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Question Pistons Euro vs. USA

I am going to be pulling my 3.2 apart this weekend for some top end work and I would like some input on pistons choices. I've done plenty of engines with the USA Mahle pistons with the 9.5 : 1 compression ratio but have not done one with the Euro. 10.3 : 1. My question is; am I going to have a detonation problem running the Euros on 91 octane fuel? Everything on the engine is original stock condition. The DME chip is original as well. I will be upgrading the chip shortly with one of Steve Wong's. I'm looking for a little more get up and go but not at the risk of a detonation problem.

Thanks in advance.

Dan
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Old 02-09-2006, 11:09 AM
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This subject was beat to death here;
Carrera Rebuild 10.3 Pistons & Cylinders
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Old 02-09-2006, 01:35 PM
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Thank you Tom. It looks as though I have some reading cut out for me tomorrow. Either way I look at it, I need to pull the motor apart. I'm not pleased with the leakdown results I got. (three cylinders in question; 22%, 24%, and 18% by the valves...the rest are within 5% leakdown) I tend to be a bit AR (anal retentive) when it comes to my cars and hobbies. I have about 4000 miles on the engine since I did the valve job. The leakdown test at the time pointed to the valves. The leakdown test I just did also pointed to the valves. (again) I spoke to the machinist that did the valve job for me and he is willing to work with me on this. I'll try and post pics as I go along. My decision on the pistons will hinge on what I read tomorrow.
Thank you for the tip on the "beat to death thread". My apologize for not doing a search first. I just shot from the hip. My bad!

More to follow....

Dan
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Old 02-09-2006, 08:18 PM
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Dan:

Anything over 9.5:1 in these larger bore engines needs twin-ignition to run on 91 octane fuel.
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Old 02-11-2006, 08:30 AM
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Quote:
Dan: Anything over 9.5:1 in these larger bore engines needs twin-ignition to run on 91 octane fuel.
I took Tom's advice and read the thread he directed me to. I'll be running the stock Mahles. The thought of going twin plug is entertaining but I want to keep the car as original as possible. I'll put one of Steve's chips in it and call it done.

Quote:
Thats a lot getting by the valves! Were the rockers set too tite? its hard to belive that they could leak that much unless they were not pressure tested when done? What seat angles did he use??
I took it to work yesterday and tried to talk myself out of taking it all apart again by doing another leakdown test. Guess what? It didn't heal itself.
I pulled the power unit out, and tore the motor down to the rods. The heads are back at the machinist. I will have to ask him what angles he used. He was as blown away with the crappy leakdown results as I was. He did pressure test them.

It was kind of cool tearing the motor down after it only had 5119 miles on it since the last time. I got to give myself a real quality control check of my own work. I took a bunch of pictures of the power plant removal, but that is going to go in another post for someone who would like to see a step by step engine removal with a G50 attached.
Heres where I left off yesterday.
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Old 02-11-2006, 11:19 AM
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Here are the leakdown results in the respective firing order. 1,6,2,4,3,5
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Old 02-11-2006, 11:25 AM
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I'm not sure why the first gauge is only showing 30#. Our compressor is running a minimum of 90 psi.. The leakdown tester is a brand new Snap On unit. I have cross compared with two other testers and the results are the same across the board. (give or take a pound or two)
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Old 02-11-2006, 12:58 PM
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If your inlet pressure is only 30# it does not take much of a leak to show a 20 percent drop, could it be there was really nothing wrong with the valves?
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Old 02-11-2006, 01:48 PM
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Trust me! It was not right. Do you actually think I would want to take my engine apart for the second time just for the fun of it? I think not!
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Old 02-11-2006, 02:03 PM
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I never had much success with your type of tester, mine purchased from our host a few years back. That tester is actually operates like the single gauge type, and the pressure used for the measurement is fixed at 30lbs. I think that's too low, and you can have problems with the rings or valves not seating for the measurement. Sometimes it helps to rotate the engine a few degrees with the pressure on to help seat them and get better results.

Get one of the real two gauge leakdown testers that let you set the pressure to 80lbs. Here is one example:

http://easterntech.com/e2m.html

That's the tester that I use now. Price under $100.

-Juan
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Old 02-14-2006, 09:32 AM
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Quote:
Originally posted by logician
I never had much success with your type of tester, mine purchased from our host a few years back. That tester is actually operates like the single gauge type, and the pressure used for the measurement is fixed at 30lbs. I think that's too low, and you can have problems with the rings or valves not seating for the measurement. Sometimes it helps to rotate the engine a few degrees with the pressure on to help seat them and get better results.

Get one of the real two gauge leakdown testers that let you set the pressure to 80lbs. Here is one example:

http://easterntech.com/e2m.html

That's the tester that I use now. Price under $100.

-Juan
Thanks Juan.
Well I tore the engine down on Friday. I'm not sorry that I did. I had three exhaust valve guides that simply just went away. My machinist was baffled as I was. He asked me if I cleaned out the spray bar for the cams. I did. The cams were brand new as were the rockers and rocker shafts. They still look beautiful! We are thinking that we just got some bad guides. The machinist is going to replace all of the exhaust guides with silicon bronze guides this time.
As to the original question of the Euros vs. the USA pistons... I decided to go with the Mahle Sport 98mm 3.4 kit. They are sitting here on the floor next to my tool box. I can't wait! I'll need to stock up on NOS octane booster.
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Old 02-14-2006, 11:06 AM
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BTW, My Nikasil 3.2 barrels & pistons are for sale if anyone is interested. They are listed in the parts section as well. They are in good shape with 132,000 on them.
*****SOLD*****
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Last edited by syncroid; 03-11-2006 at 08:24 PM..
Old 02-14-2006, 11:27 AM
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Ohwell! In for a penny....in for a pound.

I took Steve from Rennsports advice. As mentioned earlier, I went with the Mahle Sport 3.4 kit. I figured I would just be patient and do it right the first time. Twin plug it is! Its all built. (almost) I'm waiting for my lower valve covers to be finished. (spark plug holes) I'm also waiting to get all my heat back dated sheet metal from the powder coaters. I'll be ordering my chip from Steve Wong shortly. My biggest hold up is the ignition splitter from Andial. As most of you know, they are in the process of closing their service/repair facility. They will still have their "new" parts store in a new location. They are out of the splitters at the momment and won't be able to fill my order for a month or so.
Thanks to all of you out there that helped steer me in the right direction. I'm really looking forward to the finished project. I'll try and get some more pics up soon.
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Old 03-05-2006, 04:08 PM
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I really like your posts, syncroid. thanks for contributing your ideas and your great photos!
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Old 03-06-2006, 05:50 AM
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Thank you Andy.
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Old 03-06-2006, 06:17 AM
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Well I am getting pretty close. I got my sheet metal back from the powder coaters today. Its going to be hard to wait for that splitter.
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Old 03-10-2006, 04:41 PM
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Looking good!

Cheers
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Old 03-10-2006, 05:01 PM
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What? No pic of our handywork on the sheetmetal? The welds aren't that bad
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Old 03-12-2006, 11:16 AM
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Quote:
Originally posted by 87coupe
What? No pic of our handywork on the sheetmetal? The welds aren't that bad
I guess I was too excited about getting the sheet metal back from the powder coaters. I forgot to take pictures of the individual pieces.
Thanks to Brandon (aka 87coupe) for his help and crafty ideas on the sheet metal mods.
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Old 03-12-2006, 12:12 PM
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I stuffed the motor back in the old girl yesterday. I must say it looks pretty cool. Still no splitter. On a positive note...I ordered my chip from Steve today. I am going to send him my DME control unit on Monday to be upgraded to the 28 pin prom. He is going to install a custom chip for my application. Schwing! I'll try and post a few more pics tomorrow. DOH!!! I forgot to bring my camera to work again.
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Old 03-18-2006, 05:46 PM
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