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ZRP Forged Conrods

Author
Discussion

rachaeljf

6 posts

154 months

Friday 28th July
quotequote all
Thanks 227, so you think these rods are ok for a non race engine? I was about to reject them but when I look at photos in other eBay listings I see the same machining marks, so I can see mine are not a one-off fault (I doubt the advert photos are of *my* rods!).

227bhp

5,469 posts

50 months

Friday 28th July
quotequote all
rachaeljf said:
Thanks 227, so you think these rods are ok for a non race engine? I was about to reject them but when I look at photos in other eBay listings I see the same machining marks, so I can see mine are not a one-off fault (I doubt the advert photos are of *my* rods!).
If you read the whole thread it's explained in there, but I would put them in a road car after I'd checked them as well as I could and they were better than what came out.

rachaeljf

6 posts

154 months

Friday 28th July
quotequote all
I would happily use oem rods, but for my "stroker" build they won't fit. I have read that these Maxpeeding rods are actually ok but I am surprised they are knocked out with such obvious lack of precision in the milling.

e21Mark

Original Poster:

9,201 posts

95 months

Friday 28th July
quotequote all
Have to say my engine went together without issue and is performing well. I'm very happy.

rachaeljf

6 posts

154 months

Saturday 29th July
quotequote all
Did your rods have a similar finish to the one I posted?
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Inline__engine

112 posts

58 months

Sunday 30th July
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yeah the machining marks are likely to be an issue but what other machining is screwed up, hopefully not the big end bore

e21Mark

Original Poster:

9,201 posts

95 months

Sunday 30th July
quotequote all
If honest, I didn't notice any marks and my builder didn't mention anything apart from their weight. They went together with the new pistons etc no problem and I'm about 1200 miles in now.

Inline__engine

112 posts

58 months

Monday 31st July
quotequote all
Inline__engine said:
yeah the machining marks are not likely to be an issue but what other machining is screwed up, hopefully not the big end bore
i fixed this, it wouldnt let me edit it

DVandrews

955 posts

205 months

Monday 31st July
quotequote all
Look carefully at the bolt seats, I spent a long time (2 years plus) in dialogue with a Chinese steel rod manufacturer suggesting changes to the design (which have now been incorporated in all the rods they make) . Some of these were dimensional, others to do with design fundementals. The rods I have made are to the improved specification and I have had them comprehensively tested by a contact within Ricardo's. They passed the testing and were described as adequate for the use I would be putting them to which is fairly extreme. The one recurring problem I have experienced has been machining of the bolt seats which has varied from acceptable to poor (less than 50% contact area). This can be resolved by careful lapping or machining but it shouldnt be necessary.

Dave

227bhp

5,469 posts

50 months

Monday 31st July
quotequote all
DVandrews said:
Look carefully at the bolt seats, I spent a long time (2 years plus) in dialogue with a Chinese steel rod manufacturer suggesting changes to the design (which have now been incorporated in all the rods they make) . Some of these were dimensional, others to do with design fundementals. The rods I have made are to the improved specification and I have had them comprehensively tested by a contact within Ricardo's. They passed the testing and were described as adequate for the use I would be putting them to which is fairly extreme. The one recurring problem I have experienced has been machining of the bolt seats which has varied from acceptable to poor (less than 50% contact area). This can be resolved by careful lapping or machining but it shouldnt be necessary.

Dave
That's good information, do you mean that the bolt seat was not at 90' to the threaded bolt hole or just a bit rough?

Edited by 227bhp on Monday 31st July 12:39

rachaeljf

6 posts

154 months

Monday 31st July
quotequote all
Thanks for the tip. I noted where the bolt seat is milled they leave a sharp corner, another poor detail for fatigue.

DVandrews

955 posts

205 months

Monday 31st July
quotequote all
227bhp said:
That's good information, do you mean that the bolt seat was not at 90' to the threaded bolt hole or just a bit rough?

Edited by 227bhp on Monday 31st July 12:39
The bolt seat appeared to have been finished manually with a file, probably to remove burrs, the resulting seat was neither flat nor perpendicular to the bolt centre line.

Dave

Boosted LS1

16,397 posts

182 months

Monday 31st July
quotequote all
That's a bit naff then.