Anyone hear of the 3.4dohc having 275hp originally?

[Anonymous]

You are right, and there is untapped power.

IMO, and proved by a dyno sheet, it can be achieved easily with a better intake manifold, headers, and cams. Not to mention what head work, higher compression, borexstroke, etc would do to it.

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[blk92z34getrag]

Speaking of untapped power and what-not. I'm going to be needing to rebuild my engine within the next year. For boring over, I've heard .020 is fine. What kind of power gains are we talking about with any sort of boring over? I also want to deck the heads, but I forget what is safe without causing the engine to become interference.

Also, since I am boring it over, I would like to destroke slightly, to raise max RPM and cut down slightly on mass with shorter connecting rods. All of this will (obviously) have to be custom made, which I can probably find someone to do. What is the PROPER way to destroke? And is this even worth it? I know there is an optimal bore:stroke ratio.

[Anonymous]

Well you aren't going to gain much from a .020 over bore. That is a pretty small bore, basically it is good for cleaning the cylinder walls. As for the stroke, you can use a 2.8L crank, it had a lower stroke than the 3.1/3100/3.4 TDC/3400. But why not keep the stroke up? The 3.4 already can hit 7k without problems, and its been proven that it can hit 7600 with a new intake manifold, and mine will be hitting 8. And these are all on stock stroke, maybe higher. The weight gains you'll notice by shortening stroke will not be worth the power loss.

[blk92z34getrag]

I was just looking at the chart, it says .060 is the most you can do safely.

Would it even be worth it to bore that much? After the cost of pistons, rings, etc. I don't think it would be.

[Anonymous]

Well I am using Wiseco for my pistons, and the price is nearly the same if I go stock, 20, 30, or 60 over. There is like a $10 difference per piece from stock to .060 over. And since my rings are going to be custom Total Seals anyway, the price is also nearly the same. True its $5 here, 5 there, but all in all a .060 bore makes up for $100 extra.

[TheProfessor]

.60 over isnt even going to do that much besides get you right up to the edge of the safe/not safe point
i went .40 on my 3.1 rebuild and thats what i suggest to anyone that is going to do an over bore on a 660
that way incase something happens you dont have to get a new block

[Anonymous]

.60 over isnt even going to do that much besides get you right up to the edge of the safe/not safe point
i went .40 on my 3.1 rebuild and thats what i suggest to anyone that is going to do an over bore on a 660
that way incase something happens you dont have to get a new block

GM says that .060 is safe, and .070 is entering risky. And if I know GM and their issues with warrenties, I'd say them calling .060 safe is really safe, and them calling .070 risky isn't really risky, but more they wouldn't back it up. But then again, who knew that the 2.2 ecotec could handle over a 300 shot of nitrous before running into ANY problems? Yet I bet GM would say a 50 shot is risky.

[Fierobsessed]

This is a prototype Fiero built between 1986-1987. This is the engine. It is rumored to be a 3.2L. Interestingly, MANY of the features that this car exhibits were used on cars built 5-7 years later. The intstrument cluster became the 94-95 Firebirds. We all know what happened to the engine...

[RednBlack]

Someone needs to contact "Mythbusters"!

[TheProfessor]

hell yeah now thats what im saying