|
Title: Deck hight Post by: Glauco on May 06, 2015, 08:06:46 am Hoping that I don't ask a stupid question, but I hope some of you could help me.
I have nissan pistons I want to use in my engine. The pistons fit in the cilinders, that's not a problem. The issue is that the deckhight is different, only 32mm in stead op 39.6. What is the most logical way of solving this? Bigger stroke or shortening the cilinders? I was thinking 82mm stroke could come pretty close.. Or should I just skip the idea? Would be fun to try I think.. Glauco Title: Re: Deck hight Post by: dangerous on May 06, 2015, 11:11:58 am 7.6 pin height difference will allow 15.2mm stroke increase.
Another option us to shorten the barrels 7.6mm. But this means everything, pushrods, tubes etc, including tin wear, linkages and exhaust will need narrowing. Title: Re: Deck hight Post by: Zach Gomulka on May 06, 2015, 19:02:40 pm 84mm stroke with 5.4 rods would probably come pretty close to zero.
Title: Re: Deck hight Post by: Glauco on May 06, 2015, 19:34:26 pm I was thinking of using the 82mm crankshaft I have laying around together with 5.5" rods, witch I already have as well..
Title: Re: Deck hight Post by: Zach Gomulka on May 06, 2015, 20:32:51 pm That would probably be close as well. Mock it up and get back to us.
Title: Re: Deck hight Post by: DWL_Puavo on May 07, 2015, 10:55:01 am Any info shareable about those Nissan pistons and suitable cylinders?
I just built "a bit narrower stroker" with AA's "82mm stroke" pistons and only 76mm stroke crankshaft with original rods. Had to shorten original pushrods, deck the crankcase (only 0,5mm so it was more practical than shortening the barrels) and lastly, had to grind cylinder head studs a bit as they touched the rockers. Thankfully it didn't come any narrower as tinware and exhaust went straight on, even better fit than stock engine :) Puavo Title: Re: Post by: Glauco on May 07, 2015, 14:27:31 pm Well I was looking for 'cheap' alternatives for wiseco pistons and found out that nissan sr20det pistons are an almost straight fit for the 87mm cilinders, pin height is different, but wanted to give it a try, might open perspectives..
Haven't checked te connection rods, but as far as I can see they might work as wel, but a I said, I have 5.5" connection rods ready to use.. Only thing I was worried about if it would be smart to go for big stroke and smal cilinders.. Title: Re: Deck hight Post by: modnrod on May 08, 2015, 02:10:24 am I'm in the middle of doing a similar thing. Small bores and big strokes to bring the capacity back up again a bit make excellent sense in some environments, and make beautifully smooth sweet little street motors.
I'm using the stock 1500 cylinders (thanks again Wout!) at .217" thick standard :o and pistons out of an Isuzu G161 (Holden Gemini here, very common and so available) in .040" over to come up to 83mm, then machined the pistons and pins for snap-in clips as per stock VW. I now have excellent top quality hypereutectic flat top pistons that weigh in at 480g with pins, clips and rings total (stock 85.5s weigh 580g) with a compression height of 36.9mm. If combined with a 76mm crank and stock length rods, it slides together better than stock and gives a .040" deck height. I thought seriously about using a 82mm crank with my 83mm bore, coz that gives me 1776cc, and I could then get everybody all flustered and upset about NOT using a 90.5mm bore instead. Some people seem to take it as a personal insult if you DON'T use a big-bore. Jeez, I can only guess how popular I'd be on Samba............. ;D |