'51 GMC,4200 Vortec DOHC - Turbocharged

[SpiderGearsMan]

got a head off a 5 cylinder atlas in an H3 at the moment

[efi-diy]

5 hole atlas

While you have the head off - drop the exhaust valves out and port the bowl into the runner... 20-30 HP or more locked up, especially if the head has a plastic valve cover. Don't be shy there is enough wall to take out 0.1" easy.

[efi-diy]

Update time

Engine is now running full sequential EFI on MS3 extra. After the last trip it needs to come out for inspection/repair.

Finally got the last parts to bolt the 4L80e to the 4200. After breaking the tail housing last year I decided that it was time to design the parts to get a 4L80E bolted up. Got the mock up completed tonight. No more worrying if the 4L60/70 is going to gernade under boost. This winter I'll add a proper billet girdle to the engine and that is the last piece to allow the boost knob to head to 20psi. Currently at 10 and it makes 510 RWHP. Probably more now that the 9" is gone.

Got tired of waiting for GM to come out with the 8 hole crank spacer so fired up Solid Works and did my own.



Uploaded with ImageShack.us

Uploaded with ImageShack.us

[Beagle]

Damn, that's gonna be cool at 20 pounds. Are the ears for mounting? I can't see the passenger side...

[milner351]

Impressive work as always - ah to have modeling expertise and access to a machine shop!

[efi-diy]

There are ears on both side os the plate and when the boost gets cranked I want to be able to tie the engine down to frame mounted brackets. This will reduce the stress on the LH side of the block. It'll be used on a as needed basis to maintain rubber isolation for every day driving.

I'll add the holes once its installed and I have a better idea where things fit.

[efi-diy]

4L80E - update....

Finished assembling the '80 tonight with the Jake Tbrake. Thats going to be a new experience - being able to spool and leave at full boost. Think I'll be easing into that until I know what the trucks going to do when the TBrake releases.

Now that the trans is done I can get it off the stand and get the engine out for servicing... sure we're going to find pounded out rod bearings - I haven't started the truck since getting home with it 2 weeks ago. Its going to be a noisy cold start...

I'll add more pix when the engines apart.

[efi-diy]

engine update....

Ever hear a gas engine sound like an oil burner on start up... this did crap.

Long story short all the rod bearings opened up at least 0.0008 to 0.0012 the worst being #6 with 0.003 bearing clearance. Good news is the mains and the crank look mint so that is a relief. I'll get the crank out and send it in for a light polish on the rods journals to get slightly more bearing clearance (last go was 0.0015
to 0.0018 ) which is a tad tight.

The expensive part is I need new pistons/rings, the skirts were so darn short on the J&E's they collapsed. I'm keeping them for *future* usage maybe to run F-BM/MT as 4 out of 6 are reusable.

Also modifying the head to use a different style plug so I can get a colder heat range. The coldest stock plug is a close to 10 heat range in a champion plug. A bit to hot for boost.

If the parts had got hurt at full power - fine but at cruise - well it sucks.

[efi-diy]

update....

Well after a long pause progress is happening, the engine damage was more involved that originally found..

- new pistons/rings, the previous ones would fit nicely in a stock bore engine - already - preclearanced..
- replace the small end rod bushings
- new rod bearings..

While the engine is apart it was time to prep for an power step up..





Put a bit more static CR back into the engine - hopefully it will have a bit more torque at the bottom..

[Beagle]

fwiw, I clicked on the links to look at the images and my a/v just went off with some kind of "fake a/v" alert for Rogue.JS/FakePAV ...

Good to know it's coming back together!

[efi-diy]

Anyone else get this AV message?

[TheSilverBuick]

I don't have any anti-virus things running, hopefully you didn't just give me a virus! j/k! It worked for me, went right to the image shack.

[efi-diy]

Earlier this year made a decent pump gas pass at the drags 11:60 @ 118 leaving at 5 psi on the t brake. Then went back to the chassis dyno to tune up the methanol fuel system made 608 ft/lbs @ 4200 rpm (rear wheel) @ 18psi and 604 hp at 6200 rpm at 12 psi (ran out of turbo) boost fell off from 18 to 12 psi ...

Weighted the truck... 4350 lbs.. not a flyweight...


Road trip to Reno and Speed week.

Ate the turbo compressor wheel 400 miles from home, lost reverse in the 4l80 in Reno, but the diff mounted A/C compressor worked well enough to keep the frying pan cool (cab) enough to be tolerable. Finally have functional cruise control...

Put the truck in the Nuggett car show..


After installing the replacement turbo .. $ ouch

http://s240.photobucket.com/user/nex...30aea.jpg.html


http://i240.photobucket.com/albums/f...psbe2ff353.jpg

Bville at last... with Erik's 50 blue&black GMC rolling on a trailblazer chassis - 4200 powered.

[squirrel]

nice! I guess you still have a few bugs to work out, but being on the road with it is really cool

[Russell]

I have always liked this truck i am glad you are still enjoying it! I have never heard of diff mounted A/C, the faster you go the cooler you get?