Bore/Stroke

[Husky]

Hey guys. Just got a GTP Special Edition, 1994, and it has the 3.4 TDOHC in it. Just wondering if there is a way to up the displacement. I know it can be bored to 3.5, .060 over, but I was wondering if there was a way to overbore and stroke it out to maybe even 3.8. I'd love to see a 3.8 liter TDOHC engine, I think it'd give a 3800 a run for it's money easily.

[SappySE107]

RE: Bore/Stroke

jbodyperformance.com sells a crank, but from what I have read, good luck getting it. We have discussed on this site before the idea of using the new steel crank for the 3500 and grinding it to fit, and offset grinding to get different stroke.

[RacerX11]

Re: Bore/Stroke

I know it can be bored to 3.5, .060 ove

Not quite. The 3.4 is only 3350cc stock, so overboring it 0.060" brings it up to 3411cc, not not 3.5L.

Marty

[Husky]

Huh. I Was jsut getting that from the DOHC performance section on the right hand bar. I figured it was a little off since it had the displacement as 3.5 for a .060, .080, and .100 overbore. So any idea? What's the highest displacement that someone's run here?

[Scott205]

I hope you aren't really thinking this will give you much performance benefit. The better pistons and rings or doing things like Polishing and Porting the heads, intake will get you alot more horseys. If it was just all more cubic inches all the race cars would be running 8.1 L instead of 5.7, 3.0 2.0s.

I would love to see what a pair of Holly's on a 3.4 DOHC would produce. I am thinking done right with a head job you could find 400 or 500 hp. Granted you would get 12 mpg

[Q]

Not exactly.

Racing classes are usually divided up by engine displacement. That's why guys run 2.0 l engines. Their racing class is limited to 2.0 l displacement engines! Unlimited classes, like in drag racing, is where you will find monster motors. Where the class is engine size limited, those guys don't leave a fraction of a cc on the table.

Stroking the motor to get more inches, more HP and more torque is a fun thing to do. There's an old adage that: "There ain't no replacment for displacement." Ask any racer

There are drawbacks to boring and stroking, though - no question about it. Piston velocity and cylinder wall thickness were optimized by the factory for the sake of reliability. In most cases when you start to mess with them, you're messing with the longevity of the motor. But if it's not a daily driver ... then there should be nothing stopping you.

I do agree with you, though, that decent head work and a manifold designed to run a correctly sized 4-Bbl carburetor would get you them most bang for the buck. Crank work, custom pistions, custom rods and special attention to cam design are all there for the last few Lb-Ft of torque, but horsepower is in the heads.

Q

[pwmin]

Re: Bore/Stroke

I'd love to see a 3.8 liter TDOHC engine, I think it'd give a 3800 a run for it's money easily.

what do you mean? a SC 3800 cause 3.4DOHC GP's are faster than 3800 NA's. at least in my experience. every time the 3800 gets the 3.4 off the line but 3.4 always passes quickly

[Husky]

Wow, seriously? I haven't been able to figure out how fast my LQ1 is yet, it has had a bad transmission since I bought it, and feel like it's makeing maybe 90 HP to the wheels tops. It wasn't that bad a qhile ago, but it gets worse as I drive it.