1G evo 4-9 pistons in a 1g 7bolt?

[zkheasley]

Ok I'm sure at some point at some time its been ask but I can't find a direct answer anywhere.... I'm ordering parts tonight and I need to know if evo 4-9 pistons will work on 1g 7bolt rods in a 1g 7 bolt bottom end?

 

[BogusSVO]

As long as you have a 22mm wrist pin hole in the rod they will.

My question is why? Are you wanting to lower the compression?

 

[zkheasley]

No actually I wanna raise it, I was on wiesco's site and they stock 10:5:1 evo stroker pistons, I'm nt and want all the compression I can get so these would be pretty sweet! Thanks man!

 

[BogusSVO]

What wiseco part number are you looking at?

 

[zkheasley]

K669M86AP

 

[BogusSVO]

So you must want to build a 2.3 stroker 86mm bore and a 100mm stroke

You CR will be about 9.75-10:1 depending on combustion chamber size and HG thickness

The evo head is 43cc
The DSM head is 47cc, commonly 45cc after surfacing a time or three

 

[zkheasley]

Yes I already have a 2.3 but trying to get a little more out of it. I'm currently running a lower compression piston with a 1g head.... I'm switching to a higher compression piston and a 2g head.

 

[BogusSVO]

You may want to look into a Hyundai head from the old 1.6/1.8 looks just like a 4g head, but has smaller combustion chambers

 

[zkheasley]

Yeah I'd love to have one but they are hard to find. Do you know what all years work on the 4g's?

 

[miliman13]

As I found it evo 9 piston s won't fit 7 bolt rods. Because of the floating pins

 

[BogusSVO]

You can use clip fit forged pistons on stock rods, you hang them like a press fit.

You can not use press fit piston on a bushed/floating rod (h beam) there is no way to lock the wrist pin in place.

 

[zkheasley]

Oh really? Wiesco won't tell me either way and these things are freaking expensive! I have eagle h beam rods... So your saying its a no go?

 

[1990dsmkid]

No youll be fine with the h beams and wiesco. What Bogus said is you can used forged pistons on stock rods but not stock pistons on aftermarket rods that use floating pins.

 

[zkheasley]

Oh ok, you guys are awesome! I really appreciate allthe help

 

[bling5tatus]

Machine shops can modify your rods for a floater piston... but I wouldn't trust just any place to do it. You should call around and ask if they're familiar with the procedure involved.

 

[BogusSVO]

Machine shops can modify your rods for a floater piston... but I wouldn't trust just any place to do it. You should call around and ask if they're familiar with the procedure involved.

Yes they can, but why? By the time you get bushings, and the labor to install them, then add ARP rod bolts, and resize the rods, you have spent almost as much as a set of entry level H beam rods, and still have a stock rod that is not as strong as a H beam.

Figure it this way..
4 bushings about $10 each so $40
machine the small end, $15-25 per rod so $60-$100
Arp rod bolts About $50
Resize the big end $10-$15 per rod another $40-$60

so you have spent $190-$250
and still have a week rod that you can snap above 400 or so HP
a set of eagle rods is around $400 and can carry you into the 500 or so HP range.

I just do not see it as cost feasible to do it

BTW All pistons float, both press fit or clip fit. It is the rod that floats or grips the wrist pin.

 

[zkheasley]

Well guys I took all your advise in consideration, I dumped the off the shelf evo piston idea. When I finally got thru to wiesco the guy said he wouldn't guarantee them to work. In fear of getting stuck with $600 worth of paper weights I couldn't use. I had them make a custom set that's exactly what I wanted and more! Thank you all for the help!

 

[bling5tatus]

Hey it was just a suggestion... and I didn't pay anywhere near that much when I had wiseco pistons put on stock rods.