Hello,

I have just completed putting a small turbo on a Dodge 225 slant 6. This is my first attempt at turbo charging and I have some questions and apologize in advance if the questions may seem stupid but this is all new to me.

The engine fired up right away and with some minor idle adjustments was able to idle but not well and dies when put into gear. I have not had the engine warmed up yet as I live in a residential area with cranky neighbours and have open exhaust out of the turbo still. I have not been able to drive it on the street yet as I still have my front suspension apart but while the car is down would like to do as much pre tuning work as possible. After stumbling across your forum I have as many answered questions as unanswered.

What my intent is to start out small and use this stock engine as a learning tool while being able to upgrade the performance and still retain fuel mileage. I have read about similar setups getting 20 mpg and being able to run 15 second 1/4's.

Here is my setup:

1970 Dodge 225 slant 6 stock. 8.4:1 compression

Offenauser 4 BBL Inatke

Holley 390 CFM Double pumper #6895, 59/59 jets , 6.5 PV (Pri and Secondary), 4 CORNER IDLE 30CC FRONT AND REAR PUMPS, 26 FRONT AND REAR SQUIRTERS, FRONT PLATE 5850 REAR 6118, DRILLED AIR BLEEDS, QUICK FUEL MASTER KIT, MODIFIED APXIED BOOSTERS

Turbo Specs:
-Model: Garrett/Airesearch TB0335 (T3 Series)
-OE Part #: 466298-7
-Wastegate setting: ~7 psi
-Compressor Trim: 50
-Turbine Trim: 69
-Compressor Housing a/r: .42
-Turbine Housing a/r: .48
-Oil and Water Cooled

After reading many of the tech forum topics I am starting to think I have too large of a carb for this application or something that is just not going to work. Would anybody be able to clarify this for me? The carb is off of an oval track car and has had many modifications. If this carb is just "wrong" what would you suggest?

If I can work with this carb where would you recommend me starting? The car starts very easily, cold, with about 3 or 4 pumps of the pedal but then seems to want to cough and die about 6 times before it will stay running and then only if you keep the RPM up. As it is an automatic car it was a bit difficult to move into the shop.
Also, where is the best spot to get a ported vacuum source from? The carb has no orifices for this. I have added a small manifold to my bonnet.

When I use to drag race naturally aspirated engines I found that fuel pressure in excess of 7 psi started to lift the needle off the seat in Holley carbs yet in turbo apps much higher fuel pressure is run and I have read nothing about htis. Am I missing something?

Please take a look at my setup and tell me what I need to change as I did this with minimal information and have been trying to make educated guesses. I have drag raced for many years with naturally aspirated engines and second guess myself when it comes to the boost/vacuum situation.

 

I think the carb will be alright size wise. The cold start thing is the way the carbs ar without a choke. You can tune it to start a little better by richening the idle circut but you can only go so far with that. I would think about adding jet to the rear of the carb but havent tried a engine like yours before. You will have to get it warmed up to set the idle mixture and speed. It will run much better after that. I would invest in a wideband to get it running just right. It makes a world of difference. Run 6-7psi base fuel pressur. You do have a boost referenced return style fuel system right??? You are on the right track.

 

Thanks for the quick response. I have run a 3/8 hose from the bonnet to a port on the mechanical fuel pump so I should have adequate fuel pressure.

Any idea on wholesalers for widebands in western Canada? I am in Prince George. BC.

Also, what are you running for an engine? I am looking into building a turbo 440 for one of my cars and will be starting to research that in a bit.

 

I misread your originalk email.

No I only have the factory fuel system with the addition of a Carter felectric fuel pump. Can you point me in the direction for some info on building a boost referenced fuel system. I will also check the forums.

 

There is lots of info on building fuel systems in this forum. I have never ran one but a boost referenced mechanical will work with the stock six. On the widebands I have found that if you keep a eye on the Sponsors classifieds forum you can see something come up. It was $50 cheaper to ship mine from Texas then it was to buy local.

I am running a stock longblock 383 with the exception of mild cam and stainless valves in the heads. It has a whopping 7.5:1 compression and I run 13-14 lbs of boost on 91 octane fuel. It is on its third summer. If you build one and don't plan on making a TON of hp you don't have to get fancy.

 

Man that is a really cool build,

As far as your running issue, Have you played with your Idle feed curcuits any, Have you pulled the plugs after it does this to see what they look like

the only problems I see is your fuel pump, with 7#s of boost and 7#s of base fuel pressure+14psi at the pump, Now I dont know what pump you have but to me that is cutting it to close, I would recomend an in line fuel injected pump and a return fuel system. I know a few people have boost refranced there mechanical pumps and had good sucsess

It can be done on the cheap

I found this link that might be able to help with your fuel pressure refrence issue http://www.salt2salt.com/TurboStude/ozmod.htm

Next I see that you have your BOV hooked up on the carb hat, It needs to be under the carb to see vacume when the throttle blades close.

You can get a small carb spacer with a vacuum port pretty cheap

Other than that it looks awsome, I aways like strait six builds

 

Thank you for the response.

I just read your message today but had done a bunch of research in the forums yetserday and realized that I had my BOV plumbed in correctly and was running my PCV valve to the intake manifold. I modified my air cleaner and now have my PCV valve running to the base which solves that problem. I then plumbed my BOV to the manifold so when the throttle plates close the vacuum in the intake will open the BOV.

I also have a line running from the small blue manifold at the carb bonnet directly into the vent of the fuel pump using a 3/8" line. This should keep my fuel pressure at an acceptable limit, I hope. I have not reviewed the link you sent but will take a look. I am using a Carter electronic fuel pump which has a maximum of 7 psi mounted in series before the factory fuel pump and am assuming this will provide an adequate fuel volume while the referenced mechanical pump will provide the fuel pressure.

After, I made these changes and wired up my electonic fuel pump the car ran much better. I think it was starving for fuel. It now runs and idles and seems to have very good response. The carb must have been on a much larger engine as it originally had drilled throttle plates in it and I know the air bleeds have been modified. I did have to turn the idle adjustment screws in and currently they are about a half turn out for the best idle. I am waiting for a set of larger torsion bars to come in. Once I get these I will be able to ge it to the front end and exhaust shop and see how it works driving. That will be next week.

As far as the build goes, it was my intent to try to keep this setup inexpensive and so far I am there. I have spent 1000 dollars on the intake, carb, turbo, BOV and electronic ignition. I built a custom pipe to connect to the factory exhaust manifold to the turbo. I am quite happy with the way it turned out as I like things clean. Now I just need to see how well it works on the drag strip! I am hoping to get into the 15's but we will see!

Thanks for the compliments on the build.

Cheers,

James

 

can you post images of your setup and the custom pipe to connect to the factory exhaust manifold to the turbo?

 

Very interested in your discoveries , new to forced induction also . Built a Ford small block six 250 with a T3 Draw-Thru turbo in a Maverick. Ran great until too much enthusiasm. Maverick 250 now has a Blow-Thru Supercharger using a modified common Holley 2Bbl and mods to fuel and ignition systems. smooth running engine NA before adding boost and careful monitoring of AFR gauge is where I start.

A few pics would help your response applicability.

have fun

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thank you