Need help from you engine techs- 3.4 60 degree block (Page 1/1)
jjd2296 OCT 25, 07:30 PM
I do have a question for those that know more about engine building than I do. I have read that Wiseco K570M92 forged pistons from a dodge stealth will work on a 3.4 block. 0.035 oversize is the same diameter as the 3.4 at 92/3.622 and I have done some research and read some people have used these in the GM 3.4 60 degree for boosted applications. I have read that it drops the compression ratio to 8.2.1 when used in a gm 3.4 60 degree which is also fine since its boosted and stock compression is 9.1. can anyone help wth comparing the specs of the stock 3.4 to see if these would work for me? specs from wiseco:
jjd2296 OCT 26, 12:34 PM
bump
pmbrunelle OCT 26, 08:48 PM
This is for your iron head car?

I think that the biggest impediment to power will be getting air into the cylinders, and exhaust out.

Matt Hawkins did 415 whp on a stock-ish 3.4 bottom end.
Shaun very recently did 450 whp / 470 wtq on a stock 3.9.

On the platforms that flow better, we see that the 60° V6 bottom ends are holding up to some reasonable amount of BMEP.

My opinion is that you should focus on getting the engine to breathe better, and then only worry about beefing up the bottom end once your BMEP gets up there.

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There are a few things to check when buying a piston.

Bore
Compatibility with connecting rod small end
Quench
Compression ratio
Valve clearance

It's up to you to check the data and see if the above criteria are satisfied; I don't think anyone here will do your homework for you.

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In your place, I would look into using stock-replacement 3400 Gen 3 pistons. They're probably hypereutectic "good enough", they drop the compression ratio, and they're not too expensive.

I have 3100 Gen 3 pistons (because I had 89 mm cylinder bores) on my iron head car, and nothing has blown up yet. That said, my Fiero is nowhere near the big-BMEP-league of the other cars I mentioned.
jjd2296 OCT 26, 09:44 PM
Wow you made a lot of assumptions there in your response. Yes I’m already boosted, yes I modified the intake extensively, yes the heads have been completely modified with larger valves and roller rockers.

I’m just not confident yet of my own judgment when it comes to bottom end build so I was looking for a second opinion
pmbrunelle OCT 26, 10:00 PM
I know about your intake and various goodies.

I've read your posts about them.
jjd2296 OCT 27, 07:28 AM
If you have read my posts then you know the engine breaths very well now.

pmbrunelle OCT 27, 08:27 AM
I have seen how you have done things (such as the cutting+welding intake job), but I have not seen you claim any dyno or quarter mile results that would suggest you're in the high BMEP club. Maybe I missed those posts.
jjd2296 OCT 27, 09:17 AM
Wow you need to get a life. Your trolling. Thanks I haven’t had a chance to dyno yet but I will in the spring. Thanks

[This message has been edited by jjd2296 (edited 10-27-2021).]

La fiera OCT 27, 01:46 PM

quote
Originally posted by jjd2296:

Wow you need to get a life. Your trolling. Thanks I haven’t had a chance to dyno yet but I will in the spring. Thanks




JJ, don't take it personal, patrick is an engineer and he is just trying get you the best answer by asking questions.
Besided what Patrick mentioned the Steath piston is going to be about .214 inside the hole. That is by subtracting 1.464 comp height of the 3.4 piston minus 1.250 of the Steath piston.
That means that with 50cc iron heads you'll have 7.0:1 comp ratio and with 23cc aluminum head you'll end up with about 9.49:1.
Now, then comes the weight of the pistons. Wether light or heavier you'll have to get the rotating assembly balanced to those pistons if you want to do it the right way.
Hope this helps!
jjd2296 OCT 27, 05:29 PM
Thanks for the insight. It wasn’t the questions that bothered me it was the negative comments. Anyway we figured out a few things today and have sourced the proper pistons so all good thanks again!