3900 headgasket on 3400 head and other lz9 info

[Shaun41178(2)]

checked with my machinist today. factory piston sits .040 in the hole.

[The Dark Side of Will]

That's a lot.

Do you have all the numbers that result in that spec?

[Shaun41178(2)]

5.835 rod and 1.312 piston Ch

Deck and crank was not measured. I'm not the first person to find the piston this low.

Gonna get a piston with a Ch of 1.34 which will put it .010 in the hole 10.55 CR

[The Dark Side of Will]

Pretty sure the deck height is 224mm. When calc'd with your rod length, CH and piston deck numbers results in a stroke of 83mm... Spec is 84, so you may want to have some shit measured.

For 0.010 in the hole, grab a 0.025 to 0.030 head gasket.

[Shaun41178(2)]

I can have the deck height measured and the crank measured, but at this point it doesn't really matter what they spec at. I can deck the block a bit to make it square if it needs it. That is actually being looked at. I can't do anything about the crank throw though if it is at 83mm. All the specs that GM states, the pistons I ordered would actually stick out about .011. Turns out they will be in the hole about that much. Pretty sad really.

MLs gaskets are pricey, and I might just go with a generic. Not sure yet. If I go mls I'll get something to get quench around .040.

My pistons arrive tomorrow. Ill post some pics.

[Shaun41178(2)]

1.34 ch
21.8cc dish

They weigh about 6 grams more than stockers.

should be about .018 or so in the hole. we'll see.

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[The Dark Side of Will]

Will be interesting to see the measurement.

0.018 in the hole? Going to get 10.3:1? Boosting on E85? Going for 600 at the wheels?

[Shaun41178(2)]

Yea around 10.3 or so. Thought of turbo but might skip all that plumbing and just toss a 150-200 on it.

[The Dark Side of Will]

If all motor, go 12.0 or 12.5:1

[Shaun41178(2)]

short eduational video of the vvt setup on the 3.9

https://www.youtube.com/watch?v=0_POzgopkRg

[ericjon262]

thats pretty cool. I thought it used a seperate valve like the atlas I6, but I see the valve is integral to the phaser... neat.



fwiw, MS3x can control up to 4 channel VVT, making a full 3900 swap more obtainable, the only thing you would need to deal with is the cable throttle, and the variable intake, MS3x could probably handle the intake, but from what I understand, it's not really any benefit.

[The Dark Side of Will]

The variable manifold should be silly easy to control. It's just an RPM-based switch point... it's the same at VTEC and almost every controller can do that nowadays.

I thought GM used the variable manifold to flatten out the torque curve. I have read over on V6/60 that the fixed manifolds make more power. In a light car like the Fiero with an aggressively geared manual transmission, the engine doesn't need that extra few foot pounds of low end nearly as much as it does lugging a new Impala around.

[The Dark Side of Will]

fwiw, MS3x can control up to 4 channel VVT, making a full 3900 swap more obtainable, the only thing you would need to deal with is the cable throttle, and the variable intake, MS3x could probably handle the intake, but from what I understand, it's not really any benefit.

I'm starting to eyeball MS for my Ferrari 3.4. Other than how high it revs, the engine is VERY simple to control. And even the 3.4 doesn't rev *that* high... 7700 rpm factory redline, although it'll go much higher with minimal tweaking.

[Shaun41178(2)]

crappy exhaust manifold. For some reason, GM thought it a good idea to stuff 3.9 liters worth of exh into a 1.8 inch hole. This is the merge where all 6 cylinders come together in the trunk side manifold when mounted in a fiero. Porting can get it out to about 2 inches, but the walls are thin. There are options(not headers) but require fabrication

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[ericjon262]

wow, that is tiny... I think each manifold off of my 3500 had a bigger discharge, and that was for just 3 cylinders. why are headers a no go?

[Shaun41178(2)]

Flanges for headers used to be made but I don't think so anymore. I'm in contact with someone who has a set that is looking at having them duplicated.

The other option is to run a different trunk side manifold from a g6 and fab up a new merge collector of a larger ID for both banks still using the factory crossover

Something like this

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[ericjon262]

TCE lists them, but also doesn't list a price, to they may be N/A.

http://www.tcemotorsports.com/shop/all- ... -lz-detail

[Shaun41178(2)]

Yea marc is out of the biz due to health issues. That's where I originally saw them and wanted to buy from

[ericjon262]

Yea marc is out of the biz due to health issues. That's where I originally saw them and wanted to buy from

he's been having problems for the past several years, I was wondering how long it would be before BCC/TCE closed it's doors, sad to see him close up shop.

[The Dark Side of Will]

crappy exhaust manifold. For some reason, GM thought it a good idea to stuff 3.9 liters worth of exh into a 1.8 inch hole. This is the merge where all 6 cylinders come together in the trunk side manifold when mounted in a fiero. Porting can get it out to about 2 inches, but the walls are thin. There are options(not headers) but require fabrication

20170218_221138_resized.jpg

I guess that's why the car versions with the dual manifolds were rated at 245 HP and the "truck"/minivan versions with that setup were rated for 235 HP. Still 100 HP over stock. The velocity will spool the turbo, j0!