Reducing Compression for Turbo engine

Audacity Racing · Post by **Audacity Racing** » Mon Dec 26, 2005 9:32 pm

or you can use the excel i posted

come out to give you 3mm exactly to give you 8.1cr (added to a stock gasket)

Post by **PrecisionBoost** » Mon Dec 26, 2005 10:02 pm

I only added that post with the mathmatical calculations for those who might be inerested in how the numbers are generated.....

I hate the idea of simply trusting someone elses calculations without going through it myself.

Plus.... as I go through the math it helps me understand all the variables that are influencing the end results.

Audacity Racing · Post by **Audacity Racing** » Mon Dec 26, 2005 10:07 pm

i'm not shooting you down or anything, i was just pointing out that for those that do not know certain factors (such as rod length) or understand the algebra to get where you did can use a calculator like the one i posted to achieve nearly the same results.

in the end... all three sets of calculations get you to the same place (within a certain degree of accuracy)

something i was reading today on this though, is that the use of thicker headgaskets is discouraged for any higher boost engine. the fuel burn quality can be choppy with thicker gaskets (due to random shape fluctuation in the gasket), which can cause for odd turbo behavior and even post-detonation (explosion in manifold) which can be terrible for a turbo.

long and short, if you want to push more than 10psi... look into a different method of lowering your compression!

Post by **PrecisionBoost** » Tue Dec 27, 2005 4:51 pm

Here is a quick guide to spacer thickness.

To get the ideal gasket thickness simply add the gasket + spacer

Example.... factory gasket = 1.3mm and you want a 1mm spacer..... buy an MLS gasket that is 2.3mm thick when compressed.

This is meant as a "rough" estimate for compression.... it should be acurate enough to pick the right size but I'd encourage people to check the results using the spreadsheet Audacityracing gave and the calculator link I gave.

First set is the Leganza 2.2L with 9.6:1 compression
Second set is the Nubira/Forenza 2.0L with 9.6:1 compression
Third set is for the C20XE with 10.5:1 compression
Fourth set is for the Lanos 1.6L with 9.5:1 compression

Stefan · Post by **Stefan** » Wed Dec 28, 2005 2:39 pm

Here's that dxf file I created. I also added the profiles for T3 inlet and outlet flanges.

http://www.daewootech.com/users/stefan/ ... Spacer.dxf

The spacer should be 1.6mm thick stainless steel and the flanges should be at least 10mm thick.

You'll need AutoCAD to view it or another dxf viewer.

Stef

Stefan · Post by **Stefan** » Thu Dec 29, 2005 3:42 pm

Audacityracing wrote:Something i was reading today on this though, is that the use of thicker headgaskets is discouraged for any higher boost engine. the fuel burn quality can be choppy with thicker gaskets (due to random shape fluctuation in the gasket), which can cause for odd turbo behavior and even post-detonation (explosion in manifold) which can be terrible for a turbo.

long and short, if you want to push more than 10psi... look into a different method of lowering your compression!

The spacer method of lowering compression causes problems due to the combustion space becoming more knock sensitive. People have used spacers with high boost by decreasing knock sensitivity using water injection.

It's not, as you say the best approach

but it serves people well that are on a budget.

Stef

Audacity Racing · Post by **Audacity Racing** » Thu Dec 29, 2005 5:40 pm

and thanks for the dfx

Roadrunner 16V · Post by **Roadrunner 16V** » Sat Jan 14, 2006 11:50 pm

In my engine I use special pistons for the compression reduction. Whit these i come on 8,2:1

Stefan · Post by **Stefan** » Sun Jan 15, 2006 12:36 am

Those pistons are nice! So are those conrods! :twisted:
Planning for some big hp?

For other people on the board do you have the part number or job number of the pistons and the conrods? As well as the manufacturers? If you can give the info it'll help others greatly.

Stef

Roadrunner 16V · Post by **Roadrunner 16V** » Sun Jan 15, 2006 8:44 am

Yes i planing something

these pistons you can buy at www.dsop.net -->Produkte-->Motorblock and scroll down to "Kolben"

Post by **PrecisionBoost** » Sun Jan 15, 2006 9:40 pm

They have some nice stuff..... but as usual... very expensive.

We can get forged pistons over here in around the $650 USD range..... the price on that site was 999 Euro... which is about $1200 USD

dog · Post by **dog** » Wed Jan 25, 2006 8:02 pm

Erfinder@PrecisionBoost wrote:They have some nice stuff..... but as usual... very expensive.

We can get forged pistons over here in around the $650 USD range..... the price on that site was 999 Euro... which is about $1200 USD

where O where can you get forged pistons for our engine for $650. i so want to boost my car but do not want to just throw in a gasket.

Post by **PrecisionBoost** » Sun Mar 05, 2006 4:57 pm

Just noticed this additional question.....

I think it was JE Pistons that quoted me that price ..... you could get them through a distributor as well.

Debo had a group buy going for JE Pistons but nobody was interested at the time.... http://www.daewootech.com/forum/viewtopic.php?t=3274

Post by **Efratech** » Wed Mar 08, 2006 9:37 pm

getting into topic...

if i add a spacer that combined with the gasket has 1.7 mm of thickness... how much will that be?

Efrain.

Audacity Racing · Post by **Audacity Racing** » Wed Mar 08, 2006 9:39 pm

what's the gasket thickness in question?