[jdw_poncho]

Finally making some progress on my twin turbo project. I ended up with twin 78mm Precision turbos that will be run on a 512 IA2 run on methonal. Hope to have the engine on the dyno by the end of June if I get all the parts bought and the shortbolck built before then. At least thats what I shooting for, doubt I'll have it ready to run in a points class but at least I'll have time this year to test it out.

I still need to cut my old cage out and install a 25.3 cage, new rearend and re-do the tin work. Its going to be a tough few months trying to get it finished.

I almost got the "easy" header done, except for one tube I need to re-route. I'm sure the driver side wont be finished as fast. But luckliy I have to re-route my steering for the rack anyway so it wont go in the stock location.

I had 2" tube bought for this but it didnt take very long to figure out I couldnt get the radius I needed to clear the A-Arms so I went with 1 3/4" tubing the entire way. I was also looking for a 4-1 transition to the turbo. Everything I found was over a $100. I couldnt see paying that for 4 tubes and piece of 3/8" flat so I built my own. Did some research and figured out the correct angles need to make it work. Built it from .095 ERW tubing and 3/8" flat. I tried using the 16ga tubing but it was tough trying to mill out the miter cuts on thin tubing. The .095 allowed me to make bigger cuts and the tube still keep its shape.
I bought all the materials to build a set out of stainless but decided I wanted to use mild steel first in case I made a lot of mistakes.

My plan is to run low 5's in a drag radial class at Eddyville or KCIR. I would like to hope I can push the car to 4.90's but 5.20-5.30's will be a handfull to start out with.

I still have to get the second set of injectors installed and the entire fuel system bought and plumbed. March is going to be a expensive month.......
New JW trans should be here by April havent picked a converter yet.

[baron_]

Neat stuff. Very neat stuff.

[Johnny406]

W-O-W, now that is a stimilus package!!

[jdw_poncho]

Originally Posted by Johnny406

W-O-W, now that is a stimilus package!!

Not for me!!! LOL Just trying to do my part.......

[bankbook]

Nice build. Glad to see another turbo Poncho!

[bryansMtngto]

very nice looking set up so far. Look foward to more pics as you go. Toying with idea of doing twin turbos on my 77 T/A.

[aasmilyy]

your car looks awesome! Greet work!

[jdw_poncho]

Thanks guys. Progess has slowed down as work picked up. I think I finally have this weekend off so I can make some progress with the cage. I havent touched it in 5 weeks and its starting to show.

[jdw_poncho]

After being up 30 hours straight we got the engine dyno'd. Made some big power but had a few problems. Spend at least half the dyno session getting the engine wired and hooked up. Next time I go I'll have a better understanding what is needed to help save the time.

They spent some time trying get the FAST system tuned and capable of running the engine on methanol. Then started making pulls while trying to keep it fat enough. It seemed like he was constatly adding fuel and it would make more power.

We proved that a vacuum pump will not work on this engine. I seen people run their engines with it and without vac pumps so I decided to try it. It pushed oil out anywhere it could.

Finally made a few strong pulls. From the picture you can see it was making good power but we couldnt control the boost. They told me my exhuast housing are way to small and the waste gates didnt work very well.

It was blowing exhaust out the gate it just seemed like we couldnt get enough out to control it. This was the best run in all, then the bad stuff started happening. Next pull power was down about 100hp at the same 4500rpm. We stopped and pulled the plugs looked over the data and realized the fuel pressure was jumping around a little bit. After checking that out we decided to make another pull. This time the upper hose blew off and sprayed water every where at around 5400rpm. Hopefully its just a head gasket failure. But it ended my day with only 2 hours left in my dyno session. I brought a gasket but I didnt think I could get it done that quickly.

EGT's were staying good all day and never got above 1080 degrees. The last run we were worried about watching the fuel pressure and both of missed the egt's going over 1300 degrees. But it happened so fast that most likely I still would have had damage.

After getting some sleep today I'm starting to pull the motor down. All I know is I'll have to sell these turbo's and step up to a mid-size frame or a big single.

But you have to admit 1500ft/lbs of torque at 4400rpm's would make a hell of a street engine for someone if they wanted to buy the turbo's.

What we figured happened was the injectors were losing their signal or quit driving because the fuel pressure was jumping from 73lbs up to 100lbs within a few rpm's. Thats where the 1300 egt's came from on the last run.

[cgeise]

Trust me - you will need to do them in stainless - the mild sreel will not last under the heat

[jdw_poncho]

Originally Posted by cgeise

Trust me - you will need to do them in stainless - the mild sreel will not last under the heat

What type of stainless did you have yours built out of? 300 or 400?

We use a lot of 304L tubing at work, I know the problem I have there and was concerned how long the stainless would hold up. It tends to crack easier after too many high heat cycles with fluid running through them. Maybe 409 series would hold up better?

I found a company that will digitize my current headers and bend them up out of stainless. The cost is a bit much for one set but if I figured my time plus materials its probably not that out of line. Espicially if they work well.

Do you run methonal or race gas in your car?

[cgeise]

Originally Posted by jdw_poncho

What type of stainless did you have yours built out of? 300 or 400?

We use a lot of 304L tubing at work, I know the problem I have there and was concerned how long the stainless would hold up. It tends to crack easier after too many high heat cycles with fluid running through them. Maybe 409 series would hold up better?

I found a company that will digitize my current headers and bend them up out of stainless. The cost is a bit much for one set but if I figured my time plus materials its probably not that out of line. Espicially if they work well.

Do you run methonal or race gas in your car?

I run gas - C-16 - but I know that at 10 lb of boost on the chassis dyno they were glowing red - and the tune was fine - To be honest I dont know the spec on the tube - but could find out -

[jdw_poncho]

Originally Posted by Hooter

What are you putting this in?

69 tempest- I think I have a couple old pics when I first built the car.

Originally Posted by meanone

Cool build! The driver's side was easier for me, but mine's a different car. Who did you find that would digitize and reproduce headers? I thought about having a couple sets done. Probably not after I get a price, Lol!

I have the contact info at work. I cant remember the exact name and tried to google it but couldnt find it, I'll look tomorrow. You have to decide what you would be willing to pay before you call them. Its high if you compare to a single custom set and you still need weld them your self. But if I wanted to reproduce them it worth it to me. Thats why I thought itr would be worth the money if I needed to build a few sets over time. I found a couple shops that will do this, you pay for a min time for design and engineering then pay them to bend up the tubes. That first time engineering fee will hurt you if your not expecting it. LOL
I'll get the info

Did you use your stock steering box and shaft? I have a rack and pinion so I plan on re-routing my steering down under the headers through the cross member to keep it out of the way.

Originally Posted by cgeise

I run gas - C-16 - but I know that at 10 lb of boost on the chassis dyno they were glowing red - and the tune was fine - To be honest I dont know the spec on the tube - but could find out -

I'm seeing everything from schedule 10 304L pipe being used to 409 series. It seems like everybody uses it but I know how it reacts to heat. It work hardens and cracks after extreme heat cycles. I'm guessing my 16 gauge mild steel tubing wont hold up turning red very many times. I may end up with schedule 10 pipe instead of .083 304L tubing that I bought.

[Hooter]

What are you putting this in?

[meanone]

Cool build! The driver's side was easier for me, but mine's a different car. Who did you find that would digitize and reproduce headers? I thought about having a couple sets done. Probably not after I get a price, Lol!

[taff2]

JDW, if you take your completed primary pipes to an decent pipe bender he will copy each pipe out of a single piece of tube,the only welds then will be at the flange and the collector. This is how I'll be doing mine (only using lengths of gas welding rod to make a 'template' of each primary pipe to take to the bender),and then I'm going to get the completed headers plated,probably black chrome.

[62fatcat]

Cool biuld!
Nice work!

[BruceWilkie]

I like this build!

Try to build a bracket that fully supports the turbo at the exhaust flange to take the weight load off the header pipes. My old turbo corvair the factory had a .125" thick bracket that bolted between the turbine inlet and the head pipe and the bracket attached to the motor. Even after upgrading the turbo the original 1962 head pipes never had any issues.(I had that car till 77) I'm sure the cast log manifolds helped pull some heat out, but with aluminum block and air cooled there had to be considerable expansion/contraction going on. I think I can find a picture of the turbo mount if your interested.

btw currently putting a turbo on the 305 in my 84 GP till I can build a worthy Pontiac motor. Doing it as inexpensive as possible. Even making my own flanges(3/8 plate and remains of an old set of 1.625 pontiac headers). I'm using whatever I can scrounge cheap or free. (plasma cutter tips are pricey for what they are I've burnt up two so far). I decided a rochester 2jet from my old 68 Catalina will be adequate for the 305. Surprisingly finding a large base sbc 2 barrel intake wasnt easy but I did get it near free. I might get this whole project done under $500 including the turbo I bought.

Best of luck with yours, its certainly a lot nicer.

[jdw_poncho]

Originally Posted by BruceWilkie

I like this build!

Try to build a bracket that fully supports the turbo at the exhaust flange to take the weight load off the header pipes. My old turbo corvair the factory had a .125" thick bracket that bolted between the turbine inlet and the head pipe and the bracket attached to the motor. Even after upgrading the turbo the original 1962 head pipes never had any issues.(I had that car till 77) I'm sure the cast log manifolds helped pull some heat out, but with aluminum block and air cooled there had to be considerable expansion/contraction going on. I think I can find a picture of the turbo mount if your interested.

btw currently putting a turbo on the 305 in my 84 GP till I can build a worthy Pontiac motor. Doing it as inexpensive as possible. Even making my own flanges(3/8 plate and remains of an old set of 1.625 pontiac headers). I'm using whatever I can scrounge cheap or free. (plasma cutter tips are pricey for what they are I've burnt up two so far). I decided a rochester 2jet from my old 68 Catalina will be adequate for the 305. Surprisingly finding a large base sbc 2 barrel intake wasnt easy but I did get it near free. I might get this whole project done under $500 including the turbo I bought.

Best of luck with yours, its certainly a lot nicer.

Thanks, Its a big project to tackle by myself. I have a bracket made to attach the collector flange to my j-bar. It lands about 2" from it, so that should stiffen it up a lot.

I ended up milling out my collector flange and had a water jet cut out my header flanges. Using a plasma makes it tear up end mills so I wasted my time cutting one out. I'll have the water jet guys cut them my stainless flanges out next time.

Good luck on your project.

[BruceWilkie]

If you are frame mounting the turbo you may want a flex joint in the exhaust to keep "piping" forces from ruining the turbo(s).

I used up a grinding wheel cleaning up the plasma cuts on the outer edges of all my flanges, and had to sharpen my die grinder bits a few times truing up the centers. Wish I had easy (cheap) access to laser or water jet. I should have used my cut off wheel on the square flange for the turbo mount. I'didnt even want to attempt using a hole saw for the centers.