405 Sri Flat Pistons On 1.9 Gti.

[lahondal 17]

Hi all.

 

We know 1.6 pistons on 1.9 raise the compresion to about 11:1, but, what CR will achieve with the flat top pistons of the 405 SRi?

 

I have a stock 1.9 with Dellorto 40 and Megajolt management.

 

I'm thinking on doing a 1.9 engine with:

 

-Flat Pistons.

-Catcams 298º

-3 angle valve seats (inlet and exhaust) and DIY head porting

-Dellorto 40 with 36 chokes

-Megajolt

-Lightened flywheel

-Four branch manifold and 63mm GrA exhaust system.

 

I have amost all parts...

 

How many HP you think we will get?

 

Cheers, David.

[lahondal 17]

Nobody knows the RC will have with the flat pistons?

[tony perks 1]

Nobody knows the RC will have with the flat pistons?

I have done this conversion before but the compression was only around 10.7:1 as the 405 pistons have a lower compression height, Hp very difficult to quote but I would have though you could see around the 140 mark maybe a bit more with a really good head, 40's will limit the top end a bit but it will be a nice torqie engine (sorry spelling).

[lahondal 17]

Hi! Thanks for the reply.

 

Only 10.7:1, i measured the piston height in the past and i remember its the same height in a 1.6 pistons I have, and the flat pistons. Not measured GTi piston height, so it can be possible.

 

I thought that RC will reach 12:1 or similar, but I was wrong.

 

Cheers, David.

[pug_ham 244 3 Cars]

I've got some of each afaik so I can measure the pin height hopefully.

 

Graham.

[lahondal 17]

Hi graham.

 

I will be pleased if you measure the piston height, I have some DKZ pistons so I can measure it too.

 

Cheers, David.

[pug_ham 244 3 Cars]

Ok, I'll try to get to them tomorrow evening, I know where they are after moving some stuff around at the weekend.

 

Graham.

[mollisk 2 1 Cars]

I have fitted this type of piston to a 1.6 engine.

The pistons come to within 0.25mm of the top of the liners at TDC.

With the cam that is fitted to the engine I required a CR of 12:1, which was obtained by utilising the flat top pistons and skimming the head by 0.028"