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Discussion Starter #1
I've got a few questions about older Buick V6 hardware.

Are there any differences between hotair heads and intercooled heads? I searched gnttype.org pretty good and didn't find any info.

I'm comtemplating building a 4.1 (basically just checking if it's feasible) for a race GN. A stage 2 is out of the question for now, ($$$) and searching through old GSXTRA's it looked like a lot of people were running them in the early 90's. If I buy a 4.1 from the junkyard, will I need to update the heads? The other stuff like the turbo drain back and such shouldn't be a problem.

Did 4.1's have provisions for a knock sensor?

What crank? Only the bore is larger than a 3.8, right? So a turbo crank should work fine.

I plan to use stock front cover and oil pump, girdle, H-beam rods, forged pistons, ported & O-ringed stock heads, and some mildly ported intake hardware.

Like I said this is just a feasibilty study for now, but I just wanna make sure I'm not REALLY overlooking anything.

Orlando - What else did you have to do to your 4.1 other than chase low oil pressure problems? Did you scrap the project or what?

thanks for any info guys.
 

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Did 4.1's have provisions for a knock sensor?
Yes. It's the same as the 3.8

The other stuff like the turbo drain back and such shouldn't be a problem.
This isn't a problem at all. For $12 your machine shop should be able to drill the hole and tap it for 1/2" pipe thread. The 4.1 has some reinforcing ribs on either side of the hole that needs to be drilled. Then the turbo drain tube will not screw in all the way until you take a dremel to the insides of those ribs. You only have to take off a hair on either side. I did it in about 5 minutes with a dremel.

What crank? Only the bore is larger than a 3.8, right? So a turbo crank should work fine.
Yes. Matter of fact, you can use the 4.1 crank as it should be the same as the 3.8 Turbo crank with rolled fillets and all.

I plan to use stock front cover and oil pump, girdle, H-beam rods, forged pistons, ported & O-ringed stock heads, and some mildly ported intake hardware.
All that sounds fine. If you haven't bought the pistons yet, you might want to look at Federal Hyper Pistons part # H471P. These are 4.1 "Turbo" pistons that can be had from Summit for cheap. They have the correct pin height (1.807") and cc's in the dish. They can be had CHEAP and I hear Jack Cotton uses the Hypers in motors up to 600HP without problems. How cheap? Try $240 WITH the rings. If getting forged pistons, good luck. I searched and searched for a piston that had the correct pin height and cc's in the dish and came up with nothing. It was the $240 hypers or $700 custom J&E's. The hypers will keep you around 8:1 compression.

Don't forget you will need a 14bolt girdle instead of a 20 bolt. Also the 4.1 pan has no baffles in it, and I would recommend using the template at http://www.gnttype.org to add one. Using stock 3.8 heads on the 4.1 isn't a problem. I had a set of champion irons on mine. Well, I can't say that for sure, b/c my motor wasn't a success.

Head studs or not?? Dunno. I seem to have had a bad experience with the head studs in the 4.1. When I took it apart this last time, I could see where the coolant has blown past the sealant that was on the threads. I don't know why.

Head gaskets?

No clue. I have tried Felpro 1000's, & Felpro 1026's. Neither seemed to work very well... ie.. water in oil and air in radiator. Also this last time, number 6 on the head gasket was slightly blown (I didn't run the car hard at all). I think I screwed up on the HG decision, seeing how a 1026 is for an aluminum headed motor. I would have been better off trying the 1000's again, but a lot of people complain about them leaking water. DUH! So, this topic is currently unsuccessful. One more gasket available to try.

This time around I plan on using the Felpro 8723PT1's. Grey and Orange gasket that comes with a summit rebuild kit. These look like a nice gasket, and at this point it's my only option as for trying something different. Well, I could go with the Locwire, but didn't want to entertain that idea.

Orlando - What else did you have to do to your 4.1 other than chase low oil pressure problems? Did you scrap the project or what?
The engine is on the stand and I am frustrated. It's always had crappy oil pressure and I don't know what is going on at this point. At this stage it's not going to hurt it any to let it sit to give me a chance to get some enjoyment out of my 3.8. I pulled it out last time to mearly remove the girdle and reseal it to the block. While the girlde was off, some main caps were removed for inspection, and it wasn't pretty. Also I popped off the #6 rod cap and it wasn't pretty. Plus the thrust bearings don't look healthy. This is a story which has no ending yet.

The crank is finally wasted. This last time around it was 20/10 and now it's scored up again. Sad thing is, I poured about $5000 into a motor that is collecting dust at this point.

The only thing that keeps me from making a really cool coffee table out of this motor is the fact that one day it will run and run good. For the 500 miles that I did put on it, it put my 3.8 motor to shame. No lag, tons of power all at real low boost levels.

At this point, the car is back together and runs great with the good ole 3.8. I didn't take the pan or front cover off or anything. I just slapped my champion heads on it and threw it back in the car. Gotta love a motor that can power a 3680# sled to [email protected] 6 hours away from home and get 22mph on the way back.

If anyone knows where to get some voodoo magic to make these things stay together, let me know


Signed-
Frustrated

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Stock Block, Stock Cam, PTE-52, Champion Heads, V4, MSD50's, TH DP, JayJackson 62mm TB, 16position MaxEffort Chip. 3680# with Driver
12.0 @ 116.5mph w/20psi using 17.9* timing

mailto:[email protected][email protected]</A>

[This message has been edited by Orlando_87GN (edited November 12, 2001).]
 

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Discussion Starter #3
Thanks Orlando,
I've heard both ways on the head studs too, the guys in town despise them, and they seem to have pretty good luck/experience so I'll go with what they say.

Does anybody know about the hotair heads?
 

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If you mean '78-'79 heads then no, I think they are a bit different. If you mean early '80's like '85 Non-Intercooled engines, then yes.

Here is a table that shows what heads came in what year. You should be able to determine from this info what heads you can use and which ones you can't.]
I say stick with the 25518445's or 25506293's

hth's

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Stock Block, Stock Cam, PTE-52, Champion Heads, V4, MSD50's, TH DP, JayJackson 62mm TB, 16position MaxEffort Chip. 3680# with Driver
12.0 @ 116.5mph w/20psi using 17.9* timing

mailto:[email protected][email protected]</A>
 
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