ZL. 19 Posted March 10, 2014 Hey Folks Does anyone know the cc of the 3.9 and 4.0 pistons?i think by my workings out the bore is only 16thou bigger in the 4.0, the reason i need to know is my outback had a tickford head motor(91da block 92dt head) what i thought was a 4l but now that is out, i can see 3 cast on the back of the block and the sticker over the rear welsh plug says 3.9. so with a tickford head this would make it super low compression right? since 3.9 was at about 8.8 from what i can find out. so i should look for a 4.0 bottom end and use that, gain an easy 40kw? Cheers Share this post Link to post Share on other sites
ZL. 19 Posted March 11, 2014 so i took the head off a 94da 4.0 i have here and the pistons looked the same, only difference was the 94da had full counterweight crank, and the 91da had 54 stamped on each of the conrods. so i rang 13ford and they confirmed the 91 da was a 4.0 'HP'out of an EB2. so who knows why it has a 3.9 sticker on the rear welsh plug, had me goin for a while though haha. so now i dont have to look for a good 4.0 just buy some rings and a honer, mabe a set of bearings. Share this post Link to post Share on other sites
slydog 7,873 Posted March 11, 2014 Score! 1 ZL. reacted to this Share this post Link to post Share on other sites
Thom 6,651 Posted March 11, 2014 it may have the beefier conrods put of an ea if that's the case 1 ZL. reacted to this Share this post Link to post Share on other sites
