3.4 DOHC Pistons in a 3400? [Archive] - GrandAmGT.com Forum

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Dominance9
08-18-2006, 06:55 PM
I have a sealed power application guide and was comparing some specs between the 3.4 DOHC pistons and the 3400 pistons. Now obviously if the 3.4 pistons could be used the comp. ratio would go up a couple points at least, I would imagine but thats why Im intrested in this.

Has anyone tried this though?

The pin diameter is only a hair smaller (1.478 vs. 1.464), the compression distance is actually a bit less so it may not have clearance issues (1.478 vs. 1.464) The bore size is exactally the same. Minor mods and these would go right in.

Im not planning on touching the block on this car yet, but I thought it would be intresting to see if this has been tried or if it was possible. If so we would have a cheap way of really upping our compression ratio w/ stronger hyperutectic pistons for not much money at all.

Thoughts??

Vegeta
08-18-2006, 07:14 PM
Im doing this right now with coated DOHC pistons .040 over. I have a set of .030 that I am modifying the dome/reliefs on and also coating. These will be for sale after they are weight matched and finished. Pin is the same and they drop right in. Compression height is different but compression will be raised. I am hoping to get higher compression with these over the shallow dish camaro 3.4 pistons.

tejohnson
08-18-2006, 07:52 PM
What kind of a dish (in CC's) do the DOHC pistons have? The stock pistons have about a 30.2 CC dish.

Dominance9
08-18-2006, 07:54 PM
Im doing this right now with coated DOHC pistons .040 over. I have a set of .030 that I am modifying the dome/reliefs on and also coating. These will be for sale after they are weight matched and finished. Pin is the same and they drop right in. Compression height is different but compression will be raised. I am hoping to get higher compression with these over the shallow dish camaro 3.4 pistons.

NICE! So it does work!?

Did the domes have to get shaved down at all?

Any idea what the comp ratio of these or the camaro pistons are?

Good find on the older 3.4 pistons, the dish isnt nearly as wide or deep, Im guessing they drop right in?

Dominance9
08-18-2006, 07:59 PM
What kind of a dish (in CC's) do the DOHC pistons have? The stock pistons have about a 30.2 CC dish.

From the book Im looking at, none. It dosnt describe a dish at all. Certian years actually had a .040 dome according to this. But with out seeing them in person I wouldnt go 100% by this book.

The camaro pistons have a dish of .087" deep x 2.765 diameter compared to the 3400s .275 deep x 3.180" diameter...whats the difference on that? I dunno how you can get the cc's of them;crap

bszopi
08-18-2006, 08:03 PM
http://60degreev6.com/test.php?do=start

I come up with 13.73:1 CR. With a modified setup, you could bring it down some, and with a good tune, you could run it at 12.5:1 on pump gas.

Vegeta
08-18-2006, 08:37 PM
Yeah, im not sure on these but the older original DOHC pistons for a 91 had about 4.5 cc in the reliefs and no dome. Remember that it doesn't come up as high as the 3400 pistons either so that helps. Looks like there is room for the dome, which is just the middle portion of the piston. Going with the 3500 heads gives a larger cc in teh combustion chamber so I am hoping to keep it near 12:1. The camaro pistons should be around 12:1 on the 3400 heads. I can cc dished pistons no problem but the DOHC pistons are akward.

Its just now being built so I have no feedback on running DOHC pistons in a pushrod yet.

bszopi
08-18-2006, 08:45 PM
There are ways to measure a domed piston, it just takes some thinking... ;)

The values I used were 5.0cc for the dish and the piston coming up to 0.0095" below the block deck. Used stock 3400 values for the remainder of the values.

Dominance9
08-18-2006, 10:09 PM
Damn thats going to be crazy! 13.x to 1 :leg haha

Seriously let us know how it does work out. As far as what Im thinking down the road the camaro pistons sound ideal.

Thanks for the comp ratio link too

bszopi
08-18-2006, 10:23 PM
No problem... I just put it together a couple weeks ago, and just got it fully integrated into vB yesterday. I still have a few things to add to it, but it works well.

Badblack04GT
08-18-2006, 10:37 PM
Yeah, im not sure on these but the older original DOHC pistons for a 91 had about 4.5 cc in the reliefs and no dome. Remember that it doesn't come up as high as the 3400 pistons either so that helps. Looks like there is room for the dome, which is just the middle portion of the piston. Going with the 3500 heads gives a larger cc in teh combustion chamber so I am hoping to keep it near 12:1. The camaro pistons should be around 12:1 on the 3400 heads. I can cc dished pistons no problem but the DOHC pistons are akward.

Its just now being built so I have no feedback on running DOHC pistons in a pushrod yet.


Has anyone actually ran the iron head 3.4 pistons in a 3400 yet?

Since my Z24 is no longer a daily driver and my 3400 is going through a complete rebuild i'm thinking about going with either the iron head pistons or the DOHC ones..

Vegeta
08-19-2006, 07:05 AM
Yes, the camaro pistons have been used before and work well. Can't say any of them ran a stock cam though:P

Badblack04GT
08-19-2006, 10:28 AM
Yes, the camaro pistons have been used before and work well. Can't say any of them ran a stock cam though:P


You should see the regrind specs i came up with in DD2K :leg

Dominance9
08-19-2006, 12:59 PM
You should see the regrind specs i came up with in DD2K :leg

Whats DD2k? Is it that Desktop Dyno?

Vegeta
08-19-2006, 04:03 PM
Im using dynomation advanced for custom cam specs. Lorenzo on 60degreev6 had some nice regrind specs but it was a little extreme. Im hoping I can afford to buy a couple cams to test out later on. Not simulations or guesstimations by cam grinding places but actual dyno tuned runs. Really depends on how business goes though:P

Badblack04GT
08-19-2006, 07:47 PM
Whats DD2k? Is it that Desktop Dyno?


Yep..

I came up with 500 in/502 ex with a nice long duration... puts my N/A build dangerously close to 300 HP :leg