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gmc
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Discussion Starter #1
The 4200 enigne has a lot of potential for engine swaps and some folks like myself are starting to do them.


Well I don't have a trailblazer but I do have a 4200 in a '51 GMC running NO GM electronics ( megasquirt and FORD EDIS wasted spark). This winter its getting a GT42 turbo along with a stout bottom end (pistons, rods, darton sleves) and custom cam shafts. <<< doing the design for the CNC cam blanks this weekend.

Once we have the cam blanks ($500) then we'll send them to a cam grinder to get them ground into cams (another $700). The prototype turbo manifold is getting done at www.steedspeed.com. The CNC intake flange is enroute to start the build.

pix of the swap are here http://profile.imageshack.us/user/efi_diy/

Stay tuned parts are in the pipe.
 

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gmc
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Discussion Starter #3
Parts needed

What I'm having a hard time to find is a 2006 head.. anyone have any sources without buying a complete engine?
 

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2004 chevy trailblazer_ls
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888 Posts
I see heads and blocks on ebay all the time.

Im interested in this, before i even bought the TB i was thinking of boosting it, mainly a SC. But the more i look at it a turbo might be pretty good. Looking good so far :thumbsup:

Ive been looking for an engine for my s-10 blazer and this will put out pretty close to a carb SBC. Not the mention the 4200 is lighter than a 350, and it would mate to my 700r4 with no problems. I want to see some more info on your fuel and ignition setup as i dont want to run the electronics.n
 

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gmc
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Discussion Starter #6
. I want to see some more info on your fuel and ignition setup as i dont want to run the electronics.n

Well the 4200 does not have a dist. so you will need to run electronics for spark control. You could build a custom intake and run carbs - but why? It a lot less work to hookup a megasquirt than fabricate an intake. But thats just my take on things. If you do decide to go with a megasquirt I can send you the calibration file so the tuning will be real close.
 

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gmc
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Discussion Starter #7
Cam cores

Well the cam cores are designed and ready to goto the machine shop. We're getting them cut from 8620 round bar. GM does not sell cam cores for this engine and the aftermarket doesn't have them either - so the only way to get non-stock cams for this engine is to design and machine cam cores then send them to a cam grinder.

exhaust core
http://img213.imageshack.us/my.php?image=exhaustcamcoreld0.jpg

intake core

http://img215.imageshack.us/my.php?image=intakecamcoreix0.jpg

The next step is to settle on a cam grinder, currently Comp Cams will do the job.
 

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Northwest Chapter
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MEGASQUIRT huh?? :D Buddy of mine has been running that in his VW Scirocco and Rabbit for a year or so now. Swears by it, and hes NA.

Glad to see someone who uses this engine in a hot rod is actually posting up here for us!:cool: Good luck with the build, and if you have questions about the engine feel free to ask anyone (or me)!:D

What have you done with the exhaust cam VVT, nothing or have you swapped the cam already?
 

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gmc
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Discussion Starter #10
MEGASQUIRT huh?? :D Buddy of mine has been running that in his VW Scirocco and Rabbit for a year or so now. Swears by it, and hes NA.

Glad to see someone who uses this engine in a hot rod is actually posting up here for us!:cool: Good luck with the build, and if you have questions about the engine feel free to ask anyone (or me)!:D

What have you done with the exhaust cam VVT, nothing or have you swapped the cam already?
The VVT is disconnected for now. I need to get some s/w written to do the control and read the position sensor then I'll try and control it.
 

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gmc
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Discussion Starter #11
performance parts design in progress

Short update

http://profile.imageshack.us/user/efi_diy/

Turbo manifold design is 99% complete - just waiting for the wastegate to show up.

This manifold design has a dual outlet top and bottom - when installed in my 51 GMC the turbo will sit on top of the manifold with the wastegate underneath. For a trailblazer application it would be REAL easy to reduce the top outlet height to mount the wastegate and then mount a turbo on the bottom outlet.
 

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2007 chevy trailblazer_ls
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1,239 Posts
Great work!!! Love the wooden oil pan. Is that the stock TB header in pic #24? Looks like you can fab almost anything. Can you do a rear spoiler like what was on the concept TBSS?
 

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gmc
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Discussion Starter #17
spoiler

I could but there would be a design charge for it and I'd need input info as I have not seen the part.

I'm focused on the 4200 engine parts as these are what the aftermarket is not providing.

Plated cam blanks as shown are $600 for the pair.
 

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First of all I love these engines and plan on picking one up very soon. Glad to see GM bringing back the inline engines.

If you could pick up an engine complete with harness and ECU could you just let the factory ecu control everything instead of doing it with megasquirt? I understand that you are wanting to go beyond the factory setup, but would a straight swap like I mentioned work?

I love the idea of putting these in older chevy trucks, because the inline 6 is what alot of them had originally. That's my plan - to swap one of these into a 67-72 chevy p/u.

I've also registered at inliners.org because I heard some guys there have information regarding these engines, but I haven't gotten a confirmation back from them yet. It's been a week. Are you involved at inliners.org?


BTW here's a picture of a twin turbo 4200 in a concept Trailblazer that I ran across.
 

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swap question

what is the length of the block of this 4.2 I6? I am looking for a swap candidate besides an LS1,2,4,6 for my Porsche 944...Also what is the height from center crank to top of intake manifold....thanks in advance...BTW this 4.2l motor is definitely a cool motor...thanks
 

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2002 chevy trailblazer_ltz
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Let us know what sort of numbers you get in the end. I'm looking for something with potential to throw into my 83 Regal that is smooth yet powerful.
 
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