bigger problems.

Anyhow its time to go eat some turkey. Hope everyone has a fun and safe holiday.

Blaine

First,
The difference between Full sequential and semi or phased sequential. Full sequential injection will inject fuel once per engine cycle or every 2 revolutions. Old school methods were to inject on the open intake valve. However, it was found that the droplets were too big and it was found better for fuel econemy and emissions to inject on the closed valve. Then when the valve opened, the sharp edges of the valve atomized the fuel. At full throttle and top RPM where most HP is made, the fuel is injected for about 90% of the time. This means that the fuel is injected on both the open and closed valve. Full sequential injection requires a camshaft reference.

Phased sequential injection injects once per revolution or twice per engine cycle. It typically hits both an open and closed valve. This is a good comprimise for a retrifit and has a minimal effect on fuel econemy and emissions and no effect on power.

The oldest method of injection is batch fire where all injectors fire at once each revolution. It is anyones guess where they will hit on the valve being opened or closed. Batch fire works just fine and will give 99% the power and ecomemy of the sequential methods.

Blaine,
You dont need full sequential to do injector trims. Most computers should be able to do this with phased sequential and individual injector drivers. Unless you plan on some serius full time racing, I would not bother. Even Factory cars have injector trims such as Ford, but in the ECM, all the values are zero.

Dave,
As you know with low impedance injectors the electromotive system in phased sequential is only able to control the main driver that cylinder is sharing. In that case it will trim two cylinders instead of just the one which kind of defeats the idea of individual cylinder trims. The OEM's have a lot more research in their intake designs and I am sure their air distribution is much more even than mine. Until I rebuild my intake system I would be more comfortable in knowing all cylinders were getting the ideal AF. I know it is getting picky and quite likely I will never do the conversion.

Blaine

I have twin T66's on my pantera using an Accel Gen7 Ecu, and it is running flawlessly (even passed emissions here in AZ). Currently I am running a base boost of 7psi, and it's making 605hp to the wheels with nearly the same torque (598). Throttle response is perfect (no flatspots whatsoever), idles perfectly, never stalls...couldn't be happier. When I get a bit more time to play with it, the boost is going up to 15psi to get the turbos where they want to run! Here is a quick picture of where I am so far!

A quick question for all you 'horsepower endowed' Twin Turbo guys.

How many of you are running a Cleveland block? I know Crazy Dave is as he mentioned it in a previous post, what about others?

Still on the Cleveland block here. I am just keeping the rpms under 6500.

That is one cool setup Jason. What size is that cell? You must have good range with that beast. What are the individual coil packs from? I cant quite make out what those components on your intake runners are. Are they injectors? It looks like you are running your intakes through the side scoops. What are you doing for filtration? I want to do the same thing but my turbos are not mounted in quite as forgiving of a location. Excellent job!!

Joules, I must say I am not running the Cleveland block. Mine is an Windsor.

Blaine

Thanks Blaine! The fuel cell has 2 actual tanks in it, one is for pump gas, and holds 15gallons, the other is for methanol, and runs to the injectors you spotted. I don't have the system functional right now, but I use this system on a few other cars I have done with incredible success. It solves the issue of intercoolers completely, and adds octane ofcourse as well. Currently the intakes come through the side ducts, while it works well, it makes for alot of intake noise. I want to make new ducts that allow for a flat panel filter, but that will be awhile. Currently I use a screen for a filter...not the best, but for how the car gets used, it seems o.k. The Coil packs are for the next change which will be eliminating the distributor, and using a crank trigger system. I haven't had any problems with the current setup, it's more for looks I guess at this point. The car gets 24mpg on the freeway, as long as I am not beating on it.

Can one of you Turbo guys describe under what conditions how/when you introduce the methanol?

Kelly

Methanol is normally used as a form of intercooler. It is injected to reduce charge temperature and increase octane. It can also be used as supplimental fuel in a dual injector system. You can run the engine up to a certian horsepower on gasoline then add the Methanol to move hp up further.

It can be done in one of several ways. Use boost pressure to pressurize a bottle and force it in upstream of the turbo. Use a pump to inject it in via an orfice or injectors. Or other methods.