<< Previous Topic | Next Topic >>  

3A/JH HYbrid question

June 12 2002 at 9:16 PM
No score for this post
Patrick Bureau  (no login)
from IP address 12.237.164.124

 
Alright I have organized myself to upgrade my 1.8L Scirocco with a 2L bottom end from a Audi 3A engine block.

The question I have is the following;

1. is there a piston that I could use that would lower the compression from the 10:1 to 8 or 9:1 compression. the reason behind this request is that I would like to not have to add a knock box and in the future expansion of my power plant I would be able to install a Turbo setup at a later time.

2. Would anyone suggest or not changing the Audi 3A crank for one of a Diesel to provide more torque?

Thank you

Patrick Bureau

 
Scoring disabled. You must be logged in to score posts.Respond to this message   
AuthorReply
drew
(Login drewbrew)
68.65.134.253

don't sweat it...

No score for this post
June 13 2002, 7:38 AM 

I think you're overthinking it. Build the motor youve got. That is, build a normally aspirated motor, or build a turbo motor. Something that's a little bit of both( a low comp normally asp motor) will be dissapointing for the effort.

You don't need to run a knock sensing ignition on a 10;1 motor. Keep your timing conservative and run good gas, you will have no problems. I ran my ABA/JH for a year without the knock sensing ignition, worked fine. That compression gains you some torque, which it sounds like you want(who wouldn't?). also allows you to not have to worry about the deisel crank unless you really want to.

IE, both replacing pistons and the crank seem like alot of unnecesary work when the OEM 3A shortblock provide great torque as is. These motors(with a good cam and some headwork) easily make 140-145 hp with factory reliability. Not bad when you're oem motor had 90hp....

Now then, if you're building a turbo motor, I won't claim to know much there, someone around here can do a better job of answering the question than myself....

 
Scoring disabled. You must be logged in to score posts.Respond to this message   
Patrick Bureau
(no login)
12.237.164.124

Re: don't sweat it...

No score for this post
June 13 2002, 3:25 PM 

Well I don;t think I have explained my self.

1. I don;t want to rebuild my engine every 6 months.
2. I want in the future to be able to install a turbo on it
3. I was told 3a/jh hybrid = 10:1 compression
4. I rather have 8.5:1 compression for 2 reasons
(a) no need for knock box
(b) permits me to upgrade engine later on to turbo

I don;t think I am am overthinking it, I just grabbed a USED 3A engine, and though I intend on rebuilding it back to new. I might as well do it right the first time around than haveing to rebuild it in 2 years.

 
Scoring disabled. You must be logged in to score posts.Respond to this message   
kevin
(Login aventari)
68.101.148.207

similar..

No score for this post
June 14 2002, 5:46 AM 

What you're doing sounds similar to what I did when I rebuilt my JH a 3 or 4 years ago. I kept it N/A, but the compression at 8.6:1 cuz I was planning on a turbo.

It ran very well, it was completely rebuilt, p&p'd, and balanced. Then I put an old 80's turbo on, and it detonated like crazy. The piston ring lands broke off on all 4 pistons in 3 weeks.

So I sold the turbo and decked the head enough for a 9:5:1 compression and ran like that NA for a few years.

Then i got another turbo and I detonated (at 5psi boost with up to 8psi boost creep-this is what killed me) and broke another piston. 'This one lasted 6months.

Now I'm rebuilding it now with a new head, so it will be 8.5:1 again and i'm getting rid of the boost creep so it should hold up this time Stock cast pistons still. Hey, they're $100 a set, i can't go wrong


So i think your idea sounds good. low compression 2.0 in preparation for a turbo. it will work fine.

 
Scoring disabled. You must be logged in to score posts.Respond to this message   
Patrick Bureau
(no login)
12.237.164.124

Re: similar..

No score for this post
June 20 2002, 5:23 PM 

alright, the question that comes to mind is what pistons (make/model) did you choose to lower the compression from 3a/jh 2l 10:1 to 8-9:1 ?

 
Scoring disabled. You must be logged in to score posts.Respond to this message   
 
  << Previous Topic | Next Topic >>  
Find more forums on Network54Create your own forum at Network54
 Copyright © 1999-2017 Network54. All rights reserved.   Terms of Use   Privacy Statement