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A7 rods and pistons into a h22a2

Engine/Gearbox questions and discussion
spudep91
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A7 rods and pistons into a h22a2

Post by spudep91 » Sun Mar 24, 2019 6:41 pm

Hi as above can you do this with no issues. Have a7 head. Is it worth putting the higher compression pistons in the a2 block?

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A7 rods and pistons into a h22a2

Post by Anzezaf » Sun Mar 24, 2019 9:23 pm

I believe the A7 has a larger diameter crank :!:

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A7 rods and pistons into a h22a2

Post by Drax » Mon Mar 25, 2019 9:02 am

I'd have to check the crank sizes between them both as I can't remember, but there's nothing stopping you putting just the a7 pistons onto the A2 rods ;)
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A7 rods and pistons into a h22a2

Post by NafemanNathan » Mon Mar 25, 2019 9:24 am

a2 crank is 50mm. The a7 is 55mm, so yeah, you can't use the rods.

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A7 rods and pistons into a h22a2

Post by spudep91 » Mon Mar 25, 2019 2:35 pm

Is it not the main bearings that are 55 mil just?

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A7 rods and pistons into a h22a2

Post by 4thgenphil » Mon Mar 25, 2019 3:03 pm

Is the main bearing that are 55mm on an a7, the rod bearings are the same.

A7 uses floating gudgion pins, a2 doesnt but if you use a7 pistons thats not an issue.
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A7 rods and pistons into a h22a2

Post by spudep91 » Mon Mar 25, 2019 6:17 pm

Cheers lads. Ended up just putten a2 in with a7 head.

This is 3rd engine in the car fs. Keep doing bottom ends. Last one was are one fault run it down to min on dip stick and were going round track.

We have hondadta v3 this time to get it mapped to.
Use think youd gain much with the a7 pistons in?

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A7 rods and pistons into a h22a2

Post by 4thgenphil » Mon Mar 25, 2019 11:08 pm

If youre tuning it id drop the a7 pistons in, they are a fair rise in compression compared to ukdm pistons.

Are you running a baffled sump? Also what tyres are you running?
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A7 rods and pistons into a h22a2

Post by PerformanceAutoworks » Tue Mar 26, 2019 8:56 am

Yes you can use the H22a7 pistons and rods in a H22a2. The rod journal is the same on both 50mm and 55mm cranks.

You can't use the A7 pistons on A2 rods without significant machining to the A2 rod as A7 pistons are floating pins rather than pressed, plus the small end journal width is different.

In all cases of course, piston to wall and big end bearing clearances need to be measured
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